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Elbediwi M, Rolff J. Metabolic pathways and antimicrobial peptide resistance in bacteria. J Antimicrob Chemother 2024; 79:1473-1483. [PMID: 38742645 DOI: 10.1093/jac/dkae128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024] Open
Abstract
Antimicrobial resistance is a pressing concern that poses a significant threat to global public health, necessitating the exploration of alternative strategies to combat drug-resistant microbial infections. Recently, antimicrobial peptides (AMPs) have gained substantial attention as possible replacements for conventional antibiotics. Because of their pharmacodynamics and killing mechanisms, AMPs display a lower risk of bacterial resistance evolution compared with most conventional antibiotics. However, bacteria display different mechanisms to resist AMPs, and the role of metabolic pathways in the resistance mechanism is not fully understood. This review examines the intricate relationship between metabolic genes and AMP resistance, focusing on the impact of metabolic pathways on various aspects of resistance. Metabolic pathways related to guanosine pentaphosphate (pppGpp) and guanosine tetraphosphate (ppGpp) [collectively (p)ppGpp], the tricarboxylic acid (TCA) cycle, haem biosynthesis, purine and pyrimidine biosynthesis, and amino acid and lipid metabolism influence in different ways metabolic adjustments, biofilm formation and energy production that could be involved in AMP resistance. By targeting metabolic pathways and their associated genes, it could be possible to enhance the efficacy of existing antimicrobial therapies and overcome the challenges exhibited by phenotypic (recalcitrance) and genetic resistance toward AMPs. Further research in this area is needed to provide valuable insights into specific mechanisms, uncover novel therapeutic targets, and aid in the fight against antimicrobial resistance.
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Affiliation(s)
- Mohammed Elbediwi
- Evolutionary Biology, Institute for Biology, Freie Universität Berlin, 14195 Berlin, Germany
- Animal Health Research Institute, Agriculture Research Centre, 12618 Cairo, Egypt
| | - Jens Rolff
- Evolutionary Biology, Institute for Biology, Freie Universität Berlin, 14195 Berlin, Germany
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
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2
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Choi SY, Chung IY, Bae HW, Cho YH. Autolysis of Pseudomonas aeruginosa Quorum-Sensing Mutant Is Suppressed by Staphylococcus aureus through Iron-Dependent Metabolism. J Microbiol Biotechnol 2024; 34:795-803. [PMID: 38303126 DOI: 10.4014/jmb.2312.12028] [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: 12/19/2023] [Revised: 01/23/2024] [Accepted: 01/30/2024] [Indexed: 02/03/2024]
Abstract
Microorganisms usually coexist as a multifaceted polymicrobial community in the natural habitats and at mucosal sites of the human body. Two opportunistic human pathogens, Pseudomonas aeruginosa and Staphylococcus aureus commonly coexist in the bacterial infections for hospitalized and/or immunocompromised patients. Here, we observed that autolysis of the P. aeruginosa quorum-sensing (QS) mutant (lasRmvfR) was suppressed by the presence of the S. aureus cells in vitro. The QS mutant still displayed killing against S. aureus cells, suggesting the link between the S. aureus-killing activity and the autolysis suppression. Independent screens of the P. aeruginosa transposon mutants defective in the S. aureus-killing and the S. aureus transposon mutants devoid of the autolysis suppression revealed the genetic link between both phenotypes, suggesting that the iron-dependent metabolism involving S. aureus exoproteins might be central to both phenotypes. The autolysis was suppressed by iron treatment as well. These results suggest that the interaction between P. aeruginosa and S. aureus might be governed by mechanisms that necessitate the QS circuitry as well as the metabolism involving the extracellular iron resources during the polymicrobial infections in the human airway.
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Affiliation(s)
- Shin-Yae Choi
- Program of Biopharmaceutical Science and Department of Pharmacy, College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, Gyeonggi-do 13488, Republic of Korea
| | - In-Young Chung
- Program of Biopharmaceutical Science and Department of Pharmacy, College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, Gyeonggi-do 13488, Republic of Korea
| | - Hee-Won Bae
- Program of Biopharmaceutical Science and Department of Pharmacy, College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, Gyeonggi-do 13488, Republic of Korea
| | - You-Hee Cho
- Program of Biopharmaceutical Science and Department of Pharmacy, College of Pharmacy and Institute of Pharmaceutical Sciences, CHA University, Gyeonggi-do 13488, Republic of Korea
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3
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Maillard JY, Pascoe M. Disinfectants and antiseptics: mechanisms of action and resistance. Nat Rev Microbiol 2024; 22:4-17. [PMID: 37648789 DOI: 10.1038/s41579-023-00958-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2023] [Indexed: 09/01/2023]
Abstract
Chemical biocides are used for the prevention and control of infection in health care, targeted home hygiene or controlling microbial contamination for various industrial processes including but not limited to food, water and petroleum. However, their use has substantially increased since the implementation of programmes to control outbreaks of methicillin-resistant Staphylococcus aureus, Clostridioides difficile and severe acute respiratory syndrome coronavirus 2. Biocides interact with multiple targets on the bacterial cells. The number of targets affected and the severity of damage will result in an irreversible bactericidal effect or a reversible bacteriostatic one. Most biocides primarily target the cytoplasmic membrane and enzymes, although the specific bactericidal mechanisms vary among different biocide chemistries. Inappropriate usage or low concentrations of a biocide may act as a stressor while not killing bacterial pathogens, potentially leading to antimicrobial resistance. Biocides can also promote the transfer of antimicrobial resistance genes. In this Review, we explore our current understanding of the mechanisms of action of biocides, the bacterial resistance mechanisms encompassing both intrinsic and acquired resistance and the influence of bacterial biofilms on resistance. We also consider the impact of bacteria that survive biocide exposure in environmental and clinical contexts.
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Affiliation(s)
- Jean-Yves Maillard
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Wales, UK.
| | - Michael Pascoe
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Wales, UK
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4
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Becker K. Detection, Identification and Diagnostic Characterization of the Staphylococcal Small Colony-Variant (SCV) Phenotype. Antibiotics (Basel) 2023; 12:1446. [PMID: 37760742 PMCID: PMC10525764 DOI: 10.3390/antibiotics12091446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 09/08/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023] Open
Abstract
While modern molecular methods have decisively accelerated and improved microbiological diagnostics, phenotypic variants still pose a challenge for their detection, identification and characterization. This particularly applies if they are unstable and hard to detect, which is the case for the small-colony-variant (SCV) phenotype formed by staphylococci. On solid agar media, staphylococcal SCVs are characterized by tiny colonies with deviant colony morphology. Their reduced growth rate and fundamental metabolic changes are the result of their adaptation to an intracellular lifestyle, regularly leading to specific auxotrophies, such as for menadione, hemin or thymidine. These alterations make SCVs difficult to recognize and render physiological, biochemical and other growth-based methods such as antimicrobial susceptibility testing unreliable or unusable. Therefore, diagnostic procedures require prolonged incubation times and, if possible, confirmation by molecular methods. A special approach is needed for auxotrophy testing. However, standardized protocols for SCV diagnostics are missing. If available, SCVs and their putative parental isolates should be genotyped to determine clonality. Since their detection has significant implications for the treatment of the infection, which is usually chronic and relapsing, SCV findings should be specifically reported, commented on, and managed in close collaboration with the microbiological laboratory and the involved clinicians.
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Affiliation(s)
- Karsten Becker
- Friedrich Loeffler-Institute of Medical Microbiology, University Medicine Greifswald, Ferdinand-Sauerbruch-Straße 1, 17489 Greifswald, Germany
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5
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Lee BS, Singh S, Pethe K. Inhibiting respiration as a novel antibiotic strategy. Curr Opin Microbiol 2023; 74:102327. [PMID: 37235914 DOI: 10.1016/j.mib.2023.102327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/17/2023] [Accepted: 04/21/2023] [Indexed: 05/28/2023]
Abstract
The approval of the first-in-class antibacterial bedaquiline for tuberculosis marks a breakthrough in antituberculosis drug development. The drug inhibits mycobacterial respiration and represents the validation of a wholly different metabolic process as a druggable target space. In this review, we discuss the advances in the development of mycobacterial respiratory inhibitors, as well as the potential of applying this strategy to other pathogens. The non-fermentative nature of mycobacteria explains their vulnerability to respiration inhibition, and we caution that this strategy may not be equally effective in other organisms. Conversely, we also showcase fundamental studies that reveal ancillary functions of the respiratory pathway, which are crucial to some pathogens' virulence, drug susceptibility and fitness, introducing another perspective of targeting bacterial respiration as an antibiotic strategy.
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Affiliation(s)
- Bei Shi Lee
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 636921, Singapore.
| | - Samsher Singh
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 636921, Singapore
| | - Kevin Pethe
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 636921, Singapore; Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, 637551, Singapore; National Centre for Infectious Diseases, Singapore 308442, Singapore.
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6
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Islam S, Callender AC, Ho QN, Wakeman CA. Iron restriction induces the small-colony variant phenotype in Staphylococcus aureus. Front Microbiol 2022; 13:978859. [PMID: 36569073 PMCID: PMC9772265 DOI: 10.3389/fmicb.2022.978859] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 11/21/2022] [Indexed: 12/13/2022] Open
Abstract
Pathogens such as Staphylococcus aureus must overcome host-induced selective pressures, including limited iron availability. To cope with the harsh conditions of the host environment, S. aureus can adapt its physiology in multiple ways. One of these adaptations is the fermenting small-colony variant (SCV) phenotype, which is known to be inherently tolerant to certain classes of antibiotics and heme toxicity. We hypothesized that SCVs might also behave uniquely in response to iron starvation since one of the major cellular uses of iron is the respiration machinery. In this study, a respiring strain of S. aureus and fermenting SCV strains were treated with different concentrations of the iron chelator, 2,2' dipyridyl (DIP). Our data demonstrate that a major impact of iron starvation in S. aureus is the repression of respiration and the induction of the SCV phenotype. We demonstrate that the SCV phenotype transiently induced by iron starvation mimics the aminoglycoside recalcitrance exhibited by genetic SCVs. Furthermore, prolonged growth in iron starvation promotes increased emergence of stable aminoglycoside-resistant SCVs relative to the naturally occurring subpopulation of SCVs within an S. aureus community. These findings may have relevance to physiological and evolutionary processes occurring within bacterial populations infecting iron-limited host environments.
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Affiliation(s)
| | | | | | - Catherine A. Wakeman
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, United States
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Mutation to
ispA
Produces Stable Small-Colony Variants of Pseudomonas aeruginosa That Have Enhanced Aminoglycoside Resistance. Antimicrob Agents Chemother 2022; 66:e0062122. [PMID: 35852364 PMCID: PMC9295567 DOI: 10.1128/aac.00621-22] [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] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa is a major pathogen in burn wound infections. We present one of the first reports of small-colony variant (SCV) emergence of P. aeruginosa, taken from a patient under aminoglycosides for a persistent burn wound infection. We confirm the causative role of a single ispA mutation in SCV emergence and increased aminoglycoside resistance. IspA is involved in the synthesis of ubiquinone, providing a possible link between electron transport and SCV formation in P. aeruginosa.
