1
|
Hubert A, Tabuteau H, Farasin J, Loncar A, Dufresne A, Méheust Y, Le Borgne T. Fluid flow drives phenotypic heterogeneity in bacterial growth and adhesion on surfaces. Nat Commun 2024; 15:6161. [PMID: 39039040 PMCID: PMC11263347 DOI: 10.1038/s41467-024-49997-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 06/25/2024] [Indexed: 07/24/2024] Open
Abstract
Bacteria often thrive in surface-attached communities, where they can form biofilms affording them multiple advantages. In this sessile form, fluid flow is a key component of their environments, renewing nutrients and transporting metabolic products and signaling molecules. It also controls colonization patterns and growth rates on surfaces, through bacteria transport, attachment and detachment. However, the current understanding of bacterial growth on surfaces neglects the possibility that bacteria may modulate their division behavior as a response to flow. Here, we employed single-cell imaging in microfluidic experiments to demonstrate that attached Escherichia coli cells can enter a growth arrest state while simultaneously enhancing their adhesion underflow. Despite utilizing clonal populations, we observed a non-uniform response characterized by bistable dynamics, with co-existing subpopulations of non-dividing and actively dividing bacteria. As the proportion of non-dividing bacteria increased with the applied flow rate, it resulted in a reduction in the average growth rate of bacterial populations on flow-exposed surfaces. Dividing bacteria exhibited asymmetric attachment, whereas non-dividing counterparts adhered to the surface via both cell poles. Hence, this phenotypic diversity allows bacterial colonies to combine enhanced attachment with sustained growth, although at a reduced rate, which may be a significant advantage in fluctuating flow conditions.
Collapse
Affiliation(s)
- Antoine Hubert
- Géosciences Rennes, UMR 6118 University of Rennes and CNRS, Rennes, France
| | - Hervé Tabuteau
- Institut de Physique de Rennes, UMR 6251 University of Rennes and CNRS, Rennes, France.
| | - Julien Farasin
- Géosciences Rennes, UMR 6118 University of Rennes and CNRS, Rennes, France
| | - Aleksandar Loncar
- Géosciences Rennes, UMR 6118 University of Rennes and CNRS, Rennes, France
| | - Alexis Dufresne
- ECOBIO, UMR 6553 University of Rennes and CNRS, Rennes, France
| | - Yves Méheust
- Géosciences Rennes, UMR 6118 University of Rennes and CNRS, Rennes, France
| | - Tanguy Le Borgne
- Géosciences Rennes, UMR 6118 University of Rennes and CNRS, Rennes, France.
| |
Collapse
|
2
|
Malik A, Oludiran A, Poudel A, Alvarez OB, Woodward C, Purcell EB. RelQ-mediated alarmone signalling regulates growth, stress-induced biofilm formation and spore accumulation in Clostridioides difficile. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001479. [PMID: 39028551 PMCID: PMC11317968 DOI: 10.1099/mic.0.001479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 07/01/2024] [Indexed: 07/20/2024]
Abstract
The bacterial stringent response (SR) is a conserved transcriptional reprogramming pathway mediated by the nucleotide signalling alarmones, (pp)pGpp. The SR has been implicated in antibiotic survival in Clostridioides difficile, a biofilm- and spore-forming pathogen that causes resilient, highly recurrent C. difficile infections. The role of the SR in other processes and the effectors by which it regulates C. difficile physiology are unknown. C. difficile RelQ is a clostridial alarmone synthetase. Deletion of relQ dysregulates C. difficile growth in unstressed conditions, affects susceptibility to antibiotic and oxidative stressors and drastically reduces biofilm formation. While wild-type C. difficile displays increased biofilm formation in the presence of sublethal stress, the ΔrelQ strain cannot upregulate biofilm production in response to stress. Deletion of relQ slows spore accumulation in planktonic cultures but accelerates it in biofilms. This work establishes biofilm formation and spore accumulation as alarmone-mediated processes in C. difficile and reveals the importance of RelQ in stress-induced biofilm regulation.
Collapse
Affiliation(s)
- Areej Malik
- Biomedical Sciences Program, Old Dominion University, Norfolk, Virginia, 23529, USA
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Adenrele Oludiran
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Asia Poudel
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Orlando Berumen Alvarez
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Charles Woodward
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Erin B. Purcell
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| |
Collapse
|
3
|
Malik A, Oludiran A, Poudel A, Alvarez OB, Woodward C, Purcell EB. RelQ-mediated alarmone signaling regulates growth, sporulation, and stress-induced biofilm formation in Clostridioides difficile. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.14.580318. [PMID: 38405794 PMCID: PMC10888890 DOI: 10.1101/2024.02.14.580318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
The bacterial stringent response (SR) is a conserved transcriptional reprogramming pathway mediated by the nucleotide signaling alarmones, (pp)pGpp. The SR has been implicated in antibiotic survival in Clostridioides difficile, a biofilm- and spore-forming pathogen that causes resilient, highly recurrent C. difficile infections. The role of the SR in other processes and the effectors by which it regulates C. difficile physiology are unknown. C. difficile RelQ is a clostridial alarmone synthetase. Deletion of relQ dysregulates C. difficile growth in unstressed conditions, affects susceptibility to antibiotic and oxidative stressors, and drastically reduces biofilm formation. While wild-type C. difficile displays increased biofilm formation in the presence of sub-lethal stress, the ΔrelQ strain cannot upregulate biofilm production in response to stress. Deletion of relQ slows spore accumulation in planktonic cultures but accelerates it in biofilms. This work establishes biofilm formation and sporulation as alarmone-mediated processes in C. difficile and reveals the importance of RelQ in stress-induced biofilm regulation.
Collapse
Affiliation(s)
- Areej Malik
- Biomedical Sciences Program, Old Dominion University, Norfolk, Virginia, 23529, USA
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Adenrele Oludiran
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Asia Poudel
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Orlando Berumen Alvarez
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Charles Woodward
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| | - Erin B. Purcell
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, Virginia, 23529, USA
| |
Collapse
|
4
|
Increased Levels of (p)ppGpp Correlate with Virulence and Biofilm Formation, but Not with Growth, in Strains of Uropathogenic Escherichia coli. Int J Mol Sci 2023; 24:ijms24043315. [PMID: 36834725 PMCID: PMC9962837 DOI: 10.3390/ijms24043315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/26/2023] [Accepted: 02/06/2023] [Indexed: 02/10/2023] Open
Abstract
Urinary tract infections are one of the most frequent bacterial diseases worldwide. UPECs are the most prominent group of bacterial strains among pathogens responsible for prompting such infections. As a group, these extra-intestinal infection-causing bacteria have developed specific features that allow them to sustain and develop in their inhabited niche of the urinary tract. In this study, we examined 118 UPEC isolates to determine their genetic background and antibiotic resistance. Moreover, we investigated correlations of these characteristics with the ability to form biofilm and to induce a general stress response. We showed that this strain collection expressed unique UPEC attributes, with the highest representation of FimH, SitA, Aer, and Sfa factors (100%, 92.5%, 75%, and 70%, respectively). According to CRA (Congo red agar) analysis, the strains particularly predisposed to biofilm formation represented 32.5% of the isolates. Those biofilm forming strains presented a significant ability to accumulate multi-resistance traits. Most notably, these strains presented a puzzling metabolic phenotype-they showed elevated basal levels of (p)ppGpp in the planktonic phase and simultaneously exhibited a shorter generation time when compared to non-biofilm-forming strains. Moreover, our virulence analysis showed these phenotypes to be crucial for the development of severe infections in the Galleria mellonella model.
Collapse
|
5
|
Lila ASA, Rajab AAH, Abdallah MH, Rizvi SMD, Moin A, Khafagy ES, Tabrez S, Hegazy WAH. Biofilm Lifestyle in Recurrent Urinary Tract Infections. LIFE (BASEL, SWITZERLAND) 2023; 13:life13010148. [PMID: 36676100 PMCID: PMC9865985 DOI: 10.3390/life13010148] [Citation(s) in RCA: 32] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/27/2022] [Accepted: 12/30/2022] [Indexed: 01/06/2023]
Abstract
Urinary tract infections (UTIs) represent one of the most common infections that are frequently encountered in health care facilities. One of the main mechanisms used by bacteria that allows them to survive hostile environments is biofilm formation. Biofilms are closed bacterial communities that offer protection and safe hiding, allowing bacteria to evade host defenses and hide from the reach of antibiotics. Inside biofilm communities, bacteria show an increased rate of horizontal gene transfer and exchange of resistance and virulence genes. Additionally, bacterial communication within the biofilm allows them to orchestrate the expression of virulence genes, which further cements the infestation and increases the invasiveness of the infection. These facts stress the necessity of continuously updating our information and understanding of the etiology, pathogenesis, and eradication methods of this growing public health concern. This review seeks to understand the role of biofilm formation in recurrent urinary tact infections by outlining the mechanisms underlying biofilm formation in different uropathogens, in addition to shedding light on some biofilm eradication strategies.
Collapse
Affiliation(s)
- Amr S. Abu Lila
- Department of Pharmaceutics, College of Pharmacy, University of Ha’il, Ha’il 81442, Saudi Arabia
- Molecular Diagnostics and Personalized Therapeutics Unit, University of Ha’il, Ha’il 81442, Saudi Arabia
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Zagazig University, Zagazig 44519, Egypt
- Correspondence: (A.S.A.L.); (W.A.H.H.)
| | - Azza A. H. Rajab
- Department of Microbiology and Immunology, Faculty of Pharmacy, Zagazig University, Zagazig 44519, Egypt
| | - Marwa H. Abdallah
- Department of Pharmaceutics, College of Pharmacy, University of Ha’il, Ha’il 81442, Saudi Arabia
- Molecular Diagnostics and Personalized Therapeutics Unit, University of Ha’il, Ha’il 81442, Saudi Arabia
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Zagazig University, Zagazig 44519, Egypt
| | - Syed Mohd Danish Rizvi
- Department of Pharmaceutics, College of Pharmacy, University of Ha’il, Ha’il 81442, Saudi Arabia
- Molecular Diagnostics and Personalized Therapeutics Unit, University of Ha’il, Ha’il 81442, Saudi Arabia
| | - Afrasim Moin
- Department of Pharmaceutics, College of Pharmacy, University of Ha’il, Ha’il 81442, Saudi Arabia
- Molecular Diagnostics and Personalized Therapeutics Unit, University of Ha’il, Ha’il 81442, Saudi Arabia
| | - El-Sayed Khafagy
- Department of Pharmaceutics, College of Pharmacy, Prince Sattam bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt
| | - Shams Tabrez
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia
- Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Wael A. H. Hegazy
- Department of Microbiology and Immunology, Faculty of Pharmacy, Zagazig University, Zagazig 44519, Egypt
- Pharmacy Program, Department of Pharmaceutical Sciences, Oman College of Health Sciences, Muscat 113, Oman
- Correspondence: (A.S.A.L.); (W.A.H.H.)
| |
Collapse
|
6
|
Lee JB, Kim SK, Han D, Yoon JW. Mutating both relA and spoT of enteropathogenic Escherichia coli E2348/69 attenuates its virulence and induces interleukin 6 in vivo. Front Microbiol 2023; 14:1121715. [PMID: 36937293 PMCID: PMC10017862 DOI: 10.3389/fmicb.2023.1121715] [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: 12/12/2022] [Accepted: 02/08/2023] [Indexed: 03/06/2023] Open
Abstract
Here, we report for the first time that disrupting both relA and spoT genes in enteropathogenic Escherichia coli E2348/69 can attenuate its virulence and significantly induce interleukin 6 (IL-6) in vivo. Our experimental analyses demonstrated that an E2348/69 ΔrelAΔspoT double mutant strain derepressed the expression of type IV bundle forming pilus (BFP) and repressed the expression of glutamate decarboxylase (GAD) and locus of enterocyte effacement (LEE). Whole genome-scale transcriptomic analysis revealed that 1,564 EPEC genes were differentially expressed in the ΔrelAΔspoT double mutant strain (cut-off > two-fold). Such depletion of relA and spoT attenuated the virulence of E2348/69 in a Caenorhabditis elegans infection model. Surprisingly, IL-6 was highly induced in porcine macrophages infected with the ΔrelAΔspoT double mutant strain compared to those with its wildtype strain. Coinciding with these in vitro results, in vivo murine peritoneal challenge assays showed high increase of IL-6 and improved bacterial clearance in response to infection by the ΔrelAΔspoT double mutant strain. Taken together, our data suggest that relA and spoT play an essential role in regulating biological processes during EPEC pathogenesis and that their depletion can affect host immune responses by inducing IL-6.
