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Mapar M, Rydzak T, Hommes JW, Surewaard BGJ, Lewis IA. Diverse molecular mechanisms underpinning Staphylococcus aureus small colony variants. Trends Microbiol 2024:S0966-842X(24)00251-8. [PMID: 39393939 DOI: 10.1016/j.tim.2024.09.007] [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: 05/01/2024] [Revised: 09/19/2024] [Accepted: 09/20/2024] [Indexed: 10/13/2024]
Abstract
Small colony variants (SCVs) of Staphylococcus aureus are a relatively rare but clinically significant growth morphotype. Infections with SCVs are frequently difficult to treat, inherently antibiotic-resistant, and can lead to persistent infections. Despite a long history of research, the molecular underpinnings of this morphotype and their impact on the clinical trajectory of infections remain unclear. However, a growing body of literature indicates that SCVs are caused by a diverse range of molecular factors. These recent findings suggest that SCVs should be thought of as an ensemble collection of loosely related phenotypes, and not as a single phenomenon. This review describes the diverse mechanisms currently known to contribute to SCVs and proposes an ensemble model for conceptualizing this morphotype.
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Affiliation(s)
- Maryam Mapar
- Alberta Centre for Advanced Diagnostics, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Thomas Rydzak
- Alberta Centre for Advanced Diagnostics, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada
| | - Josefien W Hommes
- Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Bas G J Surewaard
- Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute for Chronic Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Ian A Lewis
- Alberta Centre for Advanced Diagnostics, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
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Komeda T, Hishinuma T, Kirikae T, Tada T. Escherichia coli with increased aminoglycoside resistance due to an amino acid substitution at position 85 of HemC. J Infect Chemother 2024:S1341-321X(24)00277-0. [PMID: 39369904 DOI: 10.1016/j.jiac.2024.10.004] [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: 07/05/2024] [Revised: 09/02/2024] [Accepted: 10/02/2024] [Indexed: 10/08/2024]
Abstract
OBJECTIVE The mechanism of aminoglycoside resistance due to abnormal hemin synthesis remains unclear. We investigate an Escherichia coli strain with a single amino acid substitution at position 85 of HemC. METHODS An aminoglycoside-resistant Escherichia coli DH5α was selected by passaging in Lysogeny Broth (LB) medium containing amikacin. Whole genome sequencing was performed to determine the genetic profile of the strain. An isogenic strain of E. coli DH5α was created. Growth rates, drug susceptibilities and expressions of the heme synthetic genes were compared between the original strain and the isogenic strain. RESULTS Whole genome sequencing revealed a nucleotide substitution at position 254 of hemC from adenine (A) to thymine (T), resulting in an amino acid substitution at position 85 of HemC from histidine (H) to leucine (L). There were no mutations in other heme synthetic genes, including hemA, hemB, hemC, hemD, hemE, hemF, hemG, hemH, hemL, hemN, hemX and hemY. The isogenic strain of E. coli DH5α with H85L in HemC was less susceptible to aminoglycosides, and its growth was slower than that of E. coli DH5α before passage. Quantitative real-time PCR showed that the expression of hemA was higher and the expressions of hemL, hemG and hemX lower in the isogenic strain than before passage. CONCLUSION This is the first report of aminoglycoside resistance due to an amino acid substitution in HemC. These findings suggested that mutations in the heme synthetic genes may indirectly affect the growth rates of E. coli strains and their susceptibilities to aminoglycosides.
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Affiliation(s)
- Tomoki Komeda
- Department of Microbiology, Juntendo University School and Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Tomomi Hishinuma
- Department of Microbiology, Juntendo University School and Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Teruo Kirikae
- Juntendo Advanced Research Institute for Health Science, Bunkyo-ku, Tokyo, Japan
| | - Tatsuya Tada
- Department of Microbiology, Juntendo University School and Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan.
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3
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Tajer L, Paillart JC, Dib H, Sabatier JM, Fajloun Z, Abi Khattar Z. Molecular Mechanisms of Bacterial Resistance to Antimicrobial Peptides in the Modern Era: An Updated Review. Microorganisms 2024; 12:1259. [PMID: 39065030 PMCID: PMC11279074 DOI: 10.3390/microorganisms12071259] [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: 05/08/2024] [Revised: 06/10/2024] [Accepted: 06/18/2024] [Indexed: 07/28/2024] Open
Abstract
Antimicrobial resistance (AMR) poses a serious global health concern, resulting in a significant number of deaths annually due to infections that are resistant to treatment. Amidst this crisis, antimicrobial peptides (AMPs) have emerged as promising alternatives to conventional antibiotics (ATBs). These cationic peptides, naturally produced by all kingdoms of life, play a crucial role in the innate immune system of multicellular organisms and in bacterial interspecies competition by exhibiting broad-spectrum activity against bacteria, fungi, viruses, and parasites. AMPs target bacterial pathogens through multiple mechanisms, most importantly by disrupting their membranes, leading to cell lysis. However, bacterial resistance to host AMPs has emerged due to a slow co-evolutionary process between microorganisms and their hosts. Alarmingly, the development of resistance to last-resort AMPs in the treatment of MDR infections, such as colistin, is attributed to the misuse of this peptide and the high rate of horizontal genetic transfer of the corresponding resistance genes. AMP-resistant bacteria employ diverse mechanisms, including but not limited to proteolytic degradation, extracellular trapping and inactivation, active efflux, as well as complex modifications in bacterial cell wall and membrane structures. This review comprehensively examines all constitutive and inducible molecular resistance mechanisms to AMPs supported by experimental evidence described to date in bacterial pathogens. We also explore the specificity of these mechanisms toward structurally diverse AMPs to broaden and enhance their potential in developing and applying them as therapeutics for MDR bacteria. Additionally, we provide insights into the significance of AMP resistance within the context of host-pathogen interactions.
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Affiliation(s)
- Layla Tajer
- Laboratory of Applied Biotechnology (LBA3B), Azm Center for Research in Biotechnology and Its Applications, Department of Cell Culture, EDST, Lebanese University, Tripoli 1300, Lebanon; (L.T.); (Z.F.)
| | - Jean-Christophe Paillart
- CNRS, Architecture et Réactivité de l’ARN, UPR 9002, Université de Strasbourg, 2 Allée Konrad Roentgen, F-67000 Strasbourg, France;
| | - Hanna Dib
- College of Engineering and Technology, American University of the Middle East, Egaila 54200, Kuwait;
| | - Jean-Marc Sabatier
- CNRS, INP, Inst Neurophysiopathol, Aix-Marseille Université, 13385 Marseille, France
| | - Ziad Fajloun
- Laboratory of Applied Biotechnology (LBA3B), Azm Center for Research in Biotechnology and Its Applications, Department of Cell Culture, EDST, Lebanese University, Tripoli 1300, Lebanon; (L.T.); (Z.F.)
- Department of Biology, Faculty of Sciences 3, Lebanese University, Campus Michel Slayman Ras Maska, Tripoli 1352, Lebanon
| | - Ziad Abi Khattar
- Faculty of Medicine and Medical Sciences, University of Balamand, Kalhat, P.O. Box 100, Tripoli, Lebanon
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van Zyl EM, Coburn JM. Functionalization of Bacterial Cellulose with the Antimicrobial Peptide KR-12 via Chimerical Cellulose-Binding Peptides. Int J Mol Sci 2024; 25:1462. [PMID: 38338739 PMCID: PMC10855235 DOI: 10.3390/ijms25031462] [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: 12/19/2023] [Revised: 01/16/2024] [Accepted: 01/20/2024] [Indexed: 02/12/2024] Open
Abstract
Bacterial-derived cellulose (BC) has been studied as a promising material for biomedical applications, including wound care, due to its biocompatibility, water-holding capacity, liquid/gas permeability, and handleability properties. Although BC has been studied as a dressing material for cutaneous wounds, to date, BC inherently lacks antibacterial properties. The current research utilizes bifunctional chimeric peptides containing carbohydrate binding peptides (CBP; either a short version or a long version) and an antimicrobial peptide (AMP), KR-12. The secondary structure of the chimeric peptides was evaluated and confirmed that the α-helix structure of KR-12 was retained for both chimeric peptides evaluated (Long-CBP-KR12 and Short-CBP-KR12). Chimeric peptides and their individual components were assessed for cytotoxicity, where only higher concentrations of Short-CBP and longer timepoints of Short-CBP-KR12 exposure exhibited negative effects on metabolic activity, which was attributed to solubility issues. All KR-12-containing peptides exhibited antibacterial activity in solution against Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa). The lipopolysaccharide (LPS) binding capability of the peptides was evaluated and the Short-CBP-KR12 peptide exhibited enhanced LPS-binding capabilities compared to KR-12 alone. Both chimeric peptides were able to bind to BC and were observed to be retained on the surface over a 7-day period. All functionalized materials exhibited no adverse effects on the metabolic activity of both normal human dermal fibroblasts (NHDFs) and human epidermal keratinocyte (HaCaT) epithelial cells. Additionally, the BC tethered chimeric peptides exhibited antibacterial activity against E. coli. Overall, this research outlines the design and evaluation of chimeric CBP-KR12 peptides for developing antimicrobial BC membranes with potential applications in wound care.
