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Sánchez-Peña A, Winans JB, Nadell CD, Limoli DH. Pseudomonas aeruginosa surface motility and invasion into competing communities enhance interspecies antagonism. mBio 2024; 15:e0095624. [PMID: 39105585 PMCID: PMC11389416 DOI: 10.1128/mbio.00956-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 07/02/2024] [Indexed: 08/07/2024] Open
Abstract
Chronic polymicrobial infections involving Pseudomonas aeruginosa and Staphylococcus aureus are prevalent, difficult to eradicate, and associated with poor health outcomes. Therefore, understanding interactions between these pathogens is important to inform improved treatment development. We previously demonstrated that P. aeruginosa is attracted to S. aureus using type IV pili (TFP)-mediated chemotaxis, but the impact of attraction on S. aureus growth and physiology remained unknown. Using live single-cell confocal imaging to visualize microcolony structure, spatial organization, and survival of S. aureus during coculture, we found that interspecies chemotaxis provides P. aeruginosa a competitive advantage by promoting invasion into and disruption of S. aureus microcolonies. This behavior renders S. aureus susceptible to P. aeruginosa antimicrobials. Conversely, in the absence of TFP motility, P. aeruginosa cells exhibit reduced invasion of S. aureus colonies. Instead, P. aeruginosa builds a cellular barrier adjacent to S. aureus and secretes diffusible, bacteriostatic antimicrobials like 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) into the S. aureus colonies. Reduced invasion leads to the formation of denser and thicker S. aureus colonies with increased HQNO-mediated lactic acid fermentation, a physiological change that could complicate treatment strategies. Finally, we show that P. aeruginosa motility modifications of spatial structure enhance competition against S. aureus. Overall, these studies expand our understanding of how P. aeruginosa TFP-mediated interspecies chemotaxis facilitates polymicrobial interactions, highlighting the importance of spatial positioning in mixed-species communities. IMPORTANCE The polymicrobial nature of many chronic infections makes their eradication challenging. Particularly, coisolation of Pseudomonas aeruginosa and Staphylococcus aureus from airways of people with cystic fibrosis and chronic wound infections is common and associated with severe clinical outcomes. The complex interplay between these pathogens is not fully understood, highlighting the need for continued research to improve management of chronic infections. Our study unveils that P. aeruginosa is attracted to S. aureus, invades into neighboring colonies, and secretes anti-staphylococcal factors into the interior of the colony. Upon inhibition of P. aeruginosa motility and thus invasion, S. aureus colony architecture changes dramatically, whereby S. aureus is protected from P. aeruginosa antagonism and responds through physiological alterations that may further hamper treatment. These studies reinforce accumulating evidence that spatial structuring can dictate community resilience and reveal that motility and chemotaxis are critical drivers of interspecies competition.
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Affiliation(s)
- Andrea Sánchez-Peña
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - James B Winans
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | - Carey D Nadell
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | - Dominique H Limoli
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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2
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Power AD, Mok WWK. Agar and agarose used for Staphylococcus aureus biofilm cultivation impact fluoroquinolone tolerance. J Appl Microbiol 2024; 135:lxae191. [PMID: 39066496 DOI: 10.1093/jambio/lxae191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 07/10/2024] [Accepted: 07/25/2024] [Indexed: 07/28/2024]
Abstract
AIMS Staphylococcus aureus is an opportunistic pathogen whose treatment is further complicated by its ability to form biofilms. In this study, we examine the impact of growing S. aureus biofilms on different polymerizing surfaces, specifically agar and agarose, on the pathogen's tolerance to fluoroquinolones. METHODS AND RESULTS Biofilms of two methicillin-resistant strains of S. aureus were grown on agar or agarose in the presence of the same added nutrients, and their antibiotic susceptibility to two fluoroquinolones, moxifloxacin (MXF) and delafloxacin (DLX), were measured. We also compared the metabolism and extracellular polymeric substances (EPS) production of biofilms that were grown on agar and agarose. CONCLUSIONS Biofilms that were grown on agarose were consistently more susceptible to antibiotics than those grown on agar. We found that in biofilms that were grown on agar, extracellular protein composition was higher, and adding EPS to agarose-grown biofilms increased their tolerance to DLX to levels that were comparable to agar-grown biofilms.
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Affiliation(s)
- Angela D Power
- Department of Molecular Biology & Biophysics, UConn Health, Farmington, CT 06032, United States
| | - Wendy W K Mok
- Department of Molecular Biology & Biophysics, UConn Health, Farmington, CT 06032, United States
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3
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Conners EM, Rengasamy K, Ranaivoarisoa T, Bose A. The phototrophic purple non-sulfur bacteria Rhodomicrobium spp. are novel chassis for bioplastic production. Microb Biotechnol 2024; 17:e14552. [PMID: 39163151 PMCID: PMC11334908 DOI: 10.1111/1751-7915.14552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 07/31/2024] [Indexed: 08/22/2024] Open
Abstract
Petroleum-based plastics levy significant environmental and economic costs that can be alleviated with sustainably sourced, biodegradable, and bio-based polymers such as polyhydroxyalkanoates (PHAs). However, industrial-scale production of PHAs faces barriers stemming from insufficient product yields and high costs. To address these challenges, we must look beyond the current suite of microbes for PHA production and investigate non-model organisms with versatile metabolisms. In that vein, we assessed PHA production by the photosynthetic purple non-sulfur bacteria (PNSB) Rhodomicrobium vannielii and Rhodomicrobium udaipurense. We show that both species accumulate PHA across photo-heterotrophic, photo-hydrogenotrophic, photo-ferrotrophic, and photo-electrotrophic growth conditions, with either ammonium chloride (NH4Cl) or dinitrogen gas (N2) as nitrogen sources. Our data indicate that nitrogen source plays a significant role in dictating PHA synthesis, with N2 fixation promoting PHA production during photoheterotrophy and photoelectrotrophy but inhibiting production during photohydrogenotrophy and photoferrotrophy. We observed the highest PHA titres (up to 44.08 mg/L, or 43.61% cell dry weight) when cells were grown photoheterotrophically on sodium butyrate with N2, while production was at its lowest during photoelectrotrophy (as low as 0.04 mg/L, or 0.16% cell dry weight). We also find that photohydrogenotrophically grown cells supplemented with NH4Cl exhibit the highest electron yields - up to 58.89% - while photoheterotrophy demonstrated the lowest (0.27%-1.39%). Finally, we highlight superior electron conversion and PHA production compared to a related PNSB, Rhodopseudomonas palustris TIE-1. This study illustrates the value of studying non-model organisms like Rhodomicrobium for sustainable PHA production and indicates future directions for exploring PNSB metabolisms.
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Affiliation(s)
- Eric M. Conners
- Department of BiologyWashington University in St. LouisSt. LouisMissouriUSA
| | | | | | - Arpita Bose
- Department of BiologyWashington University in St. LouisSt. LouisMissouriUSA
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4
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Korshoj LE, Kielian T. Bacterial single-cell RNA sequencing captures biofilm transcriptional heterogeneity and differential responses to immune pressure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.28.601229. [PMID: 38979200 PMCID: PMC11230364 DOI: 10.1101/2024.06.28.601229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Biofilm formation is an important mechanism of survival and persistence for many bacterial pathogens. These multicellular communities contain subpopulations of cells that display vast metabolic and transcriptional diversity along with high recalcitrance to antibiotics and host immune defenses. Investigating the complex heterogeneity within biofilm has been hindered by the lack of a sensitive and high-throughput method to assess stochastic transcriptional activity and regulation between bacterial subpopulations, which requires single-cell resolution. We have developed an optimized bacterial single-cell RNA sequencing method, BaSSSh-seq, to study Staphylococcus aureus diversity during biofilm growth and transcriptional adaptations following immune cell exposure. We validated the ability of BaSSSh-seq to capture extensive transcriptional heterogeneity during biofilm compared to planktonic growth. Application of new computational tools revealed transcriptional regulatory networks across the heterogeneous biofilm subpopulations and identification of gene sets that were associated with a trajectory from planktonic to biofilm growth. BaSSSh-seq also detected alterations in biofilm metabolism, stress response, and virulence that were tailored to distinct immune cell populations. This work provides an innovative platform to explore biofilm dynamics at single-cell resolution, unlocking the potential for identifying biofilm adaptations to environmental signals and immune pressure.
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5
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Bowden LC, Finlinson J, Jones B, Berges BK. Beyond the double helix: the multifaceted landscape of extracellular DNA in Staphylococcus aureus biofilms. Front Cell Infect Microbiol 2024; 14:1400648. [PMID: 38903938 PMCID: PMC11188362 DOI: 10.3389/fcimb.2024.1400648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 05/17/2024] [Indexed: 06/22/2024] Open
Abstract
Staphylococcus aureus forms biofilms consisting of cells embedded in a matrix made of proteins, polysaccharides, lipids, and extracellular DNA (eDNA). Biofilm-associated infections are difficult to treat and can promote antibiotic resistance, resulting in negative healthcare outcomes. eDNA within the matrix contributes to the stability, growth, and immune-evasive properties of S. aureus biofilms. eDNA is released by autolysis, which is mediated by murein hydrolases that access the cell wall via membrane pores formed by holin-like proteins. The eDNA content of S. aureus biofilms varies among individual strains and is influenced by environmental conditions, including the presence of antibiotics. eDNA plays an important role in biofilm development and structure by acting as an electrostatic net that facilitates protein-cell and cell-cell interactions. Because of eDNA's structural importance in biofilms and its ubiquitous presence among S. aureus isolates, it is a potential target for therapeutics. Treatment of biofilms with DNase can eradicate or drastically reduce them in size. Additionally, antibodies that target DNABII proteins, which bind to and stabilize eDNA, can also disperse biofilms. This review discusses the recent literature on the release, structure, and function of eDNA in S. aureus biofilms, in addition to a discussion of potential avenues for targeting eDNA for biofilm eradication.
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Affiliation(s)
| | | | | | - Bradford K. Berges
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States
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6
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Sánchez-Peña A, Winans JB, Nadell CD, Limoli DH. Pseudomonas aeruginosa surface motility and invasion into competing communities enhances interspecies antagonism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.03.588010. [PMID: 38617332 PMCID: PMC11014535 DOI: 10.1101/2024.04.03.588010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Chronic polymicrobial infections involving Pseudomonas aeruginosa and Staphylococcus aureus are prevalent, difficult to eradicate, and associated with poor health outcomes. Therefore, understanding interactions between these pathogens is important to inform improved treatment development. We previously demonstrated that P. aeruginosa is attracted to S. aureus using type IV pili-mediated chemotaxis, but the impact of attraction on S. aureus growth and physiology remained unknown. Using live single-cell confocal imaging to visualize microcolony structure, spatial organization, and survival of S. aureus during coculture, we found that interspecies chemotaxis provides P. aeruginosa a competitive advantage by promoting invasion into and disruption of S. aureus microcolonies. This behavior renders S. aureus susceptible to P. aeruginosa antimicrobials. Conversely, in the absence of type IV pilus motility, P. aeruginosa cells exhibit reduced invasion of S. aureus colonies. Instead, P. aeruginosa builds a cellular barrier adjacent to S. aureus and secretes diffusible, bacteriostatic antimicrobials like 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) into the S. aureus colonies. P. aeruginosa reduced invasion leads to the formation of denser and thicker S. aureus colonies with significantly increased HQNO-mediated lactic acid fermentation, a physiological change that could complicate the effective treatment of infections. Finally, we show that P. aeruginosa motility modifications of spatial structure enhance competition against S. aureus. Overall, these studies build on our understanding of how P. aeruginosa type IV pili-mediated interspecies chemotaxis mediates polymicrobial interactions, highlighting the importance of spatial positioning in mixed-species communities.
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Affiliation(s)
- Andrea Sánchez-Peña
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - James B Winans
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | - Carey D Nadell
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | - Dominique H Limoli
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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7
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Aboelnaga N, Elsayed SW, Abdelsalam NA, Salem S, Saif NA, Elsayed M, Ayman S, Nasr M, Elhadidy M. Deciphering the dynamics of methicillin-resistant Staphylococcus aureus biofilm formation: from molecular signaling to nanotherapeutic advances. Cell Commun Signal 2024; 22:188. [PMID: 38519959 PMCID: PMC10958940 DOI: 10.1186/s12964-024-01511-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 02/01/2024] [Indexed: 03/25/2024] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) represents a global threat, necessitating the development of effective solutions to combat this emerging superbug. In response to selective pressures within healthcare, community, and livestock settings, MRSA has evolved increased biofilm formation as a multifaceted virulence and defensive mechanism, enabling the bacterium to thrive in harsh conditions. This review discusses the molecular mechanisms contributing to biofilm formation across its developmental stages, hence representing a step forward in developing promising strategies for impeding or eradicating biofilms. During staphylococcal biofilm development, cell wall-anchored proteins attach bacterial cells to biotic or abiotic surfaces; extracellular polymeric substances build scaffolds for biofilm formation; the cidABC operon controls cell lysis within the biofilm, and proteases facilitate dispersal. Beside the three main sequential stages of biofilm formation (attachment, maturation, and dispersal), this review unveils two unique developmental stages in the biofilm formation process for MRSA; multiplication and exodus. We also highlighted the quorum sensing as a cell-to-cell communication process, allowing distant bacterial cells to adapt to the conditions surrounding the bacterial biofilm. In S. aureus, the quorum sensing process is mediated by autoinducing peptides (AIPs) as signaling molecules, with the accessory gene regulator system playing a pivotal role in orchestrating the production of AIPs and various virulence factors. Several quorum inhibitors showed promising anti-virulence and antibiofilm effects that vary in type and function according to the targeted molecule. Disrupting the biofilm architecture and eradicating sessile bacterial cells are crucial steps to prevent colonization on other surfaces or organs. In this context, nanoparticles emerge as efficient carriers for delivering antimicrobial and antibiofilm agents throughout the biofilm architecture. Although metal-based nanoparticles have been previously used in combatting biofilms, its non-degradability and toxicity within the human body presents a real challenge. Therefore, organic nanoparticles in conjunction with quorum inhibitors have been proposed as a promising strategy against biofilms. As nanotherapeutics continue to gain recognition as an antibiofilm strategy, the development of more antibiofilm nanotherapeutics could offer a promising solution to combat biofilm-mediated resistance.
