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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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Hallier M, Bronsard J, Dréano S, Sassi M, Cattoir V, Felden B, Augagneur Y. RNAIII is linked with the pentose phosphate pathway through the activation of RpiRc in Staphylococcus aureus. mSphere 2024; 9:e0034823. [PMID: 38591898 PMCID: PMC11237564 DOI: 10.1128/msphere.00348-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 03/18/2024] [Indexed: 04/10/2024] Open
Abstract
Staphylococcus aureus RNAIII is a dual-function regulatory RNA that controls the expression of multiple virulence genes and especially the transition from adhesion to the production of exotoxins. However, its contribution to S. aureus central metabolism remains unclear. Using MS2-affinity purification coupled with RNA sequencing, we uncovered more than 50 novel RNAIII-mRNA interactions. Among them, we demonstrate that RNAIII is a major activator of the rpiRc gene, encoding a regulator of the pentose phosphate pathway (PPP). RNAIII binds the 5' UTR of rpiRc mRNA to favor ribosome loading, leading to an increased expression of RpiRc and, subsequently, of two PPP enzymes. Finally, we show that RNAIII and RpiRc are involved in S. aureus fitness in media supplemented with various carbohydrate sources related to PPP and glycolysis. Collectively, our data depict an unprecedented phenotype associated with the RNAIII regulon, especially the direct implication of RNAIII in central metabolic activity modulation. These findings show that the contribution of RNAIII in Staphylococcus aureus adaptation goes far beyond what was initially reported. IMPORTANCE Staphylococcus aureus is a major human pathogen involved in acute and chronic infections. Highly recalcitrant to antibiotic treatment, persistent infections are mostly associated with the loss of RNAIII expression, a master RNA regulator responsible for the switch from colonization to infection. Here, we used the MS2 affinity purification coupled with RNA sequencing approach to identify novel mRNA targets of RNAIII and uncover novel functions. We demonstrate that RNAIII is an activator of the expression of genes involved in the pentose phosphate pathway and is implicated in the adjustment of bacterial fitness as a function of carbohydrate sources. Taken together, our results demonstrate an unprecedented role of RNAIII that goes beyond the knowledge gained so far and contributes to a better understanding of the role of RNAIII in bacterial adaptation expression and the coordination of a complex regulatory network.
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Affiliation(s)
- Marc Hallier
- QCPS (Quality Control in Protein Synthesis), IGDR UMR CNRS 6290, Université de Rennes 1, Rennes, France
- BRM (Bacterial Regulatory RNAs and Medicine), UMR_S 1230, Université de Rennes 1, Rennes, France
| | - Julie Bronsard
- BRM (Bacterial Regulatory RNAs and Medicine), UMR_S 1230, Université de Rennes 1, Rennes, France
| | - Stéphane Dréano
- Molecular Bases of Tumorigenesis: VHL Disease Team, CNRS UMR 6290 IGDR, BIOSIT, Université de Rennes 1, Rennes, France
| | - Mohamed Sassi
- BRM (Bacterial Regulatory RNAs and Medicine), UMR_S 1230, Université de Rennes 1, Rennes, France
| | - Vincent Cattoir
- BRM (Bacterial Regulatory RNAs and Medicine), UMR_S 1230, Université de Rennes 1, Rennes, France
| | - Brice Felden
- BRM (Bacterial Regulatory RNAs and Medicine), UMR_S 1230, Université de Rennes 1, Rennes, France
| | - Yoann Augagneur
- BRM (Bacterial Regulatory RNAs and Medicine), UMR_S 1230, Université de Rennes 1, Rennes, France
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Popova L, Carabetta VJ. The use of next-generation sequencing in personalized medicine. ARXIV 2024:arXiv:2403.03688v1. [PMID: 38495572 PMCID: PMC10942477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
The revolutionary progress in development of next-generation sequencing (NGS) technologies has made it possible to deliver accurate genomic information in a timely manner. Over the past several years, NGS has transformed biomedical and clinical research and found its application in the field of personalized medicine. Here we discuss the rise of personalized medicine and the history of NGS. We discuss current applications and uses of NGS in medicine, including infectious diseases, oncology, genomic medicine, and dermatology. We provide a brief discussion of selected studies where NGS was used to respond to wide variety of questions in biomedical research and clinical medicine. Finally, we discuss the challenges of implementing NGS into routine clinical use.