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Affiliation(s)
| | - Jeannine M. Coburn
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, USA
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5
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Theis TJ, Daubert TA, Kluthe KE, Brodd KL, Nuxoll AS. Staphylococcus aureus persisters are associated with reduced clearance in a catheter-associated biofilm infection. Front Cell Infect Microbiol 2023; 13:1178526. [PMID: 37228667 PMCID: PMC10203555 DOI: 10.3389/fcimb.2023.1178526] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 04/24/2023] [Indexed: 05/27/2023] Open
Abstract
Background Staphylococcus aureus causes a wide variety of infections, many of which are chronic or relapsing in nature. Antibiotic therapy is often ineffective against S. aureus biofilm-mediated infections. Biofilms are difficult to treat partly due to their tolerance to antibiotics, however the underlying mechanism responsible for this remains unknown. One possible explanation is the presence of persister cells-dormant-like cells that exhibit tolerance to antibiotics. Recent studies have shown a connection between a fumC (fumarase C, a gene in the tricarboxylic acid cycle) knockout strain and increased survival to antibiotics, antimicrobial peptides, and in a Drosophila melanogaster model. Objective It remained unclear whether a S. aureus high persister strain would have a survival advantage in the presence of innate and adaptive immunity. To further investigate this, a fumC knockout and wild type strains were examined in a murine catheter-associated biofilm model. Results Interestingly, mice struggled to clear both S. aureus wild type and the fumC knockout strains. We reasoned both biofilm-mediated infections predominantly consisted of persister cells. To determine the persister cell population within biofilms, expression of a persister cell marker (Pcap5A::dsRED) in a biofilm was examined. Cell sorting of biofilms challenged with antibiotics revealed cells with intermediate and high expression of cap5A had 5.9-and 4.5-fold higher percent survival compared to cells with low cap5A expression. Based on previous findings that persisters are associated with reduced membrane potential, flow cytometry analysis was used to examine the metabolic state of cells within a biofilm. We confirmed cells within biofilms had reduced membrane potential compared to both stationary phase cultures (2.5-fold) and exponential phase cultures (22.4-fold). Supporting these findings, cells within a biofilm still exhibited tolerance to antibiotic challenge following dispersal of the matrix through proteinase K. Conclusion Collectively, these data show that biofilms are largely comprised of persister cells, and this may explain why biofilm infections are often chronic and/or relapsing in clinical settings.
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Li T, Wang Z, Guo J, de la Fuente-Nunez C, Wang J, Han B, Tao H, Liu J, Wang X. Bacterial resistance to antibacterial agents: Mechanisms, control strategies, and implications for global health. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 860:160461. [PMID: 36435256 DOI: 10.1016/j.scitotenv.2022.160461] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 11/19/2022] [Accepted: 11/20/2022] [Indexed: 06/16/2023]
Abstract
The spread of bacterial drug resistance has posed a severe threat to public health globally. Here, we cover bacterial resistance to current antibacterial drugs, including traditional herbal medicines, conventional antibiotics, and antimicrobial peptides. We summarize the influence of bacterial drug resistance on global health and its economic burden while highlighting the resistance mechanisms developed by bacteria. Based on the One Health concept, we propose 4A strategies to combat bacterial resistance, including prudent Application of antibacterial agents, Administration, Assays, and Alternatives to antibiotics. Finally, we identify several opportunities and unsolved questions warranting future exploration for combating bacterial resistance, such as predicting genetic bacterial resistance through the use of more effective techniques, surveying both genetic determinants of bacterial resistance and the transmission dynamics of antibiotic resistance genes (ARGs).
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Affiliation(s)
- Ting Li
- Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China; Key Laboratory of Feed Biotechnology, Ministry of Agriculture and Rural Affairs, Beijing 100081, PR China; State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, No. 20, Dongda Street, Fengtai District, Beijing 100071, PR China
| | - Zhenlong Wang
- Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China; Key Laboratory of Feed Biotechnology, Ministry of Agriculture and Rural Affairs, Beijing 100081, PR China
| | - Jianhua Guo
- Australian Centre for Water and Environmental Biotechnology (ACWEB, formerly AWMC), The University of Queensland, St Lucia, Queensland 4072, Australia.
| | - Cesar de la Fuente-Nunez
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America; Departments of Bioengineering and Chemical and Biomolecular Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, United States of America; Penn Institute for Computational Science, University of Pennsylvania, Philadelphia, PA, United States of America.
| | - Jinquan Wang
- Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China; Key Laboratory of Feed Biotechnology, Ministry of Agriculture and Rural Affairs, Beijing 100081, PR China
| | - Bing Han
- Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China; Key Laboratory of Feed Biotechnology, Ministry of Agriculture and Rural Affairs, Beijing 100081, PR China
| | - Hui Tao
- Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China; Key Laboratory of Feed Biotechnology, Ministry of Agriculture and Rural Affairs, Beijing 100081, PR China
| | - Jie Liu
- Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China; Key Laboratory of Feed Biotechnology, Ministry of Agriculture and Rural Affairs, Beijing 100081, PR China
| | - Xiumin Wang
- Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China; Key Laboratory of Feed Biotechnology, Ministry of Agriculture and Rural Affairs, Beijing 100081, PR China.
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7
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Guo H, Tong Y, Cheng J, Abbas Z, Li Z, Wang J, Zhou Y, Si D, Zhang R. Biofilm and Small Colony Variants-An Update on Staphylococcus aureus Strategies toward Drug Resistance. Int J Mol Sci 2022; 23:ijms23031241. [PMID: 35163165 PMCID: PMC8835882 DOI: 10.3390/ijms23031241] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/16/2022] [Accepted: 01/20/2022] [Indexed: 02/07/2023] Open
Abstract
Recently, the drawbacks arising from the overuse of antibiotics have drawn growing public attention. Among them, drug-resistance (DR) and even multidrug-resistance (MDR) pose significant challenges in clinical practice. As a representative of a DR or MDR pathogen, Staphylococcus aureus can cause diversity of infections related to different organs, and can survive or adapt to the diverse hostile environments by switching into other phenotypes, including biofilm and small colony variants (SCVs), with altered physiologic or metabolic characteristics. In this review, we briefly describe the development of the DR/MDR as well as the classical mechanisms (accumulation of the resistant genes). Moreover, we use multidimensional scaling analysis to evaluate the MDR relevant hotspots in the recent published reports. Furthermore, we mainly focus on the possible non-classical resistance mechanisms triggered by the two important alternative phenotypes of the S. aureus, biofilm and SCVs, which are fundamentally caused by the different global regulation of the S. aureus population, such as the main quorum-sensing (QS) and agr system and its coordinated regulated factors, such as the SarA family proteins and the alternative sigma factor σB (SigB). Both the biofilm and the SCVs are able to escape from the host immune response, and resist the therapeutic effects of antibiotics through the physical or the biological barriers, and become less sensitive to some antibiotics by the dormant state with the limited metabolisms.
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8
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Bogut A, Magryś A. The road to success of coagulase-negative staphylococci: clinical significance of small colony variants and their pathogenic role in persistent infections. Eur J Clin Microbiol Infect Dis 2021; 40:2249-2270. [PMID: 34296355 PMCID: PMC8520507 DOI: 10.1007/s10096-021-04315-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 07/09/2021] [Indexed: 01/14/2023]
Abstract
Bacterial small colony variants represent an important aspect of bacterial variability. They are naturally occurring microbial subpopulations with distinctive phenotypic and pathogenic traits, reported for many clinically important bacteria. In clinical terms, SCVs tend to be associated with persistence in host cells and tissues and are less susceptible to antibiotics than their wild-type (WT) counterparts. The increased tendency of SCVs to reside intracellularly where they are protected against the host immune responses and antimicrobial drugs is one of the crucial aspects linking SCVs to recurrent or chronic infections, which are difficult to treat. An important aspect of the SCV ability to persist in the host is the quiescent metabolic state, reduced immune response and expression a changed pattern of virulence factors, including a reduced expression of exotoxins and an increased expression of adhesins facilitating host cell uptake. The purpose of this review is to describe in greater detail the currently available data regarding CoNS SCV and, in particular, their clinical significance and possible mechanisms by which SCVs contribute to the pathogenesis of the chronic infections. It should be emphasized that in spite of an increasing clinical significance of this group of staphylococci, the number of studies unraveling the mechanisms of CoNS SCVs formation and their impact on the course of the infectious process is still scarce, lagging behind the studies on S. aureus SCVs.
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Affiliation(s)
- Agnieszka Bogut
- Chair and Department of Medical Microbiology, Medical University of Lublin, ul. Chodźki 1, 20-093, Lublin, Poland
| | - Agnieszka Magryś
- Chair and Department of Medical Microbiology, Medical University of Lublin, ul. Chodźki 1, 20-093, Lublin, Poland.