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Affiliation(s)
- Nirmeen Aboelnaga
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt
- Biomedical Sciences Program, University of Science and Technology, Zewail City of Science and Technology, Giza, Egypt
| | - Salma W Elsayed
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt
- Biomedical Sciences Program, University of Science and Technology, Zewail City of Science and Technology, Giza, Egypt
- Department of Microbiology & Immunology, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt
| | - Nehal Adel Abdelsalam
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt
- Biomedical Sciences Program, University of Science and Technology, Zewail City of Science and Technology, Giza, Egypt
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Salma Salem
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt
- Biomedical Sciences Program, University of Science and Technology, Zewail City of Science and Technology, Giza, Egypt
| | - Nehal A Saif
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt
- Biomedical Sciences Program, University of Science and Technology, Zewail City of Science and Technology, Giza, Egypt
| | - Manar Elsayed
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt
- Biomedical Sciences Program, University of Science and Technology, Zewail City of Science and Technology, Giza, Egypt
| | - Shehab Ayman
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt
- Biomedical Sciences Program, University of Science and Technology, Zewail City of Science and Technology, Giza, Egypt
| | - Maha Nasr
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt
| | - Mohamed Elhadidy
- Center for Genomics, Helmy Institute for Medical Sciences, Zewail City of Science and Technology, Giza, Egypt.
- Biomedical Sciences Program, University of Science and Technology, Zewail City of Science and Technology, Giza, Egypt.
- Department of Bacteriology, Mycology and Immunology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, Egypt.
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8
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An NV, Hai LHL, Luong VH, Vinh NTH, Hoa PQ, Hung LV, Son NT, Hong LT, Hung DV, Kien HT, Le MN, Viet NH, Nguyen DH, Pham NV, Thang TB, Tien TV, Hoang LH. Antimicrobial Resistance Patterns of Staphylococcus Aureus Isolated at a General Hospital in Vietnam Between 2014 and 2021. Infect Drug Resist 2024; 17:259-273. [PMID: 38283112 PMCID: PMC10822110 DOI: 10.2147/idr.s437920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 01/11/2024] [Indexed: 01/30/2024] Open
Abstract
Purpose Staphylococcus aureus is a commensal bacteria species that can cause various illnesses, from mild skin infections to severe diseases, such as bacteremia. The distribution and antimicrobial resistance (AMR) pattern of S. aureus varies by population, time, geographic location, and hospital wards. In this study, we elucidated the epidemiology and AMR patterns of S. aureus isolated from a general hospital in Vietnam. Methods This was a cross-sectional study. Data on all S. aureus infections from 2014 to 2021 were collected from the Microbiology department of Military Hospital 103, Vietnam. Only the first isolation from each kind of specimen from a particular patient was analyzed using the Cochran-Armitage and chi-square tests. Results A total of 1130 individuals were diagnosed as S. aureus infection. Among them, 1087 strains were tested for AMR features. Most patients with S. aureus infection were in the age group of 41-65 years (39.82%). S. aureus isolates were predominant in the surgery wards, and pus specimens were the most common source of isolates (50.62%). S. aureus was most resistant to azithromycin (82.28%), erythromycin (82.82%), and clindamycin (82.32%) and least resistant to teicoplanin (0.0%), tigecycline (0.16%), quinupristin-dalfopristin (0.43%), linezolid (0.62%), and vancomycin (2.92%). Methicillin-resistant S. aureus (MRSA) and multidrug-resistant (MDR) S. aureus were prevalent, accounting for 73.02% and 60.90% of the total strains respectively, and the strains isolated from the intensive care unit (ICU) had the highest percentage of multidrug resistance (77.78%) among the wards. Conclusion These findings highlight the urgent need for continuous AMR surveillance and updated treatment guidelines, particularly considering high resistance in MRSA, MDR strains, and ICU isolates. Future research focusing on specific resistant populations and potential intervention strategies is crucial to combat this rising threat.
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Affiliation(s)
- Nguyen Van An
- Department of Microbiology, Military Hospital 103, Vietnam Military Medical University, Hanoi, Vietnam
| | - Le Ha long Hai
- Department of Clinical Microbiology and Parasitology, Faculty of Medical Technology, Hanoi Medical University, Hanoi, Vietnam
- Department of Biochemistry, Hematology and Immunology, National Hospital of Dermatology and Venereology, Hanoi, Vietnam
| | - Vu Huy Luong
- Department of Laser and Skin Care, National hospital of Dermatology and Venereology, Hanoi, Vietnam
- Department of Dermatology and Venereology, Hanoi Medical University, Hanoi, Vietnam
| | - Nguyen Thi Ha Vinh
- Department of Dermatology and Venereology, Hanoi Medical University, Hanoi, Vietnam
- Department of General Planning, National hospital of Dermatology and Venereology, Hanoi, Vietnam
| | - Pham Quynh Hoa
- Department of Microbiology, Mycology and Parasitology, National hospital of Dermatology and Venereology, Hanoi, Vietnam
| | - Le Van Hung
- Department of Dermatology and Venereology, Hanoi Medical University, Hanoi, Vietnam
- Department of Microbiology, Mycology and Parasitology, National hospital of Dermatology and Venereology, Hanoi, Vietnam
| | - Nguyen Thai Son
- Department of Microbiology, Military Hospital 103, Vietnam Military Medical University, Hanoi, Vietnam
| | - Le Thu Hong
- Department of Microbiology, Military Hospital 103, Vietnam Military Medical University, Hanoi, Vietnam
| | - Dinh Viet Hung
- Department of Psychiatry, Military Medical 103, Vietnam Military Medical University, Hanoi, Vietnam
| | - Hoang Trung Kien
- Department of Immunology, Vietnam Military Medical University, Hanoi, Vietnam
| | - Minh Nhat Le
- Tay Nguyen Institute of Science Research, Vietnam Academy of Science and Technology, VAST, Hanoi, Vietnam
- Antimicrobial Resistance Research Center, National Institute of Infectious Disease, Tokyo, Japan
| | - Nguyen Hoang Viet
- Molecular Pathology Department, Faculty of Medical Technology, Hanoi Medical University, Hanoi, Vietnam
| | - Duc Hoang Nguyen
- Cardiovascular Laboratories, Methodist Hospital, Merrillville, Indiana, USA
| | - Ngai Van Pham
- Medical Testing Center, Medlatec Group, Hanoi, Vietnam
| | - Ta Ba Thang
- Respiratory Center, Military Hospital 103, Vietnam Military Medical University, Hanoi, Vietnam
| | - Tran Viet Tien
- Department of Infectious diseases, Military Hospital 103, Vietnam Medical Military University, Hanoi, Vietnam
| | - Le Huy Hoang
- Department of Bacteriology, National of Hygiene and Epidemiology, Hanoi, Vietnam
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9
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Francis D, Veeramanickathadathil Hari G, Koonthanmala Subash A, Bhairaddy A, Joy A. The biofilm proteome of Staphylococcus aureus and its implications for therapeutic interventions to biofilm-associated infections. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 138:327-400. [PMID: 38220430 DOI: 10.1016/bs.apcsb.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2024]
Abstract
Staphylococcus aureus is a major healthcare concern due to its ability to inflict life-threatening infections and evolve antibiotic resistance at an alarming pace. It is frequently associated with hospital-acquired infections, especially device-associated infections. Systemic infections due to S. aureus are difficult to treat and are associated with significant mortality and morbidity. The situation is worsened by the ability of S. aureus to form social associations called biofilms. Biofilms embed a community of cells with the ability to communicate with each other and share resources within a polysaccharide or protein matrix. S. aureus establish biofilms on tissues and conditioned abiotic surfaces. Biofilms are hyper-tolerant to antibiotics and help evade host immune responses. Biofilms exacerbate the severity and recalcitrance of device-associated infections. The development of a biofilm involves various biomolecules, such as polysaccharides, proteins and nucleic acids, contributing to different structural and functional roles. Interconnected signaling pathways and regulatory molecules modulate the expression of these molecules. A comprehensive understanding of the molecular biology of biofilm development would help to devise effective anti-biofilm therapeutics. Although bactericidal agents, antimicrobial peptides, bacteriophages and nano-conjugated anti-biofilm agents have been employed with varying levels of success, there is still a requirement for effective and clinically viable anti-biofilm therapeutics. Proteins that are expressed and utilized during biofilm formation, constituting the biofilm proteome, are a particularly attractive target for anti-biofilm strategies. The proteome can be explored to identify potential anti-biofilm drug targets and utilized for rational drug discovery. With the aim of uncovering the biofilm proteome, this chapter explores the mechanism of biofilm formation and its regulation. Furthermore, it explores the antibiofilm therapeutics targeted against the biofilm proteome.
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Affiliation(s)
- Dileep Francis
- Department of Life Sciences, Kristu Jayanti College (Autonomous), Bengaluru, India.
| | | | | | - Anusha Bhairaddy
- Department of Life Sciences, Kristu Jayanti College (Autonomous), Bengaluru, India
| | - Atheene Joy
- Department of Life Sciences, Kristu Jayanti College (Autonomous), Bengaluru, India
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10
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Enriquez KT, Plummer WD, Neufer PD, Chazin WJ, Dupont WD, Skaar EP. Temporal modelling of the biofilm lifecycle (TMBL) establishes kinetic analysis of plate-based bacterial biofilm dynamics. J Microbiol Methods 2023; 212:106808. [PMID: 37595876 PMCID: PMC10528067 DOI: 10.1016/j.mimet.2023.106808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/12/2023] [Accepted: 08/12/2023] [Indexed: 08/20/2023]
Abstract
Bacterial biofilms are critical to pathogenesis and infection. They are associated with rising rates of antimicrobial resistance. Biofilms are correlated with worse clinical outcomes, making them important to infectious diseases research. There is a gap in knowledge surrounding biofilm kinetics and dynamics which makes biofilm research difficult to translate from bench to bedside. To address this gap, this work employs a well-characterized crystal violet biomass accrual and planktonic cell density assay across a clinically relevant time course and expands statistical analysis to include kinetic information in a protocol termed the TMBL (Temporal Mapping of the Biofilm Lifecycle) assay. TMBL's statistical framework quantitatively compares biofilm communities across time, species, and media conditions in a 96-well format. Measurements from TMBL can reliably be condensed into response features that inform the time-dependent behavior of adherent biomass and planktonic cell populations. Staphylococcus aureus and Pseudomonas aeruginosa biofilms were grown in conditions of metal starvation in nutrient-variable media to demonstrate the rigor and translational potential of this strategy. Significant differences in single-species biofilm formation are seen in metal-deplete conditions as compared to their controls which is consistent with the consensus literature on nutritional immunity that metal availability drives transcriptomic and metabolomic changes in numerous pathogens. Taken together, these results suggest that kinetic analysis of biofilm by TMBL represents a statistically and biologically rigorous approach to studying the biofilm lifecycle as a time-dependent process. In addition to current methods to study the impact of microbe and environmental factors on the biofilm lifecycle, this kinetic assay can inform biological discovery in biofilm formation and maintenance.
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Affiliation(s)
- Kyle T Enriquez
- Vanderbilt University Medical Scientist Training Program, Vanderbilt University School of Medicine, Nashville, TN, United States of America; Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN, United States of America; Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - W Dale Plummer
- Department of Biostatistics, Vanderbilt University, Nashville, TN, United States of America
| | - Preston D Neufer
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States of America; Department of Biochemistry, Vanderbilt University, Nashville, TN, United States of America
| | - Walter J Chazin
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, United States of America; Department of Chemistry, Vanderbilt University, Nashville, TN, United States of America; Department of Biochemistry, Vanderbilt University, Nashville, TN, United States of America
| | - William D Dupont
- Department of Biostatistics, Vanderbilt University, Nashville, TN, United States of America
| | - Eric P Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN, United States of America; Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, United States of America.
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11
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Tran NN, Morrisette T, Jorgensen SCJ, Orench-Benvenutti JM, Kebriaei R. Current therapies and challenges for the treatment of Staphylococcus aureus biofilm-related infections. Pharmacotherapy 2023; 43:816-832. [PMID: 37133439 DOI: 10.1002/phar.2806] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 03/10/2023] [Accepted: 03/16/2023] [Indexed: 05/04/2023]
Abstract
Staphylococcus aureus is a major cause of nosocomial and community-acquired infections and contributes to significant increase in morbidity and mortality especially when associated with medical devices and in biofilm form. Biofilm structure provides a pathway for the enrichment of resistant and persistent phenotypes of S. aureus leading to relapse and recurrence of infection. Minimal diffusion of antibiotics inside biofilm structure leads to heterogeneity and distinct physiological activity. Additionally, horizontal gene transfer between cells in proximity adds to the challenges associated with eradication of biofilms. This narrative review focuses on biofilm-associated infections caused by S. aureus, the impact of environmental conditions on biofilm formation, interactions inside biofilm communities, and the clinical challenges that they present. Conclusively, potential solutions, novel treatment strategies, combination therapies, and reported alternatives are discussed.