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8
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Zhou S, Rao Y, Li J, Huang Q, Rao X. Staphylococcus aureus small-colony variants: Formation, infection, and treatment. Microbiol Res 2022; 260:127040. [DOI: 10.1016/j.micres.2022.127040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 04/10/2022] [Accepted: 04/11/2022] [Indexed: 10/18/2022]
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9
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Beavers WN, Munneke MJ, Stackhouse AR, Freiberg JA, Skaar EP. Host Polyunsaturated Fatty Acids Potentiate Aminoglycoside Killing of Staphylococcus aureus. Microbiol Spectr 2022; 10:e0276721. [PMID: 35377191 PMCID: PMC9045252 DOI: 10.1128/spectrum.02767-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/15/2022] [Indexed: 12/21/2022] Open
Abstract
Aminoglycoside antibiotics rely on the proton motive force to enter the bacterial cell, and facultative anaerobes like Staphylococcus aureus can shift energy generation from respiration to fermentation, becoming tolerant of aminoglycosides. Following this metabolic shift, high concentrations of aminoglycosides are required to eradicate S. aureus infections, which endangers the host due to the toxicity of aminoglycosides. Membrane-disrupting molecules prevent aminoglycoside tolerance in S. aureus by facilitating passive entry of the drug through the membrane. Polyunsaturated fatty acids (PUFAs) increase membrane permeability when incorporated into S. aureus. Here, we report that the abundant host-derived PUFA arachidonic acid increases the susceptibility of S. aureus to aminoglycosides, decreasing the aminoglycoside concentration needed to kill S. aureus. We demonstrate that PUFAs and aminoglycosides synergize to kill multiple strains of S. aureus, including both methicillin-resistant and -susceptible S. aureus. We also present data showing that PUFAs and aminoglycosides effectively kill S. aureus small colony variants, strains that are particularly recalcitrant to killing by many antibiotics. We conclude that cotreatment with PUFAs, which are molecules with low host toxicity, and aminoglycosides decreases the aminoglycoside concentration necessary to kill S. aureus, lowering the toxic side effects to the host associated with prolonged aminoglycoside exposure. IMPORTANCE Staphylococcus aureus infects every niche of the human host, and these infections are the leading cause of Gram-positive sepsis. Aminoglycoside antibiotics are inexpensive, stable, and effective against many bacterial infections. However, S. aureus can shift its metabolism to become tolerant of aminoglycosides, requiring increased concentrations and/or longer courses of treatment, which can cause severe host toxicity. Here, we report that polyunsaturated fatty acids (PUFAs), which have low host toxicity, disrupt the S. aureus membrane, making the pathogen susceptible to aminoglycosides. Additionally, cotreatment with aminoglycosides is effective at killing S. aureus small colony variants, strains that are difficult to treat with antibiotics. Taken together, the data presented herein show the promise of PUFA cotreatment to increase the efficacy of aminoglycosides against S. aureus infections and decrease the risk to the human host of antibiotic-induced toxicity.
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Affiliation(s)
- William N. Beavers
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Department of Pathobiological Sciences, Louisiana State University and Agricultural and Mechanical College, School of Veterinary Medicine, Baton Rouge, Louisiana, USA
| | - Matthew J. Munneke
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Alex R. Stackhouse
- Department of Pathobiological Sciences, Louisiana State University and Agricultural and Mechanical College, School of Veterinary Medicine, Baton Rouge, Louisiana, USA
| | - Jeffrey A. Freiberg
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Eric P. Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Vanderbilt Institute for Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
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10
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Perry EK, Meirelles LA, Newman DK. From the soil to the clinic: the impact of microbial secondary metabolites on antibiotic tolerance and resistance. Nat Rev Microbiol 2022; 20:129-142. [PMID: 34531577 PMCID: PMC8857043 DOI: 10.1038/s41579-021-00620-w] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/02/2021] [Indexed: 02/08/2023]
Abstract
Secondary metabolites profoundly affect microbial physiology, metabolism and stress responses. Increasing evidence suggests that these molecules can modulate microbial susceptibility to commonly used antibiotics; however, secondary metabolites are typically excluded from standard antimicrobial susceptibility assays. This may in part account for why infections by diverse opportunistic bacteria that produce secondary metabolites often exhibit discrepancies between clinical antimicrobial susceptibility testing results and clinical treatment outcomes. In this Review, we explore which types of secondary metabolite alter antimicrobial susceptibility, as well as how and why this phenomenon occurs. We discuss examples of molecules that opportunistic and enteric pathogens either generate themselves or are exposed to from their neighbours, and the nuanced impacts these molecules can have on tolerance and resistance to certain antibiotics.
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Affiliation(s)
- Elena K Perry
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Lucas A Meirelles
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Dianne K Newman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
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11
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Khan NA, Kaur N, Owens P, Thomas OP, Boyd A. Bis-Indole Alkaloids Isolated from the Sponge Spongosorites calcicola Disrupt Cell Membranes of MRSA. Int J Mol Sci 2022; 23:ijms23041991. [PMID: 35216106 PMCID: PMC8874442 DOI: 10.3390/ijms23041991] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/06/2022] [Accepted: 02/08/2022] [Indexed: 02/01/2023] Open
Abstract
Antimicrobial resistance (AMR) is a global health challenge with methicillin resistant Staphylococcus aureus (MRSA), a leading cause of nosocomial infection. In the search for novel antibiotics, marine sponges have become model organisms as they produce diverse bioactive compounds. We investigated and compared the antibacterial potential of 3 bis-indole alkaloids—bromodeoxytopsentin, bromotopsentin and spongotine A—isolated from the Northeastern Atlantic sponge Spongosorites calcicola. Antimicrobial activity was determined by MIC and time-kill assays. The mechanism of action of bis-indoles was assessed using bacterial cytological profiling via fluorescence microscopy. Finally, we investigated the ability of bis-indole alkaloids to decrease the cytotoxicity of pathogens upon co-incubation with HeLa cells through the measurement of mammalian cell lysis. The bis-indoles were bactericidal to clinically relevant Gram-positive pathogens including MRSA and to the Gram-negative gastroenteric pathogen Vibrio parahaemolyticus. Furthermore, the alkaloids were synergistic in combination with conventional antibiotics. Antimicrobial activity of the bis-indole alkaloids was due to rapid disruption and permeabilization of the bacterial cell membrane. Significantly, the bis-indoles reduced pathogen cytotoxicity toward mammalian cells, indicating their ability to prevent bacterial virulence. In conclusion, sponge bis-indole alkaloids are membrane-permeabilizing agents that represent good antibiotic candidates because of their potency against Gram-positive and Gram-negative bacterial pathogens.
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Affiliation(s)
- Neyaz A. Khan
- Discipline of Microbiology, School of Natural Sciences and Ryan Institute, National University of Ireland Galway, H91 TK33 Galway, Ireland;
| | - Navdeep Kaur
- Discipline of Chemistry, School of Biological and Chemical Science and Ryan Institute, National University of Ireland Galway, H91 TK33 Galway, Ireland; (N.K.); (O.P.T.)
| | - Peter Owens
- Centre for Microscopy and Imaging, National University of Ireland, Galway, H91 TK33 Galway, Ireland;
| | - Olivier P. Thomas
- Discipline of Chemistry, School of Biological and Chemical Science and Ryan Institute, National University of Ireland Galway, H91 TK33 Galway, Ireland; (N.K.); (O.P.T.)
| | - Aoife Boyd
- Discipline of Microbiology, School of Natural Sciences and Ryan Institute, National University of Ireland Galway, H91 TK33 Galway, Ireland;
- Correspondence: ; Tel.: +353-(0)91-492404
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12
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Díaz Calvo T, Tejera N, McNamara I, Langridge GC, Wain J, Poolman M, Singh D. Genome-Scale Metabolic Modelling Approach to Understand the Metabolism of the Opportunistic Human Pathogen Staphylococcus epidermidis RP62A. Metabolites 2022; 12:metabo12020136. [PMID: 35208211 PMCID: PMC8874387 DOI: 10.3390/metabo12020136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/18/2022] [Accepted: 01/29/2022] [Indexed: 02/01/2023] Open
Abstract
Staphylococcus epidermidis is a common commensal of collagen-rich regions of the body, such as the skin, but also represents a threat to patients with medical implants (joints and heart), and to preterm babies. Far less studied than Staphylococcus aureus, the mechanisms behind this increasingly recognised pathogenicity are yet to be fully understood. Improving our knowledge of the metabolic processes that allow S. epidermidis to colonise different body sites is key to defining its pathogenic potential. Thus, we have constructed a fully curated, genome-scale metabolic model for S. epidermidis RP62A, and investigated its metabolic properties with a focus on substrate auxotrophies and its utilisation for energy and biomass production. Our results show that, although glucose is available in the medium, only a small portion of it enters the glycolytic pathways, whils most is utilised for the production of biofilm, storage and the structural components of biomass. Amino acids, proline, valine, alanine, glutamate and arginine, are preferred sources of energy and biomass production. In contrast to previous studies, we have shown that this strain has no real substrate auxotrophies, although removal of proline from the media has the highest impact on the model and the experimental growth characteristics. Further study is needed to determine the significance of proline, an abundant amino acid in collagen, in S. epidermidis colonisation.
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Affiliation(s)
- Teresa Díaz Calvo
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK;
| | - Noemi Tejera
- Microbes in the Food Chain, Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; (N.T.); (G.C.L.); (J.W.)
| | - Iain McNamara
- Norwich Medical School, University of East Anglia, Norwich NR4 7UQ, UK;
- Department of Orthopaedics and Trauma, Norfolk and Norwich University Hospital NHS Foundation Trust, Norwich NR4 7UY, UK
| | - Gemma C. Langridge
- Microbes in the Food Chain, Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; (N.T.); (G.C.L.); (J.W.)
| | - John Wain
- Microbes in the Food Chain, Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; (N.T.); (G.C.L.); (J.W.)
- Norwich Medical School, University of East Anglia, Norwich NR4 7UQ, UK;
| | - Mark Poolman
- Cell System Modelling Group, Oxford Brookes University, Oxford OX3 OBP, UK;
| | - Dipali Singh
- Microbes in the Food Chain, Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, UK; (N.T.); (G.C.L.); (J.W.)
- Correspondence:
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13
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Guo H, Tong Y, Cheng J, Abbas Z, Li Z, Wang J, Zhou Y, Si D, Zhang R. Biofilm and Small Colony Variants-An Update on Staphylococcus aureus Strategies toward Drug Resistance. Int J Mol Sci 2022; 23:ijms23031241. [PMID: 35163165 PMCID: PMC8835882 DOI: 10.3390/ijms23031241] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/16/2022] [Accepted: 01/20/2022] [Indexed: 02/07/2023] Open
Abstract
Recently, the drawbacks arising from the overuse of antibiotics have drawn growing public attention. Among them, drug-resistance (DR) and even multidrug-resistance (MDR) pose significant challenges in clinical practice. As a representative of a DR or MDR pathogen, Staphylococcus aureus can cause diversity of infections related to different organs, and can survive or adapt to the diverse hostile environments by switching into other phenotypes, including biofilm and small colony variants (SCVs), with altered physiologic or metabolic characteristics. In this review, we briefly describe the development of the DR/MDR as well as the classical mechanisms (accumulation of the resistant genes). Moreover, we use multidimensional scaling analysis to evaluate the MDR relevant hotspots in the recent published reports. Furthermore, we mainly focus on the possible non-classical resistance mechanisms triggered by the two important alternative phenotypes of the S. aureus, biofilm and SCVs, which are fundamentally caused by the different global regulation of the S. aureus population, such as the main quorum-sensing (QS) and agr system and its coordinated regulated factors, such as the SarA family proteins and the alternative sigma factor σB (SigB). Both the biofilm and the SCVs are able to escape from the host immune response, and resist the therapeutic effects of antibiotics through the physical or the biological barriers, and become less sensitive to some antibiotics by the dormant state with the limited metabolisms.