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Liu L, Beck C, Nøhr-Meldgaard K, Peschel A, Kretschmer D, Ingmer H, Vestergaard M. Inhibition of the ATP synthase sensitizes Staphylococcus aureus towards human antimicrobial peptides. Sci Rep 2020; 10:11391. [PMID: 32647350 PMCID: PMC7347559 DOI: 10.1038/s41598-020-68146-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 06/08/2020] [Indexed: 11/09/2022] Open
Abstract
Antimicrobial peptides (AMPs) are an important part of the human innate immune system for protection against bacterial infections, however the AMPs display varying degrees of activity against Staphylococcus aureus. Previously, we showed that inactivation of the ATP synthase sensitizes S. aureus towards the AMP antibiotic class of polymyxins. Here we wondered if the ATP synthase similarly is needed for tolerance towards various human AMPs, including human β-defensins (hBD1-4), LL-37 and histatin 5. Importantly, we find that the ATP synthase mutant (atpA) is more susceptible to killing by hBD4, hBD2, LL-37 and histatin 5 than wild type cells, while no changes in susceptibility was detected for hBD3 and hBD1. Administration of the ATP synthase inhibitor, resveratrol, sensitizes S. aureus towards hBD4-mediated killing. Neutrophils rely on AMPs and reactive oxygen molecules to eliminate bacteria and the atpA mutant is more susceptible to killing by neutrophils than the WT, even when the oxidative burst is inhibited.These results show that the staphylococcal ATP synthase enhance tolerance of S. aureus towards some human AMPs and this indicates that inhibition of the ATP synthase may be explored as a new therapeutic strategy that sensitizes S. aureus to naturally occurring AMPs of the innate immune system.
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Affiliation(s)
- Liping Liu
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 4, 1870, Frederiksberg C, Denmark
| | - Christian Beck
- Department of Infection Biology, Interfaculty Institute for Microbiology and Infection Medicine Tübingen (IMIT), Cluster of Excellence 'Controlling Microbes to Fight Infections', University of Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
| | - Katrine Nøhr-Meldgaard
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 4, 1870, Frederiksberg C, Denmark
| | - Andreas Peschel
- Department of Infection Biology, Interfaculty Institute for Microbiology and Infection Medicine Tübingen (IMIT), Cluster of Excellence 'Controlling Microbes to Fight Infections', University of Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
| | - Dorothee Kretschmer
- Department of Infection Biology, Interfaculty Institute for Microbiology and Infection Medicine Tübingen (IMIT), Cluster of Excellence 'Controlling Microbes to Fight Infections', University of Tübingen, Auf der Morgenstelle 28, 72076, Tübingen, Germany
| | - Hanne Ingmer
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 4, 1870, Frederiksberg C, Denmark.
| | - Martin Vestergaard
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 4, 1870, Frederiksberg C, Denmark
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Mercer DK, Torres MDT, Duay SS, Lovie E, Simpson L, von Köckritz-Blickwede M, de la Fuente-Nunez C, O'Neil DA, Angeles-Boza AM. Antimicrobial Susceptibility Testing of Antimicrobial Peptides to Better Predict Efficacy. Front Cell Infect Microbiol 2020; 10:326. [PMID: 32733816 PMCID: PMC7358464 DOI: 10.3389/fcimb.2020.00326] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 05/29/2020] [Indexed: 12/11/2022] Open
Abstract
During the development of antimicrobial peptides (AMP) as potential therapeutics, antimicrobial susceptibility testing (AST) stands as an essential part of the process in identification and optimisation of candidate AMP. Standard methods for AST, developed almost 60 years ago for testing conventional antibiotics, are not necessarily fit for purpose when it comes to determining the susceptibility of microorganisms to AMP. Without careful consideration of the parameters comprising AST there is a risk of failing to identify novel antimicrobials at a time when antimicrobial resistance (AMR) is leading the planet toward a post-antibiotic era. More physiologically/clinically relevant AST will allow better determination of the preclinical activity of drug candidates and allow the identification of lead compounds. An important consideration is the efficacy of AMP in biological matrices replicating sites of infection, e.g., blood/plasma/serum, lung bronchiolar lavage fluid/sputum, urine, biofilms, etc., as this will likely be more predictive of clinical efficacy. Additionally, specific AST for different target microorganisms may help to better predict efficacy of AMP in specific infections. In this manuscript, we describe what we believe are the key considerations for AST of AMP and hope that this information can better guide the preclinical development of AMP toward becoming a new generation of urgently needed antimicrobials.
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Affiliation(s)
| | - Marcelo D. T. Torres
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, Penn Institute for Computational Science, and Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States
| | - Searle S. Duay
- Department of Chemistry, Institute of Materials Science, University of Connecticut, Storrs, CT, United States
| | - Emma Lovie
- NovaBiotics Ltd, Aberdeen, United Kingdom
| | | | | | - Cesar de la Fuente-Nunez
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, Penn Institute for Computational Science, and Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States
| | | | - Alfredo M. Angeles-Boza
- Department of Chemistry, Institute of Materials Science, University of Connecticut, Storrs, CT, United States
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11
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Tuchscherr L, Löffler B, Proctor RA. Persistence of Staphylococcus aureus: Multiple Metabolic Pathways Impact the Expression of Virulence Factors in Small-Colony Variants (SCVs). Front Microbiol 2020; 11:1028. [PMID: 32508801 PMCID: PMC7253646 DOI: 10.3389/fmicb.2020.01028] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 04/27/2020] [Indexed: 12/30/2022] Open
Abstract
Staphylococcus aureus is able to survive within host cells by switching its phenotype to the small-colony variant (SCV) phenotype. The emergence of SCVs is associated with the development of persistent infections, which may be both chronic and recurrent. This slow-growing subpopulation of S. aureus forms small colonies on solid-medium agar, is induced within host cells, presents a non-homogenous genetic background, has reduced expression of virulence factors and presents a variable phenotype (stable or unstable). While virtually all SCVs isolated from clinical specimens can revert to the parental state with rapid growth, the stable SCVs recovered in clinical specimens have been found to contain specific mutations in metabolic pathways. In contrast, other non-stable SCVs are originated from regulatory mechanisms involving global regulators (e.g., sigB, sarA, and agr) or other non-defined mutations. One major characteristic of SCVs was the observation that SCVs were recovered from five patients with infections that could persist for decades. In these five cases, the SCVs had defects in electron transport. This linked persistent infections with SCVs. The term "persistent infection" is a clinical term wherein bacteria remain in the host for prolonged periods of time, sometimes with recurrent infection, despite apparently active antibiotics. These terms were described in vitro where bacteria remain viable in liquid culture medium in the presence of antibiotics. These bacteria are called "persisters". While SCVs can be persisters in liquid culture, not all persisters are SCVs. One mechanism associated with the metabolically variant SCVs is the reduced production of virulence factors. SCVs have consistently shown reduced levels of RNAIII, a product of the accessory gene regulatory (agrBDCA) locus that controls a quorum-sensing system and regulates the expression of a large number of virulence genes. Reduced Agr acitivity is associated with enhanced survival of SCVs within host cells. In this review, we examine the impact of the SCVs with altered metabolic pathways on agr, and we draw distinctions with other types of SCVs that emerge within mammalian cells with prolonged infection.
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Affiliation(s)
- Lorena Tuchscherr
- Institute of Medical Microbiology, Jena University Hospital, Jena, Germany.,Center for Sepsis Control and Care, Jena University Hospital, Jena, Germany
| | - Bettina Löffler
- Institute of Medical Microbiology, Jena University Hospital, Jena, Germany.,Center for Sepsis Control and Care, Jena University Hospital, Jena, Germany
| | - Richard A Proctor
- Departments of Medical Microbiology/Immunology and Medicine, University of Wisconsin Medical School, Madison, WI, United States
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12
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Proctor R. Respiration and Small Colony Variants of Staphylococcus aureus. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0069-2019. [PMID: 31198131 PMCID: PMC11257146 DOI: 10.1128/microbiolspec.gpp3-0069-2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Indexed: 12/16/2022] Open
Abstract
Respiratory mutants, both naturally occurring and genetically constructed, have taught us about the importance of metabolism in influencing virulence factor production, persistence, and antibiotic resistance. As we learn more about small colony variants, we find that Staphylococcus aureus has many pathways to produce small colony variants, although the respiratory variants are the best described clinically and in the laboratory.
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Affiliation(s)
- Richard Proctor
- Department of Medical Microbiology and Immunology University of Wisconsin School of Medicine and Public Health Madison, WI 53705
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Zhang P, Wright JA, Tymon A, Nair SP. Bicarbonate induces high-level resistance to the human antimicrobial peptide LL-37 in Staphylococcus aureus small colony variants. J Antimicrob Chemother 2019; 73:615-619. [PMID: 29211886 PMCID: PMC5890704 DOI: 10.1093/jac/dkx433] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 10/25/2017] [Indexed: 01/29/2023] Open
Abstract
Objectives Staphylococcus aureus small colony variants (SCVs) cause persistent infections and are resistant to cationic antibiotics. Antimicrobial peptides (AMPs) have been suggested as promising alternatives for treating antibiotic-resistant bacteria. We investigated the capacity of the human cationic AMP LL-37 to kill SCVs in the presence of physiological concentrations of bicarbonate, which are reported to alter bacterial membrane permeability and change resistance of bacteria to AMPs. Methods MBCs of LL-37 for S. aureus SCVs with mutations in different genes in the presence and absence of bicarbonate were determined. Results In the absence of bicarbonate, SCVs of S. aureus strains LS-1 and 8325-4 had the same level of resistance to LL-37 as the parental strain (8 mg/L). In the presence of bicarbonate, hemB, menD and aroD SCVs of LS-1 had high-level resistance to LL-37 (≥128 mg/L) compared with the parental strain (16 mg/L). However, only the aroD SCV of strain 8324-5 showed high-level resistance. 8325-4 harbours mutations in two genes, tcaR and rsbU, which are involved in antimicrobial sensing and the stress response, respectively. When rsbU was repaired in 8325-4 it displayed high-level resistance to LL-37 in the presence of bicarbonate. This phenotype was lost when tcaR was also repaired, demonstrating that RsbU and TcaR are involved in LL-37 resistance in the presence of bicarbonate Conclusions S. aureus SCVs would be resistant to high concentrations of LL-37 in niches where there are physiological concentrations of bicarbonate and therefore this AMP may not be effective in combating SCVs.