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Affiliation(s)
- Nikki N Tran
- Department of Pharmacy, The Ohio State University Wexner Medical Center - The James Cancer Hospital and Solove Research Institute, Columbus, Ohio, USA
| | - Taylor Morrisette
- Department of Clinical Pharmacy and Outcomes Sciences, Medical University of South Carolina College of Pharmacy, Charleston, South Carolina, USA
- Department of Pharmacy Services, Medical University of South Carolina Shawn Jenkins Children's Hospital, Charleston, South Carolina, USA
| | - Sarah C J Jorgensen
- Institute of Medical Science, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - José M Orench-Benvenutti
- P3 Research Laboratory, Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
| | - Razieh Kebriaei
- P3 Research Laboratory, Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, Ohio, USA
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12
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Mironova AV, Karimova AV, Bogachev MI, Kayumov AR, Trizna EY. Alterations in Antibiotic Susceptibility of Staphylococcus aureus and Klebsiella pneumoniae in Dual Species Biofilms. Int J Mol Sci 2023; 24:ijms24108475. [PMID: 37239822 DOI: 10.3390/ijms24108475] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 05/04/2023] [Accepted: 05/05/2023] [Indexed: 05/28/2023] Open
Abstract
In the last decades, it has been shown that biofilm-associated infections in most cases are caused by rather two or even more pathogens than by single microorganisms. Due to intermicrobial interactions in mixed communities, bacteria change their gene expression profile, in turn leading to alterations in the biofilm structure and properties, as well as susceptibility to antimicrobials. Here, we report the alterations of antimicrobials efficiency in mixed biofilms of Staphylococcus aureus-Klebsiella pneumoniae in comparison with mono-species biofilms of each counterpart and discuss possible mechanisms of these alterations. In cell clumps detached from dual-species biofilms, S. aureus became insensitive to vancomycin, ampicillin, and ceftazidime compared to solely S. aureus cell clumps. In turn, the increased efficiency of amikacin and ciprofloxacin against both bacteria could be observed, compared to mono-species biofilms of each counterpart. Scanning electron microscopy and confocal microscopy indicate the porous structure of the dual-species biofilm, and differential fluorescent staining revealed an increased number of polysaccharides in the matrix, in turn leading to more loose structure and thus apparently providing increased permeability of the dual-species biofilm to antimicrobials. The qRT-PCR showed that ica operon in S. aureus became repressed in mixed communities, and polysaccharides are produced mainly by K. pneumoniae. While the molecular trigger of these changes remains undiscovered, detailed knowledge of the alterations in antibiotic susceptibility to given drugs opens doors for treatment correction options for S. aureus-K. pneumoniae biofilm-associated infections.
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Affiliation(s)
- Anna V Mironova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Agniya V Karimova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Mikhail I Bogachev
- Biomedical Engineering Research Centre, St. Petersburg Electrotechnical University, 197022 St. Petersburg, Russia
| | - Airat R Kayumov
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Elena Y Trizna
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
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13
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Peng Q, Tang X, Dong W, Sun N, Yuan W. A Review of Biofilm Formation of Staphylococcus aureus and Its Regulation Mechanism. Antibiotics (Basel) 2022; 12:antibiotics12010012. [PMID: 36671212 PMCID: PMC9854888 DOI: 10.3390/antibiotics12010012] [Citation(s) in RCA: 50] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 11/23/2022] [Accepted: 11/25/2022] [Indexed: 12/24/2022] Open
Abstract
Bacteria can form biofilms in natural and clinical environments on both biotic and abiotic surfaces. The bacterial aggregates embedded in biofilms are formed by their own produced extracellular matrix. Staphylococcus aureus (S. aureus) is one of the most common pathogens of biofilm infections. The formation of biofilm can protect bacteria from being attacked by the host immune system and antibiotics and thus bacteria can be persistent against external challenges. Therefore, clinical treatments for biofilm infections are currently encountering difficulty. To address this critical challenge, a new and effective treatment method needs to be developed. A comprehensive understanding of bacterial biofilm formation and regulation mechanisms may provide meaningful insights against antibiotic resistance due to bacterial biofilms. In this review, we discuss an overview of S. aureus biofilms including the formation process, structural and functional properties of biofilm matrix, and the mechanism regulating biofilm formation.
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Affiliation(s)
- Qi Peng
- Guangzhou Key Laboratory for Clinical Rapid Diagnosis and Early Warning of Infectious Diseases, KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou 510180, China
| | - Xiaohua Tang
- Guangzhou Key Laboratory for Clinical Rapid Diagnosis and Early Warning of Infectious Diseases, KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou 510180, China
| | - Wanyang Dong
- Guangzhou Key Laboratory for Clinical Rapid Diagnosis and Early Warning of Infectious Diseases, KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou 510180, China
| | - Ning Sun
- Guangzhou First People’s Hospital, School of Medicine, South China University of Technology, Guangzhou 510180, China
- Correspondence: (N.S.); (W.Y.)
| | - Wenchang Yuan
- Guangzhou Key Laboratory for Clinical Rapid Diagnosis and Early Warning of Infectious Diseases, KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou 510180, China
- Correspondence: (N.S.); (W.Y.)
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14
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Abeysekera GS, Love MJ, Manners SH, Billington C, Dobson RCJ. Bacteriophage-encoded lethal membrane disruptors: Advances in understanding and potential applications. Front Microbiol 2022; 13:1044143. [PMID: 36345304 PMCID: PMC9636201 DOI: 10.3389/fmicb.2022.1044143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 10/10/2022] [Indexed: 09/09/2023] Open
Abstract
Holins and spanins are bacteriophage-encoded membrane proteins that control bacterial cell lysis in the final stage of the bacteriophage reproductive cycle. Due to their efficient mechanisms for lethal membrane disruption, these proteins are gaining interest in many fields, including the medical, food, biotechnological, and pharmaceutical fields. However, investigating these lethal proteins is challenging due to their toxicity in bacterial expression systems and the resultant low protein yields have hindered their analysis compared to other cell lytic proteins. Therefore, the structural and dynamic properties of holins and spanins in their native environment are not well-understood. In this article we describe recent advances in the classification, purification, and analysis of holin and spanin proteins, which are beginning to overcome the technical barriers to understanding these lethal membrane disrupting proteins, and through this, unlock many potential biotechnological applications.
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Affiliation(s)
- Gayan S. Abeysekera
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Michael J. Love
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
- Health and Environment Group, Institute of Environmental Science and Research, Christchurch, New Zealand
| | - Sarah H. Manners
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Craig Billington
- Health and Environment Group, Institute of Environmental Science and Research, Christchurch, New Zealand
| | - Renwick C. J. Dobson
- Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
- Department of Biochemistry and Molecular Biology, University of Melbourne, Melbourne, VIC, Australia
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15
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Interplay of CodY and CcpA in Regulating Central Metabolism and Biofilm Formation in Staphylococcus aureus. J Bacteriol 2022; 204:e0061721. [PMID: 35735992 PMCID: PMC9295537 DOI: 10.1128/jb.00617-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Staphylococcus aureus is a medically important pathogen with high metabolic versatility allowing it to infect various niches within a host. S. aureus utilizes two major transcriptional regulators, namely, CodY and CcpA, to remodel metabolic and virulence gene expression in response to changing environmental conditions. Previous studies revealed that inactivation of either codY or ccpA has a pronounced impact on different aspects of staphylococcal physiology and pathogenesis. To determine the contribution and interplay of these two regulators in modulating central metabolism, virulence, and biofilm development, we constructed and characterized the codY ccpA double mutant in S. aureus UAMS-1. In line with previous studies, we found that CcpA and CodY control the cellular metabolic status by altering carbon flux through the central and overflow metabolic pathways. Our results demonstrate that ccpA inactivation impairs biofilm formation and decreases incorporation of extracellular DNA (eDNA) into the biofilm matrix, whereas disrupting codY resulted in a robust structured biofilm tethered together with eDNA and polysaccharide intercellular adhesin (PIA). Interestingly, inactivation of both codY and ccpA decreases biofilm biomass and reduces eDNA release in the double mutant. Compared with the inactivation of codY, the codY ccpA mutant did not overexpress toxins but maintained overexpression of amino acid metabolism pathways. Furthermore, the codY ccpA mutant produced large amounts of PIA, in contrast to the wild-type strain and ccpA mutant. Combined, the results of this study suggest that the coordinated action of CodY and CcpA modulate central metabolism, virulence gene expression, and biofilm-associated genes to optimize growth on preferred carbon sources until starvation sets in. IMPORTANCE Staphylococcus aureus is a leading cause of biofilm-associated infections, including infective endocarditis, worldwide. A greater understanding of metabolic forces driving biofilm formation in S. aureus is essential for the identification of novel therapeutic targets and for the development of new strategies to combat this medically important pathogen. This study characterizes the interplay and regulation of central metabolism and biofilm development by two global transcriptional regulators, CodY and CcpA. We found that the lack of CcpA and/or CodY have different impacts on intracellular metabolic status leading to a formation of morphologically altered biofilms. Overall, the results of this study provide new insights into our understanding of metabolism-mediated regulation of biofilm development in S. aureus.
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16
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Stewart PS, Williamson KS, Boegli L, Hamerly T, White B, Scott L, Hu X, Mumey BM, Franklin MJ, Bothner B, Vital-Lopez FG, Wallqvist A, James GA. Search for a Shared Genetic or Biochemical Basis for Biofilm Tolerance to Antibiotics across Bacterial Species. Antimicrob Agents Chemother 2022; 66:e0002122. [PMID: 35266829 PMCID: PMC9017379 DOI: 10.1128/aac.00021-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 01/29/2022] [Indexed: 12/19/2022] Open
Abstract
Is there a universal genetically programmed defense providing tolerance to antibiotics when bacteria grow as biofilms? A comparison between biofilms of three different bacterial species by transcriptomic and metabolomic approaches uncovered no evidence of one. Single-species biofilms of three bacterial species (Pseudomonas aeruginosa, Staphylococcus aureus, and Acinetobacter baumannii) were grown in vitro for 3 days and then challenged with respective antibiotics (ciprofloxacin, daptomycin, and tigecycline) for an additional 24 h. All three microorganisms displayed reduced susceptibility in biofilms compared to planktonic cultures. Global transcriptomic profiling of gene expression comparing biofilm to planktonic and antibiotic-treated biofilm to untreated biofilm was performed. Extracellular metabolites were measured to characterize the utilization of carbon sources between biofilms, treated biofilms, and planktonic cells. While all three bacteria exhibited a species-specific signature of stationary phase, no conserved gene, gene set, or common functional pathway could be identified that changed consistently across the three microorganisms. Across the three species, glucose consumption was increased in biofilms compared to planktonic cells, and alanine and aspartic acid utilization were decreased in biofilms compared to planktonic cells. The reasons for these changes were not readily apparent in the transcriptomes. No common shift in the utilization pattern of carbon sources was discerned when comparing untreated to antibiotic-exposed biofilms. Overall, our measurements do not support the existence of a common genetic or biochemical basis for biofilm tolerance against antibiotics. Rather, there are likely myriad genes, proteins, and metabolic pathways that influence the physiological state of individual microorganisms in biofilms and contribute to antibiotic tolerance.
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Affiliation(s)
- Philip S. Stewart
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, Montana, USA
| | - Kerry S. Williamson
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, Montana, USA
| | - Laura Boegli
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
| | - Timothy Hamerly
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Ben White
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, Montana, USA
| | - Liam Scott
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Xiao Hu
- Gianforte School of Computing, Montana State University, Bozeman, Montana, USA
| | - Brendan M. Mumey
- Gianforte School of Computing, Montana State University, Bozeman, Montana, USA
| | - Michael J. Franklin
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, Montana, USA
| | - Brian Bothner
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA
| | - Francisco G. Vital-Lopez
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Development Command, Fort Detrick, Maryland, USA
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, Maryland, USA
| | - Anders Wallqvist
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, U.S. Army Medical Research and Development Command, Fort Detrick, Maryland, USA
| | - Garth A. James
- Center for Biofilm Engineering, Montana State University, Bozeman, Montana, USA
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17
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Conners EM, Rengasamy K, Bose A. "Electroactive biofilms: how microbial electron transfer enables bioelectrochemical applications". J Ind Microbiol Biotechnol 2022; 49:6563884. [PMID: 35381088 PMCID: PMC9338886 DOI: 10.1093/jimb/kuac012] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 03/30/2022] [Indexed: 11/22/2022]
Abstract
Microbial biofilms are ubiquitous. In marine and freshwater ecosystems, microbe–mineral interactions sustain biogeochemical cycles, while biofilms found on plants and animals can range from pathogens to commensals. Moreover, biofouling and biocorrosion represent significant challenges to industry. Bioprocessing is an opportunity to take advantage of biofilms and harness their utility as a chassis for biocommodity production. Electrochemical bioreactors have numerous potential applications, including wastewater treatment and commodity production. The literature examining these applications has demonstrated that the cell–surface interface is vital to facilitating these processes. Therefore, it is necessary to understand the state of knowledge regarding biofilms’ role in bioprocessing. This mini-review discusses bacterial biofilm formation, cell–surface redox interactions, and the role of microbial electron transfer in bioprocesses. It also highlights some current goals and challenges with respect to microbe-mediated bioprocessing and future perspectives.