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14
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Douglas EJA, Duggan S, Brignoli T, Massey RC. The MpsB protein contributes to both the toxicity and immune evasion capacity of Staphylococcus aureus. MICROBIOLOGY-SGM 2021; 167. [PMID: 34618666 PMCID: PMC8698210 DOI: 10.1099/mic.0.001096] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Understanding the role specific bacterial factors play in the development of severe disease in humans is critical if new approaches to tackle such infections are to be developed. In this study we focus on genes we have found to be associated with patient outcome following bacteraemia caused by the major human pathogen Staphylococcus aureus. By examining the contribution these genes make to the ability of the bacteria to survive exposure to the antibacterial factors found in serum, we identify three novel serum resistance-associated genes, mdeA, mpsB and yycH. Detailed analysis of an MpsB mutant supports its previous association with the slow growing small colony variant (SCV) phenotype of S. aureus, and we demonstrate that the effect this mutation has on membrane potential prevents the activation of the Agr quorum sensing system, and as a consequence the mutant bacteria do not produce cytolytic toxins. Given the importance of both toxin production and immune evasion for the ability of S. aureus to cause disease, we believe that these findings explain the role of the mpsB gene as a mortality-associated locus during human disease.
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Affiliation(s)
- Edward J A Douglas
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK
| | - Seána Duggan
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK
| | - Tarcisio Brignoli
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK
| | - Ruth C Massey
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, BS8 1TD, UK.,Schools of Microbiology and Medicine, University College Cork and APC Microbiome Ireland, Cork, Ireland
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15
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Zhang X, Huang D, Zhao Z, Cai X, Cai W, Li G. Bis-molybdopterin guanine dinucleotide modulates hemolysin expression under anaerobiosis and contributes to fitness in vivo in uropathogenic Escherichia coli. Mol Microbiol 2021; 116:1216-1231. [PMID: 34494331 DOI: 10.1111/mmi.14809] [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] [Received: 04/30/2021] [Revised: 08/31/2021] [Accepted: 09/05/2021] [Indexed: 01/10/2023]
Abstract
Uropathogenic Escherichia coli (UPEC) is the primary causative agent of urinary tract infections (UTIs). Successful urinary tract colonization requires appropriate expression of virulence factors in response to host environmental cues, such as limited oxygen and iron availability. Hemolysin is a pore-forming toxin, and its expression correlates with the severity of UPEC infection. Previously, we showed that hemolysin expression is enhanced under anaerobic conditions; however, the genetic basis and regulatory mechanisms involved remain undefined. Here, a transposon-based forward screen identified bis-molybdopterin guanine dinucleotide cofactor (bis-MGD) biosynthesis as an important factor for a full transcription of hemolysin under anaerobiosis but not under aerobiosis. bis-MGD positively influences hemolysin transcription via c3566-c3568, an operon immediately upstream of and cotranscribed with hlyCABD. Furthermore, suppressor mutation analysis identified the nitrogen regulator NtrC as a direct repressor of c3566-c3568-hlyCABD expression, and intact bis-MGD biosynthesis downregulated ntrC expression, thus at least partially explaining the positive role of bis-MGD in modulating hemolysin expression. Finally, bis-MGD is involved in hemolysin-mediated uroepithelial cell death and contributes to the competitive fitness of UPEC in a murine model of UTI. Collectively, our data establish that bis-MGD biosynthesis plays a crucial role in UPEC fitness in vivo, thus providing a potential target for combatting UTIs.
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Affiliation(s)
- Xinyang Zhang
- Key Laboratory of Veterinary Public Health of Ministry of Agriculture, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Dongyan Huang
- Jiangxi Engineering Research Center for Animal Health Products, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China.,Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | - Zihui Zhao
- Key Laboratory of Veterinary Public Health of Ministry of Agriculture, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Xuwang Cai
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
| | - Wentong Cai
- Key Laboratory of Veterinary Public Health of Ministry of Agriculture, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Ganwu Li
- Key Laboratory of Veterinary Public Health of Ministry of Agriculture, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.,Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
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16
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Pilát Z, Jonáš A, Pilátová J, Klementová T, Bernatová S, Šiler M, Maňka T, Kizovský M, Růžička F, Pantůček R, Neugebauer U, Samek O, Zemánek P. Analysis of Bacteriophage-Host Interaction by Raman Tweezers. Anal Chem 2020; 92:12304-12311. [PMID: 32815709 DOI: 10.1021/acs.analchem.0c01963] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bacteriophages, or "phages" for short, are viruses that replicate in bacteria. The therapeutic and biotechnological potential of phages and their lytic enzymes is of interest for their ability to selectively destroy pathogenic bacteria, including antibiotic-resistant strains. Introduction of phage preparations into medicine, biotechnology, and food industry requires a thorough characterization of phage-host interaction on a molecular level. We employed Raman tweezers to analyze the phage-host interaction of Staphylococcus aureus strain FS159 with a virulent phage JK2 (=812K1/420) of the Myoviridae family and a temperate phage 80α of the Siphoviridae family. We analyzed the timeline of phage-induced molecular changes in infected host cells. We reliably detected the presence of replicating phages in bacterial cells within 5 min after infection. Our results lay the foundations for building a Raman-based diagnostic instrument capable of real-time, in vivo, in situ, nondestructive characterization of the phage-host relationship on the level of individual cells, which has the potential of importantly contributing to the development of phage therapy and enzybiotics.
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Affiliation(s)
- Zdeněk Pilát
- Institute of Scientific Instruments of the Czech Academy of Sciences, v.v.i., Czech Academy of Sciences, Královopolská 147, 612 64 Brno, Czech Republic
| | - Alexandr Jonáš
- Institute of Scientific Instruments of the Czech Academy of Sciences, v.v.i., Czech Academy of Sciences, Královopolská 147, 612 64 Brno, Czech Republic
| | - Jana Pilátová
- Department of Experimental Plant Biology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
| | - Tereza Klementová
- Institute of Scientific Instruments of the Czech Academy of Sciences, v.v.i., Czech Academy of Sciences, Královopolská 147, 612 64 Brno, Czech Republic
| | - Silvie Bernatová
- Institute of Scientific Instruments of the Czech Academy of Sciences, v.v.i., Czech Academy of Sciences, Královopolská 147, 612 64 Brno, Czech Republic
| | - Martin Šiler
- Institute of Scientific Instruments of the Czech Academy of Sciences, v.v.i., Czech Academy of Sciences, Královopolská 147, 612 64 Brno, Czech Republic
| | - Tadeáš Maňka
- Institute of Scientific Instruments of the Czech Academy of Sciences, v.v.i., Czech Academy of Sciences, Královopolská 147, 612 64 Brno, Czech Republic
| | - Martin Kizovský
- Institute of Scientific Instruments of the Czech Academy of Sciences, v.v.i., Czech Academy of Sciences, Královopolská 147, 612 64 Brno, Czech Republic
| | - Filip Růžička
- Department of Microbiology, Faculty of Medicine, Masaryk University and St. Anne's Faculty Hospital, Pekařská 53, 656 91 Brno, Czech Republic
| | - Roman Pantůček
- Department of Experimental Biology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic
| | - Ute Neugebauer
- Center for Sepsis Control and Care (CSCC), Jena University Hospital, Am Klinikum 1, D-07747 Jena, Germany.,Leibniz Institute of Photonic Technology (Leibniz-IPHT), Albert-Einstein-Str. 9, D-07745 Jena, Germany
| | - Ota Samek
- Institute of Scientific Instruments of the Czech Academy of Sciences, v.v.i., Czech Academy of Sciences, Královopolská 147, 612 64 Brno, Czech Republic
| | - Pavel Zemánek
- Institute of Scientific Instruments of the Czech Academy of Sciences, v.v.i., Czech Academy of Sciences, Královopolská 147, 612 64 Brno, Czech Republic
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17
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Rojas-Andrade MD, Nguyen TA, Mistler WP, Armas J, Lu JE, Roseman G, Hollingsworth WR, Nichols F, Millhauser GL, Ayzner A, Saltikov C, Chen S. Antimicrobial activity of graphene oxide quantum dots: impacts of chemical reduction. NANOSCALE ADVANCES 2020; 2:1074-1083. [PMID: 36133054 PMCID: PMC9417586 DOI: 10.1039/c9na00698b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 01/19/2020] [Indexed: 06/11/2023]
Abstract
Design and engineering of graphene-based functional nanomaterials for effective antimicrobial applications has been attracting extensive interest. In the present study, graphene oxide quantum dots (GOQDs) were prepared by chemical exfoliation of carbon fibers and exhibited apparent antimicrobial activity. Transmission electron microscopic measurements showed that the lateral length ranged from a few tens to a few hundred nanometers. Upon reduction by sodium borohydride, whereas the UV-vis absorption profile remained largely unchanged, steady-state photoluminescence measurements exhibited a marked blue-shift and increase in intensity of the emission, due to (partial) removal of phenanthroline-like structural defects within the carbon skeletons. Consistent results were obtained in Raman and time-resolved photoluminescence measurements. Interestingly, the samples exhibited apparent, but clearly different, antimicrobial activity against Staphylococcus epidermidis cells. In the dark and under photoirradiation (400 nm), the as-produced GOQDs exhibited markedly higher cytotoxicity than the chemically reduced counterparts, likely because of (i) effective removal by NaBH4 reduction of redox-active phenanthroline-like moieties that interacted with the electron-transport chain of the bacterial cells, and (ii) diminished production of hydroxyl radicals that were potent bactericidal agents after chemical reduction as a result of increased conjugation within the carbon skeletons.
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Affiliation(s)
- Mauricio D Rojas-Andrade
- Department of Chemistry and Biochemistry, University of California 1156 High Street Santa Cruz California 95064 USA
| | - Tuan Anh Nguyen
- Department of Chemistry and Biochemistry, University of California 1156 High Street Santa Cruz California 95064 USA
| | - William P Mistler
- Department of Chemistry and Biochemistry, University of California 1156 High Street Santa Cruz California 95064 USA
| | - Juan Armas
- Department of Chemistry and Biochemistry, University of California 1156 High Street Santa Cruz California 95064 USA
| | - Jia En Lu
- Department of Chemistry and Biochemistry, University of California 1156 High Street Santa Cruz California 95064 USA
| | - Graham Roseman
- Department of Chemistry and Biochemistry, University of California 1156 High Street Santa Cruz California 95064 USA
| | - William R Hollingsworth
- Department of Chemistry and Biochemistry, University of California 1156 High Street Santa Cruz California 95064 USA
| | - Forrest Nichols
- Department of Chemistry and Biochemistry, University of California 1156 High Street Santa Cruz California 95064 USA
| | - Glenn L Millhauser
- Department of Chemistry and Biochemistry, University of California 1156 High Street Santa Cruz California 95064 USA
| | - Alexander Ayzner
- Department of Chemistry and Biochemistry, University of California 1156 High Street Santa Cruz California 95064 USA
| | - Chad Saltikov
- Department of Microbiology and Environmental Toxicology, University of California 1156 High Street Santa Cruz California 95064 USA
| | - Shaowei Chen
- Department of Chemistry and Biochemistry, University of California 1156 High Street Santa Cruz California 95064 USA
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18
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Vidovic N, Vidovic S. Antimicrobial Resistance and Food Animals: Influence of Livestock Environment on the Emergence and Dissemination of Antimicrobial Resistance. Antibiotics (Basel) 2020; 9:antibiotics9020052. [PMID: 32023977 PMCID: PMC7168261 DOI: 10.3390/antibiotics9020052] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 01/26/2020] [Accepted: 01/27/2020] [Indexed: 02/07/2023] Open
Abstract
The emergence and dissemination of antimicrobial resistance among human, animal and zoonotic pathogens pose an enormous threat to human health worldwide. The use of antibiotics in human and veterinary medicine, and especially the use of large quantities of antibiotics in livestock for the purpose of growth promotion of food animals is believed to be contributing to the modern trend of the emergence and spread of bacteria with antibiotic resistant traits. To better control the emergence and spread of antimicrobial resistance several countries from Western Europe implemented a ban for antibiotic use in livestock, specifically the use of antibiotics for growth promotion of food animals. This review article summarizes the recent knowledge of molecular acquisition of antimicrobial resistance and the effects of implementation of antibiotic growth promoter bans on the spread of antimicrobial resistant bacteria in animals and humans. In this article, we also discuss the main zoonotic transmission routes of antimicrobial resistance and novel approaches designed to prevent or slow down the emergence and spread of antimicrobial resistance worldwide. Finally, we provide future perspectives associated with the control and management of the emergence and spread of antimicrobial resistant bacteria.