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Affiliation(s)
- Ping Zhang
- Department of Microbial Diseases, UCL Eastman Dental Institute, 256 Gray's Inn Road, London WC1X 8LD, UK
| | - John A Wright
- Immunology Catalyst, GSK, Stevenage, Hertfordshire, UK
| | - Anna Tymon
- Department of Microbial Diseases, UCL Eastman Dental Institute, 256 Gray's Inn Road, London WC1X 8LD, UK
| | - Sean P Nair
- Department of Microbial Diseases, UCL Eastman Dental Institute, 256 Gray's Inn Road, London WC1X 8LD, UK
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Transcriptome analysis of Burkholderia pseudomallei SCV reveals an association with virulence, stress resistance and intracellular persistence. Genomics 2019; 112:501-512. [PMID: 30980902 DOI: 10.1016/j.ygeno.2019.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 03/18/2019] [Accepted: 04/01/2019] [Indexed: 01/16/2023]
Abstract
Differences in expression of potential virulence and survival genes were associated with B. pseudomallei colony morphology variants. Microarray was used to investigate B. pseudomallei transcriptome alterations among the wild type and small colony variant (SCV) pre- and post-exposed to A549 cells. SCV pre- and post-exposed have lower metabolic requirements and consume lesser energy than the wild type pre- and post-exposed to A549. However, both the wild type and SCV limit their metabolic activities post- infection of A549 cells and this is indicated by the down-regulation of genes implicated in the metabolism of amino acids, carbohydrate, lipid, and other amino acids. Many well-known virulence and survival factors, including T3SS, fimbriae, capsular polysaccharides and stress response were up-regulated in both the wild type and SCV pre- and post-exposed to A549 cells. Microarray analysis demonstrated essential differences in bacterial response associated with virulence and survival pre- and post-exposed to A549 cells.
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Ciumac D, Gong H, Hu X, Lu JR. Membrane targeting cationic antimicrobial peptides. J Colloid Interface Sci 2019; 537:163-185. [DOI: 10.1016/j.jcis.2018.10.103] [Citation(s) in RCA: 123] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/29/2018] [Accepted: 10/30/2018] [Indexed: 01/13/2023]
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16
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Magryś A, Deryło K, Bogut A, Olender A, Tchórzewski M. Intraphagolysosomal conditions predispose to Staphylococcus epidermidis small colony variants persistence in macrophages. PLoS One 2018; 13:e0207312. [PMID: 30412620 PMCID: PMC6226201 DOI: 10.1371/journal.pone.0207312] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 10/29/2018] [Indexed: 12/17/2022] Open
Abstract
Staphylococcus epidermidis small colony variants can survive inside macrophages and their survival has been proposed as a pivotal process in the pathogenesis of biomaterial associated infections. In the present study the intracellular location of clinical isolates of SCV and parental wild type strains inside macrophages was determined. Furthermore, the effect of IFN-γ and rapamycin on the level of SCV/WT as well as lysosomes colocalisation and iNOS induction in THP-activated macrophages in response to WT and SCV strains of Staphylococcus epidermidis were examined. It was demonstrated that SCV strain of S. epidermidis can survive and persist inside macrophages and its intracellular survival is supported by the induction of phagosomal acidification. The ability to reduce the high proportion of LysoTracker positive SCV containing phagosomes was exclusively found when IFN-γ was used. The findings suggest that IFN-γ mediates SCV killing via two distinct mechanisms, phagosome alkalisation and an increased iNOS synthesis, so the cytokine may control S. epidermidis WT and SCV infection in macrophages. Staphylococcus epidermidis SCV is a less potent stimulus of iNOS than the WT strain and the feature may help SCV to persist in hostile environment of macrophages. Rapamycin treatment did not influence the iNOS synthesis but reduced the percentage of both bacterial strains within acidic organelles. However, the percentage of SCV within LysoTracker positive organelles, even though reduced comparing to non-primed cells, was higher than in the WT strain indicating that Staphylococcus epidermidis possesses unique metabolic features allowing SCV to survive within macrophages.
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Affiliation(s)
- Agnieszka Magryś
- Chair and Department of Medical Microbiology, Medical University of Lublin, Lublin, Poland
- * E-mail:
| | - Kamil Deryło
- Department of Molecular Biology, Maria Curie-Skłodowska University, Lublin, Poland
| | - Agnieszka Bogut
- Chair and Department of Medical Microbiology, Medical University of Lublin, Lublin, Poland
| | - Alina Olender
- Chair and Department of Medical Microbiology, Medical University of Lublin, Lublin, Poland
| | - Marek Tchórzewski
- Department of Molecular Biology, Maria Curie-Skłodowska University, Lublin, Poland
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17
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Tada T, Uechi K, Nakasone I, Miyazato Z, Shinzato T, Shimada K, Tsuchiya M, Kirikae T, Fujita J. A hemin auxotrophic Enterobacter cloacae clinical isolate with increased resistance to carbapenems and aminoglycosides. J Med Microbiol 2017; 67:29-32. [PMID: 29205135 DOI: 10.1099/jmm.0.000655] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Small-colony variants (SCVs) were obtained from an Enterobacter cloacae clinical isolate in Okinawa, Japan. One variant showed auxotrophy for hemin with a deletion of 20 365 nucleotides, dosC-ydiK-mmuP-mmuM-tauA-tauB-tauC-tauD-hemB-yaiT-yaiV-ampH-yddQ-sbmA-yaiW-yaiY-yaiZ, including hemB, and was more resistant to aminoglycosides and carbapenems, but more susceptible to aztreonam, than the parent strain.
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Affiliation(s)
- Tatsuya Tada
- Department of Microbiology, Juntendo University School of Medicine, Tokyo, Japan.,Department of Infectious Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Kohei Uechi
- Division of Clinical Laboratory and Blood Transfusion, University Hospital of the Ryukyus, Okinawa, Japan.,Department of Infectious Diseases, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Isamu Nakasone
- Control and Prevention of Infectious Disease, University Hospital of the Ryukyus, Okinawa, Japan
| | | | | | - Kayo Shimada
- Department of Infectious Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Mitsuhiro Tsuchiya
- Department of Microbiology, Juntendo University School of Medicine, Tokyo, Japan
| | - Teruo Kirikae
- Department of Infectious Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.,Department of Microbiology, Juntendo University School of Medicine, Tokyo, Japan
| | - Jiro Fujita
- Department of Infectious Diseases, Respiratory, and Digestive Medicine, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
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18
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NP108, an Antimicrobial Polymer with Activity against Methicillin- and Mupirocin-Resistant Staphylococcus aureus. Antimicrob Agents Chemother 2017; 61:AAC.00502-17. [PMID: 28607014 PMCID: PMC5571353 DOI: 10.1128/aac.00502-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 06/03/2017] [Indexed: 02/04/2023] Open
Abstract
Staphylococcus aureus is a clinically significant human pathogen that causes infectious diseases ranging from skin and soft tissue infections (SSTI) and health care-associated infections (HAI) to potentially fatal bacteremia and endocarditis. Nasal carriage of S. aureus, especially for persistent carriage, is associated with an increased risk of subsequent infection, particularly nosocomial and surgical site infections (SSI), usually via autoinfection. NP108 is a cationic antimicrobial polymer composed of generally recognized as safe (GRAS) amino acid building blocks. NP108 is broad spectrum and rapidly bactericidal (3-log kill in ≤3 h), killing bacteria by membrane disruption and cell lysis. NP108, contrary to many antibiotics, shows equally effective antimicrobial activity against a variety of S. aureus (MIC100 = 8 to 500 mg/liter) and S. epidermidis (MIC100 = 4 to 8 mg/liter) isolates, whether exponentially growing or in stationary phase. NP108 is antimicrobially active under nutrient-limiting conditions similar to those found in the anterior nares (MIC100 = 8 mg/liter) and kills antibiotic-resilient small colony variants (MIC100 = 32 mg/liter) and S. aureus biofilms (prevention, MIC100 = 1 to 4 mg/liter; eradication, MIC100 ≥ 31.25 mg/liter). NP108 is active against isolates of S. aureus resistant to the current standard-of-care decolonization agent, mupirocin, with no significant increase in the MIC100 NP108 is water soluble and has been formulated into compatible aqueous gel vehicles for human use in which antimicrobial efficacy is retained (2.0% [wt/vol]). NP108 is a potential nonantibiotic antimicrobial alternative to antibiotics for the nasal decolonization of S. aureus, with clear advantages in its mechanism of action over the existing gold standard, mupirocin.