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Affiliation(s)
- Eric M Conners
- Department of Biology. One Brookings Drive, Washington University in St. Louis, Missouri, 63105, USA
| | - Karthikeyan Rengasamy
- Department of Biology. One Brookings Drive, Washington University in St. Louis, Missouri, 63105, USA
| | - Arpita Bose
- Department of Biology. One Brookings Drive, Washington University in St. Louis, Missouri, 63105, USA
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18
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Biofilm Formation by Pathogenic Bacteria: Applying a Staphylococcus aureus Model to Appraise Potential Targets for Therapeutic Intervention. Pathogens 2022; 11:pathogens11040388. [PMID: 35456063 PMCID: PMC9027693 DOI: 10.3390/pathogens11040388] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Revised: 03/17/2022] [Accepted: 03/21/2022] [Indexed: 01/02/2023] Open
Abstract
Carried in the nasal passages by up to 30% of humans, Staphylococcus aureus is recognized to be a successful opportunistic pathogen. It is a frequent cause of infections of the upper respiratory tract, including sinusitis, and of the skin, typically abscesses, as well as of food poisoning and medical device contamination. The antimicrobial resistance of such, often chronic, health conditions is underpinned by the unique structure of bacterial biofilm, which is the focus of increasing research to try to overcome this serious public health challenge. Due to the protective barrier of an exopolysaccharide matrix, bacteria that are embedded within biofilm are highly resistant both to an infected individual’s immune response and to any treating antibiotics. An in-depth appraisal of the stepwise progression of biofilm formation by S. aureus, used as a model infection for all cases of bacterial antibiotic resistance, has enhanced understanding of this complicated microscopic structure and served to highlight possible intervention targets for both patient cure and community infection control. While antibiotic therapy offers a practical means of treatment and prevention, the most favorable results are achieved in combination with other methods. This review provides an overview of S. aureus biofilm development, outlines the current range of anti-biofilm agents that are used against each stage and summarizes their relative merits.
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19
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Protein-conjugated microbubbles for the selective targeting of S. aureus biofilms. Biofilm 2022; 4:100074. [PMID: 35340817 PMCID: PMC8942837 DOI: 10.1016/j.bioflm.2022.100074] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 03/01/2022] [Accepted: 03/06/2022] [Indexed: 02/07/2023] Open
Abstract
Staphylococcus aureus (S. aureus) is an important human pathogen and a common cause of bloodstream infection. The ability of S. aureus to form biofilms, particularly on medical devices, makes treatment difficult, as does its tendency to spread within the body and cause secondary foci of infection. Prolonged courses of intravenous antimicrobial treatment are usually required for serious S. aureus infections. This work investigates the in vitro attachment of microbubbles to S. aureus biofilms via a novel Affimer protein, AClfA1, which targets the clumping factor A (ClfA) virulence factor – a cell-wall anchored protein associated with surface attachment. Microbubbles (MBs) are micron-sized gas-filled bubbles encapsulated by a lipid, polymer, or protein monolayer or other surfactant-based material. Affimers are small (∼12 kDa) heat-stable binding proteins developed as replacements for antibodies. The binding kinetics of AClfA1 against S. aureus ClfA showed strong binding affinity (KD = 62 ± 3 nM). AClfA1 was then shown to bind S. aureus biofilms under flow conditions both as a free ligand and when bound to microparticles (polymer beads or microbubbles). Microbubbles functionalized with AClfA1 demonstrated an 8-fold increase in binding compared to microbubbles functionalized with an identical Affimer scaffold but lacking the recognition groups. Bound MBs were able to withstand flow rates of 250 μL/min. Finally, ultrasound was applied to burst the biofilm bound MBs to determine whether this would lead to biofilm biomass loss or cell death. Application of a 2.25 MHz ultrasound profile (with a peak negative pressure of 0.8 MPa and consisting of a 22-cycle sine wave, at a pulse repetition rate of 10 kHz) for 2 s to a biofilm decorated with targeted MBs, led to a 25% increase in biomass loss and a concomitant 8% increase in dead cell count. The results of this work show that Affimers can be developed to target S. aureus biofilms and that such Affimers can be attached to contrast agents such as microbubbles or polymer beads and offer potential, with some optimization, for drug-free biofilm treatment.
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20
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Pant N, Eisen DP. Non-Antimicrobial Adjuvant Strategies to Tackle Biofilm-Related Staphylococcus aureus Prosthetic Joint Infections. Antibiotics (Basel) 2021; 10:antibiotics10091060. [PMID: 34572641 PMCID: PMC8465242 DOI: 10.3390/antibiotics10091060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 08/27/2021] [Accepted: 08/28/2021] [Indexed: 12/15/2022] Open
Abstract
Staphylococcus aureus frequently causes community- and hospital-acquired infections. S. aureus attachment followed by biofilm formation on tissues and medical devices plays a significant role in the establishment of chronic infections. Staphylococcal biofilms encase bacteria in a matrix and protect the cells from antimicrobials and the immune system, resulting in infections that are highly resistant to treatment. The biology of biofilms is complex and varies between organisms. In this review, we focus our discussion on S. aureus biofilms and describe the stages of their formation. We particularly emphasize genetic and biochemical processes that may be vulnerable to novel treatment approaches. Against this background, we discuss treatment strategies that have been successful in animal models of S. aureus biofilm-related infection and consider their possible use for the prevention and eradication of biofilm-related S. aureus prosthetic joint infection.
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21
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Abstract
Most Staphylococcus aureus strains can grow as a multicellular biofilm, a phenotype of utmost importance to clinical infections such as endocarditis, osteomyelitis, and implanted medical device infection. As biofilms are inherently more tolerant to the host immune system and antibiotics, understanding the S. aureus genes and regulatory circuits that contribute to biofilm development is an active and on-going field of research. This chapter details a high-throughput and standardized way to grow S. aureus biofilms using a classical microtiter plate assay. Biofilms can be quantified using crystal violet or by confocal microscopy imaging and COMSTAT analysis.
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22
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The Staphylococcus aureus CidA and LrgA Proteins Are Functional Holins Involved in the Transport of By-Products of Carbohydrate Metabolism. mBio 2021; 13:e0282721. [PMID: 35100878 PMCID: PMC8805020 DOI: 10.1128/mbio.02827-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The Staphylococcus aureus cidABC and lrgAB operons encode members of a well-conserved family of proteins thought to be involved in programmed cell death (PCD). Based on the structural similarities that CidA and LrgA share with bacteriophage holins, we have hypothesized that these proteins function by forming pores within the cytoplasmic membrane. To test this, we utilized a "lysis cassette" system that demonstrated the abilities of the cidA and lrgA genes to support bacteriophage endolysin-induced cell lysis. Typical of holins, CidA- and LrgA-induced lysis was dependent on the coexpression of endolysin, consistent with the proposed holin-like functions of these proteins. In addition, the CidA and LrgA proteins were shown to localize to the surface of membrane vesicles and cause leakage of small molecules, providing direct evidence of their hole-forming potential. Consistent with recent reports demonstrating a role for the lrgAB homologues in other bacterial and plant species in the transport of by-products of carbohydrate metabolism, we also show that lrgAB is important for S. aureus to utilize pyruvate during microaerobic and anaerobic growth, by promoting the uptake of pyruvate under these conditions. Combined, these data reveal that the CidA and LrgA membrane proteins possess holin-like properties that play an important role in the transport of small by-products of carbohydrate metabolism. IMPORTANCE The Staphylococcus aureus cidABC and lrgAB operons represent the founding members of a large, highly conserved family of genes that span multiple kingdoms of life. Despite the fact that they have been shown to be involved in bacterial PCD, very little is known about the molecular/biochemical functions of the proteins they encode. The results presented in this study reveal that the cidA and lrgA genes encode proteins with bacteriophage holin-like functions, consistent with their roles in cell death. However, these studies also demonstrate that these operons are involved in the transport of small metabolic by-products of carbohydrate metabolism, suggesting an intriguing link between these two seemingly disparate processes.
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23
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Schilcher K, Horswill AR. Staphylococcal Biofilm Development: Structure, Regulation, and Treatment Strategies. Microbiol Mol Biol Rev 2020; 84:e00026-19. [PMID: 32792334 PMCID: PMC7430342 DOI: 10.1128/mmbr.00026-19] [Citation(s) in RCA: 307] [Impact Index Per Article: 76.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In many natural and clinical settings, bacteria are associated with some type of biotic or abiotic surface that enables them to form biofilms, a multicellular lifestyle with bacteria embedded in an extracellular matrix. Staphylococcus aureus and Staphylococcus epidermidis, the most frequent causes of biofilm-associated infections on indwelling medical devices, can switch between an existence as single free-floating cells and multicellular biofilms. During biofilm formation, cells first attach to a surface and then multiply to form microcolonies. They subsequently produce the extracellular matrix, a hallmark of biofilm formation, which consists of polysaccharides, proteins, and extracellular DNA. After biofilm maturation into three-dimensional structures, the biofilm community undergoes a disassembly process that leads to the dissemination of staphylococcal cells. As biofilms are dynamic and complex biological systems, staphylococci have evolved a vast network of regulatory mechanisms to modify and fine-tune biofilm development upon changes in environmental conditions. Thus, biofilm formation is used as a strategy for survival and persistence in the human host and can serve as a reservoir for spreading to new infection sites. Moreover, staphylococcal biofilms provide enhanced resilience toward antibiotics and the immune response and impose remarkable therapeutic challenges in clinics worldwide. This review provides an overview and an updated perspective on staphylococcal biofilms, describing the characteristic features of biofilm formation, the structural and functional properties of the biofilm matrix, and the most important mechanisms involved in the regulation of staphylococcal biofilm formation. Finally, we highlight promising strategies and technologies, including multitargeted or combinational therapies, to eradicate staphylococcal biofilms.
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Affiliation(s)
- Katrin Schilcher
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Alexander R Horswill
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Department of Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado, USA
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24
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Schilcher K, Horswill AR. Staphylococcal Biofilm Development: Structure, Regulation, and Treatment Strategies. Microbiol Mol Biol Rev 2020. [PMID: 32792334 DOI: 10.1128/mmbr.00026-19/asset/e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023] Open
Abstract
In many natural and clinical settings, bacteria are associated with some type of biotic or abiotic surface that enables them to form biofilms, a multicellular lifestyle with bacteria embedded in an extracellular matrix. Staphylococcus aureus and Staphylococcus epidermidis, the most frequent causes of biofilm-associated infections on indwelling medical devices, can switch between an existence as single free-floating cells and multicellular biofilms. During biofilm formation, cells first attach to a surface and then multiply to form microcolonies. They subsequently produce the extracellular matrix, a hallmark of biofilm formation, which consists of polysaccharides, proteins, and extracellular DNA. After biofilm maturation into three-dimensional structures, the biofilm community undergoes a disassembly process that leads to the dissemination of staphylococcal cells. As biofilms are dynamic and complex biological systems, staphylococci have evolved a vast network of regulatory mechanisms to modify and fine-tune biofilm development upon changes in environmental conditions. Thus, biofilm formation is used as a strategy for survival and persistence in the human host and can serve as a reservoir for spreading to new infection sites. Moreover, staphylococcal biofilms provide enhanced resilience toward antibiotics and the immune response and impose remarkable therapeutic challenges in clinics worldwide. This review provides an overview and an updated perspective on staphylococcal biofilms, describing the characteristic features of biofilm formation, the structural and functional properties of the biofilm matrix, and the most important mechanisms involved in the regulation of staphylococcal biofilm formation. Finally, we highlight promising strategies and technologies, including multitargeted or combinational therapies, to eradicate staphylococcal biofilms.
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Affiliation(s)
- Katrin Schilcher
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Alexander R Horswill
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Department of Veterans Affairs Eastern Colorado Health Care System, Denver, Colorado, USA
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Wang Y, Wu F, Hu F, Wu Y, Zhou J, Xu Y, Shao X, Hu T. Drag-reducing polymers attenuates pulmonary vascular remodeling and right ventricular dysfunction in a rat model of chronic hypoxia-induced pulmonary hypertension. Clin Hemorheol Microcirc 2020; 74:189-200. [PMID: 31476149 DOI: 10.3233/ch-190668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Drag-reducing polymers (DRPs) was previously demonstrated to increase blood flow, tissue perfusion, and reduce vascular resistance. The purpose of this study was to investigate the effect of DRPs on pulmonary vascular remodeling and right ventricular dysfunction in a rat model of chronic hypoxia-induced pulmonary hypertension (HPH). A total of forty male Wistar rats were randomly and equally assigned into four experimental groups (Group I: normoxia + saline, Group II: normoxia + PEO, Group III: hypoxia + saline, Group IV: hypoxia + PEO) and maintained in normoxia (21% O2) or hypobaric hypoxia (10% O2). After four weeks, comparisons were made of the following aspects: the mean pulmonary arterial pressure (mPAP), right ventricular systolic pressure (RVSP), right ventricular hypertrophy, wall thickness of pulmonary trunk and arteries, internal diameter of pulmonary arteries, cardiomyocyte cross-sectional area (CM CSA), and ultrastructure of right ventricular. Treatment with PEO in Group IV attenuated the increases in RVSP and mPAP (40.5±7.2 and 34.7±7.0 mmHg, respectively, both P < 0.05), compared with Group III. Distal vascular remodeling was visible as a significant increase in medial wall thickness (64.2±12.3% vs. 43.95±7.0%, P < 0.01) and a remarkable decrease in internal diameter of small pulmonary arteries (35.2±9.7μ m vs. 50.4±14.7μ m, P < 0.01) in Group III, to a greater extent than that detected in Group IV. Nevertheless, no significant histopathological differences in medial wall thickness was observed in pulmonary trunk between Group III and Group IV (P > 0.05), denoting that PEO chiefly attenuated the remodeling of small pulmonary arteries rather than main arteries in hypoxic environment. Infusion of DRPs (intravenous injection twice weekly) also attenuated the index of right ventricular hypertrophy, protected against the increase of cardiomyocyte cross-sectional area, and provided protection for cardiac ultrastructure. DRP treatment with intravenous injection elicited a protective effect against pulmonary vascular remodeling and right ventricular dysfunction in the rat model of HPH. DRPs may offer a new potential approach for the treatment of HPH, which may have theoretical significance and application value to society.