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Affiliation(s)
- Nikola Vidovic
- College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK S7K 4H3, Canada;
| | - Sinisa Vidovic
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108, USA
- Correspondence:
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19
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Proctor R. Respiration and Small Colony Variants of Staphylococcus aureus. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0069-2019. [PMID: 31198131 PMCID: PMC11257146 DOI: 10.1128/microbiolspec.gpp3-0069-2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Indexed: 12/16/2022] Open
Abstract
Respiratory mutants, both naturally occurring and genetically constructed, have taught us about the importance of metabolism in influencing virulence factor production, persistence, and antibiotic resistance. As we learn more about small colony variants, we find that Staphylococcus aureus has many pathways to produce small colony variants, although the respiratory variants are the best described clinically and in the laboratory.
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Affiliation(s)
- Richard Proctor
- Department of Medical Microbiology and Immunology University of Wisconsin School of Medicine and Public Health Madison, WI 53705
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20
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Zhang P, Wright JA, Tymon A, Nair SP. Bicarbonate induces high-level resistance to the human antimicrobial peptide LL-37 in Staphylococcus aureus small colony variants. J Antimicrob Chemother 2019; 73:615-619. [PMID: 29211886 PMCID: PMC5890704 DOI: 10.1093/jac/dkx433] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 10/25/2017] [Indexed: 01/29/2023] Open
Abstract
Objectives Staphylococcus aureus small colony variants (SCVs) cause persistent infections and are resistant to cationic antibiotics. Antimicrobial peptides (AMPs) have been suggested as promising alternatives for treating antibiotic-resistant bacteria. We investigated the capacity of the human cationic AMP LL-37 to kill SCVs in the presence of physiological concentrations of bicarbonate, which are reported to alter bacterial membrane permeability and change resistance of bacteria to AMPs. Methods MBCs of LL-37 for S. aureus SCVs with mutations in different genes in the presence and absence of bicarbonate were determined. Results In the absence of bicarbonate, SCVs of S. aureus strains LS-1 and 8325-4 had the same level of resistance to LL-37 as the parental strain (8 mg/L). In the presence of bicarbonate, hemB, menD and aroD SCVs of LS-1 had high-level resistance to LL-37 (≥128 mg/L) compared with the parental strain (16 mg/L). However, only the aroD SCV of strain 8324-5 showed high-level resistance. 8325-4 harbours mutations in two genes, tcaR and rsbU, which are involved in antimicrobial sensing and the stress response, respectively. When rsbU was repaired in 8325-4 it displayed high-level resistance to LL-37 in the presence of bicarbonate. This phenotype was lost when tcaR was also repaired, demonstrating that RsbU and TcaR are involved in LL-37 resistance in the presence of bicarbonate Conclusions S. aureus SCVs would be resistant to high concentrations of LL-37 in niches where there are physiological concentrations of bicarbonate and therefore this AMP may not be effective in combating SCVs.
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Affiliation(s)
- Ping Zhang
- Department of Microbial Diseases, UCL Eastman Dental Institute, 256 Gray's Inn Road, London WC1X 8LD, UK
| | - John A Wright
- Immunology Catalyst, GSK, Stevenage, Hertfordshire, UK
| | - Anna Tymon
- Department of Microbial Diseases, UCL Eastman Dental Institute, 256 Gray's Inn Road, London WC1X 8LD, UK
| | - Sean P Nair
- Department of Microbial Diseases, UCL Eastman Dental Institute, 256 Gray's Inn Road, London WC1X 8LD, UK
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21
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Transcriptome analysis of Burkholderia pseudomallei SCV reveals an association with virulence, stress resistance and intracellular persistence. Genomics 2019; 112:501-512. [PMID: 30980902 DOI: 10.1016/j.ygeno.2019.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 03/18/2019] [Accepted: 04/01/2019] [Indexed: 01/16/2023]
Abstract
Differences in expression of potential virulence and survival genes were associated with B. pseudomallei colony morphology variants. Microarray was used to investigate B. pseudomallei transcriptome alterations among the wild type and small colony variant (SCV) pre- and post-exposed to A549 cells. SCV pre- and post-exposed have lower metabolic requirements and consume lesser energy than the wild type pre- and post-exposed to A549. However, both the wild type and SCV limit their metabolic activities post- infection of A549 cells and this is indicated by the down-regulation of genes implicated in the metabolism of amino acids, carbohydrate, lipid, and other amino acids. Many well-known virulence and survival factors, including T3SS, fimbriae, capsular polysaccharides and stress response were up-regulated in both the wild type and SCV pre- and post-exposed to A549 cells. Microarray analysis demonstrated essential differences in bacterial response associated with virulence and survival pre- and post-exposed to A549 cells.
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22
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A High-Throughput Screening Approach To Repurpose FDA-Approved Drugs for Bactericidal Applications against Staphylococcus aureus Small-Colony Variants. mSphere 2018; 3:3/5/e00422-18. [PMID: 30381352 PMCID: PMC6211227 DOI: 10.1128/msphere.00422-18] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Conventional antibiotics fail to successfully treat chronic osteomyelitis, endocarditis, and device-related and airway infections. These recurring infections are associated with the emergence of SCV, which are recalcitrant to conventional antibiotics. Studies have investigated antibiotic therapies to treat SCV-related infections but have had little success, emphasizing the need to identify novel antimicrobial drugs. However, drug discovery is a costly and time-consuming process. An alternative strategy is drug repurposing, which could identify FDA-approved and well-characterized drugs that could have off-label utility in treating SCV. In this study, we adapted a high-throughput AK-based assay to identify 4 FDA-approved drugs, daunorubicin, ketoconazole, rifapentine, and sitafloxacin, which display antimicrobial activity against S. aureus SCV, suggesting an avenue for drug repurposing in order to effectively treat SCV-related infections. Additionally, this screening paradigm can easily be adapted for other drug/chemical libraries to identify compounds bactericidal against SCV. Drug repurposing offers an expedited and economical route to develop new clinical therapeutics in comparison to traditional drug development. Growth-based high-throughput screening is concomitant with drug repurposing and enables rapid identification of new therapeutic uses for investigated drugs; however, this traditional method is not compatible with microorganisms with abnormal growth patterns such as Staphylococcus aureus small-colony variants (SCV). SCV subpopulations are auxotrophic for key compounds in biosynthetic pathways, which result in low growth rate. SCV formation is also associated with reduced antibiotic susceptibility, and the SCV’s ability to revert to the normal cell growth state is thought to contribute to recurrence of S. aureus infections. Thus, there is a critical need to identify antimicrobial agents that are potent against SCV in order to effectively treat chronic infections. Accordingly, here we describe adapting an adenylate kinase (AK)-based cell death reporter assay to identify members of a Food and Drug Administration (FDA)-approved drug library that display bactericidal activity against S. aureus SCV. Four library members, daunorubicin, ketoconazole, rifapentine, and sitafloxacin, exhibited potent SCV bactericidal activity against a stable S. aureus SCV. Further investigation showed that sitafloxacin was potent against methicillin-susceptible and -resistant S. aureus, as well as S. aureus within an established biofilm. Taken together, these results demonstrate the ability to use the AK assay to screen small-molecule libraries for SCV bactericidal agents and highlight the therapeutic potential of sitafloxacin to be repurposed to treat chronic S. aureus infections associated with SCV and/or biofilm growth states. IMPORTANCE Conventional antibiotics fail to successfully treat chronic osteomyelitis, endocarditis, and device-related and airway infections. These recurring infections are associated with the emergence of SCV, which are recalcitrant to conventional antibiotics. Studies have investigated antibiotic therapies to treat SCV-related infections but have had little success, emphasizing the need to identify novel antimicrobial drugs. However, drug discovery is a costly and time-consuming process. An alternative strategy is drug repurposing, which could identify FDA-approved and well-characterized drugs that could have off-label utility in treating SCV. In this study, we adapted a high-throughput AK-based assay to identify 4 FDA-approved drugs, daunorubicin, ketoconazole, rifapentine, and sitafloxacin, which display antimicrobial activity against S. aureus SCV, suggesting an avenue for drug repurposing in order to effectively treat SCV-related infections. Additionally, this screening paradigm can easily be adapted for other drug/chemical libraries to identify compounds bactericidal against SCV.
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23
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Adaptive Metabolism in Staphylococci: Survival and Persistence in Environmental and Clinical Settings. J Pathog 2018; 2018:1092632. [PMID: 30327733 PMCID: PMC6171259 DOI: 10.1155/2018/1092632] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/28/2018] [Accepted: 08/12/2018] [Indexed: 01/04/2023] Open
Abstract
Staphylococci are highly successful at colonizing a variety of dynamic environments, both nonpathogenic and those of clinical importance, and comprise the list of pathogens of global public health significance. Their remarkable survival and persistence can be attributed to a host of strategies, one of which is metabolic versatility—their ability to rapidly alter their metabolism in the presence of transient or long-term bacteriostatic and bactericidal conditions and facilitate cellular homeostasis. These attributes contribute to their widespread dissemination and challenging eradication particularly from clinical settings. The study of microbial behaviour at the metabolite level provides insight into mechanisms of survival and persistence under defined environmental and clinical conditions. This paper reviews the range of metabolic modulations that facilitate staphylococcal acclimatization and persistence in varying terrestrial and host conditions, and their public health ramifications in these settings.
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24
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Ibacache-Quiroga C, Oliveros JC, Couce A, Blázquez J. Parallel Evolution of High-Level Aminoglycoside Resistance in Escherichia coli Under Low and High Mutation Supply Rates. Front Microbiol 2018; 9:427. [PMID: 29615988 PMCID: PMC5867336 DOI: 10.3389/fmicb.2018.00427] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 02/22/2018] [Indexed: 11/16/2022] Open
Abstract
Antibiotic resistance is a major concern in public health worldwide, thus there is much interest in characterizing the mutational pathways through which susceptible bacteria evolve resistance. Here we use experimental evolution to explore the mutational pathways toward aminoglycoside resistance, using gentamicin as a model, under low and high mutation supply rates. Our results show that both normo and hypermutable strains of Escherichia coli are able to develop resistance to drug dosages > 1,000-fold higher than the minimal inhibitory concentration for their ancestors. Interestingly, such level of resistance was often associated with changes in susceptibility to other antibiotics, most prominently with increased resistance to fosfomycin. Whole-genome sequencing revealed that all resistant derivatives presented diverse mutations in five common genetic elements: fhuA, fusA and the atpIBEFHAGDC, cyoABCDE, and potABCD operons. Despite the large number of mutations acquired, hypermutable strains did not pay, apparently, fitness cost. In contrast to recent studies, we found that the mutation supply rate mainly affected the speed (tempo) but not the pattern (mode) of evolution: both backgrounds acquired the mutations in the same order, although the hypermutator strain did it faster. This observation is compatible with the adaptive landscape for high-level gentamicin resistance being relatively smooth, with few local maxima; which might be a common feature among antibiotics for which resistance involves multiple loci.