Collapse
|
7
|
Fernández-Vázquez J, Cabrer-Panes JD, Åberg A, Juárez A, Madrid C, Gaviria-Cantin T, Fernández-Coll L, Vargas-Sinisterra AF, Jiménez CJ, Balsalobre C. ppGpp, the General Stress Response Alarmone, Is Required for the Expression of the α-Hemolysin Toxin in the Uropathogenic Escherichia coli Isolate, J96. Int J Mol Sci 2022; 23:ijms232012256. [PMID: 36293122 PMCID: PMC9602796 DOI: 10.3390/ijms232012256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 10/11/2022] [Accepted: 10/12/2022] [Indexed: 11/08/2022] Open
Abstract
ppGpp is an intracellular sensor that, in response to different types of stress, coordinates the rearrangement of the gene expression pattern of bacteria to promote adaptation and survival to new environmental conditions. First described to modulate metabolic adaptive responses, ppGpp modulates the expression of genes belonging to very diverse functional categories. In Escherichia coli, ppGpp regulates the expression of cellular factors that are important during urinary tract infections. Here, we characterize the role of this alarmone in the regulation of the hlyCABDII operon of the UPEC isolate J96, encoding the toxin α-hemolysin that induces cytotoxicity during infection of bladder epithelial cells. ppGpp is required for the expression of the α-hemolysin encoded in hlyCABDII by stimulating its transcriptional expression. Prototrophy suppressor mutations in a ppGpp-deficient strain restore the α-hemolysin expression from this operon to wild-type levels, confirming the requirement of ppGpp for its expression. ppGpp stimulates hlyCABDII expression independently of RpoS, RfaH, Zur, and H-NS. The expression of hlyCABDII is promoted at 37 °C and at low osmolarity. ppGpp is required for the thermoregulation but not for the osmoregulation of the hlyCABDII operon. Studies in both commensal and UPEC isolates demonstrate that no UPEC specific factor is strictly required for the ppGpp-mediated regulation described. Our data further support the role of ppGpp participating in the coordinated regulation of the expression of bacterial factors required during infection.
Collapse
Affiliation(s)
- Jorge Fernández-Vázquez
- Department of Genetics, Microbiology and Statistics, School of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Juan David Cabrer-Panes
- Department of Genetics, Microbiology and Statistics, School of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Anna Åberg
- Department of Medical Biochemistry and Biophysics, Umeå University, SE-90187 Umeå, Sweden
| | - Antonio Juárez
- Department of Genetics, Microbiology and Statistics, School of Biology, University of Barcelona, 08028 Barcelona, Spain
- Institute for Bioengineering of Catalonia, The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain
| | - Cristina Madrid
- Department of Genetics, Microbiology and Statistics, School of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Tania Gaviria-Cantin
- Department of Genetics, Microbiology and Statistics, School of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Llorenç Fernández-Coll
- Department of Genetics, Microbiology and Statistics, School of Biology, University of Barcelona, 08028 Barcelona, Spain
| | | | - Carlos Jonay Jiménez
- Department of Genetics, Microbiology and Statistics, School of Biology, University of Barcelona, 08028 Barcelona, Spain
| | - Carlos Balsalobre
- Department of Genetics, Microbiology and Statistics, School of Biology, University of Barcelona, 08028 Barcelona, Spain
- Correspondence: ; Tel.: +34-934-034-622
| |
Collapse
|
8
|
Veetilvalappil VV, Aranjani JM, Mahammad FS, Joseph A. Awakening sleeper cells: a narrative review on bacterial magic spot synthetases as potential drug targets to overcome persistence. Curr Genet 2022; 68:49-60. [PMID: 34787710 PMCID: PMC8801413 DOI: 10.1007/s00294-021-01221-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 10/24/2021] [Accepted: 10/25/2021] [Indexed: 10/29/2022]
Abstract
Magic spot synthetases are emerging targets to overcome persistence caused by stringent response. The 'stringent response' is a bacterial stress survival mechanism, which results in the accumulation of alarmones (also called Magic spots) leading to the formation of dormant persister cells. These 'sleeper cells' evade antibiotic treatment and could result in relapse of infection. This review broadly investigates the phenomenon of stringent response and persistence, and specifically discusses the distribution, classification, and nomenclature of proteins such as Rel/SpoT homologs (RSH), responsible for alarmone synthesis. The authors further explain the relevance of RSH as potential drug targets to break the dormancy of persister cells commonly seen in biofilms. One of the significant factors that initiate alarmone synthesis is nutrient deficiency. In a starved condition, ribosome-associated RSH detects deacylated tRNA and initiates alarmone synthesis. Accumulation of alarmones has a considerable effect on bacterial physiology, virulence, biofilm formation, and persister cell formation. Preventing alarmone synthesis by inhibiting RSH responsible for alarmone synthesis will prevent or reduce persister cells' formation. Magic spot synthetases are thus potential targets that could be explored to overcome persistence seen in biofilms.
Collapse
Affiliation(s)
- Vimal Venu Veetilvalappil
- Department of Pharmaceutical Biotechnology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Udupi, Karnataka, 576104, India
| | - Jesil Mathew Aranjani
- Department of Pharmaceutical Biotechnology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Udupi, Karnataka, 576104, India.
| | - Fayaz Shaik Mahammad
- Department of Biotechnology, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal, Udupi, Karnataka, 576104, India
| | - Alex Joseph
- Department of Pharmaceutical Chemistry, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education, Manipal, Udupi, Karnataka, 576104, India
| |
Collapse
|
9
|
Bessaiah H, Anamalé C, Sung J, Dozois CM. What Flips the Switch? Signals and Stress Regulating Extraintestinal Pathogenic Escherichia coli Type 1 Fimbriae (Pili). Microorganisms 2021; 10:5. [PMID: 35056454 PMCID: PMC8777976 DOI: 10.3390/microorganisms10010005] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/13/2021] [Accepted: 12/15/2021] [Indexed: 12/18/2022] Open
Abstract
Pathogens are exposed to a multitude of harmful conditions imposed by the environment of the host. Bacterial responses against these stresses are pivotal for successful host colonization and pathogenesis. In the case of many E. coli strains, type 1 fimbriae (pili) are an important colonization factor that can contribute to diseases such as urinary tract infections and neonatal meningitis. Production of type 1 fimbriae in E. coli is dependent on an invertible promoter element, fimS, which serves as a phase variation switch determining whether or not a bacterial cell will produce type 1 fimbriae. In this review, we present aspects of signaling and stress involved in mediating regulation of type 1 fimbriae in extraintestinal E. coli; in particular, how certain regulatory mechanisms, some of which are linked to stress response, can influence production of fimbriae and influence bacterial colonization and infection. We suggest that regulation of type 1 fimbriae is potentially linked to environmental stress responses, providing a perspective for how environmental cues in the host and bacterial stress response during infection both play an important role in regulating extraintestinal pathogenic E. coli colonization and virulence.
Collapse
Affiliation(s)
- Hicham Bessaiah
- Institut National de Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada; (H.B.); (C.A.); (J.S.)
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Saint-Hyacinthe, QC J2S 2M2, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, QC H3G 0B1, Canada
| | - Carole Anamalé
- Institut National de Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada; (H.B.); (C.A.); (J.S.)
| | - Jacqueline Sung
- Institut National de Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada; (H.B.); (C.A.); (J.S.)
- Department of Microbiology and Immunology, McGill University, Montreal, QC H3G 0B1, Canada
| | - Charles M. Dozois
- Institut National de Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie, Laval, QC H7V 1B7, Canada; (H.B.); (C.A.); (J.S.)
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Saint-Hyacinthe, QC J2S 2M2, Canada
| |
Collapse
|
10
|
Afonso AC, Oliveira D, Saavedra MJ, Borges A, Simões M. Biofilms in Diabetic Foot Ulcers: Impact, Risk Factors and Control Strategies. Int J Mol Sci 2021; 22:8278. [PMID: 34361044 PMCID: PMC8347492 DOI: 10.3390/ijms22158278] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/13/2022] Open
Abstract
Diabetic foot ulcers (DFUs) are a serious complication from diabetes mellitus, with a huge economic, social and psychological impact on the patients' life. One of the main reasons why DFUs are so difficult to heal is related to the presence of biofilms. Biofilms promote wound inflammation and a remarkable lack of response to host defences/treatment options, which can lead to disease progression and chronicity. In fact, appropriate treatment for the elimination of these microbial communities can prevent the disease evolution and, in some cases, even avoid more serious outcomes, such as amputation or death. However, the detection of biofilm-associated DFUs is difficult due to the lack of methods for diagnostics in clinical settings. In this review, the current knowledge on the involvement of biofilms in DFUs is discussed, as well as how the surrounding environment influences biofilm formation and regulation, along with its clinical implications. A special focus is also given to biofilm-associated DFU diagnosis and therapeutic strategies. An overview on promising alternative therapeutics is provided and an algorithm considering biofilm detection and treatment is proposed.
Collapse
Affiliation(s)
- Ana C. Afonso
- LEPABE—Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal; (A.C.A.); (D.O.); (A.B.)
- CITAB—Centre for the Research and Technology for Agro-Environment and Biological Sciences, University of Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal;
- CEB—Centre of Biological Engineering, Campus de Gualtar, University of Minho, 4710-057 Braga, Portugal
| | - Diana Oliveira
- LEPABE—Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal; (A.C.A.); (D.O.); (A.B.)
- CIQUP, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal
| | - Maria José Saavedra
- CITAB—Centre for the Research and Technology for Agro-Environment and Biological Sciences, University of Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal;
- Department of Veterinary Sciences, School of Agrarian and Veterinary Sciences, University of Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal
| | - Anabela Borges
- LEPABE—Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal; (A.C.A.); (D.O.); (A.B.)
| | - Manuel Simões
- LEPABE—Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal; (A.C.A.); (D.O.); (A.B.)
| |
Collapse
|
11
|
Srinivasan R, Santhakumari S, Poonguzhali P, Geetha M, Dyavaiah M, Xiangmin L. Bacterial Biofilm Inhibition: A Focused Review on Recent Therapeutic Strategies for Combating the Biofilm Mediated Infections. Front Microbiol 2021; 12:676458. [PMID: 34054785 PMCID: PMC8149761 DOI: 10.3389/fmicb.2021.676458] [Citation(s) in RCA: 121] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 04/14/2021] [Indexed: 12/31/2022] Open
Abstract
Biofilm formation is a major concern in various sectors and cause severe problems to public health, medicine, and industry. Bacterial biofilm formation is a major persistent threat, as it increases morbidity and mortality, thereby imposing heavy economic pressure on the healthcare sector. Bacterial biofilms also strengthen biofouling, affecting shipping functions, and the offshore industries in their natural environment. Besides, they accomplish harsh roles in the corrosion of pipelines in industries. At biofilm state, bacterial pathogens are significantly resistant to external attack like antibiotics, chemicals, disinfectants, etc. Within a cell, they are insensitive to drugs and host immune responses. The development of intact biofilms is very critical for the spreading and persistence of bacterial infections in the host. Further, bacteria form biofilms on every probable substratum, and their infections have been found in plants, livestock, and humans. The advent of novel strategies for treating and preventing biofilm formation has gained a great deal of attention. To prevent the development of resistant mutants, a feasible technique that may target adhesive properties without affecting the bacterial vitality is needed. This stimulated research is a rapidly growing field for applicable control measures to prevent biofilm formation. Therefore, this review discusses the current understanding of antibiotic resistance mechanisms in bacterial biofilm and intensely emphasized the novel therapeutic strategies for combating biofilm mediated infections. The forthcoming experimental studies will focus on these recent therapeutic strategies that may lead to the development of effective biofilm inhibitors than conventional treatments.