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Affiliation(s)
- Liya Popova
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden NJ, 08103
| | - Valerie J. Carabetta
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden NJ, 08103
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Ryan H, Ballard E, Stockwell RE, Duplancic C, Thomson RM, Smith K, Bell SC. A systematic review of the clinical impact of small colony variants in patients with cystic fibrosis. BMC Pulm Med 2023; 23:323. [PMID: 37658311 PMCID: PMC10474644 DOI: 10.1186/s12890-023-02611-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 08/24/2023] [Indexed: 09/03/2023] Open
Abstract
BACKGROUND Cystic fibrosis (CF) is a life-limiting disorder that is characterised by respiratory tract inflammation that is mediated by a range of microbial pathogens. Small colony variants (SCVs) of common respiratory pathogens are being increasingly recognised in CF. The aim of this systematic review is to investigate the prevalence of SCVs, clinical characteristics and health outcomes for patients with CF, and laboratory diagnostic features of SCVs compared to non-small colony variants (NCVs) for a range of Gram-positive and Gram-negative respiratory pathogens. METHODS A literature search was conducted (PubMed, Web of Science, Embase and Scopus) in April 2020 to identify articles of interest. Data pertaining to demographic characteristics of participants, diagnostic criteria of SCVs, SCV prevalence and impact on lung function were extracted from included studies for analysis. RESULTS Twenty-five of 673 studies were included in the systematic review. Individuals infected with SCVs of Staphylococcus aureus (S. aureus) were more likely to have had prior use of the broad-spectrum antibiotic trimethoprim sulfamethoxazole (p < 0.001), and the prevalence of SCVs in patients infected with S. aureus was estimated to be 19.3% (95% CI: 13.5% to 25.9%). Additionally, patients infected with SCVs of Gram-negative and Gram-positive pathogens were identified to have a lower forced expiratory volume in one second percentage predicted (-16.8, 95% CI: -23.2 to -10.4) than those infected by NCVs. Gram-positive SCVs were commonly described as small and non-haemolytic, grown on Mannitol salt or blood agar for 24 h at 35°C and confirmed using tube coagulase testing. CONCLUSION The findings of this systematic review demonstrate that SCVs of S. aureus have a high prevalence in the CF community, and that the occurrence of SCVs in Gram-positive and Gram-negative pathogens is linked to poorer respiratory function. Further investigation is necessary to determine the effect of infection by SCVs on the CF population.
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Affiliation(s)
- Harrigan Ryan
- Centre for Children's Health Research, Faculty of Medicine, The University of Queensland, South Brisbane, QLD, Australia
| | - Emma Ballard
- Statistics Unit, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Rebecca E Stockwell
- Centre for Children's Health Research, Faculty of Medicine, The University of Queensland, South Brisbane, QLD, Australia
- Adult Cystic Fibrosis Centre, The Prince Charles Hospital, Chermside, QLD, Australia
| | - Christine Duplancic
- Centre for Children's Health Research, Faculty of Medicine, The University of Queensland, South Brisbane, QLD, Australia
| | - Rachel M Thomson
- Respiratory Research Group, Gallipoli Medical Research Foundation, Greenslopes, QLD, Australia
| | - Kimberley Smith
- Centre for Children's Health Research, Faculty of Medicine, The University of Queensland, South Brisbane, QLD, Australia
| | - Scott C Bell
- Centre for Children's Health Research, Faculty of Medicine, The University of Queensland, South Brisbane, QLD, Australia.
- Adult Cystic Fibrosis Centre, The Prince Charles Hospital, Chermside, QLD, Australia.
- Translational Research Institute, Woolloongabba, QLD, Australia.
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Millette G, Séguin DL, Isabelle C, Chamberland S, Lucier JF, Rodrigue S, Cantin AM, Malouin F. Staphylococcus aureus Small-Colony Variants from Airways of Adult Cystic Fibrosis Patients as Precursors of Adaptive Antibiotic-Resistant Mutations. Antibiotics (Basel) 2023; 12:1069. [PMID: 37370388 PMCID: PMC10294822 DOI: 10.3390/antibiotics12061069] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/14/2023] [Accepted: 06/15/2023] [Indexed: 06/29/2023] Open
Abstract
Prototypic Staphylococcus aureus and their small-colony variants (SCVs) are predominant in cystic fibrosis (CF), but the interdependence of these phenotypes is poorly understood. We characterized S. aureus isolates from adult CF patients over several years. Of 18 S. aureus-positive patients (58%), 13 (72%) were positive for SCVs. Characterization included genotyping, SCCmec types, auxotrophy, biofilm production, antibiotic susceptibilities and tolerance, and resistance acquisition rates. Whole-genome sequencing revealed that several patients were colonized with prototypical and SCV-related clones. Some clonal pairs showed acquisition of aminoglycoside resistance that was not explained by aminoglycoside-modifying enzymes, suggesting a mutation-based process. The characteristics of SCVs that could play a role in resistance acquisition were thus investigated further. For instance, SCV isolates produced more biofilm (p < 0.05) and showed a higher survival rate upon exposure to ciprofloxacin and vancomycin compared to their prototypic associated clones. SCVs also developed spontaneous rifampicin resistance mutations at a higher frequency. Accordingly, a laboratory-derived SCV (ΔhemB) acquired resistance to ciprofloxacin and gentamicin faster than its parent counterpart after serial passages in the presence of sub-inhibitory concentrations of antibiotics. These results suggest a role for SCVs in the establishment of persistent antibiotic-resistant clones in adult CF patients.