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Doulgeraki AI, Di Ciccio P, Ianieri A, Nychas GJE. Methicillin-resistant food-related Staphylococcus aureus: a review of current knowledge and biofilm formation for future studies and applications. Res Microbiol 2017; 168:1-15. [DOI: 10.1016/j.resmic.2016.08.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 07/18/2016] [Accepted: 08/05/2016] [Indexed: 12/18/2022]
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20
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Kubicek-Sutherland JZ, Lofton H, Vestergaard M, Hjort K, Ingmer H, Andersson DI. Antimicrobial peptide exposure selects for Staphylococcus aureus resistance to human defence peptides. J Antimicrob Chemother 2016; 72:115-127. [PMID: 27650186 PMCID: PMC5161045 DOI: 10.1093/jac/dkw381] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 07/29/2016] [Accepted: 08/12/2016] [Indexed: 02/06/2023] Open
Abstract
Background The clinical development of antimicrobial peptides (AMPs) is currently under evaluation to combat the rapid increase in MDR bacterial pathogens. However, many AMPs closely resemble components of the human innate immune system and the ramifications of prolonged bacterial exposure to AMPs are not fully understood. Objectives We show that in vitro serial passage of a clinical USA300 MRSA strain in a host-mimicking environment containing host-derived AMPs results in the selection of stable AMP resistance. Methods Serial passage experiments were conducted using steadily increasing concentrations of LL-37, PR-39 or wheat germ histones. WGS and proteomic analysis by MS were used to identify the molecular mechanism associated with increased tolerance of AMPs. AMP-resistant mutants were characterized by measuring in vitro fitness, AMP and antibiotic susceptibility, and virulence in a mouse model of sepsis. Results AMP-resistant Staphylococcus aureus mutants often displayed little to no fitness cost and caused invasive disease in mice. Further, this phenotype coincided with diminished susceptibility to both clinically prescribed antibiotics and human defence peptides. Conclusions These findings suggest that therapeutic use of AMPs could select for virulent mutants with cross-resistance to human innate immunity as well as antibiotic therapy. Thus, therapeutic use of AMPs and the implications of cross-resistance need to be carefully monitored and evaluated.
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Affiliation(s)
| | - Hava Lofton
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, 75123, Uppsala, Sweden
| | - Martin Vestergaard
- Department of Veterinary Disease Biology, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg C, Copenhagen, Denmark
| | - Karin Hjort
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, 75123, Uppsala, Sweden
| | - Hanne Ingmer
- Department of Veterinary Disease Biology, University of Copenhagen, Stigbøjlen 4, 1870 Frederiksberg C, Copenhagen, Denmark
| | - Dan I Andersson
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, 75123, Uppsala, Sweden
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Andersson D, Hughes D, Kubicek-Sutherland J. Mechanisms and consequences of bacterial resistance to antimicrobial peptides. Drug Resist Updat 2016; 26:43-57. [DOI: 10.1016/j.drup.2016.04.002] [Citation(s) in RCA: 319] [Impact Index Per Article: 39.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 04/07/2016] [Accepted: 04/11/2016] [Indexed: 10/21/2022]
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Kim NH, Kang YM, Han WD, Park KU, Park KH, Yoo JI, Lee DG, Park C, Song KH, Kim ES, Park SW, Kim NJ, Oh MD, Kim HB. Small-Colony Variants in Persistent and Recurrent Staphylococcus aureus Bacteremia. Microb Drug Resist 2016; 22:538-544. [PMID: 26982169 DOI: 10.1089/mdr.2015.0262] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The small-colony variant (SCV) phenotype of Staphylococcus aureus is associated with intracellular persistence and reduced antimicrobial susceptibility, which can lead to therapeutic failure. Since SCVs grow slowly and have a confusing morphology, the identification of infections due to SCV is difficult. We have identified SCVs in two patients who presented with persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia complicated by surgical site infections after cardiothoracic surgery. Nine blood isolates were collected from the two patients for species identification, antimicrobial susceptibility testing, and phenotypic and genotypic characterization. Colonies on Columbia blood agar were pinpoint, nonpigmented, nonhemolytic, and reverted to normal colonies after 48 hr of incubation on Schaedler agar. Auxotrophy assays revealed hemin dependence. Susceptibility to vancomycin (minimal inhibitory concentrations 1.0 μg/mL) was confirmed by E-test and broth microdilution test. All the isolates were identified as MRSA by multiplex polymerase chain reaction specific for the mecA, femA, and 16S rRNA genes, and all had the same genotype: Multilocus sequence typing ST5, SCCmec type II, agr type II, and spa type t2460. Moreover pulsed-field gel electrophoresis typing revealed that all nine isolates belonged to the same clone. Mutations in the relA gene were not found, and none of the isolates was identified as hVISA by population analysis profiling-AUC ratio. A high level of suspicion is required to detect SCVs, and although it is not common, the possibility of the SCV phenotype has to be considered in persistent S. aureus bacteremia.
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Affiliation(s)
- Nak-Hyun Kim
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Yu Min Kang
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Woong Dae Han
- 2 Division of Infectious Diseases, Seoul National University Bundang Hospital , Seongnam, Republic of Korea
| | - Kyoung Un Park
- 3 Department of Laboratory Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Kay-Hyun Park
- 4 Department of Thoracic Surgery, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Jae Il Yoo
- 5 Division of Antimicrobial Resistance, Center for Infectious Diseases, Korea National Institute of Health , Cheongwon, Republic of Korea
| | - Dong-Gun Lee
- 6 Vaccine Bio Research Institute, Catholic University of Korea , Seoul, Republic of Korea
| | - Chulmin Park
- 6 Vaccine Bio Research Institute, Catholic University of Korea , Seoul, Republic of Korea
| | - Kyoung-Ho Song
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea.,2 Division of Infectious Diseases, Seoul National University Bundang Hospital , Seongnam, Republic of Korea
| | - Eu Suk Kim
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea.,2 Division of Infectious Diseases, Seoul National University Bundang Hospital , Seongnam, Republic of Korea
| | - Sang Won Park
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Nam Joong Kim
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Myoung-Don Oh
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea
| | - Hong Bin Kim
- 1 Department of Internal Medicine, Seoul National University College of Medicine , Seoul, Republic of Korea.,2 Division of Infectious Diseases, Seoul National University Bundang Hospital , Seongnam, Republic of Korea
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23
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Vestergaard M, Paulander W, Ingmer H. Activation of the SOS response increases the frequency of small colony variants. BMC Res Notes 2015; 8:749. [PMID: 26643526 PMCID: PMC4672542 DOI: 10.1186/s13104-015-1735-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 11/24/2015] [Indexed: 02/07/2023] Open
Abstract
Background In Staphylococcus aureus sub-populations of slow-growing cells forming small colony variants (SCVs) are associated with persistent and recurrent infections that are difficult to eradicate with antibiotic therapies. In SCVs that are resistant towards aminoglycosides, mutations have been identified in genes encoding components of the respiratory chain. Given the high frequencies of SCVs isolated clinically it is vital to understand the conditions that promote or select for SCVs. Results In this study we have examined how exposure to sub-inhibitory concentrations of antibiotics with different mechanism of action influence the formation of SCVs that are resistant to otherwise lethal concentrations of the aminoglycoside, gentamicin. We found that exposure of S. aureus to fluoroquinolones and mitomycin C increased the frequency of gentamicin resistant SCVs, while other antibiotic classes failed to do so. The higher proportion of SCVs in cultures exposed to fluoroquinolones and mitomycin C compared to un-exposed cultures correlate with an increased mutation rate monitored by rifampicin resistance and followed induction of the SOS DNA damage response. Conclusion Our observations suggest that environmental stimuli, including antimicrobials that reduce replication fidelity, increase the formation of SCVs through activation of the SOS response and thereby potentially promote persistent infections that are difficult to treat.
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Affiliation(s)
- Martin Vestergaard
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 4, 1870, Frederiksberg C, Denmark.
| | - Wilhelm Paulander
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 4, 1870, Frederiksberg C, Denmark.
| | - Hanne Ingmer
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Stigbøjlen 4, 1870, Frederiksberg C, Denmark.