Collapse
Affiliation(s)
- Ramanathan Srinivasan
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fujian, China.,Key Laboratory of Crop Ecology and Molecular Physiology (Fujian Agriculture and Forestry University), Fujian Province University, Fujian, China
| | - Sivasubramanian Santhakumari
- Department of Biochemistry and Molecular Biology, School of Life Sciences, Pondicherry University, Puducherry, India
| | | | - Mani Geetha
- PG Research and Department of Microbiology, St. Joseph's College of Arts and Science (Autonomous), Tamil Nadu, India
| | - Madhu Dyavaiah
- Department of Biochemistry and Molecular Biology, School of Life Sciences, Pondicherry University, Puducherry, India
| | - Lin Xiangmin
- Fujian Provincial Key Laboratory of Agroecological Processing and Safety Monitoring, School of Life Sciences, Fujian Agriculture and Forestry University, Fujian, China.,Key Laboratory of Crop Ecology and Molecular Physiology (Fujian Agriculture and Forestry University), Fujian Province University, Fujian, China.,Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fujian, China
| |
Collapse
|
12
|
Irving SE, Choudhury NR, Corrigan RM. The stringent response and physiological roles of (pp)pGpp in bacteria. Nat Rev Microbiol 2020; 19:256-271. [PMID: 33149273 DOI: 10.1038/s41579-020-00470-y] [Citation(s) in RCA: 187] [Impact Index Per Article: 46.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2020] [Indexed: 01/10/2023]
Abstract
The stringent response is a stress signalling system mediated by the alarmones guanosine tetraphosphate (ppGpp) and guanosine pentaphosphate (pppGpp) in response to nutrient deprivation. Recent research highlights the complexity and broad range of functions that these alarmones control. This Review provides an update on our current understanding of the enzymes involved in ppGpp, pppGpp and guanosine 5'-monophosphate 3'-diphosphate (pGpp) (collectively (pp)pGpp) turnover, including those shown to produce pGpp and its analogue (pp)pApp. We describe the well-known interactions with RNA polymerase as well as a broader range of cellular target pathways controlled by (pp)pGpp, including DNA replication, transcription, nucleotide synthesis, ribosome biogenesis and function, as well as lipid metabolism. Finally, we review the role of ppGpp and pppGpp in bacterial pathogenesis, providing examples of how these nucleotides are involved in regulating many aspects of virulence and chronic infection.
Collapse
Affiliation(s)
- Sophie E Irving
- The Florey Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Naznin R Choudhury
- The Florey Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK
| | - Rebecca M Corrigan
- The Florey Institute, Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, UK.
| |
Collapse
|
13
|
Mutational analysis of Escherichia coli GreA protein reveals new functional activity independent of antipause and lethal when overexpressed. Sci Rep 2020; 10:16074. [PMID: 32999370 PMCID: PMC7527559 DOI: 10.1038/s41598-020-73069-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 09/07/2020] [Indexed: 12/17/2022] Open
Abstract
There is a growing appreciation for the diverse regulatory consequences of the family of proteins that bind to the secondary channel of E. coli RNA polymerase (RNAP), such as GreA, GreB or DksA. Similar binding sites could suggest a competition between them. GreA is characterised to rescue stalled RNAP complexes due to its antipause activity, but also it is involved in transcription fidelity and proofreading. Here, overexpression of GreA is noted to be lethal independent of its antipause activity. A library of random GreA variants has been used to isolate lethality suppressors to assess important residues for GreA functionality and its interaction with the RNA polymerase. Some mutant defects are inferred to be associated with altered binding competition with DksA, while other variants seem to have antipause activity defects that cannot reverse a GreA-sensitive pause site in a fliC::lacZ reporter system. Surprisingly, apparent binding and cleavage defects are found scattered throughout both the coiled-coil and globular domains. Thus, the coiled-coil of GreA is not just a measuring stick ensuring placement of acidic residues precisely at the catalytic centre but also seems to have binding functions. These lethality suppressor mutants may provide valuable tools for future structural and functional studies.
Collapse
|
14
|
Salzer A, Keinhörster D, Kästle C, Kästle B, Wolz C. Small Alarmone Synthetases RelP and RelQ of Staphylococcus aureus Are Involved in Biofilm Formation and Maintenance Under Cell Wall Stress Conditions. Front Microbiol 2020; 11:575882. [PMID: 33072039 PMCID: PMC7533549 DOI: 10.3389/fmicb.2020.575882] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 08/25/2020] [Indexed: 12/15/2022] Open
Abstract
The stringent response is characterized by the synthesis of the alarmone (p)ppGpp. The phenotypic consequences resulting from (p)ppGpp accumulation vary among species, and for several pathogenic bacteria, it has been shown that the activation of the stringent response strongly affects biofilm formation and maintenance. In Staphylococcus aureus, (p)ppGpp can be synthesized by the RelA/SpoT homolog Rel upon amino acid deprivation or by the two small alarmone synthetases RelP and RelQ under cell wall stress. We found that relP and relQ increase biofilm formation under cell wall stress conditions induced by a subinhibitory vancomycin concentration. However, the effect of (p)ppGpp on biofilm formation is independent of the regulators CodY and Agr. Biofilms formed by the strain HG001 or its (p)ppGpp-defective mutants are mainly composed of extracellular DNA and proteins. Furthermore, the induction of the RelPQ-mediated stringent response contributes to biofilm-related antibiotic tolerance. The proposed (p)ppGpp-inhibiting peptide DJK-5 shows bactericidal and biofilm-inhibitory activity. However, a non-(p)ppGpp-producing strain is even more vulnerable to DJK-5. This strongly argues against the assumption that DJK-5 acts via (p)ppGpp inhibition. In summary, RelP and RelQ play a major role in biofilm formation and maintenance under cell wall stress conditions.
Collapse
Affiliation(s)
| | | | | | | | - Christiane Wolz
- Interfaculty Institute of Microbiology and Infection Medicine, University of Tübingen, Tübingen, Germany
| |
Collapse
|
15
|
Spira B, Ospino K. Diversity in E. coli (p)ppGpp Levels and Its Consequences. Front Microbiol 2020; 11:1759. [PMID: 32903406 PMCID: PMC7434938 DOI: 10.3389/fmicb.2020.01759] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 07/06/2020] [Indexed: 12/21/2022] Open
Abstract
(p)ppGpp is at the core of global bacterial regulation as it controls growth, the most important aspect of life. It would therefore be expected that at least across a species the intrinsic (basal) levels of (p)ppGpp would be reasonably constant. On the other hand, the historical contingency driven by the selective pressures on bacterial populations vary widely resulting in broad genetic polymorphism. Given that (p)ppGpp controls the expression of many genes including those involved in the bacterial response to environmental challenges, it is not surprising that the intrinsic levels of (p)ppGpp would also vary considerably. In fact, null mutations or less severe genetic polymorphisms in genes associated with (p)ppGpp synthesis and hydrolysis are common. Such variation can be observed in laboratory strains, in natural isolates as well as in evolution experiments. High (p)ppGpp levels result in low growth rate and high tolerance to environmental stresses. Other aspects such as virulence and antimicrobial resistance are also influenced by the intrinsic levels of (p)ppGpp. A case in point is the production of Shiga toxin by certain E. coli strains which is inversely correlated to (p)ppGpp basal level. Conversely, (p)ppGpp concentration is positively correlated to increased tolerance to different antibiotics such as β-lactams, vancomycin, and others. Here we review the variations in intrinsic (p)ppGpp levels and its consequences across the E. coli species.
Collapse
Affiliation(s)
- Beny Spira
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Katia Ospino
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| |
Collapse
|
16
|
Cabrer-Panes JD, Fernández-Coll L, Fernández-Vázquez J, Gaviria-Cantin TC, El Mouali Y, Åberg A, Balsalobre C. ppGpp mediates the growth phase-dependent regulation of agn43, a phase variable gene, by stimulating its promoter activity. ENVIRONMENTAL MICROBIOLOGY REPORTS 2020; 12:444-453. [PMID: 32548953 DOI: 10.1111/1758-2229.12860] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 06/12/2020] [Indexed: 06/11/2023]
Abstract
Antigen 43 (Ag43) is a self-recognizing outer membrane protein of Escherichia coli expressed during intracellular growth and biofilm formation, suggesting a role in infection. The expression of agn43 is under phase variation control, meaning that there are regulatory mechanisms adjusting the percentage of agn43-expressing cells in the population, in addition to mechanisms modulating the transcriptional expression level in each expressing cell. Phenotypic and transcriptional studies indicate that Ag43 expression is induced upon entry into the stationary phase in a ppGpp-dependent and RpoS-independent manner. The use of single-cell approaches and phase variation deficient strains let to conclude that ppGpp stimulates agn43 promoter activity, rather than affecting the percentage of agn43-expressing cells. The data highlight the relevance that promoter activity regulation may have, without any involvement of the phase variation state, in the final Ag43 expression output. The agn43 promoter of the MG1655 strain carries an AT-rich discriminator between positions -10 and +1, which is highly conserved among the agn43 genes present in the different pathotypes of E. coli. Remarkably, the AT-rich discriminator is required for the positive transcriptional control mediated by ppGpp.
Collapse
Affiliation(s)
- Juan David Cabrer-Panes
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Barcelona, Spain
| | - Llorenç Fernández-Coll
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Barcelona, Spain
- Section on Molecular Regulation, Program in Genomics of Differentiation, Eunice Kennedy Shriver NICHD, NIH, Bethesda, MD, USA
| | - Jorge Fernández-Vázquez
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Barcelona, Spain
| | | | - Youssef El Mouali
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Barcelona, Spain
| | - Anna Åberg
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Carlos Balsalobre
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Barcelona, Spain
| |
Collapse
|
17
|
Yang HW, Yu M, Lee JH, Chatnaparat T, Zhao Y. The stringent response regulator (p) ppGpp mediates virulence gene expression and survival in Erwinia amylovora. BMC Genomics 2020; 21:261. [PMID: 32228459 PMCID: PMC7106674 DOI: 10.1186/s12864-020-6699-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/24/2020] [Indexed: 01/30/2023] Open
Abstract
Background The nucleotide second messengers, i.e., guanosine tetraphosphate and pentaphosphate [collectively referred to as (p) ppGpp], trigger the stringent response under nutrient starvation conditions and play an essential role in virulence in the fire blight pathogen Erwinia amylovora. Here, we present transcriptomic analyses to uncover the overall effect of (p) ppGpp-mediated stringent response in E. amylovora in the hrp-inducing minimal medium (HMM). Results In this study, we investigated the transcriptomic changes of the (p) ppGpp0 mutant under the type III secretion system (T3SS)-inducing condition using RNA-seq. A total of 1314 differentially expressed genes (DEGs) was uncovered, representing more than one third (36.8%) of all genes in the E. amylovora genome. Compared to the wild-type, the (p) ppGpp0 mutant showed down-regulation of genes involved in peptide ATP-binding cassette (ABC) transporters and virulence-related processes, including type III secretion system (T3SS), biofilm, and motility. Interestingly, in contrast to previous reports, the (p) ppGpp0 mutant showed up-regulation of amino acid biosynthesis genes, suggesting that it might be due to that these amino acid biosynthesis genes are indirectly regulated by (p) ppGpp in E. amylovora or represent specific culturing condition used. Furthermore, the (p) ppGpp0 mutant exhibited up-regulation of genes involved in translation, SOS response, DNA replication, chromosome segregation, as well as biosynthesis of nucleotide, fatty acid and lipid. Conclusion These findings suggested that in HMM environment, E. amylovora might use (p) ppGpp as a signal to activate virulence gene expression, and simultaneously mediate the balance between virulence and survival by negatively regulating DNA replication, translation, cell division, as well as biosynthesis of nucleotide, amino acid, fatty acid, and lipid. Therefore, (p) ppGpp could be a promising target for developing novel control measures to fight against this devastating disease of apples and pears.