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Affiliation(s)
- Yali Wang
- Department of Respiratory Medicine, The Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, China
| | - Feng Wu
- Department of Respiratory Medicine, The Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, China
| | - Feng Hu
- Cardiac Arrhythmia Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yunjiang Wu
- Department of Thoracic Surgery, The Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, China
| | - Jun Zhou
- Department of Respiratory Medicine, The Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, China
| | - Yan Xu
- Department of Respiratory Medicine, The Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, China
| | - Xiangrong Shao
- Department of Respiratory Medicine, The Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, China
| | - Tao Hu
- Department of Respiratory Medicine, The Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, China
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Genetic and Biochemical Analysis of CodY-Mediated Cell Aggregation in Staphylococcus aureus Reveals an Interaction between Extracellular DNA and Polysaccharide in the Extracellular Matrix. J Bacteriol 2020; 202:JB.00593-19. [PMID: 32015143 DOI: 10.1128/jb.00593-19] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 01/24/2020] [Indexed: 12/14/2022] Open
Abstract
The global regulator CodY links nutrient availability to the regulation of virulence factor gene expression in Staphylococcus aureus, including many genes whose products affect biofilm formation. Antithetical phenotypes of both biofilm deficiency and accumulation have been reported for codY-null mutants; thus, the role of CodY in biofilm development remains unclear. codY mutant cells of a strain producing a robust biofilm elaborate proaggregation surface-associated features not present on codY mutant cells that do not produce a robust biofilm. Biochemical analysis of the clinical isolate SA564, which aggregates when deficient for CodY, revealed that these features are sensitive to nuclease treatment and are resistant to protease exposure. Genetic analyses revealed that disrupting lgt (the diacylglycerol transferase gene) in codY mutant cells severely weakened aggregation, indicating a role for lipoproteins in the attachment of the biofilm matrix to the cell surface. An additional and critical role of IcaB in producing functional poly-N-acetylglucosamine (PIA) polysaccharide in extracellular DNA (eDNA)-dependent biofilm formation was shown. Moreover, overproducing PIA is sufficient to promote aggregation in a DNA-dependent manner regardless of source of nucleic acids. Taken together, our results point to PIA synthesis as the primary determinant of biofilm formation when CodY activity is reduced and suggest a modified electrostatic net model for matrix attachment whereby PIA associates with eDNA, which interacts with the cell surface via covalently attached membrane lipoproteins. This work counters the prevailing view that polysaccharide- and eDNA/protein-based biofilms are mutually exclusive. Rather, we demonstrate that eDNA and PIA can work synergistically to form a biofilm.IMPORTANCE Staphylococcus aureus remains a global health concern and exemplifies the ability of an opportunistic pathogen to adapt and persist within multiple environments, including host tissue. Not only does biofilm contribute to persistence and immune evasion in the host environment, it also may aid in the transition to invasive disease. Thus, understanding how biofilms form is critical for developing strategies for dispersing biofilms and improving biofilm disease-related outcomes. Using biochemical, genetic, and cell biology approaches, we reveal a synergistic interaction between PIA and eDNA that promotes cell aggregation and biofilm formation in a CodY-dependent manner in S. aureus We also reveal that envelope-associated lipoproteins mediate attachment of the biofilm matrix to the cell surface.
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27
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Basu A, Shields KE, Yap MNF. The hibernating 100S complex is a target of ribosome-recycling factor and elongation factor G in Staphylococcus aureus. J Biol Chem 2020; 295:6053-6063. [PMID: 32209660 PMCID: PMC7196661 DOI: 10.1074/jbc.ra119.012307] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 03/18/2020] [Indexed: 12/24/2022] Open
Abstract
The formation of translationally inactive 70S dimers (called 100S ribosomes) by hibernation-promoting factor is a widespread survival strategy among bacteria. Ribosome dimerization is thought to be reversible, with the dissociation of the 100S complexes enabling ribosome recycling for participation in new rounds of translation. The precise pathway of 100S ribosome recycling has been unclear. We previously found that the heat-shock GTPase HflX in the human pathogen Staphylococcus aureus is a minor disassembly factor. Cells lacking hflX do not accumulate 100S ribosomes unless they are subjected to heat exposure, suggesting the existence of an alternative pathway during nonstressed conditions. Here, we provide biochemical and genetic evidence that two essential translation factors, ribosome-recycling factor (RRF) and GTPase elongation factor G (EF-G), synergistically split 100S ribosomes in a GTP-dependent but tRNA translocation-independent manner. We found that although HflX and the RRF/EF-G pair are functionally interchangeable, HflX is expressed at low levels and is dispensable under normal growth conditions. The bacterial RRF/EF-G pair was previously known to target only the post-termination 70S complexes; our results reveal a new role in the reversal of ribosome hibernation that is intimately linked to bacterial pathogenesis, persister formation, stress responses, and ribosome integrity.
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Affiliation(s)
- Arnab Basu
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104
| | - Kathryn E Shields
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104
| | - Mee-Ngan F Yap
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104; Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611.
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28
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Dahyot S, Oxaran V, Niepceron M, Dupart E, Legris S, Destruel L, Didi J, Clamens T, Lesouhaitier O, Zerdoumi Y, Flaman JM, Pestel-Caron M. Role of the LytSR Two-Component Regulatory System in Staphylococcus lugdunensis Biofilm Formation and Pathogenesis. Front Microbiol 2020; 11:39. [PMID: 32038604 PMCID: PMC6993578 DOI: 10.3389/fmicb.2020.00039] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 01/09/2020] [Indexed: 11/21/2022] Open
Abstract
Staphylococcus lugdunensis is a coagulase negative Staphylococcus recognized as a virulent pathogen. It is responsible for a wide variety of infections, some of which are associated with biofilm production, such as implanted medical device infections or endocarditis. However, little is known about S. lugdunensis regulation of virulence factor expression. Two-component regulatory systems (TCS) play a critical role in bacterial adaptation, survival, and virulence. Among them, LytSR is widely conserved but has variable roles in different organisms, all connected to metabolism or cell death and lysis occurring during biofilm development. Therefore, we investigated here the functions of LytSR in S. lugdunensis pathogenesis. Deletion of lytSR in S. lugdunensis DSM 4804 strain did not alter either susceptibility to Triton X-100 induced autolysis or death induced by antibiotics targeting cell wall synthesis. Interestingly, ΔlytSR biofilm was characterized by a lower biomass, a lack of tower structures, and a higher rate of dead cells compared to the wild-type strain. Virulence toward Caenorhabditis elegans using a slow-killing assay was significantly reduced for the mutant compared to the wild-type strain. By contrast, the deletion of lytSR had no effect on the cytotoxicity of S. lugdunensis toward the human keratinocyte cell line HaCaT. Transcriptional analyses conducted at mid- and late-exponential phases showed that lytSR deletion affected the expression of 286 genes. Most of them were involved in basic functions such as the metabolism of amino acids, carbohydrates, and nucleotides. Furthermore, LytSR appeared to be involved in the regulation of genes encoding known or putative virulence and colonization factors, including the fibrinogen-binding protein Fbl, the major autolysin AtlL, and the type VII secretion system. Overall, our data suggest that the LytSR TCS is implicated in S. lugdunensis pathogenesis, through its involvement in biofilm formation and potentially by the control of genes encoding putative virulence factors.
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Affiliation(s)
- Sandrine Dahyot
- Groupe de Recherche sur l’Adaptation Microbienne (GRAM 2.0), Department of Bacteriology, Rouen University Hospital, Normandie University, UNIROUEN, UNICAEN, Rouen, France
| | - Virginie Oxaran
- Department of Biological Sciences, Border Biomedical Research Center, University of Texas at El Paso, El Paso, TX, United States
| | - Maïté Niepceron
- Groupe de Recherche sur l’Adaptation Microbienne (GRAM 2.0), Normandie University, UNIROUEN, UNICAEN, Rouen, France
| | - Eddy Dupart
- Groupe de Recherche sur l’Adaptation Microbienne (GRAM 2.0), Normandie University, UNIROUEN, UNICAEN, Rouen, France
| | - Stéphanie Legris
- Groupe de Recherche sur l’Adaptation Microbienne (GRAM 2.0), Normandie University, UNIROUEN, UNICAEN, Rouen, France
| | - Laurie Destruel
- Groupe de Recherche sur l’Adaptation Microbienne (GRAM 2.0), Normandie University, UNIROUEN, UNICAEN, Rouen, France
| | - Jennifer Didi
- Groupe de Recherche sur l’Adaptation Microbienne (GRAM 2.0), Normandie University, UNIROUEN, UNICAEN, Rouen, France
| | - Thomas Clamens
- Laboratory of Microbiology Signals and Microenvironment (LMSM), Normandie University, UNIROUEN, Evreux, France
| | - Olivier Lesouhaitier
- Laboratory of Microbiology Signals and Microenvironment (LMSM), Normandie University, UNIROUEN, Evreux, France
| | - Yasmine Zerdoumi
- INSERM U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen University Hospital, Normandie University, UNIROUEN, Rouen, France
| | - Jean-Michel Flaman
- INSERM U1245, Normandy Centre for Genomic and Personalized Medicine, Rouen University Hospital, Normandie University, UNIROUEN, Rouen, France
| | - Martine Pestel-Caron
- Groupe de Recherche sur l’Adaptation Microbienne (GRAM 2.0), Department of Bacteriology, Rouen University Hospital, Normandie University, UNIROUEN, UNICAEN, Rouen, France
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Abstract
Biofilm formation on indwelling medical devices represents an exclusive evasion mechanism for many pathogenic bacteria to establish chronic infections. Staphylococcus aureus is one of the major bacterial pathogens that are able to induce both animal and human infections. The continued emergence of multiple drug-resistant S. aureus, especially methicillin-resistant S. aureus, is problematic due to limited treatment options. Biofilm formation by S. aureus complicates the treatment of methicillin-resistant S. aureus infections. Therefore, elucidating the mechanisms of biofilm formation in this pathogen is important for the development of alternative therapeutic strategies. Various environmental and genetic factors contribute to biofilm formation. In this review, we address the environmental factors and discuss how they affect biofilm formation by S. aureus.
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Affiliation(s)
- Ying Liu
- Shanghai Vocational College of Agriculture and Forestry, Shanghai, China
- Department of Veterinary Biomedical Science, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN, USA
| | - Jiang Zhang
- Shanghai Vocational College of Agriculture and Forestry, Shanghai, China
| | - Yinduo Ji
- Department of Veterinary Biomedical Science, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN, USA
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30
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Augagneur Y, King AN, Germain-Amiot N, Sassi M, Fitzgerald JW, Sahukhal GS, Elasri MO, Felden B, Brinsmade SR. Analysis of the CodY RNome reveals RsaD as a stress-responsive riboregulator of overflow metabolism in Staphylococcus aureus. Mol Microbiol 2019; 113:309-325. [PMID: 31696578 DOI: 10.1111/mmi.14418] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/05/2019] [Indexed: 11/28/2022]
Abstract
In Staphylococcus aureus, the transcription factor CodY modulates the expression of hundreds of genes, including most virulence factors, in response to the availability of key nutrients like GTP and branched-chain amino acids. Despite numerous studies examining how CodY controls gene expression directly or indirectly, virtually nothing is known about the extent to which CodY exerts its effect through small regulatory RNAs (sRNAs). Herein, we report the first set of sRNAs under the control of CodY. We reveal that staphylococcal sRNA RsaD is overexpressed >20-fold in a CodY-deficient strain in three S. aureus clinical isolates and in S. epidermidis. We validated the CodY-dependent regulation of rsaD and demonstrated that CodY directly represses rsaD expression by binding the promoter. Using a combination of molecular techniques, we show that RsaD posttranscriptionally regulates alsS (acetolactate synthase) mRNA and enzyme levels. We further show that RsaD redirects carbon overflow metabolism, contributing to stationary phase cell death during exposure to weak acid stress. Taken together, our data delineate a role for CodY in controlling sRNA expression in a major human pathogen and indicate that RsaD may integrate nutrient depletion and other signals to mount a response to physiological stress experienced by S. aureus in diverse environments.
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Affiliation(s)
- Yoann Augagneur
- INSERM U1230 Biochimie Pharmaceutique, Université de Rennes I, Rennes, France
| | - Alyssa N King
- Department of Biology, Georgetown University, Washington, DC, USA
| | | | - Mohamed Sassi
- INSERM U1230 Biochimie Pharmaceutique, Université de Rennes I, Rennes, France
| | | | - Gyan S Sahukhal
- Center of Molecular and Cellular Biosciences, The University of Southern Mississippi, Hattiesburg, MS, USA
| | - Mohamed O Elasri
- Center of Molecular and Cellular Biosciences, The University of Southern Mississippi, Hattiesburg, MS, USA
| | - Brice Felden
- INSERM U1230 Biochimie Pharmaceutique, Université de Rennes I, Rennes, France
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31
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Bisht K, Wakeman CA. Discovery and Therapeutic Targeting of Differentiated Biofilm Subpopulations. Front Microbiol 2019; 10:1908. [PMID: 31507548 PMCID: PMC6718512 DOI: 10.3389/fmicb.2019.01908] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 08/05/2019] [Indexed: 12/21/2022] Open
Abstract
The association of microorganisms into biofilms produces functionally organized microbial structures that promote community survival in a wide range of environments. Much like when individual cells within a multicellular organism express different genes from the same DNA blueprint, individual microbial cells located within different regions of a biofilm structure can exhibit distinct genetic programs. These spatially defined regions of physiologically differentiated cells are reminiscent of the role of tissues in multicellular organisms, with specific subpopulations in the microbial community serving defined roles to promote the overall health of the biofilm. The functions of these subpopulations are quite diverse and can range from dormant cells that can withstand antibiotic onslaughts to cells actively producing extracellular polymeric substances providing integrity to the entire community. The purpose of this review is to discuss the diverse roles of subpopulations in the stability and function of clonal biofilms, the methods for studying these subpopulations, and the ways these subpopulations can potentially be exploited for therapeutic intervention.