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Affiliation(s)
- Guillaume Millette
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
| | - David Lalonde Séguin
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
| | - Charles Isabelle
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
| | - Suzanne Chamberland
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
| | - Jean-François Lucier
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
| | - Sébastien Rodrigue
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
| | - André M. Cantin
- Service de Pneumologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada;
| | - François Malouin
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada; (G.M.); (D.L.S.); (C.I.); (S.C.); (J.-F.L.); (S.R.)
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Planet PJ. Adaptation and Evolution of Pathogens in the Cystic Fibrosis Lung. J Pediatric Infect Dis Soc 2022; 11:S23-S31. [PMID: 36069898 PMCID: PMC9451014 DOI: 10.1093/jpids/piac073] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 07/11/2022] [Indexed: 02/05/2023]
Abstract
As opposed to acute respiratory infections, the persistent bacterial infections of the lung that characterize cystic fibrosis (CF) provide ample time for bacteria to evolve and adapt. The process of adaptation is recorded in mutations that accumulate over time in the genomes of the infecting bacteria. Some of these mutations lead to obvious phenotypic differences such as antibiotic resistance or the well-known mucoid phenotype of Pseudomonas aeruginosa. Other mutations may be just as important but harder to detect such as increased mutation rates, cell surface changes, and shifts in metabolism and nutrient acquisition. Remarkably, many of the adaptations occur again and again in different patients, signaling that bacteria are adapting to solve specific challenges in the CF respiratory tract. This parallel evolution even extends across distinct bacterial species. This review addresses the bacterial systems that are known to change in long-term CF infections with a special emphasis on cross-species comparisons. Consideration is given to how adaptation may impact health in CF, and the possible evolutionary mechanisms that lead to the repeated parallel adaptations.
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Affiliation(s)
- Paul J Planet
- Corresponding Author: Paul J. Planet, MD, PhD, 3615 Civic Center Blvd, Philadelphia, PA 19104. E-mail:
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Biswas L, Götz F. Molecular Mechanisms of Staphylococcus and Pseudomonas Interactions in Cystic Fibrosis. Front Cell Infect Microbiol 2022; 11:824042. [PMID: 35071057 PMCID: PMC8770549 DOI: 10.3389/fcimb.2021.824042] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 12/16/2021] [Indexed: 11/15/2022] Open
Abstract
Cystic fibrosis (CF) is an autosomal recessive genetic disorder that is characterized by recurrent and chronic infections of the lung predominantly by the opportunistic pathogens, Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa. While S. aureus is the main colonizing bacteria of the CF lungs during infancy and early childhood, its incidence declines thereafter and infections by P. aeruginosa become more prominent with increasing age. The competitive and cooperative interactions exhibited by these two pathogens influence their survival, antibiotic susceptibility, persistence and, consequently the disease progression. For instance, P. aeruginosa secretes small respiratory inhibitors like hydrogen cyanide, pyocyanin and quinoline N-oxides that block the electron transport pathway and suppress the growth of S. aureus. However, S. aureus survives this respiratory attack by adapting to respiration-defective small colony variant (SCV) phenotype. SCVs cause persistent and recurrent infections and are also resistant to antibiotics, especially aminoglycosides, antifolate antibiotics, and to host antimicrobial peptides such as LL-37, human β-defensin (HBD) 2 and HBD3; and lactoferricin B. The interaction between P. aeruginosa and S. aureus is multifaceted. In mucoid P. aeruginosa strains, siderophores and rhamnolipids are downregulated thus enhancing the survival of S. aureus. Conversely, protein A from S. aureus inhibits P. aeruginosa biofilm formation while protecting both P. aeruginosa and S. aureus from phagocytosis by neutrophils. This review attempts to summarize the current understanding of the molecular mechanisms that drive the competitive and cooperative interactions between S. aureus and P. aeruginosa in the CF lungs that could influence the disease outcome.