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Affiliation(s)
- Claudia Ibacache-Quiroga
- Centro Nacional de Biotecnología, Madrid, Spain.,Centro de Micro-Bioinnovación, Escuela de Nutrición y Dietética, Facultad de Farmacia, Universidad de Valparaíso, Valparaíso, Chile
| | | | - Alejandro Couce
- Unité Mixte de Recherche 1137, Infection, Antimicrobiens, Modélisation, Evolution, INSERM, Université Paris Diderot, Paris, France
| | - Jesus Blázquez
- Centro Nacional de Biotecnología, Madrid, Spain.,Unidad de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Hospital Universitario Virgen del Rocío, Sevilla, Spain
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25
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Nagar SD, Aggarwal B, Joon S, Bhatnagar R, Bhatnagar S. A Network Biology Approach to Decipher Stress Response in Bacteria Using Escherichia coli As a Model. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2018; 20:310-24. [PMID: 27195968 DOI: 10.1089/omi.2016.0028] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The development of drug-resistant pathogenic bacteria poses challenges to global health for their treatment and control. In this context, stress response enables bacterial populations to survive extreme perturbations in the environment but remains poorly understood. Specific modules are activated for unique stressors with few recognized global regulators. The phenomenon of cross-stress protection strongly suggests the presence of central proteins that control the diverse stress responses. In this work, Escherichia coli was used to model the bacterial stress response. A Protein-Protein Interaction Network was generated by integrating differentially expressed genes in eight stress conditions of pH, temperature, and antibiotics with relevant gene ontology terms. Topological analysis identified 24 central proteins. The well-documented role of 16 central proteins in stress indicates central control of the response, while the remaining eight proteins may have a novel role in stress response. Cluster analysis of the generated network implicated RNA binding, flagellar assembly, ABC transporters, and DNA repair as important processes during response to stress. Pathway analysis showed crosstalk of Two Component Systems with metabolic processes, oxidative phosphorylation, and ABC transporters. The results were further validated by analysis of an independent cross-stress protection dataset. This study also reports on the ways in which bacterial stress response can progress to biofilm formation. In conclusion, we suggest that drug targets or pathways disrupting bacterial stress responses can potentially be exploited to combat antibiotic tolerance and multidrug resistance in the future.
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Affiliation(s)
- Shashwat Deepali Nagar
- 1 Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , New Delhi, India
| | - Bhavye Aggarwal
- 1 Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , New Delhi, India
| | - Shikha Joon
- 1 Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , New Delhi, India .,2 Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University , New Delhi, India
| | - Rakesh Bhatnagar
- 2 Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University , New Delhi, India
| | - Sonika Bhatnagar
- 1 Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , New Delhi, India
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26
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Richter K, Thomas N, Zhang G, Prestidge CA, Coenye T, Wormald PJ, Vreugde S. Deferiprone and Gallium-Protoporphyrin Have the Capacity to Potentiate the Activity of Antibiotics in Staphylococcus aureus Small Colony Variants. Front Cell Infect Microbiol 2017; 7:280. [PMID: 28690982 PMCID: PMC5479885 DOI: 10.3389/fcimb.2017.00280] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 06/08/2017] [Indexed: 11/13/2022] Open
Abstract
Small colony variants (SCVs) of bacteria like Staphylococcus aureus are characterized by a reduced colony size and are linked to increased antibiotic tolerance and resistance. Their altered expression of virulence factors, slow growing properties and their ability to form biofilms make the eradication of SCVs challenging. In the context of biofilm-related infectious diseases involving S. aureus SCVs, a therapy targeting bacterial iron metabolism was evaluated. The combination of the iron-chelator deferiprone (Def) and the heme-analog gallium-protoporphyrin (GaPP), in solution and incorporated in a surgical wound gel, was tested for activity against planktonic and sessile SCVs. To this end, the activity of Def-GaPP was assessed against planktonic S. aureus SCVs, as well as against in vitro and in vivo biofilms in the colony biofilm model, an artificial wound model and a Caenorhabditis elegans infection model. While Def alone failed to show substantial antibacterial activity, GaPP and the combination of Def-GaPP demonstrated concentration- and strain-dependent antibacterial properties. Specifically, the Def-GaPP combination significantly reduced the bacterial load in an artificial wound model and increased the survival of S. aureus SCV infected C. elegans. When Def-GaPP were combined with gentamicin or ciprofloxacin, the triple combinations exceeded the antibiofilm activity of the individual compounds in the colony biofilm model. In targeting bacterial iron metabolism, Def-GaPP showed significant activity against planktonic and sessile SCVs. Moreover, Def-GaPP could potentiate the activity of gentamicin and ciprofloxacin. Delivered in a wound healing gel, Def-GaPP showed promise as a new topical strategy against infections with S. aureus SCVs.
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Affiliation(s)
- Katharina Richter
- Department of Surgery, Otolaryngology Head and Neck Surgery, Basil Hetzel Institute for Translational Health Research, The Queen Elizabeth Hospital, University of AdelaideAdelaide, SA, Australia
| | - Nicky Thomas
- School of Pharmacy and Medical Sciences, University of South AustraliaAdelaide, SA, Australia.,Adelaide Biofilm Test Facility, Sansom Institute for Health Research, University of South AustraliaAdelaide, SA, Australia
| | - Guimin Zhang
- Department of Otolaryngology Head and Neck Surgery, Tianjin First Center HospitalTianjin, China
| | - Clive A Prestidge
- School of Pharmacy and Medical Sciences, University of South AustraliaAdelaide, SA, Australia.,ARC Centre of Excellence in Convergent Bio-Nano Science and TechnologyAdelaide, SA, Australia
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent UniversityGhent, Belgium
| | - Peter-John Wormald
- Department of Surgery, Otolaryngology Head and Neck Surgery, Basil Hetzel Institute for Translational Health Research, The Queen Elizabeth Hospital, University of AdelaideAdelaide, SA, Australia
| | - Sarah Vreugde
- Department of Surgery, Otolaryngology Head and Neck Surgery, Basil Hetzel Institute for Translational Health Research, The Queen Elizabeth Hospital, University of AdelaideAdelaide, SA, Australia
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27
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Yadav MK, Chae SW, Go YY, Im GJ, Song JJ. In vitro Multi-Species Biofilms of Methicillin-Resistant Staphylococcus aureus and Pseudomonas aeruginosa and Their Host Interaction during In vivo Colonization of an Otitis Media Rat Model. Front Cell Infect Microbiol 2017; 7:125. [PMID: 28459043 PMCID: PMC5394157 DOI: 10.3389/fcimb.2017.00125] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 03/27/2017] [Indexed: 01/30/2023] Open
Abstract
Staphylococcus aureus (SA) and Pseudomonas aeruginosa (PA) are known to cause biofilm-related infections. MRSA and PA have been frequently isolated from chronically infected wounds, cystic fibrosis, chronic suppurative otitis media (CSOM), and from indwelling medical devices, and these bacteria co-exist; however, their interaction with each-other or with the host is not well known. In this study, we investigated MRSA and PA multi-species biofilm communities in vitro and their interaction with the host during in vivo colonization using an OM rat-model. In-vitro biofilm formation and in-vivo colonization were studied using CV-microtiter plate assay and OM rat-model respectively. The biofilms were viewed under scanning electron microscope and bacteria were enumerated using cfu counts. The differential gene expressions of rat mucosa colonized with single or multi-species of MRSA or PA were studied using RNA-sequencing of total transcriptome. In multi-species in-vitro biofilms PA partially inhibited SA growth. However, no significant inhibition of MRSA was detected during in-vivo colonization of multi-species in rat bullae. A total of 1,797 genes were significantly (p < 0.05) differentially expressed in MRSA or PA or MRSA + PA colonized rat middle ear mucosa with respect to the control. The poly-microbial colonization of MRSA and PA induced the differential expression of a significant number of genes that are involved in immune response, inflammation, signaling, development, and defense; these were not expressed with single species colonization by either MRSA or PA. Genes involved in defense, immune response, inflammatory response, and developmental process were exclusively up-regulated, and genes that are involved in nervous system signaling, development and transmission, regulation of cell growth and development, anatomical and system development, and cell differentiation were down-regulated after multi-species inoculation. These results indicate that poly-microbial colonization induces a host response that is different from that induced by single species infection.
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Affiliation(s)
- Mukesh K Yadav
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of MedicineSeoul, South Korea.,Institute for Medical Device Clinical Trials, Korea University College of MedicineSeoul, South Korea
| | - Sung-Won Chae
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of MedicineSeoul, South Korea
| | - Yoon Young Go
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of MedicineSeoul, South Korea
| | - Gi Jung Im
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of MedicineSeoul, South Korea
| | - Jae-Jun Song
- Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of MedicineSeoul, South Korea
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28
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Vestergaard M, Paulander W, Leng B, Nielsen JB, Westh HT, Ingmer H. Novel Pathways for Ameliorating the Fitness Cost of Gentamicin Resistant Small Colony Variants. Front Microbiol 2016; 7:1866. [PMID: 27920765 PMCID: PMC5119051 DOI: 10.3389/fmicb.2016.01866] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 11/04/2016] [Indexed: 01/08/2023] Open
Abstract
Small colony variants (SCVs) of the human pathogen Staphylococcus aureus are associated with persistent infections. Phenotypically, SCVs are characterized by slow growth and they can arise upon interruption of the electron transport chain that consequently reduce membrane potential and thereby limit uptake of aminoglycosides (e.g., gentamicin). In this study, we have examined the pathways by which the fitness cost of SCVs can be ameliorated. Five gentamicin resistant SCVs derived from S. aureus JE2 were independently selected on agar plates supplemented with gentamicin. The SCVs carried mutations in the menaquinone and hemin biosynthesis pathways, which caused a significant reduction in exponential growth rates relative to wild type (WT; 0.59-0.72) and reduced membrane potentials. Fifty independent lineages of the low-fitness, resistant mutants were serially passaged for up to 500 generations with or without sub-lethal concentrations of gentamicin. Amelioration of the fitness cost followed three evolutionary trajectories and was dependent on the initial mutation type (point mutation vs. deletion) and the passage condition (absence or presence of gentamicin). For SCVs evolved in the absence of gentamicin, 12 out of 15 lineages derived from SCVs with point mutations acquired intra-codonic suppressor mutations restoring membrane potential, growth rate, gentamicin susceptibility and colony size to WT levels. For the SCVs carrying deletions, all lineages enhanced fitness independent of membrane potential restoration without alterations in gentamicin resistance levels. By whole genome sequencing, we identified compensatory mutations in genes related to the σB stress response (7 out of 10 lineages). Inactivation of rpoF that encode for the alternative sigma factor SigB (σB) partially restored fitness of SCVs. For all lineages passaged in the presence of gentamicin, fitness compensation via membrane potential restoration was suppressed, however, selected for secondary mutations in fusA and SAUSA300_0749. This study is the first to describe fitness compensatory events in SCVs with deletion mutations and adaptation of SCVs to continued exposure to gentamicin.
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Affiliation(s)
- Martin Vestergaard
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Wilhelm Paulander
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Bingfeng Leng
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Jesper B Nielsen
- MRSA Knowledge Center, Department of Clinical Microbiology, Hvidovre Hospital Hvidovre, Denmark
| | - Henrik T Westh
- MRSA Knowledge Center, Department of Clinical Microbiology, Hvidovre Hospital Hvidovre, Denmark
| | - Hanne Ingmer
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen Frederiksberg, Denmark
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29
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Clinical Significance and Pathogenesis of Staphylococcal Small Colony Variants in Persistent Infections. Clin Microbiol Rev 2016; 29:401-27. [PMID: 26960941 DOI: 10.1128/cmr.00069-15] [Citation(s) in RCA: 212] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Small colony variants (SCVs) were first described more than 100 years ago for Staphylococcus aureus and various coagulase-negative staphylococci. Two decades ago, an association between chronic staphylococcal infections and the presence of SCVs was observed. Since then, many clinical studies and observations have been published which tie recurrent, persistent staphylococcal infections, including device-associated infections, bone and tissue infections, and airway infections of cystic fibrosis patients, to this special phenotype. By their intracellular lifestyle, SCVs exhibit so-called phenotypic (or functional) resistance beyond the classical resistance mechanisms, and they can often be retrieved from therapy-refractory courses of infection. In this review, the various clinical infections where SCVs can be expected and isolated, diagnostic procedures for optimized species confirmation, and the pathogenesis of SCVs, including defined underlying molecular mechanisms and the phenotype switch phenomenon, are presented. Moreover, relevant animal models and suggested treatment regimens, as well as the requirements for future research areas, are highlighted.