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Affiliation(s)
- Karishma Bisht
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, United States
| | - Catherine Ann Wakeman
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, United States
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32
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Cattò C, Cappitelli F. Testing Anti-Biofilm Polymeric Surfaces: Where to Start? Int J Mol Sci 2019; 20:E3794. [PMID: 31382580 PMCID: PMC6696330 DOI: 10.3390/ijms20153794] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 08/02/2019] [Indexed: 12/11/2022] Open
Abstract
Present day awareness of biofilm colonization on polymeric surfaces has prompted the scientific community to develop an ever-increasing number of new materials with anti-biofilm features. However, compared to the large amount of work put into discovering potent biofilm inhibitors, only a small number of papers deal with their validation, a critical step in the translation of research into practical applications. This is due to the lack of standardized testing methods and/or of well-controlled in vivo studies that show biofilm prevention on polymeric surfaces; furthermore, there has been little correlation with the reduced incidence of material deterioration. Here an overview of the most common methods for studying biofilms and for testing the anti-biofilm properties of new surfaces is provided.
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Affiliation(s)
- Cristina Cattò
- Department of Food Environmental and Nutritional Sciences, Università degli Studi di Milano, via Celoria 2, 20133 Milano, Italy
| | - Francesca Cappitelli
- Department of Food Environmental and Nutritional Sciences, Università degli Studi di Milano, via Celoria 2, 20133 Milano, Italy.
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33
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Zeng S, Constant P, Yang D, Baulard A, Lefèvre P, Daffé M, Wattiez R, Fontaine V. Cpn60.1 (GroEL1) Contributes to Mycobacterial Crabtree Effect: Implications for Biofilm Formation. Front Microbiol 2019; 10:1149. [PMID: 31244785 PMCID: PMC6579834 DOI: 10.3389/fmicb.2019.01149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 05/06/2019] [Indexed: 12/18/2022] Open
Abstract
Biofilm formation is a survival strategy for microorganisms facing a hostile environment. Under biofilm, bacteria are better protected against antibacterial drugs and the immune response, increasing treatment difficulty, as persistent populations recalcitrant to chemotherapy are promoted. Deciphering mechanisms leading to biofilms could, thus, be beneficial to obtain new antibacterial drug candidates. Here, we show that mycobacterial biofilm formation is linked to excess glycerol adaptation and the concomitant establishment of the Crabtree effect. This effect is characterized by respiratory reprogramming, ATP downregulation, and secretion of various metabolites including pyruvate, acetate, succinate, and glutamate. Interestingly, the Crabtree effect was abnormal in a mycobacterial strain deficient for Cpn60.1 (GroEL1). Indeed, this mutant strain had a compromised ability to downregulate ATP and secreted more pyruvate, acetate, succinate, and glutamate in the culture medium. Importantly, the mutant strain had higher intracellular pyruvate and produced more toxic methylglyoxal, suggesting a glycolytic stress leading to growth stasis and consequently biofilm failure. This study demonstrates, for the first time, the link between mycobacterial biofilm formation and the Crabtree effect.
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Affiliation(s)
- Sheng Zeng
- Microbiology, Bioorganic and Macromolecular Chemistry Research Unit, Faculté de Pharmacie, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Patricia Constant
- Department of Tuberculosis and Infection Biology, Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Dong Yang
- Microbiology, Bioorganic and Macromolecular Chemistry Research Unit, Faculté de Pharmacie, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Alain Baulard
- Institut Pasteur de Lille, Université de Lille, CNRS, INSERM, CHU Lille, U1019-UMR 8204, Center for Infection and Immunity of Lille, Lille, France
| | - Philippe Lefèvre
- Microbiology, Bioorganic and Macromolecular Chemistry Research Unit, Faculté de Pharmacie, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Mamadou Daffé
- Department of Tuberculosis and Infection Biology, Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Ruddy Wattiez
- Department of Proteomics and Microbiology, University of Mons, Mons, Belgium
| | - Véronique Fontaine
- Microbiology, Bioorganic and Macromolecular Chemistry Research Unit, Faculté de Pharmacie, Université Libre de Bruxelles (ULB), Brussels, Belgium
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34
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Crabbé A, Jensen PØ, Bjarnsholt T, Coenye T. Antimicrobial Tolerance and Metabolic Adaptations in Microbial Biofilms. Trends Microbiol 2019; 27:850-863. [PMID: 31178124 DOI: 10.1016/j.tim.2019.05.003] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/25/2019] [Accepted: 05/07/2019] [Indexed: 01/04/2023]
Abstract
Active bacterial metabolism is a prerequisite for optimal activity of many classes of antibiotics. Hence, bacteria have developed strategies to reduce or modulate metabolic pathways to become tolerant. This review describes the tight relationship between metabolism and tolerance in bacterial biofilms, and how physicochemical properties of the microenvironment at the host-pathogen interface (such as oxygen and nutritional content) are key to this relationship. Understanding how metabolic adaptations lead to tolerance brings us to novel approaches to tackle antibiotic-tolerant biofilms. We describe the use of hyperbaric oxygen therapy, metabolism-stimulating metabolites, and alternative strategies to redirect bacterial metabolism towards an antibiotic-susceptible phenotype.
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Affiliation(s)
- Aurélie Crabbé
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium
| | - Peter Østrup Jensen
- Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark; Institute for Inflammation Research, Center for Rheumatology and Spine Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Thomas Bjarnsholt
- Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium.
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35
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Contribution of YjbIH to Virulence Factor Expression and Host Colonization in Staphylococcus aureus. Infect Immun 2019; 87:IAI.00155-19. [PMID: 30885928 DOI: 10.1128/iai.00155-19] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 03/10/2019] [Indexed: 12/17/2022] Open
Abstract
To persist within the host and cause disease, Staphylococcus aureus relies on its ability to precisely fine-tune virulence factor expression in response to rapidly changing environments. During an unbiased transposon mutant screen, we observed that disruption of a two-gene operon, yjbIH, resulted in decreased levels of pigmentation and aureolysin (Aur) activity relative to the wild-type strain. Further analyses revealed that YjbH, a predicted thioredoxin-like oxidoreductase, is predominantly responsible for the observed yjbIH mutant phenotypes, though a minor role exists for the putative truncated hemoglobin YjbI. These differences were due to significantly decreased expression of crtOPQMN and aur Previous studies found that YjbH targets the disulfide- and oxidative stress-responsive regulator Spx for degradation by ClpXP. The absence of yjbH or yjbI resulted in altered sensitivities to nitrosative and oxidative stress and iron deprivation. Additionally, aconitase activity was altered in the yjbH and yjbI mutant strains. Decreased levels of pigmentation and aureolysin (Aur) activity in the yjbH mutant were found to be Spx dependent. Lastly, we used a murine sepsis model to determine the effect of the yjbIH deletion on pathogenesis and found that the mutant was better able to colonize the kidneys and spleens during an acute infection than the wild-type strain. These studies identified changes in pigmentation and protease activity in response to YjbIH and are the first to have shown a role for these proteins during infection.
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36
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Marincola G, Wencker FDR, Ziebuhr W. The Many Facets of the Small Non-coding RNA RsaE (RoxS) in Metabolic Niche Adaptation of Gram-Positive Bacteria. J Mol Biol 2019; 431:4684-4698. [PMID: 30914292 DOI: 10.1016/j.jmb.2019.03.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 03/13/2019] [Accepted: 03/13/2019] [Indexed: 01/01/2023]
Abstract
Small regulatory RNAs (sRNAs) are increasingly recognized as players in the complex regulatory networks governing bacterial gene expression. RsaE (synonym RoxS) is an sRNA that is highly conserved in bacteria of the Bacillales order. Recent analyses in Bacillus subtilis, Staphylococcus aureus and Staphylococcus epidermidis identified RsaE/RoxS as a potent riboregulator of central carbon metabolism and energy balance with many molecular RsaE/RoxS functions and targets being shared across species. Similarities and species-specific differences in cellular processes modulated by RsaE/RoxS suggest that this sRNA plays a prominent role in the adaptation of Gram-positive bacteria to niches with varying nutrient availabilities and environmental cues. This review summarizes recent findings on the molecular function of RsaE/RoxS and its interaction with mRNA targets. Special emphasis will be on the integration of RsaE/RoxS into metabolic regulatory circuits and, derived from this, the role of RsaE/RoxS as a putative driver to generate phenotypic heterogeneity in bacterial populations. In this respect, we will particularly discuss heterogeneous RsaE expression in S. epidermidis biofilms and its possible contribution to metabolic niche diversification, programmed bacterial lysis and biofilm matrix production.
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Affiliation(s)
- Gabriella Marincola
- Institute of Molecular Infection Biology, University of Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Freya D R Wencker
- Institute of Molecular Infection Biology, University of Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Wilma Ziebuhr
- Institute of Molecular Infection Biology, University of Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany.
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37
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Schoenfelder SMK, Lange C, Prakash SA, Marincola G, Lerch MF, Wencker FDR, Förstner KU, Sharma CM, Ziebuhr W. The small non-coding RNA RsaE influences extracellular matrix composition in Staphylococcus epidermidis biofilm communities. PLoS Pathog 2019; 15:e1007618. [PMID: 30870530 PMCID: PMC6435200 DOI: 10.1371/journal.ppat.1007618] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 03/26/2019] [Accepted: 02/04/2019] [Indexed: 12/15/2022] Open
Abstract
RsaE is a conserved small regulatory RNA (sRNA) which was previously reported to represent a riboregulator of central carbon flow and other metabolic pathways in Staphylococcus aureus and Bacillus subtilis. Here we show that RsaE contributes to extracellular (e)DNA release and biofilm-matrix switching towards polysaccharide intercellular adhesin (PIA) production in a hypervariable Staphylococcus epidermidis isolate. Transcriptome analysis through differential RNA sequencing (dRNA-seq) in combination with confocal laser scanning microscopy (CLSM) and reporter gene fusions demonstrate that S. epidermidis protein- and PIA-biofilm matrix producers differ with respect to RsaE and metabolic gene expression. RsaE is spatiotemporally expressed within S. epidermidis PIA-mediated biofilms, and its overexpression triggers a PIA biofilm phenotype as well as eDNA release in an S. epidermidis protein biofilm matrix-producing strain background. dRNA-seq and Northern blot analyses revealed RsaE to exist as a major full-length 100-nt transcript and a minor processed species lacking approximately 20 nucleotides at the 5'-end. RsaE processing results in expansion of the mRNA target spectrum. Thus, full-length RsaE interacts with S. epidermidis antiholin-encoding lrgA mRNA, facilitating bacterial lysis and eDNA release. Processed RsaE, however, interacts with the 5'-UTR of icaR and sucCD mRNAs, encoding the icaADBC biofilm operon repressor IcaR and succinyl-CoA synthetase of the tricarboxylic acid (TCA) cycle, respectively. RsaE augments PIA-mediated biofilm matrix production, most likely through activation of icaADBC operon expression via repression of icaR as well as by TCA cycle inhibition and re-programming of staphylococcal central carbon metabolism towards PIA precursor synthesis. Additionally, RsaE supports biofilm formation by mediating the release of eDNA as stabilizing biofilm matrix component. As RsaE itself is heterogeneously expressed within biofilms, we consider this sRNA to function as a factor favoring phenotypic heterogeneity and supporting division of labor in S. epidermidis biofilm communities. Bacterial biofilms are highly organized structures which functionally emulate multicellular organisms, last but not least through heterogeneous gene expression patterns displayed by biofilm subpopulations. Here we analyzed the functions of the non-coding RNA RsaE in Staphylococcus epidermidis biofilm communities. RsaE exerted unexpected influences on S. epidermidis biofilm matrix composition by triggering localized eDNA release and facilitating PIA expression. RsaE accomplishes these effects by targeting mRNAs involved in bacterial lysis control, icaADBC expression and TCA cycle activity, with RsaE undergoing processing to exploit its full target potential. Interestingly, RsaE interaction with lysis-engaged lrgA mRNA is specific for S. epidermidis lrgA, but does not occur with lrgA mRNA from S. aureus, suggesting species-specific differences in staphylococcal lysis control. We speculate that RsaE-mediated bacterial lysis might represent a form of bacterial altruism contributing to biofilm structuring by providing nutrients to neighboring bacterial cells as well as by releasing eDNA as stabilizing biofilm matrix component. Due to its heterogeneous expression, we consider RsaE as a supporting factor that facilitates population diversity. Together, the data give insight into an unanticipated role of sRNAs as players in S. epidermidis biofilm organization.