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24
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Lysocin E is a new antibiotic that targets menaquinone in the bacterial membrane. Nat Chem Biol 2014; 11:127-33. [DOI: 10.1038/nchembio.1710] [Citation(s) in RCA: 162] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 10/08/2014] [Indexed: 12/28/2022]
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25
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Lee S, Kwon KT, Kim HI, Chang HH, Lee JM, Choe PG, Park WB, Kim NJ, Oh MD, Song DY, Kim SW. Clinical Implications of Cefazolin Inoculum Effect and β-Lactamase Type on Methicillin-SusceptibleStaphylococcus aureusBacteremia. Microb Drug Resist 2014; 20:568-74. [DOI: 10.1089/mdr.2013.0229] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Shinwon Lee
- Department of Internal Medicine, Pusan National University School of Medicine, Medical Research Institute, Pusan National University Hospital, Busan, Republic of Korea
| | - Ki Tae Kwon
- Division of Infectious Diseases, Department of Internal Medicine, Daegu Fatima Hospital, Daegu, Republic of Korea
| | - Hye-In Kim
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Hyun Ha Chang
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Jong-Myung Lee
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
| | - Pyoeng Gyun Choe
- Department of Internal Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea
| | - Wan Beom Park
- Department of Internal Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea
| | - Nam Joong Kim
- Department of Internal Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea
| | - Myoung-Don Oh
- Department of Internal Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea
| | - Do Young Song
- Department of Laboratory Medicine, Daegu Fatima Hospital, Daegu, Republic of Korea
| | - Shin-Woo Kim
- Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
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Moon JH, Lee JH, Lee JY. Microarray analysis of the transcriptional responses of Porphyromonas gingivalis to polyphosphate. BMC Microbiol 2014; 14:218. [PMID: 25148905 PMCID: PMC4236598 DOI: 10.1186/s12866-014-0218-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 08/12/2014] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Polyphosphate (polyP) has bactericidal activity against a gram-negative periodontopathogen Porphyromonas gingivalis, a black-pigmented gram-negative anaerobic rod. However, current knowledge about the mode of action of polyP against P. gingivalis is incomplete. To elucidate the mechanisms of antibacterial action of polyP against P. gingivalis, we performed the full-genome gene expression microarrays, and gene ontology (GO) and protein-protein interaction network analysis of differentially expressed genes (DEGs). RESULTS We successfully identified 349 up-regulated genes and 357 down-regulated genes (>1.5-fold, P < 0.05) in P. gingivalis W83 treated with polyP75 (sodium polyphosphate, Na(n+2)P(n)O3(n+1); n = 75). Real-time PCR confirmed the up- and down-regulation of some selected genes. GO analysis of the DEGs identified distinct biological themes. Using 202 DEGs belonging to the biological themes, we generated the protein-protein interaction network based on a database of known and predicted protein interactions. The network analysis identified biological meaningful clusters related to hemin acquisition, energy metabolism, cell envelope and cell division, ribosomal proteins, and transposon function. CONCLUSIONS polyP probably exerts its antibacterial effect through inhibition of hemin acquisition by the bacterium, resulting in severe perturbation of energy metabolism, cell envelope biosynthesis and cell division, and elevated transposition. Further studies will be needed to elucidate the exact mechanism by which polyP induces up-regulation of the genes related to ribosomal proteins. Our results will shed new light on the study of the antibacterial mechanism of polyP against other related bacteria belonging to the black-pigmented Bacteroides species.
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Affiliation(s)
- Ji-Hoi Moon
- Department of Maxillofacial Biomedical Engineering, School of Dentistry, and Institute of Oral Biology, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 130-701, Republic of Korea
- Department of Life and Nanopharmaceutical Sciences, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 130-701, Republic of Korea
| | - Jae-Hyung Lee
- Department of Maxillofacial Biomedical Engineering, School of Dentistry, and Institute of Oral Biology, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 130-701, Republic of Korea
- Department of Life and Nanopharmaceutical Sciences, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 130-701, Republic of Korea
| | - Jin-Yong Lee
- Department of Maxillofacial Biomedical Engineering, School of Dentistry, and Institute of Oral Biology, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 130-701, Republic of Korea
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27
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Proctor RA, Kriegeskorte A, Kahl BC, Becker K, Löffler B, Peters G. Staphylococcus aureus Small Colony Variants (SCVs): a road map for the metabolic pathways involved in persistent infections. Front Cell Infect Microbiol 2014; 4:99. [PMID: 25120957 PMCID: PMC4112797 DOI: 10.3389/fcimb.2014.00099] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 07/07/2014] [Indexed: 12/31/2022] Open
Abstract
Persistent and relapsing infections, despite apparently adequate antibiotic therapy, occur frequently with many pathogens, but it is an especially prominent problem with Staphylococcus aureus infections. For the purposes of this review, persistence will encompass both of the concepts of long term survival within the host, including colonization, and the concept of resisting antibiotic therapy even when susceptible in the clinical microbiology laboratory. Over the past two decades, the mechanisms whereby bacteria achieve persistence are slowly being unraveled. S. aureus small colony variants (SCVs) are linked to chronic, recurrent, and antibiotic-resistant infections, and the study of SCVs has contributed significantly to understanding of persistence. In our earlier work, defects in electron transport and thymidylate biosynthesis were linked to the development of the SCV phenotype (reviewed in 2006), thus this work will be discussed only briefly. Since 2006, it has been found that persistent organisms including SCVs are part of the normal life cycle of bacteria, and often they arise in response to harsh conditions, e.g., antibiotics, starvation, host cationic peptides. Many of the changes found in these early SCVs have provided a map for the discovery mechanisms (pathways) for the development of persistent organisms. For example, changes in RNA processing, stringent response, toxin-antitoxin, ribosome protein L6 (RplF), and cold shock protein B (CspB) found in SCVs are also found in other persisters. In addition, many classic persister organisms also show slow growth, hence SCVs. Recent work on S. aureus USA300 has elucidated the impact of aerobic expression of arginine deiminase genes on its ability to chronically colonize the skin and survive in abscesses. S. aureus SCVs also express arginine deiminase genes aerobically as well. Thus, many pathways found activated in electron transport type of SCVs are also increased in persisters that have intact electron transport. Many of these changes in metabolism result in slow growth; hence, small colonies are formed. Another common theme is that slow growth is also associated with reduced expression of virulence factors and enhanced uptake/survival within host cells. These adaptations to survive within the host are rooted in responses that were required for organisms to survive in a harsh environment long before they were mammals on the earth.
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Affiliation(s)
- Richard A Proctor
- Departments of Medical Microbiology/Immunology and Medicine, University of Wisconsin School of Medicine and Public Health Madison, WI, USA
| | - André Kriegeskorte
- Institute of Medical Microbiology, University Hospital, Münster Münster, Germany
| | - Barbara C Kahl
- Institute of Medical Microbiology, University Hospital, Münster Münster, Germany
| | - Karsten Becker
- Institute of Medical Microbiology, University Hospital, Münster Münster, Germany
| | - Bettina Löffler
- Institute of Medical Microbiology, University Hospital, Münster Münster, Germany
| | - Georg Peters
- Institute of Medical Microbiology, University Hospital, Münster Münster, Germany
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Purrello S, Daum R, Edwards G, Lina G, Lindsay J, Peters G, Stefani S. Meticillin-resistant Staphylococcus aureus (MRSA) update: New insights into bacterial adaptation and therapeutic targets. J Glob Antimicrob Resist 2014; 2:61-69. [DOI: 10.1016/j.jgar.2014.02.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 02/06/2014] [Indexed: 12/23/2022] Open
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Garmendia J, Viadas C, Calatayud L, Mell JC, Martí-Lliteras P, Euba B, Llobet E, Gil C, Bengoechea JA, Redfield RJ, Liñares J. Characterization of nontypable Haemophilus influenzae isolates recovered from adult patients with underlying chronic lung disease reveals genotypic and phenotypic traits associated with persistent infection. PLoS One 2014; 9:e97020. [PMID: 24824990 PMCID: PMC4019658 DOI: 10.1371/journal.pone.0097020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 04/14/2014] [Indexed: 01/09/2023] Open
Abstract
Nontypable Haemophilus influenzae (NTHi) has emerged as an important opportunistic pathogen causing infection in adults suffering obstructive lung diseases. Existing evidence associates chronic infection by NTHi to the progression of the chronic respiratory disease, but specific features of NTHi associated with persistence have not been comprehensively addressed. To provide clues about adaptive strategies adopted by NTHi during persistent infection, we compared sequential persistent isolates with newly acquired isolates in sputa from six patients with chronic obstructive lung disease. Pulse field gel electrophoresis (PFGE) identified three patients with consecutive persistent strains and three with new strains. Phenotypic characterisation included infection of respiratory epithelial cells, bacterial self-aggregation, biofilm formation and resistance to antimicrobial peptides (AMP). Persistent isolates differed from new strains in showing low epithelial adhesion and inability to form biofilms when grown under continuous-flow culture conditions in microfermenters. Self-aggregation clustered the strains by patient, not by persistence. Increasing resistance to AMPs was observed for each series of persistent isolates; this was not associated with lipooligosaccharide decoration with phosphorylcholine or with lipid A acylation. Variation was further analyzed for the series of three persistent isolates recovered from patient 1. These isolates displayed comparable growth rate, natural transformation frequency and murine pulmonary infection. Genome sequencing of these three isolates revealed sequential acquisition of single-nucleotide variants in the AMP permease sapC, the heme acquisition systems hgpB, hgpC, hup and hxuC, the 3-deoxy-D-manno-octulosonic acid kinase kdkA, the long-chain fatty acid transporter ompP1, and the phosphoribosylamine glycine ligase purD. Collectively, we frame a range of pathogenic traits and a repertoire of genetic variants in the context of persistent infection by NTHi.