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30
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Matarlo JS, Lu Y, Daryaee F, Daryaee T, Ruzsicska B, Walker SG, Tonge PJ. A Methyl 4-Oxo-4-phenylbut-2-enoate with in Vivo Activity against MRSA that Inhibits MenB in the Bacterial Menaquinone Biosynthesis Pathway. ACS Infect Dis 2016; 2:329-340. [PMID: 27294200 DOI: 10.1021/acsinfecdis.6b00023] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
4-Oxo-4-phenyl-but-2-enoates inhibit MenB, the 1,4-dihydroxyl-2-naphthoyl-CoA synthase in the bacterial menaquinone (MK) biosynthesis pathway, through the formation of an adduct with coenzyme A (CoA). Here, we show that the corresponding methyl butenoates have MIC values as low as 0.35-0.75 µg/mL against drug sensitive and resistant strains of Staphylococcus aureus. Mode of action studies on the most potent compound, methyl 4-(4-chlorophenyl)-4-oxobut-2-enoate (1), reveal that 1 is converted into the corresponding CoA adduct in S. aureus cells, and that this adduct binds to the S. aureus MenB (saMenB) with a Kd value of 2 µM. The antibacterial spectrum of 1 is limited to bacteria that utilize MK for respiration, and the activity of 1 can be complemented with exogenous MK or menadione. Finally, treatment of methicillin-resistant S. aureus (MRSA) with 1 results in the small colony variant phenotype and thus 1 phenocopies knockout of the menB gene. Taken together the data indicate that the antibacterial activity of 1 results from a specific effect on MK biosynthesis. We also evaluated the in vivo efficacy of 1 using two mouse models of MRSA infection. Notably, compound 1 increased survival in a systemic infection model and resulted in a dose-dependent decrease in bacterial load in a thigh infection model, validating MenB as a target for the development of new anti-MRSA candidates.
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Affiliation(s)
- Joe S. Matarlo
- Institute of Chemical Biology & Drug Discovery, Department of Chemistry, and ‡Department of Oral Biology and Pathology, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Yang Lu
- Institute of Chemical Biology & Drug Discovery, Department of Chemistry, and ‡Department of Oral Biology and Pathology, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Fereidoon Daryaee
- Institute of Chemical Biology & Drug Discovery, Department of Chemistry, and ‡Department of Oral Biology and Pathology, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Taraneh Daryaee
- Institute of Chemical Biology & Drug Discovery, Department of Chemistry, and ‡Department of Oral Biology and Pathology, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Bela Ruzsicska
- Institute of Chemical Biology & Drug Discovery, Department of Chemistry, and ‡Department of Oral Biology and Pathology, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Stephen G. Walker
- Institute of Chemical Biology & Drug Discovery, Department of Chemistry, and ‡Department of Oral Biology and Pathology, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Peter J. Tonge
- Institute of Chemical Biology & Drug Discovery, Department of Chemistry, and ‡Department of Oral Biology and Pathology, Stony Brook University, Stony Brook, New York 11794-3400, United States
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31
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Day M. Yeast petites and small colony variants: for everything there is a season. ADVANCES IN APPLIED MICROBIOLOGY 2016; 85:1-41. [PMID: 23942147 DOI: 10.1016/b978-0-12-407672-3.00001-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The yeast petite mutant was first found in the yeast Saccharomyces cerevisiae. The colony is small because of a block in the aerobic respiratory chain pathway, which generates ATP. The petite yeasts are thus unable to grow on nonfermentable carbon sources (such as glycerol or ethanol), and form small anaerobic-sized colonies when grown in the presence of fermentable carbon sources (such as glucose). The petite phenotype results from mutations in the mitochondrial genome, loss of mitochondria, or mutations in the host cell genome. The latter mutations affect nuclear-encoded genes involved in oxidative phosphorylation and these mutants are termed neutral petites. They all produce wild-type progeny when crossed with a wild-type strain. The staphylococcal small colony variant (SCV) is a slow-growing mutant that typically exhibits the loss of many phenotypic characteristics and pathogenic traits. SCVs are mostly small, nonpigmented, and nonhaemolytic. Their small size is often due to an inability to synthesize electron transport chain components and so cannot generate ATP by oxidative phosphorylation. Evidence suggests that they are responsible for persistent and/or recurrent infections. This chapter compares the physiological and genetic basis of the petite mutants and SCVs. The review focuses principally on two representatives, the eukaryote S. cerevisiae and the prokaryote Staphylococcus aureus. There is, clearly, commonality in the physiological response. Interestingly, the similarity, based on their physiological states, has not been commented on previously. The finding of an overlapping physiological response that occurs across a taxonomic divide is novel.
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Affiliation(s)
- Martin Day
- School of Biosciences, Cardiff University, Cardiff, United Kingdom.
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32
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Suh SJ, Shuman J, Carroll LP, Silo-Suh L. BEEP: An assay to detect bio-energetic and envelope permeability alterations in Pseudomonas aeruginosa. J Microbiol Methods 2016; 125:81-6. [PMID: 27089860 DOI: 10.1016/j.mimet.2016.04.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 04/13/2016] [Accepted: 04/13/2016] [Indexed: 12/21/2022]
Abstract
We developed an effective and rapid assay to detect both bio-energetic and envelope permeability (BEEP) alterations of Pseudomonas aeruginosa. The assay is based on quantification of extracellular ATP in bacterial cultures using luciferase as a reporter. To demonstrate the validity of our assay we conducted a biased screen of a transposon insertion library in P. aeruginosa strain PAO1 in order to expedite the isolation of mutants with defects in bioenergetic pathways. We successfully isolated insertion mutants that were reduced for extracellular ATP accumulation and identified the corresponding mutations that caused the phenotype. Most of the genes identified from this analysis were associated with energy metabolism and several appeared to be potentially novel bioenergetic targets. In addition, we show that treatment of P. aeruginosa strain PAO1 with antibiotics that disrupt the bacterial cell envelope leads to greater extracellular ATP accumulation. In summary, increases in extracellular ATP accumulation above wild type levels indicated a perturbation of membrane permeability while decreases in extracellular ATP accumulation indicated defects in bioenergetics.
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Affiliation(s)
- Sang-Jin Suh
- Department of Biological Sciences, Auburn University, AL 36849, United States.
| | - Jon Shuman
- Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, GA 31207, United States.
| | - Leslie P Carroll
- Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, GA 31207, United States.
| | - Laura Silo-Suh
- Division of Basic Medical Sciences, Mercer University School of Medicine, Macon, GA 31207, United States.
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33
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Kim NH, Kang YM, Han WD, Park KU, Park KH, Yoo JI, Lee DG, Park C, Song KH, Kim ES, Park SW, Kim NJ, Oh MD, Kim HB. Small-Colony Variants in Persistent and Recurrent Staphylococcus aureus Bacteremia. Microb Drug Resist 2016; 22:538-544. [PMID: 26982169 DOI: 10.1089/mdr.2015.0262] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The small-colony variant (SCV) phenotype of Staphylococcus aureus is associated with intracellular persistence and reduced antimicrobial susceptibility, which can lead to therapeutic failure. Since SCVs grow slowly and have a confusing morphology, the identification of infections due to SCV is difficult. We have identified SCVs in two patients who presented with persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia complicated by surgical site infections after cardiothoracic surgery. Nine blood isolates were collected from the two patients for species identification, antimicrobial susceptibility testing, and phenotypic and genotypic characterization. Colonies on Columbia blood agar were pinpoint, nonpigmented, nonhemolytic, and reverted to normal colonies after 48 hr of incubation on Schaedler agar. Auxotrophy assays revealed hemin dependence. Susceptibility to vancomycin (minimal inhibitory concentrations 1.0 μg/mL) was confirmed by E-test and broth microdilution test. All the isolates were identified as MRSA by multiplex polymerase chain reaction specific for the mecA, femA, and 16S rRNA genes, and all had the same genotype: Multilocus sequence typing ST5, SCCmec type II, agr type II, and spa type t2460. Moreover pulsed-field gel electrophoresis typing revealed that all nine isolates belonged to the same clone. Mutations in the relA gene were not found, and none of the isolates was identified as hVISA by population analysis profiling-AUC ratio. A high level of suspicion is required to detect SCVs, and although it is not common, the possibility of the SCV phenotype has to be considered in persistent S. aureus bacteremia.
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Affiliation(s)
- Nak-Hyun Kim
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Yu Min Kang
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Woong Dae Han
- 2 Division of Infectious Diseases, Seoul National University Bundang Hospital , Seongnam, Republic of Korea
| | - Kyoung Un Park
- 3 Department of Laboratory Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Kay-Hyun Park
- 4 Department of Thoracic Surgery, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Jae Il Yoo
- 5 Division of Antimicrobial Resistance, Center for Infectious Diseases, Korea National Institute of Health , Cheongwon, Republic of Korea
| | - Dong-Gun Lee
- 6 Vaccine Bio Research Institute, Catholic University of Korea , Seoul, Republic of Korea
| | - Chulmin Park
- 6 Vaccine Bio Research Institute, Catholic University of Korea , Seoul, Republic of Korea
| | - Kyoung-Ho Song
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea.,2 Division of Infectious Diseases, Seoul National University Bundang Hospital , Seongnam, Republic of Korea
| | - Eu Suk Kim
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea.,2 Division of Infectious Diseases, Seoul National University Bundang Hospital , Seongnam, Republic of Korea
| | - Sang Won Park
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Nam Joong Kim
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Myoung-Don Oh
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Hong Bin Kim
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea.,2 Division of Infectious Diseases, Seoul National University Bundang Hospital , Seongnam, Republic of Korea
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34
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Johns BE, Purdy KJ, Tucker NP, Maddocks SE. Phenotypic and Genotypic Characteristics of Small Colony Variants and Their Role in Chronic Infection. Microbiol Insights 2015; 8:15-23. [PMID: 26448688 PMCID: PMC4581789 DOI: 10.4137/mbi.s25800] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 08/09/2015] [Accepted: 08/13/2015] [Indexed: 01/02/2023] Open
Abstract
Small colony variant (SCV) bacteria arise spontaneously within apparently homogeneous microbial populations, largely in response to environmental stresses, such as antimicrobial treatment. They display unique phenotypic characteristics conferred in part by heritable genetic changes. Characteristically slow growing, SCVs comprise a minor proportion of the population from which they arise but persist by virtue of their inherent resilience and host adaptability. Consequently, SCVs are problematic in chronic infection, where antimicrobial treatment is administered during the acute phase of infection but fails to eradicate SCVs, which remain within the host causing recurrent or chronic infection. This review discusses some of the phenotypic and genotypic changes that enable SCVs to successfully proliferate within the host environment as potential pathogens and strategies that could ameliorate the resolution of infection where SCVs are present.