Collapse
Affiliation(s)
- Ho-Wen Yang
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr, Urbana, IL, 61801, USA
| | - Menghao Yu
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr, Urbana, IL, 61801, USA
| | - Jae Hoon Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr, Urbana, IL, 61801, USA
| | - Tiyakhon Chatnaparat
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr, Urbana, IL, 61801, USA
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr, Urbana, IL, 61801, USA.
| |
Collapse
|
18
|
Anti-Biofilm Effects of Synthetic Antimicrobial Peptides Against Drug-Resistant Pseudomonas aeruginosa and Staphylococcus aureus Planktonic Cells and Biofilm. Molecules 2019; 24:molecules24244560. [PMID: 31842508 PMCID: PMC6943720 DOI: 10.3390/molecules24244560] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 12/02/2019] [Accepted: 12/11/2019] [Indexed: 02/08/2023] Open
Abstract
Biofilm-associated infections are difficult to manage or treat as biofilms or biofilm-embedded bacteria are difficult to eradicate. Antimicrobial peptides have gained increasing attention as a possible alternative to conventional drugs to combat drug-resistant microorganisms because they inhibit the growth of planktonic bacteria by disrupting the cytoplasmic membrane. The current study investigated the effects of synthetic peptides (PS1-2, PS1-5, and PS1-6) and conventional antibiotics on the growth, biofilm formation, and biofilm reduction of drug-resistant Pseudomonas aeruginosa and Staphylococcus aureus. The effects of PS1-2, PS1-5, and PS1-6 were also tested in vivo using a mouse model. All peptides inhibited planktonic cell growth and biofilm formation in a dose-dependent manner. They also reduced preformed biofilm masses by removing the carbohydrates, extracellular DNA, and lipids that comprised extracellular polymeric substances (EPSs) but did not affect proteins. In vivo, PS1-2 showed the greatest efficacy against preformed biofilms with no cytotoxicity. Our findings indicate that the PS1-2 peptide has potential as a next-generation therapeutic drug to overcome multidrug resistance and to regulate inflammatory response in biofilm-associated infections.
Collapse
|
19
|
Yin HB, Boomer A, Chen CH, Patel J. Antibiofilm Efficacy of Peptide 1018 against Listeria monocytogenes and Shiga Toxigenic Escherichia coli on Equipment Surfaces. J Food Prot 2019; 82:1837-1843. [PMID: 31599650 DOI: 10.4315/0362-028x.jfp-19-168] [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] [Indexed: 12/23/2022]
Abstract
Listeria monocytogenes and Shiga toxigenic Escherichia coli (STEC) are important foodborne bacterial pathogens that can form biofilms on equipment surfaces at food processing facilities. Pathogens in biofilms are resistant to conventional antimicrobials and require higher antimicrobial concentrations to be inactivated. In this study, the efficacy of a synthetic innate defense regulator peptide 1018 (peptide 1018) for inactivating L. monocytogenes and STEC (O26, O111, O145, O157) biofilms on stainless steel and polycarbonate surfaces was investigated. Stainless steel and polycarbonate coupons (12 mm in diameter) were used in a Centers for Disease Control and Prevention biofilm reactor containing 400 mL of 10% tryptic soy broth (TSB) that had been inoculated with an individual strain of L. monocytogenes or STEC to obtain 6 log CFU/mL populations. The reactor was set with a constant flow rate at 50 mL/h of 10% TSB for 48 h. After 48 h, coupons were treated with peptide 1018 at 0, 10, 20, or 50 μg/mL in phosphate buffer saline (PBS) for 24 h. Surviving bacterial populations were determined by scraping off the coupons and spiral plating on selective media. Significantly higher levels of pathogens in biofilms formed by certain bacterial strains, including L. monocytogenes F6854, E. coli O157:H7 RM4407 and NADC5713, and non-O157 E. coli NADC3629, were recovered on polycarbonate surfaces than on stainless steel. Antibiofilm efficacy of peptide 1018 against pathogens was concentration-dependent and varied with the type of pathogen and material surfaces. Peptide 1018 at 50 μg/mL significantly inactivated all tested bacterial biofilms on both surfaces compared with the PBS control (P < 0.05). L. monocytogenes was the bacterium most sensitive to peptide 1018; on stainless steel surfaces treated with 50 μg/mL peptide 1018, there was a 3.7- to 4.6-log CFU/cm2 reduction in Listeria populations compared with a 1.0- to 3.5-log CFU/cm2 reduction of STEC. Results suggest that peptide 1018 may be used to inactivate L. monocytogenes and STEC biofilms on equipment surfaces.
Collapse
Affiliation(s)
- Hsin-Bai Yin
- Environmental Microbial and Food Safety Laboratory, U.S. Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, Building 201, BARC-East, Beltsville, Maryland 20705 (ORCID: https://orcid.org/0000-0002-1420-5723 [J.P.]); and
| | - Ashley Boomer
- Environmental Microbial and Food Safety Laboratory, U.S. Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, Building 201, BARC-East, Beltsville, Maryland 20705 (ORCID: https://orcid.org/0000-0002-1420-5723 [J.P.]); and
| | - Chi-Hung Chen
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland 20742, USA
| | - Jitendra Patel
- Environmental Microbial and Food Safety Laboratory, U.S. Department of Agriculture, Agricultural Research Service, 10300 Baltimore Avenue, Building 201, BARC-East, Beltsville, Maryland 20705 (ORCID: https://orcid.org/0000-0002-1420-5723 [J.P.]); and
| |
Collapse
|
20
|
A short peptide with selective anti-biofilm activity against Pseudomonas aeruginosa and Klebsiella pneumoniae carbapenemase-producing bacteria. Microb Pathog 2019; 135:103605. [DOI: 10.1016/j.micpath.2019.103605] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 06/10/2019] [Accepted: 06/19/2019] [Indexed: 12/12/2022]
|
21
|
Bessaiah H, Pokharel P, Habouria H, Houle S, Dozois CM. yqhG Contributes to Oxidative Stress Resistance and Virulence of Uropathogenic Escherichia coli and Identification of Other Genes Altering Expression of Type 1 Fimbriae. Front Cell Infect Microbiol 2019; 9:312. [PMID: 31555608 PMCID: PMC6727828 DOI: 10.3389/fcimb.2019.00312] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 08/16/2019] [Indexed: 12/15/2022] Open
Abstract
Urinary tract infections (UTIs) are common bacterial infections and the vast majority of UTIs are caused by extraintestinal pathogenic Escherichia coli (ExPEC) strains referred to as uropathogenic E. coli (UPEC). Successful colonization of the human urinary tract by UPEC is mediated by secreted or surface exposed virulence factors-toxins, iron transport systems, and adhesins, such as type 1 fimbriae (pili). To identify factors involved in the expression of type 1 fimbriae, we constructed a chromosomal transcriptional reporter consisting of lux under the control of the fimbrial promoter region, fimS and this construct was inserted into the reference UPEC strain CFT073 genome at the attTn7 site. This fimS reporter strain was used to generate a Tn10 transposon mutant library, coupled with high-throughput sequencing to identify genes that affect the expression of type 1 fimbriae. Transposon insertion sites were linked to genes involved in protein fate and synthesis, energy metabolism, adherence, transcriptional regulation, and transport. We showed that YqhG, a predicted periplasmic protein, is one of the important mediators that contribute to the decreased expression of type 1 fimbriae in UPEC strain CFT073. The ΔyqhG mutant had reduced expression of type 1 fimbriae and a decreased capacity to colonize the murine urinary tract. Reduced expression of type 1 fimbriae correlated with an increased bias for orientation of the fim switch in the OFF position. Interestingly, the ΔyqhG mutant was more motile than the WT strain and was also significantly more sensitive to hydrogen peroxide. Taken together, loss of yqhG may decrease virulence in the urinary tract due to a decrease in production of type 1 fimbriae and a greater sensitivity to oxidative stress.
Collapse
Affiliation(s)
- Hicham Bessaiah
- INRS-Centre Armand-Frappier Santé Biotechnologie, Laval, QC, Canada
- CRIPA-Centre de Recherche en Infectiologie Porcine et Avicole, Saint-Hyacinthe, QC, Canada
| | - Pravil Pokharel
- INRS-Centre Armand-Frappier Santé Biotechnologie, Laval, QC, Canada
- CRIPA-Centre de Recherche en Infectiologie Porcine et Avicole, Saint-Hyacinthe, QC, Canada
| | - Hajer Habouria
- INRS-Centre Armand-Frappier Santé Biotechnologie, Laval, QC, Canada
- CRIPA-Centre de Recherche en Infectiologie Porcine et Avicole, Saint-Hyacinthe, QC, Canada
| | - Sébastien Houle
- INRS-Centre Armand-Frappier Santé Biotechnologie, Laval, QC, Canada
- CRIPA-Centre de Recherche en Infectiologie Porcine et Avicole, Saint-Hyacinthe, QC, Canada
| | - Charles M. Dozois
- INRS-Centre Armand-Frappier Santé Biotechnologie, Laval, QC, Canada
- CRIPA-Centre de Recherche en Infectiologie Porcine et Avicole, Saint-Hyacinthe, QC, Canada
| |
Collapse
|
22
|
Flexible Metabolism and Suppression of Latent Enzymes Are Important for Escherichia coli Adaptation to Diverse Environments within the Host. J Bacteriol 2019; 201:JB.00181-19. [PMID: 31160397 DOI: 10.1128/jb.00181-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 05/27/2019] [Indexed: 12/13/2022] Open
Abstract
Bacterial metabolism is necessary for adaptation to the host microenvironment. Flexible metabolic pathways allow uropathogenic Escherichia coli (UPEC) to harmlessly reside in the human intestinal tract and cause disease upon extraintestinal colonization. E. coli intestinal colonization requires carbohydrates as a carbon source, while UPEC extraintestinal colonization requires gluconeogenesis and the tricarboxylic acid cycle. UPEC containing disruptions in two irreversible glycolytic steps involving 6-carbon (6-phosphofructokinase; pfkA) and 3-carbon (pyruvate kinase; pykA) substrates have no fitness defect during urinary tract infection (UTI); however, both reactions are catalyzed by isozymes: 6-phosphofructokinases Pfk1 and Pfk2, encoded by pfkA and pfkB, and pyruvate kinases Pyk II and Pyk I, encoded by pykA and pykF UPEC strains lacking one or both phosphofructokinase-encoding genes (pfkB and pfkA pfkB) and strains lacking one or both pyruvate kinase genes (pykF and pykA pykF) were investigated to determine their regulatory roles in carbon flow during glycolysis by examining their fitness during UTI and in vitro growth requirements. Loss of a single phosphofructokinase-encoding gene has no effect on fitness, while the pfkA pfkB double mutant outcompeted the parental strain in the bladder. A defect in bladder and kidney colonization was observed with loss of pykF, while loss of pykA resulted in a fitness advantage. The pykA pykF mutant was indistinguishable from wild-type in vivo, suggesting that the presence of Pyk II rather than the loss of Pyk I itself is responsible for the fitness defect in the pykF mutant. These findings suggest that E. coli suppresses latent enzymes to survive in the host urinary tract.IMPORTANCE Urinary tract infections are the most frequently diagnosed urologic disease, with uropathogenic Escherichia coli (UPEC) infections placing a significant financial burden on the health care system by generating more than two billion dollars in annual costs. This, in combination with steadily increasing antibiotic resistances to present day treatments, necessitates the discovery of new antimicrobial agents to combat these infections. By broadening our scope beyond the study of virulence properties and investigating bacterial physiology and metabolism, we gain a better understanding of how pathogens use nutrients and compete within host microenvironments, enabling us to cultivate new therapeutics to exploit and target pathogen growth requirements in a specific host environment.
Collapse
|
23
|
Westfall C, Flores-Mireles AL, Robinson JI, Lynch AJL, Hultgren S, Henderson JP, Levin PA. The Widely Used Antimicrobial Triclosan Induces High Levels of Antibiotic Tolerance In Vitro and Reduces Antibiotic Efficacy up to 100-Fold In Vivo. Antimicrob Agents Chemother 2019; 63:e02312-18. [PMID: 30782996 PMCID: PMC6496070 DOI: 10.1128/aac.02312-18] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 02/06/2019] [Indexed: 12/27/2022] Open
Abstract
The antimicrobial triclosan is used in a wide range of consumer products ranging from toothpaste, cleansers, socks, and baby toys. A bacteriostatic inhibitor of fatty acid synthesis, triclosan is extremely stable and accumulates in the environment. Approximately 75% of adults in the United States have detectable levels of the compound in their urine, with a sizeable fraction of individuals (>10%) having urine concentrations equal to or greater than the minimal inhibitory concentration for Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA). Previous work has identified connections between defects in fatty acid synthesis and accumulation of the alarmone guanosine tetraphosphate (ppGpp), which has been repeatedly associated with antibiotic tolerance and persistence. Based on these data, we hypothesized that triclosan exposure may inadvertently drive bacteria into a state in which they are able to tolerate normally lethal concentrations of antibiotics. Here we report that clinically relevant concentrations of triclosan increased E. coli and MRSA tolerance to bactericidal antibiotics as much as 10,000-fold in vitro and reduced antibiotic efficacy up to 100-fold in a mouse urinary tract infection model. Genetic analysis indicated that triclosan-mediated antibiotic tolerance requires ppGpp synthesis but is independent of growth. These data highlight an unexpected and certainly unintended consequence of adding high concentrations of antimicrobials in consumer products, supporting an urgent need to reevaluate the costs and benefits of the prophylactic use of triclosan and other bacteriostatic compounds.