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Affiliation(s)
- Junkal Garmendia
- Instituto de Agrobiotecnología, CSIC-Universidad Pública Navarra-Gobierno Navarra, Mutilva, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Laboratory Microbial Pathogenesis, Fundación Investigación Sanitaria Illes Balears, Bunyola, Spain
- * E-mail:
| | - Cristina Viadas
- Instituto de Agrobiotecnología, CSIC-Universidad Pública Navarra-Gobierno Navarra, Mutilva, Spain
| | - Laura Calatayud
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Microbiology Department, University Hospital Bellvitge, IDIBELL, University of Barcelona, Barcelona, Spain
| | - Joshua Chang Mell
- Department of Zoology, University British Columbia, Vancouver, British Columbia, Canada
- Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Pau Martí-Lliteras
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Laboratory Microbial Pathogenesis, Fundación Investigación Sanitaria Illes Balears, Bunyola, Spain
| | - Begoña Euba
- Instituto de Agrobiotecnología, CSIC-Universidad Pública Navarra-Gobierno Navarra, Mutilva, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
| | - Enrique Llobet
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Laboratory Microbial Pathogenesis, Fundación Investigación Sanitaria Illes Balears, Bunyola, Spain
| | - Carmen Gil
- Instituto de Agrobiotecnología, CSIC-Universidad Pública Navarra-Gobierno Navarra, Mutilva, Spain
| | - José Antonio Bengoechea
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Laboratory Microbial Pathogenesis, Fundación Investigación Sanitaria Illes Balears, Bunyola, Spain
- Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Rosemary J. Redfield
- Department of Zoology, University British Columbia, Vancouver, British Columbia, Canada
| | - Josefina Liñares
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Madrid, Spain
- Microbiology Department, University Hospital Bellvitge, IDIBELL, University of Barcelona, Barcelona, Spain
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Decreased susceptibility of Staphylococcus aureus small-colony variants toward human antimicrobial peptides. J Invest Dermatol 2014; 134:2347-2350. [PMID: 24717245 DOI: 10.1038/jid.2014.176] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 03/07/2014] [Accepted: 03/10/2014] [Indexed: 11/08/2022]
Abstract
Staphylococcus aureus is a frequent resident of human nose and skin in many individuals, but it is also able to cause a variety of serious infections including those of the skin and soft tissue. There is increasing evidence that particularly persistent, relapsing, and difficult-to-treat infections caused by S. aureus are associated with the formation of the small-colony variant (SCV) phenotype. The aim of this study was to investigate the hypothesis that (i) skin-derived antimicrobial peptides (AMPs) exhibit a reduced activity against SCVs and (ii) that switching into the SCV phenotype may endow S. aureus with a decreased susceptibility toward the killing activity of human stratum corneum. Here, we show that clinically derived S. aureus SCVs are less susceptible to the bactericidal activity of different human skin-derived AMPs as compared with their isogenic corresponding wild-type strains. Similarly, a S. aureus hemB mutant displaying the SCV phenotype was less susceptible to the antimicrobial activity of AMPs than its hemB-complemented mutant. These findings were accompanied by a higher resistance of SCVs to the killing activity of human stratum corneum. Switching into the SCV phenotype may help S. aureus to subvert cutaneous innate defense, thus contributing to the establishment and persistence of infection.
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Small colony variants (SCVs) of Staphylococcus aureus--a bacterial survival strategy. INFECTION GENETICS AND EVOLUTION 2013; 21:515-22. [PMID: 23722021 DOI: 10.1016/j.meegid.2013.05.016] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Revised: 05/11/2013] [Accepted: 05/18/2013] [Indexed: 01/28/2023]
Abstract
Small colony variants (SCVs) of Staphylococcus aureus have been implicated in chronic recurrent infections and have therefore gained renewed interest during the last decade. Moreover, SCVs have been shown to be part of the regular growth cycle, are highly dynamic or stable and can be selected during various harsh conditions. As such, the emergence of SCVs has been described not only in human, but also in veterinary medicine as well as in food microbiology. SCVs are characterized by impaired growth, down-regulation of genes for metabolism and virulence, while sigB and genes important for persistence and biofilm formation are up-regulated. Furthermore, SCVs are resistant to various antibiotics such as aminoglycosides, trimethoprim-sulfamethoxazole, fluorquinolones, fusidic acid or even to antiseptics such as triclosan. An underlying mechanism has been determined for hemin-, menadione- and thymidine-dependent SCVs as well as for SCVs which are impaired in their stress response. SCVs are optimized for persistence in the host. They are able to reverse and thereby constitute a highly dynamic subpopulation of S. aureus. Such phenotype switching constitutes an integral part of the infection process enabling the bacteria to hide inside the host cell without eliciting a strong host response.
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Garcia LG, Lemaire S, Kahl BC, Becker K, Proctor RA, Denis O, Tulkens PM, Van Bambeke F. Antibiotic activity against small-colony variants of Staphylococcus aureus: review of in vitro, animal and clinical data. J Antimicrob Chemother 2013; 68:1455-64. [DOI: 10.1093/jac/dkt072] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Ramli NSK, Eng Guan C, Nathan S, Vadivelu J. The effect of environmental conditions on biofilm formation of Burkholderia pseudomallei clinical isolates. PLoS One 2012; 7:e44104. [PMID: 22970167 PMCID: PMC3435415 DOI: 10.1371/journal.pone.0044104] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 07/30/2012] [Indexed: 01/30/2023] Open
Abstract
Burkholderia pseudomallei, a Gram-negative saprophytic bacterium, is the causative agent of the potentially fatal melioidosis disease in humans. In this study, environmental parameters including temperature, nutrient content, pH and the presence of glucose were shown to play a role in in vitro biofilm formation by 28 B. pseudomallei clinical isolates, including four isolates with large colony variants (LCVs) and small colony variants (SCVs) morphotypes. Enhanced biofilm formation was observed when the isolates were tested in LB medium, at 30°C, at pH 7.2, and in the presence of as little as 2 mM glucose respectively. It was also shown that all SVCs displayed significantly greater capacity to form biofilms than the corresponding LCVs when cultured in LB at 37°C. In addition, octanoyl-homoserine lactone (C8-HSL), a quorum sensing molecule, was identified by mass spectrometry analysis in bacterial isolates referred to as LCV CTH, LCV VIT, SCV TOM, SCV CTH, 1 and 3, and the presence of other AHL's with higher masses; decanoyl-homoserine lactone (C10-HSL) and dodecanoyl-homoserine lactone (C12-HSL) were also found in all tested strain in this study. Last but not least, we had successfully acquired two Bacillus sp. soil isolates, termed KW and SA respectively, which possessed strong AHLs degradation activity. Biofilm formation of B. pseudomallei isolates was significantly decreased after treated with culture supernatants of KW and SA strains, demonstrating that AHLs may play a role in B. pseudomallei biofilm formation.
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Affiliation(s)
- Nur Siti K. Ramli
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Chua Eng Guan
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Sheila Nathan
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia
| | - Jamuna Vadivelu
- Department of Medical Microbiology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
- * E-mail:
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Elias S, Banin E. Multi-species biofilms: living with friendly neighbors. FEMS Microbiol Rev 2012; 36:990-1004. [PMID: 22229800 DOI: 10.1111/j.1574-6976.2012.00325.x] [Citation(s) in RCA: 446] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 11/14/2011] [Accepted: 01/03/2012] [Indexed: 01/23/2023] Open
Abstract
Our knowledge regarding the nature and development of microbial biofilms has grown significantly since the first report of these communities by Antonie van Leeuwenhoek in the late 1600s. Nevertheless, most biofilm studies examine mono-species cultures, whereas nearly all biofilm communities in nature comprise a variety of microorganisms. The species that constitute a mixed biofilm and the interactions between these microorganisms critically influence the development and shape of the community. In this review, we focus on interactions occurring within a multi-species biofilm and their effects on the nature of the mixed community. In general, interspecies interactions involve communication, typically via quorum sensing, and metabolic cooperation or competition. Interactions among species within a biofilm can be antagonistic, such as competition over nutrients and growth inhibition, or synergistic. The latter can result in the development of several beneficial phenotypes. These include the promotion of biofilm formation by co-aggregation, metabolic cooperation where one species utilizes a metabolite produced by a neighboring species, and increased resistance to antibiotics or host immune responses compared to the mono-species biofilms. These beneficial interactions in mixed biofilms have important environmental, industrial, and clinical implications. The latter, for example, impacts the course and treatment of biofilm-related infections, such as those manifested in the lungs of cystic fibrosis patients.