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Affiliation(s)
| | - Claudia Lange
- University of Würzburg, Institute of Molecular Infection Biology, Würzburg, Germany
| | | | - Gabriella Marincola
- University of Würzburg, Institute of Molecular Infection Biology, Würzburg, Germany
| | - Maike F. Lerch
- University of Würzburg, Institute of Molecular Infection Biology, Würzburg, Germany
| | - Freya D. R. Wencker
- University of Würzburg, Institute of Molecular Infection Biology, Würzburg, Germany
| | - Konrad U. Förstner
- University of Würzburg, Institute of Molecular Infection Biology, Würzburg, Germany
| | - Cynthia M. Sharma
- University of Würzburg, Institute of Molecular Infection Biology, Würzburg, Germany
| | - Wilma Ziebuhr
- University of Würzburg, Institute of Molecular Infection Biology, Würzburg, Germany
- * E-mail:
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Manandhar S, Singh A, Varma A, Pandey S, Shrivastava N. Biofilm Producing Clinical Staphylococcus aureus Isolates Augmented Prevalence of Antibiotic Resistant Cases in Tertiary Care Hospitals of Nepal. Front Microbiol 2018; 9:2749. [PMID: 30538678 PMCID: PMC6277500 DOI: 10.3389/fmicb.2018.02749] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 10/26/2018] [Indexed: 11/21/2022] Open
Abstract
Staphylococcus aureus, a notorious human pathogen, is a major cause of the community as well as healthcare associated infections. It can cause a diversity of recalcitrant infections mainly due to the acquisition of resistance to multiple drugs, its diverse range of virulence factors, and the ability to produce biofilm in indwelling medical devices. Such biofilm associated chronic infections often lead to increase in morbidity and mortality posing a high socio-economic burden, especially in developing countries. Since biofilm formation and antibiotic resistance function dependent on each other, detection of biofilm expression in clinical isolates would be advantageous in treatment decision. In this premise, we attempt to investigate the biofilm formation and its association with antibiotic resistance in clinical isolates from the patients visiting tertiary health care hospitals in Nepal. Bacterial cells isolated from clinical samples identified as S. aureus were examined for in-vitro biofilm production using both phenotypic and genotypic assays. The S. aureus isolates were also examined for susceptibility patterns of clinically relevant antibiotics as well as inducible clindamycin resistance using standard microbiological techniques and D-test, respectively. Among 161 S. aureus isolates, 131 (81.4%) were methicillin resistant S. aureus (MRSA) and 30 (18.6%) were methicillin sensitive S. aureus (MSSA) strains. Although a majority of MRSA strains (69.6%) showed inducible clindamycin resistance, almost all isolates (97% and 94%) were sensitive toward chloramphenicol and tetracycline, respectively. Detection of in vitro production of biofilm revealed the association of biofilm with methicillin as well as inducible clindamycin resistance among the clinical S. aureus isolates.
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Affiliation(s)
- Sarita Manandhar
- Tri-Chandra Multiple College, Tribhuvan University, Kathmandu, Nepal.,Amity Institute of Microbial Technology, Amity University, Noida, India
| | - Anjana Singh
- Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal
| | - Ajit Varma
- Amity Institute of Microbial Technology, Amity University, Noida, India
| | - Shanti Pandey
- The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Neeraj Shrivastava
- Amity Institute of Microbial Technology, Amity University, Noida, India.,Institute of Biotechnology, Zhejiang University, Hangzhou, China
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Redirection of Metabolism in Response to Fatty Acid Kinase in Staphylococcus aureus. J Bacteriol 2018; 200:JB.00345-18. [PMID: 30012726 DOI: 10.1128/jb.00345-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 07/06/2018] [Indexed: 12/23/2022] Open
Abstract
Staphylococcus aureus is capable of phosphorylating exogenous fatty acids for incorporation into the bacterium's membrane via the fatty acid kinase, FakA. Additionally, FakA plays a significant role in virulence factor regulation and skin infections. We previously showed that a fakA mutant displays altered growth kinetics in vitro, observed during the late-exponential phase of growth. Here, we demonstrate that the absence of FakA leads to key metabolic changes. First, the fakA mutant has an altered acetate metabolism, with acetate being consumed at an increased rate than in the wild-type strain. Moreover, the growth benefit was diminished with inactivation of the acetate-generating enzyme AckA. Using a mass spectrometry-based approach, we identified altered concentrations of tricarboxylic acid (TCA) cycle intermediates and both intracellular and extracellular amino acids. Together, these data demonstrate a change in carbohydrate carbon utilization and altered amino acid metabolism in the fakA mutant. Energy status analysis revealed the mutant had a similar ADP/ATP ratio to that of the wild type, but a reduced adenylate energy charge. The inactivation of fakA changed the NAD+/NADH and NADP+/NADPH ratios, indicating a more oxidized cellular environment. Evidence points to the global metabolic regulatory proteins CcpA and CodY being important contributors to the altered growth in a fakA mutant. Indeed, it was found that directing amino acids from the urea cycle into the TCA cycle via glutamate dehydrogenase was an essential component of S. aureus growth after glucose depletion. Together, these data identify a previously unidentified role of FakA in the global physiology of S. aureus, linking external fatty acid utilization and central metabolism.IMPORTANCE The fatty acid kinase, FakA, of Staphylococcus aureus plays several important roles in the cell. FakA is important for the activation of the SaeRS two-component system and secreted virulence factors like α-hemolysin. However, the contribution of FakA to cellular metabolism has not been explored. Here, we highlight the metabolic consequence of removal of FakA from the cell. The absence of FakA leads to altered acetate metabolism and altered redox balance, as well as a change in intracellular amino acids. Additionally, the use of environmental amino acid sources is affected by FakA. Together, these results demonstrate for the first time that FakA provides a link between the pathways for exogenous fatty acid use, virulence factor regulation, and other metabolic processes.
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Guanine Limitation Results in CodY-Dependent and -Independent Alteration of Staphylococcus aureus Physiology and Gene Expression. J Bacteriol 2018; 200:JB.00136-18. [PMID: 29712876 DOI: 10.1128/jb.00136-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 04/25/2018] [Indexed: 02/03/2023] Open
Abstract
In Staphylococcus aureus, the global transcriptional regulator CodY modulates the expression of hundreds of genes in response to the availability of GTP and the branched-chain amino acids isoleucine, leucine, and valine (ILV). CodY DNA-binding activity is high when GTP and ILV are abundant. When GTP and ILV are limited, CodY's affinity for DNA drops, altering expression of CodY-regulated targets. In this work, we investigated the impact of guanine nucleotides (GNs) on S. aureus physiology and CodY activity by constructing a guaA null mutant (ΔguaA strain). De novo biosynthesis of guanine monophosphate is abolished due to the guaA mutation; thus, the mutant cells require exogenous guanosine for growth. We also found that CodY activity was reduced when we knocked out guaA, activating the Agr two-component system and increasing secreted protease activity. Notably, in a rich, complex medium, we detected an increase in alternative sigma factor B activity in the ΔguaA mutant, which results in a 5-fold increase in production of the antioxidant pigment staphyloxanthin. Under biologically relevant flow conditions, ΔguaA cells failed to form robust biofilms when limited for guanine or guanosine. Transcriptome sequencing (RNA-Seq) analysis of the S. aureus transcriptome during growth in guanosine-limited chemostats revealed substantial CodY-dependent and -independent alterations of gene expression profiles. Importantly, these changes increase production of proteases and δ-toxin, suggesting that S. aureus exhibits a more invasive lifestyle when limited for guanosine. Further, gene products upregulated under GN limitation, including those necessary for lipoic acid biosynthesis and sugar transport, may prove to be useful drug targets for treating Gram-positive infections.IMPORTANCE Staphylococcus aureus infections impose a serious economic burden on health care facilities and patients because of the emergence of strains resistant to last-line antibiotics. Understanding the physiological processes governing fitness and virulence of S. aureus in response to environmental cues is critical for developing efficient diagnostics and treatments. De novo purine biosynthesis is essential for both fitness and virulence in S. aureus since inhibiting production cripples S. aureus's ability to cause infection. Here, we corroborate these findings and show that blocking guanine nucleotide synthesis severely affects S. aureus fitness by altering metabolic and virulence gene expression. Characterizing pathways and gene products upregulated in response to guanine limitation can aid in the development of novel adjuvant strategies to combat S. aureus infections.
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Nutritional Regulation of the Sae Two-Component System by CodY in Staphylococcus aureus. J Bacteriol 2018; 200:JB.00012-18. [PMID: 29378891 DOI: 10.1128/jb.00012-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 01/23/2018] [Indexed: 01/22/2023] Open
Abstract
Staphylococcus aureus subverts innate defenses during infection in part by killing host immune cells to exacerbate disease. This human pathogen intercepts host cues and activates a transcriptional response via the S. aureus exoprotein expression (SaeR/SaeS [SaeR/S]) two-component system to secrete virulence factors critical for pathogenesis. We recently showed that the transcriptional repressor CodY adjusts nuclease (nuc) gene expression via SaeR/S, but the mechanism remained unknown. Here, we identified two CodY binding motifs upstream of the sae P1 promoter, which suggested direct regulation by this global regulator. We show that CodY shares a binding site with the positive activator SaeR and that alleviating direct CodY repression at this site is sufficient to abrogate stochastic expression, suggesting that CodY represses sae expression by blocking SaeR binding. Epistasis experiments support a model that CodY also controls sae indirectly through Agr and Rot-mediated repression of the sae P1 promoter. We also demonstrate that CodY repression of sae restrains production of secreted cytotoxins that kill human neutrophils. We conclude that CodY plays a previously unrecognized role in controlling virulence gene expression via SaeR/S and suggest a mechanism by which CodY acts as a master regulator of pathogenesis by tying nutrient availability to virulence gene expression.IMPORTANCE Bacterial mechanisms that mediate the switch from a commensal to pathogenic lifestyle are among the biggest unanswered questions in infectious disease research. Since the expression of most virulence genes is often correlated with nutrient depletion, this implies that virulence is a response to the lack of nourishment in host tissues and that pathogens like S. aureus produce virulence factors in order to gain access to nutrients in the host. Here, we show that specific nutrient depletion signals appear to be funneled to the SaeR/S system through the global regulator CodY. Our findings reveal a strategy by which S. aureus delays the production of immune evasion and immune-cell-killing proteins until key nutrients are depleted.
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42
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Thiran E, Di Ciccio P, Graber H, Zanardi E, Ianieri A, Hummerjohann J. Biofilm formation of Staphylococcus aureus dairy isolates representing different genotypes. J Dairy Sci 2018; 101:1000-1012. [DOI: 10.3168/jds.2017-13696] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 09/22/2017] [Indexed: 02/03/2023]
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Manandhar S, Singh A, Varma A, Pandey S, Shrivastava N. Biofilm Producing Clinical Staphylococcus aureus Isolates Augmented Prevalence of Antibiotic Resistant Cases in Tertiary Care Hospitals of Nepal. Front Microbiol 2018. [PMID: 30538678 DOI: 10.3389/fmicb.2018.02749/full] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/15/2023] Open
Abstract
Staphylococcus aureus, a notorious human pathogen, is a major cause of the community as well as healthcare associated infections. It can cause a diversity of recalcitrant infections mainly due to the acquisition of resistance to multiple drugs, its diverse range of virulence factors, and the ability to produce biofilm in indwelling medical devices. Such biofilm associated chronic infections often lead to increase in morbidity and mortality posing a high socio-economic burden, especially in developing countries. Since biofilm formation and antibiotic resistance function dependent on each other, detection of biofilm expression in clinical isolates would be advantageous in treatment decision. In this premise, we attempt to investigate the biofilm formation and its association with antibiotic resistance in clinical isolates from the patients visiting tertiary health care hospitals in Nepal. Bacterial cells isolated from clinical samples identified as S. aureus were examined for in-vitro biofilm production using both phenotypic and genotypic assays. The S. aureus isolates were also examined for susceptibility patterns of clinically relevant antibiotics as well as inducible clindamycin resistance using standard microbiological techniques and D-test, respectively. Among 161 S. aureus isolates, 131 (81.4%) were methicillin resistant S. aureus (MRSA) and 30 (18.6%) were methicillin sensitive S. aureus (MSSA) strains. Although a majority of MRSA strains (69.6%) showed inducible clindamycin resistance, almost all isolates (97% and 94%) were sensitive toward chloramphenicol and tetracycline, respectively. Detection of in vitro production of biofilm revealed the association of biofilm with methicillin as well as inducible clindamycin resistance among the clinical S. aureus isolates.
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Affiliation(s)
- Sarita Manandhar
- Tri-Chandra Multiple College, Tribhuvan University, Kathmandu, Nepal
- Amity Institute of Microbial Technology, Amity University, Noida, India
| | - Anjana Singh
- Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal
| | - Ajit Varma
- Amity Institute of Microbial Technology, Amity University, Noida, India
| | - Shanti Pandey
- The University of Southern Mississippi, Hattiesburg, MS, United States
| | - Neeraj Shrivastava
- Amity Institute of Microbial Technology, Amity University, Noida, India
- Institute of Biotechnology, Zhejiang University, Hangzhou, China
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O'Gara JP. Into the storm: Chasing the opportunistic pathogen Staphylococcus aureus from skin colonisation to life-threatening infections. Environ Microbiol 2017. [PMID: 28631399 DOI: 10.1111/1462-2920.13833] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Colonisation of the human skin by Staphylococcus aureus is a precursor for a variety of infections ranging from boils to sepsis and pneumonia. The rapid emergence of methicillin-resistant S. aureus following the clinical introduction of this antimicrobial drug and reports of resistance to all currently used anti-staphylococcal drugs has added to its formidable reputation. S. aureus survival on the skin and in vivo virulence is underpinned by a remarkable environmental adaptability, made possible by highly orchestrated regulation of gene expression and a capacity to undertake genome remodelling. Depending on the ecological or infection niche, controlled expression of a variety of adhesins can be initiated to facilitate adherence to extracellular matrix proteins, survival against desiccation or biofilm accumulation on implanted medical devices and host tissue. These adherence mechanisms complement toxin and enzyme production, immune evasion strategies, and antibiotic resistance and tolerance to collectively thwart efforts to develop reliable antimicrobial drug regimens and an effective S. aureus vaccine.