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Affiliation(s)
- Lalitha Biswas
- Centre for Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Kochi, India
| | - Friedrich Götz
- Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, Tübingen, Germany
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Heme-Dependent Siderophore Utilization Promotes Iron-Restricted Growth of the Staphylococcus aureus hemB Small-Colony Variant. J Bacteriol 2021; 203:e0045821. [PMID: 34606375 DOI: 10.1128/jb.00458-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Respiration-deficient Staphylococcus aureus small-colony variants (SCVs) frequently cause persistent infections, which necessitates they acquire iron, yet how SCVs obtain iron remains unknown. To address this, we created a stable hemB mutant from S. aureus USA300 strain LAC. The hemB SCV utilized exogenously supplied hemin but was attenuated for growth under conditions of iron starvation. Transcriptome sequencing (RNA-seq) showed that both wild-type (WT) S. aureus and the hemB mutant sense and respond to iron starvation; however, growth assays show that the hemB mutant is defective for siderophore-mediated iron acquisition. Indeed, the hemB SCV demonstrated limited utilization of endogenous staphyloferrin B or exogenously provided staphyloferrin A, deferoxamine mesylate (Desferal), and epinephrine. Direct measurement of intracellular ATP in hemB and WT S. aureus revealed that both strains can generate comparable levels of ATP during exponential growth, suggesting defects in ATP production cannot account for the inability to efficiently utilize siderophores. Defective siderophore utilization by hemB bacteria was also evident in vivo, as administration of Desferal failed to promote hemB bacterial growth in every organ analyzed except for the kidneys. In support of the hypothesis that S. aureus accesses heme in kidney abscesses, in vitro analyses revealed that increased hemin availability enables hemB bacteria to utilize siderophores for growth when iron availability is restricted. Taken together, our data support the conclusion that hemin is used not only as an iron source itself but also as a nutrient that promotes utilization of siderophore-iron complexes. IMPORTANCE S. aureus small-colony variants (SCVs) are associated with chronic recurrent infection and worsened clinical outcome. SCVs persist within the host despite administration of antibiotics. This study yields insight into how S. aureus SCVs acquire iron, which during infection of a host is a difficult-to-acquire metal nutrient. Under hemin-limited conditions, hemB S. aureus is impaired for siderophore-dependent growth, and in agreement, murine infection indicates that hemin-deficient SCVs meet their nutritional requirement for iron through utilization of hemin. Importantly, we demonstrate that hemB SCVs rely upon hemin as a nutrient to promote siderophore utilization. Therefore, perturbation of heme biosynthesis and/or utilization represents a viable to strategy to mitigate the ability of SCV bacteria to acquire siderophore-bound iron during infection.
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Demontier E, Dubé-Duquette A, Brouillette E, Larose A, Ster C, Lucier JF, Rodrigue S, Park S, Jung D, Ruffini J, Ronholm J, Dufour S, Roy JP, Ramanathan S, Malouin F. Relative virulence of Staphylococcus aureus bovine mastitis strains representing the main Canadian spa types and clonal complexes as determined using in vitro and in vivo mastitis models. J Dairy Sci 2021; 104:11904-11921. [PMID: 34454755 DOI: 10.3168/jds.2020-19904] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 07/07/2021] [Indexed: 11/19/2022]
Abstract
Staphylococcus aureus is one of the main pathogens leading to both clinical and subclinical bovine mastitis in dairy cattle. Prediction of disease evolution based on the characteristics of Staph. aureus isolates that cause intramammary infections and understanding the host-pathogen interactions may improve management of mastitis in dairy herds. For this study, several strains were selected from each of the 6 major Canadian spa types associated with mastitis (t267, t359, t529, t605, t2445, and t13401). Adherence to host cells and intracellular persistence of these strains were studied using a bovine mammary gland epithelial cell line (MAC-T). Additionally, relative virulence and host response (cytokines production) were also studied in vivo using a mouse model of mastitis. Whole-genome sequencing was performed on all strains and associations between clonal complex, sequence type, and presence of certain virulence factors were also investigated. Results show that spa type t2445 was correlated with persistence in MAC-T cells. Strains from spa t359 and t529 showed better ability to colonize mouse mammary glands. The exception was strain sa3154 (spa t529), which showed less colonization of glands compared with other t359 and t529 strains but possessed the highest number of superantigen genes including tst. All strains possessed hemolysins, but spa types t529 and t2445 showed the largest diameter of β-hemolysis on blood agar plates. Although several spa types possessed 2 or 3 serine-aspartate rich proteins (Sdr) believed to be involved in many pathogenic processes, most t529 strains expressed only an allelic variant of sdrE. The spa types t605 (positive for the biofilm associated protein gene; bap+) and t13401 (bap-), that produced the largest amounts of biofilm in vitro, were the least virulent in vivo. Finally, strains from spa type t529 (ST151) elicited a cytokine expression profile (TNF-α, IL-1β and IL-12) that suggests a potential for severe inflammation. This study suggests that determination of the spa type may help predict the severity of the disease and the ability of the immune system to eliminate intramammary infections caused by Staph. aureus.