Collapse
Affiliation(s)
- Corey Westfall
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Ana Lidia Flores-Mireles
- Department of Molecular Microbiology and Microbial Pathogenesis, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - John Isaac Robinson
- Division of Infectious Diseases, John T. Milliken Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Aaron J L Lynch
- Department of Molecular Microbiology and Microbial Pathogenesis, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Scott Hultgren
- Department of Molecular Microbiology and Microbial Pathogenesis, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jeffrey P Henderson
- Division of Infectious Diseases, John T. Milliken Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Petra Anne Levin
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
| |
Collapse
|
24
|
Abstract
ABSTRACT
Streptococcus pneumoniae
undergoes phase variation or spontaneous, reversible phenotypic variation in colony opacity, encapsulation, and pilus expression. The variation in colony opacity appears to occur in all strains, whereas the switches in the production of the capsule and pilus have been observed in several strains. This chapter elaborates on the variation in colony opacity since this phenomenon has been extensively characterized.
S. pneumoniae
produces opaque and transparent colonies on the translucent agar medium. The different colony phases are fundamentally distinct phenotypes in their metabolism and multiple characteristics, as exemplified by cell surface features and phenotypes in colonization and virulence. Opaque variants, which express more capsular polysaccharides and fewer teichoic acids, are more virulent in animal models of sepsis but colonize the nasopharynx poorly. In contrast, transparent variants, with fewer capsular polysaccharides and more teichoic acid, colonize the nasopharynx in animal models more efficiently but are relatively avirulent. Lastly, pneumococcal opacity variants are generated by differential methylation of the genome DNA variation. The reversible switch in the methylation pattern is caused by DNA inversions in three homologous
hsdS
genes of the colony opacity determinant (
cod
) or SpnD39III locus, a conserved type I restriction-modification (RM) system. The
hsdS
gene encodes the sequence recognition subunit of the type I RM DNA methyltransferase. The combination of DNA inversion and differential methylation, a complex mechanism of phase variation, generates a mixed population that may allow for the selection of organisms
in vivo
with characteristics permissive for either carriage or systemic infection.
Collapse
|
25
|
Haney EF, Straus SK, Hancock REW. Reassessing the Host Defense Peptide Landscape. Front Chem 2019; 7:43. [PMID: 30778385 PMCID: PMC6369191 DOI: 10.3389/fchem.2019.00043] [Citation(s) in RCA: 216] [Impact Index Per Article: 43.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 01/15/2019] [Indexed: 12/18/2022] Open
Abstract
Current research has demonstrated that small cationic amphipathic peptides have strong potential not only as antimicrobials, but also as antibiofilm agents, immune modulators, and anti-inflammatories. Although traditionally termed antimicrobial peptides (AMPs) these additional roles have prompted a shift in terminology to use the broader term host defense peptides (HDPs) to capture the multi-functional nature of these molecules. In this review, we critically examined the role of AMPs and HDPs in infectious diseases and inflammation. It is generally accepted that HDPs are multi-faceted mediators of a wide range of biological processes, with individual activities dependent on their polypeptide sequence. In this context, we explore the concept of chemical space as it applies to HDPs and hypothesize that the various functions and activities of this class of molecule exist on independent but overlapping activity landscapes. Finally, we outline several emerging functions and roles of HDPs and highlight how an improved understanding of these processes can potentially be leveraged to more fully realize the therapeutic promise of HDPs.
Collapse
Affiliation(s)
- Evan F Haney
- Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, BC, Canada
| | - Suzana K Straus
- Department of Chemistry, University of British Columbia, Vancouver, BC, Canada
| | - Robert E W Hancock
- Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, BC, Canada
| |
Collapse
|
26
|
Abstract
Antibiotic tolerance, the capacity of genetically susceptible bacteria to survive the lethal effects of antibiotic treatment, plays a critical and underappreciated role in the disease burden of bacterial infections. Here, we take a pathogen-by-pathogen approach to illustrate the clinical significance of antibiotic tolerance and discuss how the physiology of specific pathogens in their infection environments impacts the mechanistic underpinnings of tolerance. We describe how these insights are leading to the development of species-specific therapeutic strategies for targeting antibiotic tolerance and highlight experimental platforms that are enabling us to better understand the complexities of drug-tolerant pathogens in in vivo settings.
Collapse
Affiliation(s)
- Sylvain Meylan
- Department of Biomedicine, Basel University Hospital, Basel, CH-4031, Switzerland; Division of Infectious Diseases and Hospital Epidemiology, Basel University Hospital, Basel, CH-4031, Switzerland; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | - Ian W Andrews
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA; Institute for Medical Engineering & Science, Department of Biological Engineering, and Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - James J Collins
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA; Institute for Medical Engineering & Science, Department of Biological Engineering, and Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Harvard-MIT Program in Health Sciences and Technology, Cambridge, MA 02139, USA.
| |
Collapse
|
27
|
Yasir M, Willcox MDP, Dutta D. Action of Antimicrobial Peptides against Bacterial Biofilms. MATERIALS 2018; 11:ma11122468. [PMID: 30563067 PMCID: PMC6317029 DOI: 10.3390/ma11122468] [Citation(s) in RCA: 161] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 11/30/2018] [Accepted: 12/01/2018] [Indexed: 12/22/2022]
Abstract
Microbes are known to colonize surfaces and form biofilms. These biofilms are communities of microbes encased in a self-produced matrix that often contains polysaccharides, DNA and proteins. Antimicrobial peptides (AMPs) have been used to control the formation and to eradicate mature biofilms. Naturally occurring or synthetic antimicrobial peptides have been shown to prevent microbial colonization of surfaces, to kill bacteria in biofilms and to disrupt the biofilm structure. This review systemically analyzed published data since 1970 to summarize the possible anti-biofilm mechanisms of AMPs. One hundred and sixty-two published reports were initially selected for this review following searches using the criteria ‘antimicrobial peptide’ OR ‘peptide’ AND ‘mechanism of action’ AND ‘biofilm’ OR ‘antibiofilm’ in the databases PubMed; Scopus; Web of Science; MEDLINE; and Cochrane Library. Studies that investigated anti-biofilm activities without describing the possible mechanisms were removed from the analysis. A total of 17 original reports were included which have articulated the mechanism of antimicrobial action of AMPs against biofilms. The major anti-biofilm mechanisms of antimicrobial peptides are: (1) disruption or degradation of the membrane potential of biofilm embedded cells; (2) interruption of bacterial cell signaling systems; (3) degradation of the polysaccharide and biofilm matrix; (4) inhibition of the alarmone system to avoid the bacterial stringent response; (5) downregulation of genes responsible for biofilm formation and transportation of binding proteins.
Collapse
Affiliation(s)
- Muhammad Yasir
- School of Optometry and Vision Science, University of New South Wales, Sydney, NSW 2052, Australia.
| | | | - Debarun Dutta
- School of Optometry and Vision Science, University of New South Wales, Sydney, NSW 2052, Australia.
| |
Collapse
|
28
|
Berne C, Ellison CK, Ducret A, Brun YV. Bacterial adhesion at the single-cell level. Nat Rev Microbiol 2018; 16:616-627. [DOI: 10.1038/s41579-018-0057-5] [Citation(s) in RCA: 266] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
29
|
Hüttener M, Prieto A, Espelt J, Bernabeu M, Juárez A. Stringent Response and AggR-Dependent Virulence Regulation in the Enteroaggregative Escherichia coli Strain 042. Front Microbiol 2018; 9:717. [PMID: 29692772 PMCID: PMC5902536 DOI: 10.3389/fmicb.2018.00717] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/27/2018] [Indexed: 12/22/2022] Open
Abstract
Virulence expression in the enteroaggregative Escherichia coli strain 042 requires the transcriptional activator AggR. We show in this report that, as reported for other virulence factors, the nucleotide second messenger (p)ppGpp is needed for a high expression level of AggR. As expected from these findings, expression of AggR-activated genes such as the AafA pilin subunit is downregulated in the absence of (p)ppGpp. Considering the fact that biofilm formation in strain 042 requires the AafA protein, biofilm development in strain 042 is impaired in derivatives that lack either the AggR protein, the virulence plasmid that encodes AggR (pAA2) or the ability to synthesize (p)ppGpp. These results show a direct correlation between (p)ppGpp, expression of AggR and biofilm development in strain 042.
Collapse
Affiliation(s)
- Mário Hüttener
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Alejandro Prieto
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Joan Espelt
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Manuel Bernabeu
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Antonio Juárez
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain.,Institute for Bioengineering of Catalonia, The Barcelona Institute of Science and Technology, Barcelona, Spain
| |
Collapse
|
30
|
Markova JA, Anganova EV, Turskaya AL, Bybin VA, Savilov ED. Regulation of Escherichia coli Biofilm Formation (Review). APPL BIOCHEM MICRO+ 2018. [DOI: 10.1134/s0003683818010040] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
31
|
Werneburg GT, Thanassi DG. Pili Assembled by the Chaperone/Usher Pathway in Escherichia coli and Salmonella. EcoSal Plus 2018; 8:10.1128/ecosalplus.ESP-0007-2017. [PMID: 29536829 PMCID: PMC5940347 DOI: 10.1128/ecosalplus.esp-0007-2017] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Indexed: 12/12/2022]
Abstract
Gram-negative bacteria assemble a variety of surface structures, including the hair-like organelles known as pili or fimbriae. Pili typically function in adhesion and mediate interactions with various surfaces, with other bacteria, and with other types of cells such as host cells. The chaperone/usher (CU) pathway assembles a widespread class of adhesive and virulence-associated pili. Pilus biogenesis by the CU pathway requires a dedicated periplasmic chaperone and integral outer membrane protein termed the usher, which forms a multifunctional assembly and secretion platform. This review addresses the molecular and biochemical aspects of the CU pathway in detail, focusing on the type 1 and P pili expressed by uropathogenic Escherichia coli as model systems. We provide an overview of representative CU pili expressed by E. coli and Salmonella, and conclude with a discussion of potential approaches to develop antivirulence therapeutics that interfere with pilus assembly or function.
Collapse
Affiliation(s)
- Glenn T. Werneburg
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, NY, USA
| | - David G. Thanassi
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, NY, USA
| |
Collapse
|
32
|
Temporal Regulation of fim Genes in Uropathogenic Escherichia coli during Infection of the Murine Urinary Tract. J Pathog 2017; 2017:8694356. [PMID: 29445547 PMCID: PMC5763102 DOI: 10.1155/2017/8694356] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 11/28/2017] [Accepted: 12/07/2017] [Indexed: 11/17/2022] Open
Abstract
Uropathogenic Escherichia coli (UPEC) adhere to cells in the human urinary tract via type 1 pili that undergo phase variation where a 314-bp fimS DNA element flips between Phase-ON and Phase-OFF orientations through two site-specific recombinases, FimB and FimE. Three fim-lux operon transcriptional fusions were created and moved into the clinical UPEC isolate NU149 to determine their temporal regulation in UPEC growing in the urinary tract. Within murine urinary tracts, the UPEC strains demonstrated elevated transcription of fimA and fimB early in the infection, but lower transcription by the fifth day in murine kidneys. In contrast, fimE transcription was much lower than either fimA or fimB early, increased markedly at 24 h after inoculation, and then dropped five days after inoculation. Positioning of fimS was primarily in the Phase-ON position over the time span in UPEC infected bladders, whereas in UPEC infected murine kidneys the Phase-OFF orientation was favored by the fifth day after inoculation. Hemagglutination titers with guinea pig erythrocytes remained constant in UPEC growing in infected murine bladders but fell substantially in UPEC infected kidneys over time. Our results show temporal in vivo regulation of fim gene expression in different environmental niches when UPEC infects the murine urinary tract.