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Affiliation(s)
- Benjamin E Johns
- Department of Biomedical Science, Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Kevin J Purdy
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Nicholas P Tucker
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Sarah E Maddocks
- Department of Biomedical Science, Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK
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35
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Coculture of Staphylococcus aureus with Pseudomonas aeruginosa Drives S. aureus towards Fermentative Metabolism and Reduced Viability in a Cystic Fibrosis Model. J Bacteriol 2015; 197:2252-64. [PMID: 25917910 DOI: 10.1128/jb.00059-15] [Citation(s) in RCA: 217] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 04/23/2015] [Indexed: 01/22/2023] Open
Abstract
UNLABELLED The airways of patients with cystic fibrosis are colonized with diverse bacterial communities that change dynamically during pediatric years and early adulthood. Staphylococcus aureus is the most prevalent pathogen during early childhood, but during late teens and early adulthood, a shift in microbial composition occurs leading to Pseudomonas aeruginosa community predominance in ∼50% of adults. We developed a robust dual-bacterial in vitro coculture system of P. aeruginosa and S. aureus on monolayers of human bronchial epithelial cells homozygous for the ΔF508 cystic fibrosis transmembrane conductance regulator (CFTR) mutation to better model the mechanisms of this interaction. We show that P. aeruginosa drives the S. aureus expression profile from that of aerobic respiration to fermentation. This shift is dependent on the production of both 2-heptyl-4-hydroxyquinoline N-oxide (HQNO) and siderophores by P. aeruginosa. Furthermore, S. aureus-produced lactate is a carbon source that P. aeruginosa preferentially consumes over medium-supplied glucose. We find that initially S. aureus and P. aeruginosa coexist; however, over extended coculture P. aeruginosa reduces S. aureus viability, also in an HQNO- and P. aeruginosa siderophore-dependent manner. Interestingly, S. aureus small-colony-variant (SCV) genetic mutant strains, which have defects in their electron transport chain, experience reduced killing by P. aeruginosa compared to their wild-type parent strains; thus, SCVs may provide a mechanism for persistence of S. aureus in the presence of P. aeruginosa. We propose that the mechanism of P. aeruginosa-mediated killing of S. aureus is multifactorial, requiring HQNO and P. aeruginosa siderophores as well as additional genetic, environmental, and nutritional factors. IMPORTANCE In individuals with cystic fibrosis, Staphylococcus aureus is the primary respiratory pathogen during childhood. During adulthood, Pseudomonas aeruginosa predominates and correlates with worse patient outcome. The mechanism(s) by which P. aeruginosa outcompetes or kills S. aureus is not well understood. We describe an in vitro dual-bacterial species coculture system on cystic fibrosis-derived airway cells, which models interactions relevant to patients with cystic fibrosis. Further, we show that molecules produced by P. aeruginosa additively induce a transition of S. aureus metabolism from aerobic respiration to fermentation and eventually lead to loss of S. aureus viability. Elucidating the molecular mechanisms of P. aeruginosa community predominance can provide new therapeutic targets and approaches to impede this microbial community transition and subsequent patient worsening.
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36
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Glycolytic dependency of high-level nitric oxide resistance and virulence in Staphylococcus aureus. mBio 2015; 6:mBio.00045-15. [PMID: 25852157 PMCID: PMC4453550 DOI: 10.1128/mbio.00045-15] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Staphylococcus aureus is a prolific human pathogen capable of causing severe invasive disease with a myriad of presentations. The ability of S. aureus to cause infection is strongly linked with its capacity to overcome the effects of innate immunity, whether by directly killing immune cells or expressing factors that diminish the impact of immune effectors. One such scenario is the induction of lactic acid fermentation by S. aureus in response to host nitric oxide (NO·). This fermentative activity allows S. aureus to balance redox during NO·-induced respiration inhibition. However, little is known about the metabolic substrates and pathways that support this activity. Here, we identify glycolytic hexose catabolism as being essential for S. aureus growth in the presence of high levels of NO·. We determine that glycolysis supports S. aureus NO· resistance by allowing for ATP and precursor metabolite production in a redox-balanced and respiration-independent manner. We further demonstrate that glycolysis is required for NO· resistance during phagocytosis and that increased levels of extracellular glucose limit the effectiveness of phagocytic killing by enhancing NO· resistance. Finally, we demonstrate that S. aureus glycolysis is essential for virulence in both sepsis and skin/soft tissue models of infection in a time frame consistent with the induction of innate immunity and host NO· production. Staphylococcus aureus is a leading human bacterial pathogen capable of causing a wide variety of diseases that, as a result of antibiotic resistance, are very difficult to treat. The frequency of S. aureus tissue invasion suggests that this bacterium has evolved to resist innate immunity and grow using the nutrients present in otherwise sterile host tissue. We have identified glycolysis as an essential component of S. aureus virulence and attribute its importance to promoting nitric oxide resistance and growth under low oxygen conditions. Our data suggest that diabetics, a patient population characterized by excess serum glucose, may be more susceptible to S. aureus as a result of increased glucose availability. Furthermore, the essential nature of S. aureus glycolysis indicates that a newly developed glycolysis inhibitor may be a highly effective treatment for S. aureus infections.
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37
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Santiago M, Matano LM, Moussa SH, Gilmore MS, Walker S, Meredith TC. A new platform for ultra-high density Staphylococcus aureus transposon libraries. BMC Genomics 2015; 16:252. [PMID: 25888466 PMCID: PMC4389836 DOI: 10.1186/s12864-015-1361-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 02/19/2015] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Staphylococcus aureus readily develops resistance to antibiotics and achieving effective therapies to overcome resistance requires in-depth understanding of S. aureus biology. High throughput, parallel-sequencing methods for analyzing transposon mutant libraries have the potential to revolutionize studies of S. aureus, but the genetic tools to take advantage of the power of next generation sequencing have not been fully developed. RESULTS Here we report a phage-based transposition system to make ultra-high density transposon libraries for genome-wide analysis of mutant fitness in any Φ11-transducible S. aureus strain. The high efficiency of the delivery system has made it possible to multiplex transposon cassettes containing different regulatory elements in order to make libraries in which genes are over- or under-expressed as well as deleted. By incorporating transposon-specific barcodes into the cassettes, we can evaluate how null mutations and changes in gene expression levels affect fitness in a single sequencing data set. Demonstrating the power of the system, we have prepared a library containing more than 690,000 unique insertions. Because one unique feature of the phage-based approach is that temperature-sensitive mutants are retained, we have carried out a genome-wide study of S. aureus genes involved in withstanding temperature stress. We find that many genes previously identified as essential are temperature sensitive and also identify a number of genes that, when disrupted, confer a growth advantage at elevated temperatures. CONCLUSIONS The platform described here reliably provides mutant collections of unparalleled genotypic diversity and will enable a wide range of functional genomic studies in S. aureus.
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Affiliation(s)
- Marina Santiago
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA.
| | - Leigh M Matano
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA.
| | - Samir H Moussa
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA.
| | - Michael S Gilmore
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA.
- Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA, 02114, USA.
| | - Suzanne Walker
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA.
| | - Timothy C Meredith
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA.
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, 16802, USA.
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38
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Unraveling the structure-activity relationship of tomatidine, a steroid alkaloid with unique antibiotic properties against persistent forms of Staphylococcus aureus. Eur J Med Chem 2015; 80:605-20. [PMID: 24877760 DOI: 10.1016/j.ejmech.2013.11.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 11/13/2013] [Accepted: 11/15/2013] [Indexed: 11/24/2022]
Abstract
Staphylococcus aureus (S. aureus) is responsible for difficult-to-treat and relapsing infections and constitutes one of the most problematic pathogens due to its multiple resistances to clinically available antibiotics. Additionally, the ability of S. aureus to develop small-colony variants is associated with a reduced susceptibility to aminoglycoside antibiotics and in vivo persistence. We have recently demonstrated that tomatidine, a steroid alkaloid isolated from tomato plants, possesses anti-virulence activity against normal strains of S. aureus as well as the ability to potentiate the effect of aminoglycoside antibiotics. In addition, tomatidine has shown antibiotic activity against small-colony variants of S. aureus. We herein report the first study of the structure-activity relationship of tomatidine against S. aureus.
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Churkina L, Vaneechoutte M, Kiprianova E, Perunova N, Avdeeva L, Bukharin O. Batumin—A Selective Inhibitor of Staphylococci—Reduces Biofilm Formation in Methicillin Resistant <i>Staphylococcus aureus</i>. ACTA ACUST UNITED AC 2015. [DOI: 10.4236/ojmm.2015.54024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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The Staphylococcus aureus NuoL-like protein MpsA contributes to the generation of membrane potential. J Bacteriol 2014; 197:794-806. [PMID: 25448817 DOI: 10.1128/jb.02127-14] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In aerobic microorganisms, the entry point of respiratory electron transfer is represented by the NADH:quinone oxidoreductase. The enzyme couples the oxidation of NADH with the reduction of quinone. In the type 1 NADH:quinone oxidoreductase (Ndh1), this reaction is accompanied by the translocation of cations, such as H(+) or Na(+). In Escherichia coli, cation translocation is accomplished by the subunit NuoL, thus generating membrane potential (Δψ). Some microorganisms achieve NADH oxidation by the alternative, nonelectrogenic type 2 NADH:quinone oxidoreductase (Ndh2), which is not cation translocating. Since these enzymes had not been described in Staphylococcus aureus, the goal of this study was to identify proteins operating in the NADH:quinone segment of its respiratory chain. We demonstrated that Ndh2 represents a NADH:quinone oxidoreductase in S. aureus. Additionally, we identified a hypothetical protein in S. aureus showing sequence similarity to the proton-translocating subunit NuoL of complex I in E. coli: the NuoL-like protein MpsA. Mutants with deletion of the nuoL-like gene mpsA and its corresponding operon, mpsABC (mps for membrane potential-generating system), exhibited a small-colony-variant-like phenotype and were severely affected in Δψ and oxygen consumption rates. The MpsABC proteins did not confer NADH oxidation activity. Using an Na(+)/H(+) antiporter-deficient E. coli strain, we could show that MpsABC constitute a cation-translocating system capable of Na(+) transport. Our study demonstrates that MpsABC represent an important functional system of the respiratory chain of S. aureus that acts as an electrogenic unit responsible for the generation of Δψ.
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Abstract
The emergence and spread of drug-resistant pathogens and our inability to develop new antimicrobials to overcome resistance has inspired scientists to consider new targets for drug development. Cellular bioenergetics is an area showing promise for the development of new antimicrobials, particularly in the discovery of new anti-tuberculosis drugs where several new compounds have entered clinical trials. In this review, we have examined the bioenergetics of various bacterial pathogens, highlighting the versatility of electron donor and acceptor utilisation and the modularity of electron transport chain components in bacteria. In addition to re-examining classical concepts, we explore new literature that reveals the intricacies of pathogen energetics, for example, how Salmonella enterica and Campylobacter jejuni exploit host and microbiota to derive powerful electron donors and sinks; the strategies Mycobacterium tuberculosis and Pseudomonas aeruginosa use to persist in lung tissues; and the importance of sodium energetics and electron bifurcation in the chemiosmotic anaerobe Fusobacterium nucleatum. A combination of physiological, biochemical, and pharmacological data suggests that, in addition to the clinically-approved target F1Fo-ATP synthase, NADH dehydrogenase type II, succinate dehydrogenase, hydrogenase, cytochrome bd oxidase, and menaquinone biosynthesis pathways are particularly promising next-generation drug targets. The realisation of cellular energetics as a rich target space for the development of new antimicrobials will be dependent upon gaining increased understanding of the energetic processes utilised by pathogens in host environments and the ability to design bacterial-specific inhibitors of these processes.