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Affiliation(s)
- Elodie Demontier
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Alexis Dubé-Duquette
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Eric Brouillette
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Audrey Larose
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Céline Ster
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Jean-François Lucier
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Sébastien Rodrigue
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Soyoun Park
- Faculty of agricultural and environmental sciences, Macdonald campus, McGill University, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Dongyun Jung
- Faculty of agricultural and environmental sciences, Macdonald campus, McGill University, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Janina Ruffini
- Faculty of agricultural and environmental sciences, Macdonald campus, McGill University, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Jennifer Ronholm
- Faculty of agricultural and environmental sciences, Macdonald campus, McGill University, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Simon Dufour
- Département de pathologie et microbiologie and Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, St-Hyacinthe, QC, J2S 2M2, Canada
| | - Jean-Philippe Roy
- Département de pathologie et microbiologie and Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, St-Hyacinthe, QC, J2S 2M2, Canada
| | - Sheela Ramanathan
- Département d'immunologie et de biologie cellulaire, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, J1H 5N4, Canada
| | - François Malouin
- Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada.
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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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Vozza EG, Mulcahy ME, McLoughlin RM. Making the Most of the Host; Targeting the Autophagy Pathway Facilitates Staphylococcus aureus Intracellular Survival in Neutrophils. Front Immunol 2021; 12:667387. [PMID: 34220813 PMCID: PMC8242348 DOI: 10.3389/fimmu.2021.667387] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 05/28/2021] [Indexed: 12/21/2022] Open
Abstract
The success of Staphylococcus aureus as a human commensal and an opportunistic pathogen relies on its ability to adapt to several niches within the host. The innate immune response plays a key role in protecting the host against S. aureus infection; however, S. aureus adeptness at evading the innate immune system is indisputably evident. The “Trojan horse” theory has been postulated to describe a mechanism by which S. aureus takes advantage of phagocytes as a survival niche within the host to facilitate dissemination of S. aureus to secondary sites during systemic infection. Several studies have determined that S. aureus can parasitize both professional and non-professional phagocytes by manipulating the host autophagy pathway in order to create an intracellular survival niche. Neutrophils represent a critical cell type in S. aureus infection as demonstrated by the increased risk of infection among patients with congenital neutrophil disorders. However, S. aureus has been repeatedly shown to survive intracellularly within neutrophils with evidence now supporting a pathogenic role of host autophagy. By manipulating this pathway, S. aureus can also alter the apoptotic fate of the neutrophil and potentially skew other important signalling pathways for its own gain. Understanding these critical host-pathogen interactions could lead to the development of new host directed therapeutics for the treatment of S. aureus infection by removing its intracellular niche and restoring host bactericidal functions. This review discusses the current findings surrounding intracellular survival of S. aureus within neutrophils, the pathogenic role autophagy plays in this process and considers the therapeutic potential for targeting this immune evasion mechanism.
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Affiliation(s)
- Emilio G Vozza
- Host-Pathogen Interactions Group, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | - Michelle E Mulcahy
- Host-Pathogen Interactions Group, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | - Rachel M McLoughlin
- Host-Pathogen Interactions Group, School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
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12
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Camus L, Briaud P, Vandenesch F, Moreau K. How Bacterial Adaptation to Cystic Fibrosis Environment Shapes Interactions Between Pseudomonas aeruginosa and Staphylococcus aureus. Front Microbiol 2021; 12:617784. [PMID: 33746915 PMCID: PMC7966511 DOI: 10.3389/fmicb.2021.617784] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 02/10/2021] [Indexed: 12/12/2022] Open
Abstract
Pseudomonas aeruginosa and Staphylococcus aureus are the two most prevalent bacteria species in the lungs of cystic fibrosis (CF) patients and are associated with poor clinical outcomes. Co-infection by the two species is a frequent situation that promotes their interaction. The ability of P. aeruginosa to outperform S. aureus has been widely described, and this competitive interaction was, for a long time, the only one considered. More recently, several studies have described that the two species are able to coexist. This change in relationship is linked to the evolution of bacterial strains in the lungs. This review attempts to decipher how bacterial adaptation to the CF environment can induce a change in the type of interaction and promote coexisting interaction between P. aeruginosa and S. aureus. The impact of coexistence on the establishment and maintenance of a chronic infection will also be presented, by considering the latest research on the subject.