Collapse
|
33
|
The stringent response promotes biofilm dispersal in Pseudomonas putida. Sci Rep 2017; 7:18055. [PMID: 29273811 PMCID: PMC5741744 DOI: 10.1038/s41598-017-18518-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 12/12/2017] [Indexed: 01/08/2023] Open
Abstract
Biofilm dispersal is a genetically programmed response enabling bacterial cells to exit the biofilm in response to particular physiological or environmental conditions. In Pseudomonas putida biofilms, nutrient starvation triggers c-di-GMP hydrolysis by phosphodiesterase BifA, releasing inhibition of protease LapG by the c-di-GMP effector protein LapD, and resulting in proteolysis of the adhesin LapA and the subsequent release of biofilm cells. Here we demonstrate that the stringent response, a ubiquitous bacterial stress response, is accountable for relaying the nutrient stress signal to the biofilm dispersal machinery. Mutants lacking elements of the stringent response - (p)ppGpp sythetases [RelA and SpoT] and/or DksA - were defective in biofilm dispersal. Ectopic (p)ppGpp synthesis restored biofilm dispersal in a ∆relA ∆spoT mutant. In vivo gene expression analysis showed that (p)ppGpp positively regulates transcription of bifA, and negatively regulates transcription of lapA and the lapBC, and lapE operons, encoding a LapA-specific secretion system. Further in vivo and in vitro characterization revealed that the PbifA promoter is dependent on the flagellar σ factor FliA, and positively regulated by ppGpp and DksA. Our results indicate that the stringent response stimulates biofilm dispersal under nutrient limitation by coordinately promoting LapA proteolysis and preventing de novo LapA synthesis and secretion.
Collapse
|
34
|
Loiko NG, Lobanov KV, Nikolaev YA, Kozlova AN, El’-Registan GI. Regulation of phase variation in type I pili formation in Escherichia coli: Role of alkylresorcinols, microbial autoregulators. Microbiology (Reading) 2017. [DOI: 10.1134/s0026261717050149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
|
35
|
ppGpp and cytotoxicity diversity in Shiga toxin-producing Escherichia coli (STEC) isolates. Epidemiol Infect 2017; 145:2204-2211. [PMID: 28587697 DOI: 10.1017/s0950268817001091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) is a known food pathogen, which main reservoir is the intestine of ruminants. The abundance of different STEC lineages in nature reflect a heterogeneity that is characterised by the differential expression of certain genotypic characteristics, which in turn are influenced by the environmental conditions to which the microorganism is exposed. Bacterial homeostasis and stress response are under the control of the alarmone guanosine tetraphosphate (ppGpp), which intrinsic levels varies across the E. coli species. In the present study, 50 STEC isolates from healthy sheep were evaluated regarding their ppGpp content, cytotoxicity and other relevant genetic and phenotypic characteristics. We found that the level of ppGpp and cytotoxicity varied considerably among the examined strains. Isolates that harboured the stx2 gene were the least cytotoxic and presented the highest levels of ppGpp. All stx2 isolates belonged to phylogroup A, while strains that carried stx1 or both stx1 and stx2 genes pertained to phylogroup B1. All but two stx2 isolates belonged to the stx2b subtype. Strains that belonged to phylogroup B1 displayed on average low levels of ppGpp and high cytotoxicity. Overall, there was a negative correlation between cytotoxicity and ppGpp.
Collapse
|
36
|
Mansour SC, Pletzer D, de la Fuente-Núñez C, Kim P, Cheung GYC, Joo HS, Otto M, Hancock REW. Bacterial Abscess Formation Is Controlled by the Stringent Stress Response and Can Be Targeted Therapeutically. EBioMedicine 2016; 12:219-226. [PMID: 27658736 PMCID: PMC5078632 DOI: 10.1016/j.ebiom.2016.09.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 09/12/2016] [Accepted: 09/16/2016] [Indexed: 01/08/2023] Open
Abstract
Cutaneous abscess infections are difficult to treat with current therapies and alternatives to conventional antibiotics are needed. Understanding the regulatory mechanisms that govern abscess pathology should reveal therapeutic interventions for these recalcitrant infections. Here we demonstrated that the stringent stress response employed by bacteria to cope and adapt to environmental stressors was essential for the formation of lesions, but not bacterial growth, in a methicillin resistant Staphylococcus aureus (MRSA) cutaneous abscess mouse model. To pharmacologically confirm the role of the stringent response in abscess formation, a cationic peptide that causes rapid degradation of the stringent response mediator, guanosine tetraphosphate (ppGpp), was employed. The therapeutic application of this peptide strongly inhibited lesion formation in mice infected with Gram-positive MRSA and Gram-negative Pseudomonas aeruginosa. Overall, we provide insights into the mechanisms governing abscess formation and a paradigm for treating multidrug resistant cutaneous abscesses. Universal stringent stress response mediators drive abscess formation. Targeting stress response reduces the severity of cutaneous abscess infections. Pharmacological suppression of S. aureus cutaneous toxin production. Paradigm for treating Gram-positive and Gram-negative bacterial abscess infections.
Collapse
Affiliation(s)
- Sarah C Mansour
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Daniel Pletzer
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - César de la Fuente-Núñez
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Paul Kim
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Gordon Y C Cheung
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20814, United States
| | - Hwang-Soo Joo
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20814, United States
| | - Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20814, United States
| | - Robert E W Hancock
- Centre for Microbial Diseases and Immunity Research, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
| |
Collapse
|
37
|
The UbiI (VisC) Aerobic Ubiquinone Synthase Is Required for Expression of Type 1 Pili, Biofilm Formation, and Pathogenesis in Uropathogenic Escherichia coli. J Bacteriol 2016; 198:2662-72. [PMID: 27161114 DOI: 10.1128/jb.00030-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 05/04/2016] [Indexed: 01/03/2023] Open
Abstract
UNLABELLED Uropathogenic Escherichia coli (UPEC), which causes the majority of urinary tract infections (UTI), uses pilus-mediated adherence to initiate biofilm formation in the urinary tract. Oxygen gradients within E. coli biofilms regulate expression and localization of adhesive type 1 pili. A transposon mutant screen for strains defective in biofilm formation identified the ubiI (formerly visC) aerobic ubiquinone synthase gene as critical for UPEC biofilm formation. In this study, we characterized a nonpolar ubiI deletion mutant and compared its behavior to that of wild-type bacteria grown under aerobic and anoxic conditions. Consistent with its function as an aerobic ubiquinone-8 synthase, deletion of ubiI in UPEC resulted in reduced membrane potential, diminished motility, and reduced expression of chaperone-usher pathway pili. Loss of aerobic respiration was previously shown to negatively impact expression of type 1 pili. To determine whether this reduction in type 1 pili was due to an energy deficit, wild-type UPEC and the ubiI mutant were compared for energy-dependent phenotypes under anoxic conditions, in which quinone synthesis is undertaken by anaerobic quinone synthases. Under anoxic conditions, the two strains exhibited wild-type levels of motility but produced diminished numbers of type 1 pili, suggesting that the reduction of type 1 pilus expression in the absence of oxygen is not due to a cellular energy deficit. Acute- and chronic-infection studies in a mouse model of UTI revealed a significant virulence deficit in the ubiI mutant, indicating that UPEC encounters enough oxygen in the bladder to induce aerobic ubiquinone synthesis during infection. IMPORTANCE The majority of urinary tract infections are caused by uropathogenic E. coli, a bacterium that can respire in the presence and absence of oxygen. The bladder environment is hypoxic, with oxygen concentrations ranging from 4% to 7%, compared to 21% atmospheric oxygen. This work provides evidence that aerobic ubiquinone synthesis must be engaged during bladder infection, indicating that UPEC bacteria sense and use oxygen as a terminal electron acceptor in the bladder and that this ability drives infection potential despite the fact that UPEC is a facultative anaerobe.
Collapse
|
38
|
Epigenetic Switch Driven by DNA Inversions Dictates Phase Variation in Streptococcus pneumoniae. PLoS Pathog 2016; 12:e1005762. [PMID: 27427949 PMCID: PMC4948785 DOI: 10.1371/journal.ppat.1005762] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 06/20/2016] [Indexed: 02/05/2023] Open
Abstract
DNA methylation is an important epigenetic mechanism for phenotypic diversification in all forms of life. We previously described remarkable cell-to-cell heterogeneity in epigenetic pattern within a clonal population of Streptococcus pneumoniae, a leading human pathogen. We here report that the epigenetic diversity is caused by extensive DNA inversions among hsdSA,hsdSB, and hsdSC, three methyltransferase hsdS genes in the Spn556II type-I restriction modification (R-M) locus. Because hsdSA encodes the sequence recognition subunit of this type-I R-M DNA methyltransferase, these site-specific recombinations generate pneumococcal cells with variable HsdSA alleles and thereby diverse genome methylation patterns. Most importantly, the DNA methylation pattern specified by the HsdSA1 allele leads to the formation of opaque colonies, whereas the pneumococci lacking HsdSA1 produce transparent colonies. Furthermore, this HsdSA1-dependent phase variation requires intact DNA methylase activity encoded by hsdM in the Spn556II (renamed colony opacity determinant or cod) locus. Thus, the DNA inversion-driven ON/OFF switch of the hsdSA1 allele in the cod locus and resulting epigenetic switch dictate the phase variation between the opaque and transparent phenotypes. Phase variation has been well documented for its importance in pneumococcal carriage and invasive infection, but its molecular basis remains unclear. Our work has discovered a novel epigenetic cause for this significant pathobiology phenomenon in S. pneumoniae. Lastly, our findings broadly represents a significant advancement in our understanding of bacterial R-M systems and their potential in shaping epigenetic and phenotypic diversity of the prokaryotic organisms because similar site-specific recombination systems widely exist in many archaeal and bacterial species. DNA methylation is a well-known epigenetic mechanism for phenotypic diversification in all forms of life. This study reports our discovery that the Spn556II type-I RM locus in human pathogen Streptococcus pneumoniae undergoes extensive DNA inversions among three homologous DNA methyltransferase genes. These site-specific recombinations generate subpopulations of progeny cells with dramatic epigenetic and phenotypic differences. This is exemplified by the striking differences in colony morphology among the pneumococcal variants that carried different allelic variants of the methyltransferase genes. Phase variation has been well documented for its importance in pneumococcal pathogenesis, but it is currently unknown how this phenotypic switch occurs at the molecular level. This work has thus discovered an epigenetic cause for pneumococcal phase variation. Our findings have a broad implication on the epigenetic and phenotypic diversification in prokaryotic organisms because similar DNA rearrangement systems also exist in many archaeal and bacterial species.
Collapse
|
39
|
Sarkar S, Roberts LW, Phan MD, Tan L, Lo AW, Peters KM, Paterson DL, Upton M, Ulett GC, Beatson SA, Totsika M, Schembri MA. Comprehensive analysis of type 1 fimbriae regulation in fimB-null strains from the multidrug resistant Escherichia coli ST131 clone. Mol Microbiol 2016; 101:1069-87. [PMID: 27309594 DOI: 10.1111/mmi.13442] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2016] [Indexed: 12/17/2022]
Abstract
Uropathogenic Escherichia coli (UPEC) of sequence type 131 (ST131) are a pandemic multidrug resistant clone associated with urinary tract and bloodstream infections. Type 1 fimbriae, a major UPEC virulence factor, are essential for ST131 bladder colonization. The globally dominant sub-lineage of ST131 strains, clade C/H30-R, possess an ISEc55 insertion in the fimB gene that controls phase-variable type 1 fimbriae expression via the invertible fimS promoter. We report that inactivation of fimB in these strains causes altered regulation of type 1 fimbriae expression. Using a novel read-mapping approach based on Illumina sequencing, we demonstrate that 'off' to 'on' fimS inversion is reduced in these strains and controlled by recombinases encoded by the fimE and fimX genes. Unlike typical UPEC strains, the nucleoid-associated H-NS protein does not strongly repress fimE transcription in clade C ST131 strains. Using a genetic screen to identify novel regulators of fimE and fimX in the clade C ST131 strain EC958, we defined a new role for the guaB gene in the regulation of type 1 fimbriae and in colonisation of the mouse bladder. Our results provide a comprehensive analysis of type 1 fimbriae regulation in ST131, and highlight important differences in its control compared to non-ST131 UPEC.