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Hamza T, Li B. Differential responses of osteoblasts and macrophages upon Staphylococcus aureus infection. BMC Microbiol 2014; 14:207. [PMID: 25059520 PMCID: PMC4116603 DOI: 10.1186/s12866-014-0207-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 07/18/2014] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Staphylococcus aureus (S. aureus) is one of the primary causes of bone infections which are often chronic and difficult to eradicate. Bacteria like S. aureus may survive upon internalization in cells and may be responsible for chronic and recurrent infections. In this study, we compared the responses of a phagocytic cell (i.e. macrophage) to a non-phagocytic cell (i.e. osteoblast) upon S. aureus internalization. RESULTS We found that upon internalization, S. aureus could survive for up to 5 and 7 days within macrophages and osteoblasts, respectively. Significantly more S. aureus was internalized in macrophages compared to osteoblasts and a significantly higher (100 fold) level of live intracellular S. aureus was detected in macrophages compared to osteoblasts. However, the percentage of S. aureus survival after infection was significantly lower in macrophages compared to osteoblasts at post-infection days 1-6. Interestingly, macrophages had relatively lower viability in shorter infection time periods (i.e. 0.5-4 h; significant at 2 h) but higher viability in longer infection time periods (i.e. 6-8 h; significant at 8 h) compared to osteoblasts. In addition, S. aureus infection led to significant changes in reactive oxygen species production in both macrophages and osteoblasts. Moreover, infected osteoblasts had significantly lower alkaline phosphatase activity at post-infection day 7 and infected macrophages had higher phagocytosis activity compared to non-infected cells. CONCLUSIONS S. aureus was found to internalize and survive within osteoblasts and macrophages and led to differential responses between osteoblasts and macrophages. These findings may assist in evaluation of the pathogenesis of chronic and recurrent infections which may be related to the intracellular persistence of bacteria within host cells.
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Affiliation(s)
| | - Bingyun Li
- Department of Orthopaedics, School of Medicine, West Virginia University, Morgantown 26506, WV, USA.
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Triclosan-induced aminoglycoside-tolerant Listeria monocytogenes isolates can appear as small-colony variants. Antimicrob Agents Chemother 2014; 58:3124-32. [PMID: 24637686 DOI: 10.1128/aac.02266-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Exposure of the human food-borne pathogen Listeria monocytogenes to sublethal concentrations of triclosan can cause resistance to several aminoglycosides. Aminoglycoside-resistant isolates exhibit two colony morphologies: normal-size and pinpoint colonies. The purposes of the present study were to characterize the small colonies of L. monocytogenes and to determine if specific genetic changes could explain the triclosan-induced aminoglycoside resistance in both pinpoint and normal-size isolates. Isolates from the pinpoint colonies grew poorly under aerated conditions, but growth was restored by addition of antibiotics. Pinpoint isolates had decreased hemolytic activity under stagnant conditions and a changed spectrum of carbohydrate utilization compared to the wild type and isolates from normal-size colonies. Genome sequence comparison revealed that all seven pinpoint isolates had a mutation in a heme gene, and addition of heme caused the pinpoint isolates to revert to normal colony size. Triclosan-induced gentamicin-resistant isolates had mutations in several different genes, and it cannot be directly concluded how the different mutations caused gentamicin resistance. However, since many of the mutations affected proteins involved in respiration, it seems likely that the mutations affected the active transport of the antibiotic and thereby caused resistance by decreasing the amount of aminoglycoside that enters the bacterial cell. Our study emphasizes that triclosan likely has more targets than just fabI and that exposure to triclosan can cause resistance to antibiotics that enters the cell via active transport. Further studies are needed to elucidate if L. monocytogenes pinpoint isolates could have any clinical impact, e.g., in persistent infections.
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Identification of point mutations in clinical Staphylococcus aureus strains that produce small-colony variants auxotrophic for menadione. Infect Immun 2014; 82:1600-5. [PMID: 24452687 DOI: 10.1128/iai.01487-13] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Staphylococcus aureus small-colony variants (SCVs) are implicated in chronic and relapsing infections that are difficult to diagnose and treat. Despite many years of study, the underlying molecular mechanisms and virulence effect of the small-colony phenotype remain incompletely understood. We sequenced the genomes of five S. aureus SCV strains recovered from human patients and discovered previously unidentified nonsynonymous point mutations in three genes encoding proteins in the menadione biosynthesis pathway. Analysis of genetic revertants and complementation with wild-type alleles confirmed that these mutations caused the SCV phenotype and decreased virulence for mice.
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Grant SS, Hung DT. Persistent bacterial infections, antibiotic tolerance, and the oxidative stress response. Virulence 2013; 4:273-83. [PMID: 23563389 PMCID: PMC3710330 DOI: 10.4161/viru.23987] [Citation(s) in RCA: 213] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Certain bacterial pathogens are able to evade the host immune system and persist within the human host. The consequences of persistent bacterial infections potentially include increased morbidity and mortality from the infection itself as well as an increased risk of dissemination of disease. Eradication of persistent infections is difficult, often requiring prolonged or repeated courses of antibiotics. During persistent infections, a population or subpopulation of bacteria exists that is refractory to traditional antibiotics, possibly in a non-replicating or metabolically altered state. This review highlights the clinical significance of persistent infections and discusses different in vitro models used to investigate the altered physiology of bacteria during persistent infections. We specifically focus on recent work establishing increased protection against oxidative stress as a key element of the altered physiologic state across different in vitro models and pathogens.
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Garcia LG, Lemaire S, Kahl BC, Becker K, Proctor RA, Denis O, Tulkens PM, Van Bambeke F. Antibiotic activity against small-colony variants of Staphylococcus aureus: review of in vitro, animal and clinical data. J Antimicrob Chemother 2013; 68:1455-64. [DOI: 10.1093/jac/dkt072] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Bánky D, Iván G, Grolmusz V. Equal opportunity for low-degree network nodes: a PageRank-based method for protein target identification in metabolic graphs. PLoS One 2013; 8:e54204. [PMID: 23382878 PMCID: PMC3558500 DOI: 10.1371/journal.pone.0054204] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 12/11/2012] [Indexed: 11/19/2022] Open
Abstract
Biological network data, such as metabolic-, signaling- or physical interaction graphs of proteins are increasingly available in public repositories for important species. Tools for the quantitative analysis of these networks are being developed today. Protein network-based drug target identification methods usually return protein hubs with large degrees in the networks as potentially important targets. Some known, important protein targets, however, are not hubs at all, and perturbing protein hubs in these networks may have several unwanted physiological effects, due to their interaction with numerous partners. Here, we show a novel method applicable in networks with directed edges (such as metabolic networks) that compensates for the low degree (non-hub) vertices in the network, and identifies important nodes, regardless of their hub properties. Our method computes the PageRank for the nodes of the network, and divides the PageRank by the in-degree (i.e., the number of incoming edges) of the node. This quotient is the same in all nodes in an undirected graph (even for large- and low-degree nodes, that is, for hubs and non-hubs as well), but may differ significantly from node to node in directed graphs. We suggest to assign importance to non-hub nodes with large PageRank/in-degree quotient. Consequently, our method gives high scores to nodes with large PageRank, relative to their degrees: therefore non-hub important nodes can easily be identified in large networks. We demonstrate that these relatively high PageRank scores have biological relevance: the method correctly finds numerous already validated drug targets in distinct organisms (Mycobacterium tuberculosis, Plasmodium falciparum and MRSA Staphylococcus aureus), and consequently, it may suggest new possible protein targets as well. Additionally, our scoring method was not chosen arbitrarily: its value for all nodes of all undirected graphs is constant; therefore its high value captures importance in the directed edge structure of the graph.
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Affiliation(s)
- Dániel Bánky
- Protein Information Technology Group, Eötvös University, Pázmány Péter stny. 1/C, Budapest, Hungary
- Uratim Ltd., Budapest, Hungary
| | - Gábor Iván
- Protein Information Technology Group, Eötvös University, Pázmány Péter stny. 1/C, Budapest, Hungary
- Uratim Ltd., Budapest, Hungary
| | - Vince Grolmusz
- Protein Information Technology Group, Eötvös University, Pázmány Péter stny. 1/C, Budapest, Hungary
- Uratim Ltd., Budapest, Hungary
- * E-mail:
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Garcia LG, Lemaire S, Kahl BC, Becker K, Proctor RA, Tulkens PM, Van Bambeke F. Intracellular forms of menadione-dependent small-colony variants of methicillin-resistant Staphylococcus aureus are hypersusceptible to -lactams in a THP-1 cell model due to cooperation between vacuolar acidic pH and oxidant species. J Antimicrob Chemother 2012; 67:2873-81. [DOI: 10.1093/jac/dks325] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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Maduka-Ezeh AN, Greenwood-Quaintance KE, Karau MJ, Berbari EF, Osmon DR, Hanssen AD, Steckelberg JM, Patel R. Antimicrobial susceptibility and biofilm formation of Staphylococcus epidermidis small colony variants associated with prosthetic joint infection. Diagn Microbiol Infect Dis 2012; 74:224-9. [PMID: 22901790 DOI: 10.1016/j.diagmicrobio.2012.06.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 06/21/2012] [Accepted: 06/29/2012] [Indexed: 10/28/2022]
Abstract
We determined the frequency of isolation of non-aureus staphylococcal small colony variants (SCVs) from 31 patients with staphylococcal prosthetic joint infection (PJI) and described the antimicrobial susceptibility, auxotrophy, and biofilm-forming capacity of these SCVs. Eleven non-aureus SCVs were recovered, all of which were Staphylococcus epidermidis, and none of which was auxotrophic for hemin, menadione, or thymidine. Aminoglycoside resistance was detected in 5. Two were proficient, and 7 were poor, biofilm formers. With passage on antimicrobial free media, we observed a fluctuating phenotype in 3 isolates. We also noted a difference in antimicrobial susceptibility of different morphology isolates recovered from the same joints despite similar pulsed-field gel electrophoresis patterns. Our findings suggest S. epidermidis SCVs are common in PJI, and while they have a similar appearance to S. aureus SCVs, they do not necessarily share such characteristics as aminoglycoside resistance; auxotrophy for hemin, menadione, or thymidine; or enhanced biofilm formation. We also underscore the importance of antimicrobial susceptibility testing of all morphologies of isolates recovered from PJI.
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Affiliation(s)
- Awele N Maduka-Ezeh
- Division of Infectious Diseases, Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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Churkina LN, Bidnenko SI, Lopes dos Santos Santiago G, Vaneechoutte M, Avdeeva LV, Lutko OB, Oserjanskaja NM. Application of the antibiotic batumin for accurate and rapid identification of staphylococcal small colony variants. BMC Res Notes 2012; 5:374. [PMID: 22828414 PMCID: PMC3439339 DOI: 10.1186/1756-0500-5-374] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 06/30/2012] [Indexed: 12/23/2022] Open
Abstract
Background Staphylococcus aureus is a major human pathogen causing significant morbidity and mortality. The S. aureus colonies in osteomyelitis, in patients with cystic fibrosis and patients with endoprosthesis rejection frequently have an atypical morphology, i.e. staphylococcal small-colony variants, which form a naturally occurring subpopulation of clinically important staphylococci. Identification of these small colony variants is difficult, because of the loss of typical phenotypic characteristics of these variants. We wanted to improve and simplify the diagnosis of staphylococcal infection using a diagnostic preparation, consisting of 5 μg batumin paper disks. Batumin possesses a unique selective activity against all studied Staphylococcus spp., whereas all other species tested thus far are batumin resistant. We assessed the efficacy of the batumin diagnostic preparation to identify staphylococcal small colony variants, isolated from osteomyelitis patients. Findings With the batumin diagnostic preparation, all 30 tested staphylococcal small-colony variants had a growth inhibition zone around the disk of minimum 25 mm, accordant with the inhibition zones of the parent strains, isolated from the same patients. Conclusions The batumin diagnostic preparation correctly identified the small-colony variants of S. aureus, S. haemolyticus and S. epidermidis as belonging to the genus Staphylococcus, which differ profoundly from parental strains and are difficult to identify with standard methods. Identification of staphylococcal small-colony variants with the batumin diagnostic preparation is technically simple and can facilitate practical laboratory work.
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Affiliation(s)
- Larisa N Churkina
- Institute of Microbiology and Virology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
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