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Affiliation(s)
- Laura Camus
- CIRI-Centre International de Recherche en Infectiologie, Université de Lyon/Inserm U1111/Université Claude Bernard Lyon 1/CNRS UMR 5308/ENS de Lyon, Lyon, France
| | - Paul Briaud
- CIRI-Centre International de Recherche en Infectiologie, Université de Lyon/Inserm U1111/Université Claude Bernard Lyon 1/CNRS UMR 5308/ENS de Lyon, Lyon, France
| | - François Vandenesch
- CIRI-Centre International de Recherche en Infectiologie, Université de Lyon/Inserm U1111/Université Claude Bernard Lyon 1/CNRS UMR 5308/ENS de Lyon, Lyon, France.,Centre National de Référence des Staphylocoques, Hospices Civils de Lyon, Lyon, France.,Institut des Agents Infectieux, Hospices Civils de Lyon, Lyon, France
| | - Karen Moreau
- CIRI-Centre International de Recherche en Infectiologie, Université de Lyon/Inserm U1111/Université Claude Bernard Lyon 1/CNRS UMR 5308/ENS de Lyon, Lyon, France
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13
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Acapsular Staphylococcus aureus with a non-functional agr regains capsule expression after passage through the bloodstream in a bacteremia mouse model. Sci Rep 2020; 10:14108. [PMID: 32839485 PMCID: PMC7445255 DOI: 10.1038/s41598-020-70671-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 07/23/2020] [Indexed: 01/18/2023] Open
Abstract
Selection pressures exerted on Staphylococcus aureus by host factors during infection may lead to the emergence of regulatory phenotypes better adapted to the infection site. Traits convenient for persistence may be fixed by mutation thus turning these mutants into microevolution endpoints. The feasibility that stable, non-encapsulated S. aureus mutants can regain expression of key virulence factors for survival in the bloodstream was investigated. S. aureus agr mutant HU-14 (IS256 insertion in agrC) from a patient with chronic osteomyelitis was passed through the bloodstream using a bacteriemia mouse model and derivative P3.1 was obtained. Although IS256 remained inserted in agrC, P3.1 regained production of capsular polysaccharide type 5 (CP5) and staphyloxanthin. Furthermore, P3.1 expressed higher levels of asp23/SigB when compared with parental strain HU-14. Strain P3.1 displayed decreased osteoclastogenesis capacity, thus indicating decreased adaptability to bone compared with strain HU-14 and exhibited a trend to be more virulent than parental strain HU-14. Strain P3.1 exhibited the loss of one IS256 copy, which was originally located in the HU-14 noncoding region between dnaG (DNA primase) and rpoD (sigA). This loss may be associated with the observed phenotype change but the mechanism remains unknown. In conclusion, S. aureus organisms that escape the infected bone may recover the expression of key virulence factors through a rapid microevolution pathway involving SigB regulation of key virulence factors.
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14
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Häffner N, Bär J, Dengler Haunreiter V, Mairpady Shambat S, Seidl K, Crosby HA, Horswill AR, Zinkernagel AS. Intracellular Environment and agr System Affect Colony Size Heterogeneity of Staphylococcus aureus. Front Microbiol 2020; 11:1415. [PMID: 32695082 PMCID: PMC7339952 DOI: 10.3389/fmicb.2020.01415] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 06/02/2020] [Indexed: 12/21/2022] Open
Abstract
Staphylococcus aureus causes chronic and relapsing infections, which may be difficult to treat. So-called small colony variants (SCVs) have been associated with chronic infections and their occurrence has been shown to increase under antibiotic pressure, low pH and intracellular localization. In clinics, S. aureus isolated from invasive infections often show a dysfunction in the accessory gene regulator (agr), a major virulence regulatory system in S. aureus. To assess whether intracellular environment and agr function influence SCV formation, an infection model was established using lung epithelial cells and skin fibroblasts. This allowed analyzing intracellular survival and localization of a panel of S. aureus wild type strains and their isogenic agr knock out mutants as well as a natural dysfunctional agr strain by confocal laser scanning microscopy (CLSM). Furthermore, bacterial colonies were quantified after 1, 3, and 5 days of intracellular survival by time-lapse analysis to determine kinetics of colony appearance and SCV formation. Here, we show that S. aureus strains with an agr knock out predominantly resided in a neutral environment, whereas wild type strains and an agr complemented strain resided in an acidic environment. S. aureus agr mutants derived from an intracellular environment showed a higher percentage of SCVs as compared to their corresponding wild type strains. Neutralizing acidic phagolysosomes with chloroquine resulted in a significant reduction of SCVs in S. aureus wild type strain 6850, but not in its agr mutant indicating a pH dependent formation of SCVs in the wild type strain. The in-depth understanding of the interplay between intracellular persistence, agr function and pH should help to identify new therapeutic options facilitating the treatment of chronic S. aureus infections in the future.