Collapse
Affiliation(s)
- Sohinee Sarkar
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia.,Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Queensland, 4072, Australia.,Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, 4059, Australia
| | - Leah W Roberts
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia.,Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Minh-Duy Phan
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia.,Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Lendl Tan
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia.,Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Alvin W Lo
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia.,Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Kate M Peters
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia.,Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - David L Paterson
- Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Queensland, 4072, Australia.,Royal Brisbane and Women's Hospital, University of Queensland Centre for Clinical Research, Brisbane, Queensland, 4029, Australia
| | - Mathew Upton
- Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth, PL4 8AA, UK
| | - Glen C Ulett
- School of Medical Science, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, 4222, Australia
| | - Scott A Beatson
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia. .,Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Queensland, 4072, Australia.
| | - Makrina Totsika
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia. .,Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Queensland, 4072, Australia. .,Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, 4059, Australia.
| | - Mark A Schembri
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia. .,Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Queensland, 4072, Australia.
| |
Collapse
|
40
|
Xu X, Yu H, Zhang D, Xiong J, Qiu J, Xin R, He X, Sheng H, Cai W, Jiang L, Zhang K, Hu X. Role of ppGpp in Pseudomonas aeruginosa acute pulmonary infection and virulence regulation. Microbiol Res 2016; 192:84-95. [PMID: 27664726 DOI: 10.1016/j.micres.2016.06.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 06/09/2016] [Accepted: 06/10/2016] [Indexed: 11/28/2022]
Abstract
During infection, bacteria might generate adaptive responses to facilitate their survival and colonization in the host environment. The alarmone guanosine 5'-triphosphate-3'-diphosphate (ppGpp), the levels of which are regulated by the RelA and SpoT enzymes, plays a critical role in mediating bacterial adaptive responses and virulence. However, the mechanism by which ppGpp regulates virulence-associated traits in Pseudomonas aeruginosa is poorly understood. To investigate the regulatory role of ppGpp, the ppGpp-deficient strain ΔRS (relA and spoT gene double mutant) and the complemented strain ΔRS(++) (complemented with relA and spoT genes) were constructed. Herein, we reported that the ΔRS strain showed decreased cytotoxicity towards A549 human alveolar adenocarcinoma cell lines and led to reduced mortality, lung edema and inflammatory cell infiltration in a mouse model of acute pneumonia compared to wild-type PAO1 and the complemented strain ΔRS(++). Subsequent analyses demonstrated that the ΔRS strain displayed reduced T3SS expression, decreased levels of elastase activity, pyocyanin, pyoverdin and alginate, and inhibited swarming and biofilm formation compared to PAO1 and the complemented strain ΔRS(++). In addition, the results demonstrate that ppGpp-mediated regulation of T3SS, virulence factor production, and swarming occurs in a quinolone quorum-sensing system-dependent manner. Taken together, these results suggest that ppGpp is required for virulence regulation in P. aeruginosa, providing new clues for the development of interference strategies against bacterial infection.
Collapse
Affiliation(s)
- Xiaohui Xu
- Central Laboratory, Xinqiao Hospital, Third Military Medical University, Chongqing, China; Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing, China
| | - Hua Yu
- Central Laboratory, Xinqiao Hospital, Third Military Medical University, Chongqing, China; Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing, China
| | - Di Zhang
- Central Laboratory, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Junzhi Xiong
- Central Laboratory, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Jing Qiu
- Central Laboratory, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Rong Xin
- Central Laboratory, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Xiaomei He
- Central Laboratory, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Halei Sheng
- Central Laboratory, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Wenqiang Cai
- Central Laboratory, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Lu Jiang
- Central Laboratory, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Kebin Zhang
- Central Laboratory, Xinqiao Hospital, Third Military Medical University, Chongqing, China.
| | - Xiaomei Hu
- Central Laboratory, Xinqiao Hospital, Third Military Medical University, Chongqing, China; Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing, China.
| |
Collapse
|
41
|
Zhang H, Susanto TT, Wan Y, Chen SL. Comprehensive mutagenesis of the fimS promoter regulatory switch reveals novel regulation of type 1 pili in uropathogenic Escherichia coli. Proc Natl Acad Sci U S A 2016; 113:4182-7. [PMID: 27035967 PMCID: PMC4839427 DOI: 10.1073/pnas.1522958113] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Type 1 pili (T1P) are major virulence factors for uropathogenic Escherichia coli (UPEC), which cause both acute and recurrent urinary tract infections. T1P expression therefore is of direct relevance for disease. T1P are phase variable (both piliated and nonpiliated bacteria exist in a clonal population) and are controlled by an invertible DNA switch (fimS), which contains the promoter for the fim operon encoding T1P. Inversion of fimS is stochastic but may be biased by environmental conditions and other signals that ultimately converge at fimS itself. Previous studies of fimS sequences important for T1P phase variation have focused on laboratory-adapted E coli strains and have been limited in the number of mutations or by alteration of the fimS genomic context. We surmounted these limitations by using saturating genomic mutagenesis of fimS coupled with accurate sequencing to detect both mutations and phase status simultaneously. In addition to the sequences known to be important for biasing fimS inversion, our method also identifies a previously unknown pair of 5' UTR inverted repeats that act by altering the relative fimA levels to control phase variation. Thus we have uncovered an additional layer of T1P regulation potentially impacting virulence and the coordinate expression of multiple pilus systems.
Collapse
Affiliation(s)
- Huibin Zhang
- Infectious Diseases Group, Genome Institute of Singapore, Singapore 138672
| | - Teodorus T Susanto
- Stem Cell and Development, Genome Institute of Singapore, Singapore 138672
| | - Yue Wan
- Stem Cell and Development, Genome Institute of Singapore, Singapore 138672
| | - Swaine L Chen
- Infectious Diseases Group, Genome Institute of Singapore, Singapore 138672; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119074
| |
Collapse
|
42
|
de la Fuente-Núñez C, Reffuveille F, Mansour SC, Reckseidler-Zenteno SL, Hernández D, Brackman G, Coenye T, Hancock REW. D-enantiomeric peptides that eradicate wild-type and multidrug-resistant biofilms and protect against lethal Pseudomonas aeruginosa infections. ACTA ACUST UNITED AC 2015; 22:196-205. [PMID: 25699603 DOI: 10.1016/j.chembiol.2015.01.002] [Citation(s) in RCA: 221] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 12/11/2014] [Accepted: 01/06/2015] [Indexed: 12/26/2022]
Abstract
In many infections, bacteria form surface-associated communities known as biofilms that are substantially more resistant to antibiotics than their planktonic counterparts. Based on the design features of active antibiofilm peptides, we made a series of related 12-amino acid L-, D- and retro-inverso derivatives. Specific D-enantiomeric peptides were the most potent at inhibiting biofilm development and eradicating preformed biofilms of seven species of wild-type and multiply antibiotic-resistant Gram-negative pathogens. Moreover, these peptides showed strong synergy with conventional antibiotics, reducing the antibiotic concentrations required for complete biofilm inhibition by up to 64-fold. As shown previously for 1018, these D-amino acid peptides targeted the intracellular stringent response signal (p)ppGpp. The most potent peptides DJK-5 and DJK-6 protected invertebrates from lethal Pseudomonas aeruginosa infections and were considerably more active than a previously described L-amino acid peptide 1018. Thus, the protease-resistant peptides produced here were more effective both in vitro and in vivo.
Collapse
Affiliation(s)
- César de la Fuente-Núñez
- Department of Microbiology and Immunology, Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Fany Reffuveille
- Department of Microbiology and Immunology, Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Sarah C Mansour
- Department of Microbiology and Immunology, Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | | | - Diego Hernández
- Faculty of Science and Technology, Athabasca University, Athabasca, AB T9S 3A3, Canada
| | - Gilles Brackman
- Laboratory of Pharmaceutical Microbiology, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - Tom Coenye
- Laboratory of Pharmaceutical Microbiology, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - Robert E W Hancock
- Department of Microbiology and Immunology, Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
| |
Collapse
|
43
|
Li G, Xie F, Zhang Y, Bossé JT, Langford PR, Wang C. Role of (p)ppGpp in Viability and Biofilm Formation of Actinobacillus pleuropneumoniae S8. PLoS One 2015; 10:e0141501. [PMID: 26509499 PMCID: PMC4624843 DOI: 10.1371/journal.pone.0141501] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/08/2015] [Indexed: 12/04/2022] Open
Abstract
Actinobacillus pleuropneumoniae is a Gram-negative bacterium and the cause of porcine pleuropneumonia. When the bacterium encounters nutritional starvation, the relA-dependent (p)ppGpp-mediated stringent response is activated. The modified nucleotides guanosine 5’-diphosphate 3’-diphosphate (ppGpp) and guanosine 5’-triphosphate 3’-diphosphate (pppGpp) are known to be signaling molecules in other prokaryotes. Here, to investigate the role of (p)ppGpp in A. pleuropneumoniae, we created a mutant A. pleuropneumoniae strain, S8ΔrelA, which lacks the (p)ppGpp-synthesizing enzyme RelA, and investigated its phenotype in vitro. S8ΔrelA did not survive after stationary phase (starvation condition) and grew exclusively as non-extended cells. Compared to the wild-type (WT) strain, the S8ΔrelA mutant had an increased ability to form a biofilm. Transcriptional profiles of early stationary phase cultures revealed that a total of 405 bacterial genes were differentially expressed (including 380 up-regulated and 25 down-regulated genes) in S8ΔrelA as compared with the WT strain. Most of the up-regulated genes are involved in ribosomal structure and biogenesis, amino acid transport and metabolism, translation cell wall/membrane/envelope biogenesis. The data indicate that (p)ppGpp coordinates the growth, viability, morphology, biofilm formation and metabolic ability of A. pleuropneumoniae in starvation conditions. Furthermore, S8ΔrelA could not use certain sugars nor produce urease which has been associated with the virulence of A. pleuropneumoniae, suggesting that (p)ppGpp may directly or indirectly affect the pathogenesis of A. pleuropneumoniae during the infection process. In summary, (p)ppGpp signaling represents an essential component of the regulatory network governing stress adaptation and virulence in A. pleuropneumoniae.
Collapse
Affiliation(s)
- Gang Li
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Fang Xie
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yanhe Zhang
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Janine T. Bossé
- Section of Paediatrics, Department of Medicine, Imperial College London, St. Mary’s Campus, London, United Kingdom
| | - Paul R. Langford
- Section of Paediatrics, Department of Medicine, Imperial College London, St. Mary’s Campus, London, United Kingdom
| | - Chunlai Wang
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
- * E-mail:
| |
Collapse
|
44
|
Chatnaparat T, Li Z, Korban SS, Zhao Y. The Stringent Response Mediated by (p)ppGpp Is Required for Virulence of Pseudomonas syringae pv. tomato and Its Survival on Tomato. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:776-789. [PMID: 25675257 DOI: 10.1094/mpmi-11-14-0378-r] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The hypersensitive response and pathogenicity (hrp) type III secretion system (T3SS) is a key pathogenicity factor in Pseudomonas syringae pv. tomato DC3000 (DC3000). In this study, the role of the second messenger (p)ppGpp on virulence and survival of DC3000 was investigated. Results have demonstrated that (p)ppGpp-deficient mutant (ppGpp(0)) of DC3000 exhibited lower levels of expression of the T3SS and genes of other virulence traits, such as coronatine toxin. The ppGpp(0) mutant of DC3000 was greatly impaired in causing disease and in growth in planta. Furthermore, (p)ppGpp was required for swarming motility, pyoverdine production, the oxidative stress response, as well as γ-amino butyric acid utilization. Screening of amino acids, major signals in activation of ppGpp biosynthesis, revealed that promoter activities of the avrPto gene could be either activated or suppressed by various amino acids in a ppGpp-dependent or -independent manner. Moreover, the ppGpp(0) mutant exhibited increased cell size and decreased survival on plant surfaces. Altogether, these findings indicate that ppGpp acts as an internal signal that regulates the T3SS as well as other virulence factors in pseudomonads and suggest that bacterial pathogens utilize intracellular messengers to sense environmental and nutritional signals for rapid, precise, and reversible control of their pathogenesis and survival.