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Affiliation(s)
- James P O'Gara
- Department of Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland
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45
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Heparin Mimics Extracellular DNA in Binding to Cell Surface-Localized Proteins and Promoting Staphylococcus aureus Biofilm Formation. mSphere 2017; 2:mSphere00135-17. [PMID: 28656173 PMCID: PMC5480030 DOI: 10.1128/msphere.00135-17] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 06/02/2017] [Indexed: 01/18/2023] Open
Abstract
Staphylococcus aureus and coagulase-negative staphylococci (CoNS) are the leading causes of catheter implant infections. Identifying the factors that stimulate catheter infection and the mechanism involved is important for preventing such infections. Heparin, the main component of catheter lock solutions, has been shown previously to stimulate S. aureus biofilm formation through an unknown pathway. This work identifies multiple heparin-binding proteins in S. aureus, and it reveals a potential mechanism through which heparin enhances biofilm capacity. Understanding the details of the heparin enhancement effect could guide future use of appropriate lock solutions for catheter implants. Staphylococcus aureus is a leading cause of catheter-related bloodstream infections. Biofilms form on these implants and are held together by a matrix composed of proteins, polysaccharides, and extracellular DNA (eDNA). Heparin is a sulfated glycosaminoglycan that is routinely used in central venous catheters to prevent thrombosis, but it has been shown to stimulate S. aureus biofilm formation through an unknown mechanism. Data presented here reveal that heparin enhances biofilm capacity in many S. aureus and coagulase-negative staphylococcal strains, and it is incorporated into the USA300 methicillin-resistant S. aureus (MRSA) biofilm matrix. The S. aureus USA300 biofilms containing heparin are sensitive to proteinase K treatment, which suggests that proteins have an important structural role during heparin incorporation. Multiple heparin-binding proteins were identified by proteomics of the secreted and cell wall fractions. Proteins known to contribute to biofilm were identified, and some proteins were reported to have the ability to bind eDNA, such as the major autolysin (Atl) and the immunodominant surface protein B (IsaB). Mutants defective in IsaB showed a moderate decrease in biofilm capacity in the presence of heparin. Our findings suggested that heparin is substituting for eDNA during S. aureus biofilm development. To test this model, eDNA content was increased in biofilms through inactivation of nuclease activity, and the heparin enhancement effect was attenuated. Collectively, these data support the hypothesis that S. aureus can incorporate heparin into the matrix and enhance biofilm capacity by taking advantage of existing eDNA-binding proteins. IMPORTANCEStaphylococcus aureus and coagulase-negative staphylococci (CoNS) are the leading causes of catheter implant infections. Identifying the factors that stimulate catheter infection and the mechanism involved is important for preventing such infections. Heparin, the main component of catheter lock solutions, has been shown previously to stimulate S. aureus biofilm formation through an unknown pathway. This work identifies multiple heparin-binding proteins in S. aureus, and it reveals a potential mechanism through which heparin enhances biofilm capacity. Understanding the details of the heparin enhancement effect could guide future use of appropriate lock solutions for catheter implants.
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Goetz C, Tremblay YDN, Lamarche D, Blondeau A, Gaudreau AM, Labrie J, Malouin F, Jacques M. Coagulase-negative staphylococci species affect biofilm formation of other coagulase-negative and coagulase-positive staphylococci. J Dairy Sci 2017. [PMID: 28624271 DOI: 10.3168/jds.2017-12629] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Coagulase-negative staphylococci (CNS) are considered to be commensal bacteria in humans and animals, but are now also recognized as etiological agents in several infections, including bovine mastitis. Biofilm formation appears to be an important factor in CNS pathogenicity. Furthermore, some researchers have proposed that CNS colonization of the intramammary environment has a protective effect against other pathogens. The mechanisms behind the protective effect of CNS have yet to be characterized. The aim of this study was to evaluate the effect of CNS isolates with a weak-biofilm phenotype on the biofilm formation of other staphylococcal isolates. We selected 10 CNS with a weak-biofilm phenotype and 30 staphylococcal isolates with a strong-biofilm phenotype for this study. We measured biofilm production by individual isolates using a standard polystyrene microtiter plate assay and compared the findings with biofilm produced in mixed cultures. We confirmed the results using confocal microscopy and a microfluidic system with low shear force. Four of the CNS isolates with a weak-biofilm phenotype (Staphylococcus chromogenes C and E and Staphylococcus simulans F and H) significantly reduced biofilm formation in approximately 80% of the staphylococcal species tested, including coagulase-positive Staphylococcus aureus. The 4 Staph. chromogenes and Staph. simulans isolates were also able to disperse pre-established biofilms, but to a lesser extent. We also performed a deferred antagonism assay and recorded the number of colony-forming units in the mixed-biofilm assays on differential or selective agar plates. Overall, CNS with a weak-biofilm phenotype did not inhibit the growth of isolates with a strong-biofilm phenotype. These results suggest that some CNS isolates can negatively affect the ability of other staphylococcal isolates and species to form biofilms via a mechanism that does not involve growth inhibition.
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Affiliation(s)
- Coralie Goetz
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Québec, Canada J2S 2M2; Canadian Bovine Mastitis and Milk Quality Research Network, St-Hyacinthe, Québec, Canada J2S 2M2
| | - Yannick D N Tremblay
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Québec, Canada J2S 2M2; Canadian Bovine Mastitis and Milk Quality Research Network, St-Hyacinthe, Québec, Canada J2S 2M2
| | - Daphnée Lamarche
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Québec, Canada J2S 2M2
| | - Andréanne Blondeau
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Québec, Canada J2S 2M2
| | - Annie M Gaudreau
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Québec, Canada J2S 2M2
| | - Josée Labrie
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Québec, Canada J2S 2M2
| | - François Malouin
- Canadian Bovine Mastitis and Milk Quality Research Network, St-Hyacinthe, Québec, Canada J2S 2M2; Department of Biology, Faculty of Science, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1
| | - Mario Jacques
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, St-Hyacinthe, Québec, Canada J2S 2M2; Canadian Bovine Mastitis and Milk Quality Research Network, St-Hyacinthe, Québec, Canada J2S 2M2.
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Guilhen C, Forestier C, Balestrino D. Biofilm dispersal: multiple elaborate strategies for dissemination of bacteria with unique properties. Mol Microbiol 2017; 105:188-210. [PMID: 28422332 DOI: 10.1111/mmi.13698] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2017] [Indexed: 01/22/2023]
Abstract
In most environments, microorganisms evolve in a sessile mode of growth, designated as biofilm, which is characterized by cells embedded in a self-produced extracellular matrix. Although a biofilm is commonly described as a "cozy house" where resident bacteria are protected from aggression, bacteria are able to break their biofilm bonds and escape to colonize new environments. This regulated process is observed in a wide variety of species; it is referred to as biofilm dispersal, and is triggered in response to various environmental and biological signals. The first part of this review reports the main regulatory mechanisms and effectors involved in biofilm dispersal. There is some evidence that dispersal is a necessary step between the persistence of bacteria inside biofilm and their dissemination. In the second part, an overview of the main methods used so far to study the dispersal process and to harvest dispersed bacteria was provided. Then focus was on the properties of the biofilm-dispersed bacteria and the fundamental role of the dispersal process in pathogen dissemination within a host organism. In light of the current body of knowledge, it was suggested that dispersal acts as a potent means of disseminating bacteria with enhanced colonization properties in the surrounding environment.
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Affiliation(s)
- Cyril Guilhen
- Laboratoire Microorganismes : Génome et Environnement, UMR CNRS 6023, Université Clermont Auvergne, Clermont Ferrand, F-63001, France
| | - Christiane Forestier
- Laboratoire Microorganismes : Génome et Environnement, UMR CNRS 6023, Université Clermont Auvergne, Clermont Ferrand, F-63001, France
| | - Damien Balestrino
- Laboratoire Microorganismes : Génome et Environnement, UMR CNRS 6023, Université Clermont Auvergne, Clermont Ferrand, F-63001, France
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Moormeier DE, Bayles KW. Staphylococcus aureus biofilm: a complex developmental organism. Mol Microbiol 2017; 104:365-376. [PMID: 28142193 DOI: 10.1111/mmi.13634] [Citation(s) in RCA: 307] [Impact Index Per Article: 43.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/24/2017] [Indexed: 12/11/2022]
Abstract
Chronic biofilm-associated infections caused by Staphylococcus aureus often lead to significant increases in morbidity and mortality, particularly when associated with indwelling medical devices. This has triggered a great deal of research attempting to understand the molecular mechanisms that control S. aureus biofilm formation and the basis for the recalcitrance of these multicellular structures to antibiotic therapy. The purpose of this review is to summarize our current understanding of S. aureus biofilm development, focusing on the description of a newly-defined, five-stage model of biofilm development and the mechanisms required for each stage. Importantly, this model includes an alternate view of the processes involved in microcolony formation in S. aureus and suggests that these structures originate as a result of stochastically regulated metabolic heterogeneity and proliferation within a maturing biofilm population, rather than a subtractive process involving the release of cell clusters from a thick, unstructured biofilm. Importantly, it is proposed that this new model of biofilm development involves the genetically programmed generation of metabolically distinct subpopulations of cells, resulting in an overall population that is better able to adapt to rapidly changing environmental conditions.
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Affiliation(s)
- Derek E Moormeier
- Center for Staphylococcal Research, Department of Pathology & Microbiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Kenneth W Bayles
- Center for Staphylococcal Research, Department of Pathology & Microbiology, University of Nebraska Medical Center, Omaha, NE, USA
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49
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Antibiotic tolerance and the alternative lifestyles of Staphylococcus aureus. Essays Biochem 2017; 61:71-79. [PMID: 28258231 DOI: 10.1042/ebc20160061] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 11/22/2016] [Accepted: 11/25/2016] [Indexed: 12/11/2022]
Abstract
Staphylococcus aureus has an incredible ability to survive, either by adapting to environmental conditions or defending against exogenous stress. Although there are certainly important genetic traits, in part this ability is provided by the breadth of modes of growth S. aureus can adopt. It has been proposed that while within their host, S. aureus survives host-generated and therapeutic antimicrobial stress via alternative lifestyles: a persister sub-population, through biofilm growth on host tissue or by growing as small colony variants (SCVs). Key to an understanding of chronic and relapsing S. aureus infections is determining the molecular basis for its switch to these quasi-dormant lifestyles. In a multicellular biofilm, the metabolically quiescent bacterial community additionally produces a highly protective extracellular polymeric substance (EPS). Furthermore, there are bacteria within a biofilm community that have an altered physiology potentially equivalent to persister cells. Recent studies have directly linked the cellular ATP production by persister cells as their key feature and the basis for their tolerance of a range of antibiotics. In clinical settings, SCVs of S. aureus have been observed for many years; when cultured, these cells form non-pigmented colonies and are approximately ten times smaller than their counterparts. Various genotypic factors have been identified in attempts to characterize S. aureus SCVs and different environmental stresses have been implicated as important inducers.
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Rice KC, Turner ME, Carney OV, Gu T, Ahn SJ. Modification of the Streptococcus mutans transcriptome by LrgAB and environmental stressors. Microb Genom 2017; 3:e000104. [PMID: 28348880 PMCID: PMC5361627 DOI: 10.1099/mgen.0.000104] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 12/20/2016] [Indexed: 12/14/2022] Open
Abstract
The Streptococcus mutans Cid/Lrg system is central to the physiology of this cariogenic organism, affecting oxidative stress resistance, biofilm formation and competence. Previous transcriptome analyses of lytS (responsible for the regulation of lrgAB expression) and cidB mutants have revealed pleiotropic effects on carbohydrate metabolism and stress resistance genes. In this study, it was found that an lrgAB mutant, previously shown to have diminished aerobic and oxidative stress growth, was also much more growth impaired in the presence of heat and vancomycin stresses, relative to wild-type, lrgA and lrgB mutants. To obtain a more holistic picture of LrgAB and its involvement in stress resistance, RNA sequencing and bioinformatics analyses were used to assess the transcriptional response of wild-type and isogenic lrgAB mutants under anaerobic (control) and stress-inducing culture conditions (aerobic, heat and vancomycin). Hierarchical clustering and principal components analyses of all differentially expressed genes revealed that the most distinct gene expression profiles between S. mutans UA159 and lrgAB mutant occurred during aerobic and high-temperature growth. Similar to previous studies of a cidB mutant, lrgAB stress transcriptomes were characterized by a variety of gene expression changes related to genomic islands, CRISPR-C as systems, ABC transporters, competence, bacteriocins, glucosyltransferases, protein translation, tricarboxylic acid cycle, carbohydrate metabolism/storage and transport. Notably, expression of lrgAB was upregulated in the wild-type strain under all three stress conditions. Collectively, these results demonstrate that mutation of lrgAB alters the transcriptional response to stress, and further support the idea that the Cid/Lrg system acts to promote cell homeostasis in the face of environmental stress.
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Affiliation(s)
- Kelly C Rice
- 1Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA
| | - Matthew E Turner
- 1Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA
| | - O'neshia V Carney
- 1Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.,†Present address: Department of Health Outcomes and Policy, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Tongjun Gu
- 2Bioinformatics, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32610, USA
| | - Sang-Joon Ahn
- 3Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610, USA
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