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Affiliation(s)
- Nicola Häffner
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Julian Bär
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Vanina Dengler Haunreiter
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Srikanth Mairpady Shambat
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Kati Seidl
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Heidi A Crosby
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States
| | - Alexander R Horswill
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, United States.,Department of Veterans Affairs Eastern Colorado Health Care System, Denver, CO, United States
| | - Annelies S Zinkernagel
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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15
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For the Greater (Bacterial) Good: Heterogeneous Expression of Energetically Costly Virulence Factors. Infect Immun 2020; 88:IAI.00911-19. [PMID: 32041785 DOI: 10.1128/iai.00911-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Bacterial populations are phenotypically heterogeneous, which allows subsets of cells to survive and thrive following changes in environmental conditions. For bacterial pathogens, changes within the host environment occur over the course of the immune response to infection and can result in exposure to host-derived, secreted antimicrobials or force direct interactions with immune cells. Many recent studies have shown host cell interactions promote virulence factor expression, forcing subsets of bacterial cells to battle the host response, while other bacteria reap the benefits of this pacification. It still remains unclear whether virulence factor expression is truly energetically costly within host tissues and whether expression is sufficient to impact the growth kinetics of virulence factor-expressing cells. However, it is clear that slow-growing subsets of bacteria emerge during infection and that these subsets are particularly difficult to eliminate with antibiotics. This minireview will focus on our current understanding of heterogenous virulence factor expression and discuss the evidence that supports or refutes the hypothesis that virulence factor expression is linked to slowed growth and antibiotic tolerance.
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16
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Watkins KE, Unnikrishnan M. Evasion of host defenses by intracellular Staphylococcus aureus. ADVANCES IN APPLIED MICROBIOLOGY 2020; 112:105-141. [PMID: 32762866 DOI: 10.1016/bs.aambs.2020.05.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Staphylococcus aureus is one of the leading causes of hospital and community-acquired infections worldwide. The increasing occurrence of antibiotic resistant strains and the high rates of recurrent staphylococcal infections have placed several treatment challenges on healthcare systems. In recent years, it has become evident that S. aureus is a facultative intracellular pathogen, able to invade and survive in a range of cell types. The ability to survive intracellularly provides this pathogen with yet another way to evade antibiotics and immune responses during infection. Intracellular S. aureus have been strongly linked to several recurrent infections, including severe bone infections and septicemias. S. aureus is armed with an array of virulence factors as well as an intricate network of regulators that enable it to survive, replicate and escape from a number of immune and nonimmune host cells. It is able to successfully manipulate host cell pathways and use it as a niche to multiply, disseminate, as well as persist during an infection. This bacterium is also known to adapt to the intracellular environment by forming small colony variants, which are metabolically inactive. In this review we will discuss the clinical evidence, the molecular pathways involved in S. aureus intracellular persistence, and new treatment strategies for targeting intracellular S. aureus.
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17
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Lee J, Zilm PS, Kidd SP. Novel Research Models for Staphylococcus aureus Small Colony Variants (SCV) Development: Co-pathogenesis and Growth Rate. Front Microbiol 2020; 11:321. [PMID: 32184775 PMCID: PMC7058586 DOI: 10.3389/fmicb.2020.00321] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/13/2020] [Indexed: 01/08/2023] Open
Abstract
Staphylococcus aureus remains a great burden on the healthcare system. Despite prescribed treatments often seemingly to be successful, S. aureus can survive and cause a relapsing infection which cannot be cleared. These infections are in part due to quasi-dormant sub-population which is tolerant to antibiotics and able to evade the host immune response. These include Small Colony Variants (SCVs). Because SCVs readily revert to non-SCV cell types under laboratory conditions, the characterization of SCVs has been problematic. This mini-review covers the phenotypic and genetic changes in stable SCVs including the selection of SCVs by and interactions with other bacterial species.