Collapse
Affiliation(s)
- Tiyakhon Chatnaparat
- 1 Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
| | - Zhong Li
- 2 Metabolomics Center, Roy J. Carver Biotechnology Center, University of Illinois at-Urbana-Champaign
| | - Schuyler S Korban
- 3 Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign
- 4 Department of Biology, University of Massachusetts Boston, Boston, MA 02125, U.S.A
| | - Youfu Zhao
- 1 Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
| |
Collapse
|
45
|
Abstract
ABSTRACT
Type 1 fimbriae of
E. coli
, a chaperon-usher bacterial adhesin, are synthesized by the majority of strains of the bacterium. Although frequently produced by commensal strains, the adhesin is nevertheless a virulence factor in Extraintestinal Pathogenic
E. coli
(ExPEC). The role of the adhesin in pathogenesis is best understood in Uropathogenic
E. coli
(UPEC). Host attachment and invasion by type 1 fimbriate bacteria activates inflammatory pathways, with TLR4 signaling playing a predominant role. In a mouse model of cystitis, type 1 fimbriation not only enhances UPEC adherence to the surface of superficial umbrella cells of the bladder urothelium, but is both necessary and sufficient for their invasion. Moreover the adhesin plays a role in the formation of transient intracellular bacterial communities (IBCs) within the cytoplasm of urothelial cells as part of UPEC cycles of invasion. The expression of type 1 fimbriation is controlled by phase variation at the transcriptional level, a mode of gene regulation in which bacteria switch reversibly between fimbriate and afimbriate phases. Phase variation has been widely considered to be a mechanism enabling immune evasion. Notwithstanding the apparently random nature of phase variation, switching of type 1 fimbrial expression is nevertheless controlled by a range of environmental signals that include the amino sugars sialic acid and N-acetylglucosamine (GlcNAc). Sialic acid plays a pivotal role in innate immunity, including signaling by the toll-like receptors. Here how sialic acid and GlcNAc control type 1 fimbriation is described and the potential significance of this regulatory response is discussed.
Collapse
|
46
|
Broad-spectrum anti-biofilm peptide that targets a cellular stress response. PLoS Pathog 2014; 10:e1004152. [PMID: 24852171 PMCID: PMC4031209 DOI: 10.1371/journal.ppat.1004152] [Citation(s) in RCA: 368] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 04/14/2014] [Indexed: 11/22/2022] Open
Abstract
Bacteria form multicellular communities known as biofilms that cause two thirds of all infections and demonstrate a 10 to 1000 fold increase in adaptive resistance to conventional antibiotics. Currently, there are no approved drugs that specifically target bacterial biofilms. Here we identified a potent anti-biofilm peptide 1018 that worked by blocking (p)ppGpp, an important signal in biofilm development. At concentrations that did not affect planktonic growth, peptide treatment completely prevented biofilm formation and led to the eradication of mature biofilms in representative strains of both Gram-negative and Gram-positive bacterial pathogens including Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, methicillin resistant Staphylococcus aureus, Salmonella Typhimurium and Burkholderia cenocepacia. Low levels of the peptide led to biofilm dispersal, while higher doses triggered biofilm cell death. We hypothesized that the peptide acted to inhibit a common stress response in target species, and that the stringent response, mediating (p)ppGpp synthesis through the enzymes RelA and SpoT, was targeted. Consistent with this, increasing (p)ppGpp synthesis by addition of serine hydroxamate or over-expression of relA led to reduced susceptibility to the peptide. Furthermore, relA and spoT mutations blocking production of (p)ppGpp replicated the effects of the peptide, leading to a reduction of biofilm formation in the four tested target species. Also, eliminating (p)ppGpp expression after two days of biofilm growth by removal of arabinose from a strain expressing relA behind an arabinose-inducible promoter, reciprocated the effect of peptide added at the same time, leading to loss of biofilm. NMR and chromatography studies showed that the peptide acted on cells to cause degradation of (p)ppGpp within 30 minutes, and in vitro directly interacted with ppGpp. We thus propose that 1018 targets (p)ppGpp and marks it for degradation in cells. Targeting (p)ppGpp represents a new approach against biofilm-related drug resistance. Bacteria colonize most environments, including the host by forming biofilms, which are extremely (adaptively) resistant to conventional antibiotics. Biofilms cause at least 65% of all human infections, being particularly prevalent in device-related infections, infections on body surfaces and in chronic infections. Currently there is a severe problem with antibiotic-resistant organisms, given the explosion of antibiotic resistance whereby our entire arsenal of antibiotics is gradually losing effectiveness, combined with the paucity of truly novel compounds under development or entering the clinic. Thus the even greater resistance of biofilms adds to the major concerns being expressed by physicians and medical authorities. Consequently, there is an urgent need for new strategies to treat biofilm infections and we demonstrate in the present study an approach, based on the inhibition of (p)ppGpp by a small peptide, that eradicates biofilms formed by four of the so-called ESKAPE pathogens, identified by the Infectious Diseases Society of America as the most recalcitrant and resistant organisms in our society. The strategy presented here represents a significant advance in the search for new agents that specifically target bacterial biofilms.
Collapse
|
47
|
Chen YW, Teng CH, Ho YH, Jessica Ho TY, Huang WC, Hashimoto M, Chiang IY, Chen CS. Identification of bacterial factors involved in type 1 fimbria expression using an Escherichia coli K12 proteome chip. Mol Cell Proteomics 2014; 13:1485-94. [PMID: 24692643 DOI: 10.1074/mcp.m113.035667] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type 1 fimbriae are filamentous structures on Escherichia coli. These structures are important adherence factors. Because binding to the host cells is the first step of infection, type 1 fimbria is an important virulence factor of pathogenic E. coli. Expression of type 1 fimbria is regulated by a phase variation in which each individual bacterium can alternate between fimbriated (phase-ON) and nonfimbriated (phase-OFF) states. The phase variation is regulated by the flipping of the 314-bp fimS fragment, which contains the promoter driving the expression of the genes required for the synthesis of type 1 fimbria. Thus, the bacterial proteins able to interact with fimS are likely to be involved in regulating the expression of type 1 fimbria. To identify novel type 1 fimbria-regulating factors, we used an E. coli K12 proteome chip to screen for the bacterial factors able to interact with a 602-bp DNA fragment containing fimS and its adjacent regions. The Spr protein was identified by the proteome chip-based screening and further confirmed to be able to interact with fimS by electrophoretic mobility shift assay. Deletion of spr in the neonatal meningitis E. coli strain RS218 significantly increased the ratio of the bacterial colonies that contained the type 1 fimbria phase-ON cells on agar plates. In addition, Spr interfered with the interactions of fimS with the site-specific recombinases, FimB and FimE, which are responsible for mediating the flipping of fimS. These results suggest that Spr is involved in the regulation of type 1 fimbria expression through direct interaction with the invertible element fimS. These findings facilitate our understanding of the regulation of type 1 fimbria.
Collapse
Affiliation(s)
- Yi-Wen Chen
- From the ‡Graduate Institute of Systems Biology and Bioinformatics, National Central University, Jhongli City, Taiwan
| | - Ching-Hao Teng
- §Institute of Molecular Medicine, National Cheng Kung University Medical College, Tainan City, Taiwan; ¶Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan City, Taiwan; ‖Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan City, Taiwan
| | - Yu-Hsuan Ho
- From the ‡Graduate Institute of Systems Biology and Bioinformatics, National Central University, Jhongli City, Taiwan
| | - Tien Yu Jessica Ho
- From the ‡Graduate Institute of Systems Biology and Bioinformatics, National Central University, Jhongli City, Taiwan
| | - Wen-Chun Huang
- ¶Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan City, Taiwan
| | - Masayuki Hashimoto
- §Institute of Molecular Medicine, National Cheng Kung University Medical College, Tainan City, Taiwan; ‖Center of Infectious Disease and Signaling Research, National Cheng Kung University, Tainan City, Taiwan
| | - I-Yuan Chiang
- **Department of Nutrition and Health Sciences, Kainan University. No. 1, Kainan Road, Luzhu Township, Taoyuan Country, Taiwan
| | - Chien-Sheng Chen
- From the ‡Graduate Institute of Systems Biology and Bioinformatics, National Central University, Jhongli City, Taiwan;
| |
Collapse
|
48
|
relA enhances the adherence of enteropathogenic Escherichia coli. PLoS One 2014; 9:e91703. [PMID: 24643076 PMCID: PMC3958371 DOI: 10.1371/journal.pone.0091703] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 02/14/2014] [Indexed: 11/19/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) is a known causative agent of diarrhea in children. In the process of colonization of the small intestine, EPEC synthesizes two types of adhesins, the bundle-forming pilus (BFP) and intimin. The BFP pilus is an adhesin associated with the initial stages of adherence of EPEC to epithelial cells, while the outer membrane protein intimin carries out the intimate adherence that takes place at the third stage of infection. BFP is encoded by the bfp operon located in plasmid EAF, present only in typical EPEC isolates, while eae, the gene that encodes intimin is situated in the LEE, a chromosomal pathogenicity island. Transcription of bfp and eae is regulated by the products of the perABC operon, also present in plasmid EAF. Here we show that deletion of relA, that encodes a guanosine penta and tetraphosphate synthetase impairs EPEC adherence to epithelial cells in vitro. In the absence of relA, the transcription of the regulatory operon perABC is reduced, resulting in lower levels of BFP and intimin. Bacterial adherence, BFP and intimin synthesis and perABC expression are restored upon complementation with the wild-type relA allele.
Collapse
|
49
|
Abstract
The phase variation (reversible on-off switching) of the type 1 fimbrial adhesin of Escherichia coli involves a DNA inversion catalyzed by FimB (switching in either direction) or FimE (on-to-off switching). Here, we demonstrate that RfaH activates expression of a FimB-LacZ protein fusion while having a modest inhibitory effect on a comparable fimB-lacZ operon construct and on a FimE-LacZ protein fusion, indicating that RfaH selectively controls fimB expression at the posttranscriptional level. Further work demonstrates that loss of RfaH enables small RNA (sRNA) MicA inhibition of fimB expression even in the absence of exogenous inducing stress. This effect is explained by induction of σ(E), and hence MicA, in the absence of RfaH. Additional work confirms that the procaine-dependent induction of micA requires OmpR, as reported previously (A. Coornaert et al., Mol. Microbiol. 76:467-479, 2010, doi:10.1111/j.1365-2958.2010.07115.x), but also demonstrates that RfaH inhibition of fimB transcription is enhanced by procaine independently of OmpR. While the effect of procaine on fimB transcription is shown to be independent of RcsB, it was found to require SlyA, another known regulator of fimB transcription. These results demonstrate a complex role for RfaH as a regulator of fimB expression.
Collapse
|
50
|
Kalivoda EJ, Brothers KM, Stella NA, Schmitt MJ, Shanks RMQ. Bacterial cyclic AMP-phosphodiesterase activity coordinates biofilm formation. PLoS One 2013; 8:e71267. [PMID: 23923059 PMCID: PMC3726613 DOI: 10.1371/journal.pone.0071267] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 06/27/2013] [Indexed: 12/26/2022] Open
Abstract
Biofilm-related infections are a major contributor to human disease, and the capacity for surface attachment and biofilm formation are key attributes for the pathogenesis of microbes. Serratia marcescens type I fimbriae-dependent biofilms are coordinated by the adenylate cyclase, CyaA, and the cyclic 3′,5′-adenosine monophosphate (cAMP)-cAMP receptor protein (CRP) complex. This study uses S. marcescens as a model system to test the role of cAMP-phosphodiesterase activity in controlling biofilm formation. Herein we describe the characterization of a putative S. marcescens cAMP-phosphodiesterase gene (SMA3506), designated as cpdS, and demonstrated to be a functional cAMP-phosphodiesterase both in vitro and in vivo. Deletion of cpdS resulted in defective biofilm formation and reduced type I fimbriae production, whereas multicopy expression of cpdS conferred a type I fimbriae-dependent hyper-biofilm. Together, these results support a model in which bacterial cAMP-phosphodiesterase activity modulates biofilm formation.
Collapse
Affiliation(s)
- Eric J. Kalivoda
- Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, Unites States of America
| | - Kimberly M. Brothers
- Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, Unites States of America
| | - Nicholas A. Stella
- Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, Unites States of America
| | - Matthew J. Schmitt
- Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, Unites States of America
| | - Robert M. Q. Shanks
- Charles T. Campbell Laboratory of Ophthalmic Microbiology, Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, Unites States of America
- * E-mail:
| |
Collapse
|