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Affiliation(s)
- Sivan Elias
- The Bacterial Biofilm Research Laboratory, The Institute for Nanotechnology and Advanced Materials, The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
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35
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Pränting M, Andersson DI. Mechanisms and physiological effects of protamine resistance in Salmonella enterica serovar Typhimurium LT2. J Antimicrob Chemother 2010; 65:876-87. [DOI: 10.1093/jac/dkq059] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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36
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Li SS, Tsai HJ. Transgenic microalgae as a non-antibiotic bactericide producer to defend against bacterial pathogen infection in the fish digestive tract. FISH & SHELLFISH IMMUNOLOGY 2009; 26:316-325. [PMID: 18691655 DOI: 10.1016/j.fsi.2008.07.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Revised: 07/12/2008] [Accepted: 07/12/2008] [Indexed: 05/26/2023]
Abstract
Antibiotics are commonly employed in most fish aquacultures to prevent disease. One major risk in this practice is that antibiotic-resistant pathogens may be selected. Therefore, we wanted to examine the feasibility of producing an economical, non-antibiotic alternative. The microalga Nannochloropsis oculata is an essential phytoplankton used as live feed for fish larvae. We attempted to culture N. oculata in a way that would provide an organism against bacterial pathogenic infection. To test this idea, we constructed an algae-codon-optimized bovine lactoferricin (LFB) fused with a red fluorescent protein (DsRed) driven by a heat-inducible promoter, which is a heat shock protein 70A promoter combined with a ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit 2' promoter from Chlamydomonas reinhardtii. After electroporation, we examined 491 microalgal clones and generated two stable transgenic lines, each expressing a stable transgene inheritance for at least 26 months. This was confirmed by the positive detection of the mRNA transcript and the protein of LFB-DsRed produced by the transgenic microalgae. To test the efficacy of the antimicrobial peptide LFB, medaka fish (Oryzias latipes) were adapted from freshwater to seawater and were fed with the transgenic algae by oral-in-tube delivery method. Bacterial infection with 1 x 10(5)Vibrio parahaemolyticus per fish was induced 6h thereafter by oral-in-tube delivery as well. For medaka fish fed with 1 x 10(8) transgenic algae per fish, the average survival rate after a 24-h period of infection was much higher than that of medaka fed with wild-type algae (85+/-7.1% versus 5+/-7.1%). This result suggests that medaka fish fed with the LFB-containing transgenic microalgae will have bactericidal defense against V. parahaemolyticus infection in its digestive tract.
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Affiliation(s)
- Si-Shen Li
- Institute of Molecular and Cellular Biology, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 106, Taiwan
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37
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Santos AOD, Ueda-Nakamura T, Dias Filho BP, Veiga Junior VF, Pinto AC, Nakamura CV. Antimicrobial activity of Brazilian copaiba oils obtained from different species of the Copaifera genus. Mem Inst Oswaldo Cruz 2008; 103:277-81. [PMID: 18545856 DOI: 10.1590/s0074-02762008005000015] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Accepted: 04/28/2008] [Indexed: 12/20/2022] Open
Abstract
The antimicrobial activity of copaiba oils was tested against Gram-positive and Gram-negative bacteria, yeast, and dermatophytes. Oils obtained from Copaifera martii, Copaifera officinalis, and Copaifera reticulata (collected in the state of Acre) were active against Gram-positive species (Staphylococcus aureus, methicillin-resistant S. aureus, Staphylococcus epidermidis, Bacillus subtilis, and Enterococcus faecalis) with minimum inhibitory concentrations ranging from 31.3-62.5 microg/ml. The oils showed bactericidal activity, decreasing the viability of these Gram-positive bacteria within 3 h. Moderate activity was observed against dermatophyte fungi (Trichophyton rubrum and Microsporum canis). The oils showed no activity against Gram-negative bacteria and yeast. Scannning electron microscopy of S. aureus treated with resin oil from C. martii revealed lysis of the bacteria, causing cellular agglomerates. Transmission electron microscopy revealed disruption and damage to the cell wall, resulting in the release of cytoplasmic compounds, alterations in morphology, and a decrease in cell volume, indicating that copaiba oil may affect the cell wall.
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38
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Goldstein EJC, Proctor RA. Role of Folate Antagonists in the Treatment of Methicillin-Resistant Staphylococcus aureus Infection. Clin Infect Dis 2008; 46:584-93. [DOI: 10.1086/525536] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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39
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von Eiff C, Becker K. Small-colony variants (SCVs) of staphylococci: a role in foreign body-associated infections. Int J Artif Organs 2008; 30:778-85. [PMID: 17918122 DOI: 10.1177/039139880703000906] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Staphylococci have various strategies for resisting therapy that extend beyond classic mechanisms. Clinical experience with device-associated infections as well as with infections due to small-colony variants (SCVs) clearly shows that both antibacterial chemotherapy and host defense mechanisms are often unable to eliminate the pathogens and cure these infections. Of particular interest is the fact that in the past few years an increasing number of various foreign body-related infections due to staphylococcal SCVs have been reported. In this overview, the characteristics of SCVs recovered from clinical specimens and of defined mutants displaying the SCV phenotype are described. Their slow growth and changing biochemical and physiological features represent a challenge to clinical laboratory personnel, because recovery, identification, as well as susceptibility testing of these variants need particular efforts. In addition, the reduced susceptibility to aminoglycosides and the ability of SCVs to persist intracellularly require specific attention for the treatment of these infections. Thus, special efforts to search for these variants formed by Staphylococcus aureus or by coagulase-negative staphylococci should be considered when an infection is particularly resistant to therapy, persists for a long period or fails to respond to apparently adequate therapy with antimicrobial compounds.
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Affiliation(s)
- C von Eiff
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany.
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40
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Chatterjee I, Kriegeskorte A, Fischer A, Deiwick S, Theimann N, Proctor RA, Peters G, Herrmann M, Kahl BC. In vivo mutations of thymidylate synthase (encoded by thyA) are responsible for thymidine dependency in clinical small-colony variants of Staphylococcus aureus. J Bacteriol 2007; 190:834-42. [PMID: 17905979 PMCID: PMC2223566 DOI: 10.1128/jb.00912-07] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Trimethoprim-sulfamethoxazole (SXT)-resistant Staphylococcus aureus thymidine-dependent small-colony variants (TD-SCVs) are frequently isolated from the airways of cystic fibrosis (CF) patients, often in combination with isogenic normal strains if patients were treated with SXT for extended periods. As SXT inhibits the synthesis of tetrahydrofolic acid, which acts as a cofactor for thymidylate synthase (thyA), the survival of TD-SCVs depends exclusively on the availability of external thymidine. Since the underlying mechanism for thymidine dependency is unknown, we investigated if alterations in the thyA nucleotide sequences were responsible for this phenomenon. Sequence analysis of several clinical TD-SCVs and their isogenic normal strains with reference to previously published S. aureus thyA nucleotide sequences was performed. Three clinical TD-SCVs were complemented by transforming TD-SCVs with the vector pCX19 expressing ThyA from S. aureus 8325-4. Transcriptional analysis of metabolic and virulence genes and regulators (agr, hla, spa, citB, thyA, and nupC) was performed by quantitative reverse transcription-PCR. The previously published sequences of thyA and two normal clinical strains were highly conserved, while thyA of four normal strains and four SCVs had nonsynonymous point mutations. In 8/10 SCVs, deletions occurred, resulting in stop codons which were located in 4/10 SCVs close to or within the active site of the protein (dUMP binding). Complementation of TD-SCVs with thyA almost fully reversed the phenotype, growth characteristics, and transcription patterns. In conclusion, we demonstrated that mutations of the thyA gene were responsible for the phenotype of TD-SCVs. Complementation of TD-SCVs with thyA revealed that a functional ThyA protein is necessary and sufficient to change the SCV phenotype and behavior back to normal.
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Affiliation(s)
- Indranil Chatterjee
- Institute of Medical Microbiology and Hygiene, Institutes of Infectious Disease Medicine, University of Saarland, Homburg/Saar, Germany
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41
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Affiliation(s)
- Anne Eglash
- Department of Family Medicine, University of Wisconsin School of Medicine and Public Health, Mt. Horeb, WI 53572, USA.
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Abstract
Antimicrobial peptides are ancient components of the innate immune system and have been isolated from organisms spanning the phylogenetic spectrum. Over an evolutionary time span, these peptides have retained potency, in the face of highly mutable target microorganisms. This fact suggests important coevolutionary influences in the host-pathogen relationship. Despite their diverse origins, the majority of antimicrobial peptides have common biophysical parameters that are likely essential for activity, including small size, cationicity, and amphipathicity. Although more than 900 different antimicrobial peptides have been characterized, most can be grouped as belonging to one of three structural classes: (1) linear, often of alpha-helical propensity; (2) cysteine stabilized, most commonly conforming to beta-sheet structure; and (3) those with one or more predominant amino acid residues, but variable in structure. Interestingly, these biophysical and structural features are retained in ribosomally as well as nonribosomally synthesized peptides. Therefore, it appears that a relatively limited set of physicochemical features is required for antimicrobial peptide efficacy against a broad spectrum of microbial pathogens. During the past several years, a number of themes have emerged within the field of antimicrobial peptide immunobiology. One developing area expands upon known microbicidal mechanisms of antimicrobial peptides to include targets beyond the plasma membrane. Examples include antimicrobial peptide activity involving structures such as extracellular polysaccharide and cell wall components, as well as the identification of an increasing number of intracellular targets. Additional areas of interest include an expanding recognition of antimicrobial peptide multifunctionality, and the identification of large antimicrobial proteins, and antimicrobial peptide or protein fragments derived thereof. The following discussion highlights such recent developments in antimicrobial peptide immunobiology, with an emphasis on the biophysical aspects of host-defense polypeptide action and mechanisms of microbial resistance.
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Affiliation(s)
- Nannette Y Yount
- Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, CA 90509, USA
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