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Affiliation(s)
- James Lee
- Department of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SA, Australia.,Research Centre for Infectious Diseases, Adelaide, SA, Australia.,Australian Centre for Antimicrobial Resistance Ecology, Adelaide, SA, Australia
| | - Peter S Zilm
- Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA, Australia
| | - Stephen P Kidd
- Department of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SA, Australia.,Research Centre for Infectious Diseases, Adelaide, SA, Australia.,Australian Centre for Antimicrobial Resistance Ecology, Adelaide, SA, Australia
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18
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Millette G, Langlois JP, Brouillette E, Frost EH, Cantin AM, Malouin F. Despite Antagonism in vitro, Pseudomonas aeruginosa Enhances Staphylococcus aureus Colonization in a Murine Lung Infection Model. Front Microbiol 2019; 10:2880. [PMID: 31921058 PMCID: PMC6923662 DOI: 10.3389/fmicb.2019.02880] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 11/29/2019] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus and Pseudomonas aeruginosa are prevalent lung pathogens in cystic fibrosis (CF). Whereas co-infection worsens the clinical outcome, prototypical strains are usually antagonistic in vitro. We sought to resolve the discrepancy between these in vitro and in vivo observations. In vitro, growth kinetics for co-cultures of co-isolates from CF patients showed that not all P. aeruginosa strains affected S. aureus viability. On solid media, S. aureus slow-growing colonies were visualized around some P. aeruginosa strains whether or not S. aureus viability was reduced in liquid co-cultures. The S. aureus-P. aeruginosa interactions were then characterized in a mouse lung infection model. Lung homogenates were plated on selective media allowing colony counts of either bacterium. Overall, 35 P. aeruginosa and 10 S. aureus strains (clinical, reference, and mutant strains), for a total of 200 co-infections, were evaluated. We observed that S. aureus colonization of lung tissues was promoted by P. aeruginosa and even by strains showing antagonism in vitro. Promotion was proportional to the extent of P. aeruginosa colonization, but no correlation was found with the degree of myeloperoxidase quantification (as marker of inflammation) or with specific virulence-associated factors using known mutant strains of S. aureus and P. aeruginosa. On the other hand, P. aeruginosa significantly increased the expression of two possible cell receptors for S. aureus, i.e., ICAM-1 and ITGA-5 (marker for integrin α5β1) in lung tissue, while mono-infections by S. aureus did not. This study provides insights on polymicrobial interactions that may influence the progression of CF-associated pulmonary infections.
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Affiliation(s)
- Guillaume Millette
- Centre d'Étude et de Valorisation de la Diversité Microbienne, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Jean-Philippe Langlois
- Centre d'Étude et de Valorisation de la Diversité Microbienne, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Eric Brouillette
- Centre d'Étude et de Valorisation de la Diversité Microbienne, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Eric H Frost
- Département de Microbiologie et d'Infectiologie, Faculté de Médecine et de Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - André M Cantin
- Service de Pneumologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - François Malouin
- Centre d'Étude et de Valorisation de la Diversité Microbienne, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
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19
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Schleimer N, Kaspar U, Ballhausen B, Fotiadis SA, Streu JM, Kriegeskorte A, Proctor RA, Becker K. Adaption of an Episomal Antisense Silencing Approach for Investigation of the Phenotype Switch of Staphylococcus aureus Small-Colony Variants. Front Microbiol 2019; 10:2044. [PMID: 31551979 PMCID: PMC6738336 DOI: 10.3389/fmicb.2019.02044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/20/2019] [Indexed: 11/13/2022] Open
Abstract
Staphylococcus aureus small-colony variants (SCVs) are associated with chronic, persistent, and relapsing courses of infection and are characterized by slow growth combined with other phenotypic and molecular traits. Although certain mechanisms have been described, the genetic basis of clinical SCVs remains often unknown. Hence, we adapted an episomal tool for rapid identification and investigation of putative SCV phenotype-associated genes via antisense gene silencing based on previously described Tnl0-encoded tet-regulatory elements. Targeting the SCV phenotype-inducing enoyl-acyl-carrier-protein reductase gene (fabI), plasmid pSN1-AS‘fabI’ was generated leading to antisense silencing, which was proven by pronounced growth retardation in liquid cultures, phenotype switch on solid medium, and 200-fold increase of antisense ‘fabI’ expression. A crucial role of TetR repression in effective regulation of the system was demonstrated. Based on the use of anhydrotetracycline as effector, an easy-to-handle one-plasmid setup was set that may be applicable to different S. aureus backgrounds and cell culture studies. However, selection of the appropriate antisense fragment of the target gene remains a critical factor for effectiveness of silencing. This inducible gene expression system may help to identify SCV phenotype-inducing genes, which is prerequisite for the development of new antistaphylococcal agents and future alternative strategies to improve treatment of therapy-refractory SCV-related infections by iatrogenically induced phenotypic switch. Moreover, it can be used as controllable phenotype switcher to examine important aspects of SCV biology in cell culture as well as in vivo.
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Affiliation(s)
- Nina Schleimer
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Ursula Kaspar
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Britta Ballhausen
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Sarah A Fotiadis
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Jessica M Streu
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - André Kriegeskorte
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Richard A Proctor
- Departments of Medical Microbiology/Immunology and Medicine, School of Medicine and Public Health, University of Wisconsin, Madison, WI, United States
| | - Karsten Becker
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
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20
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Mordmuang A, Brouillette E, Voravuthikunchai SP, Malouin F. Evaluation of a Rhodomyrtus tomentosa ethanolic extract for its therapeutic potential on Staphylococcus aureus infections using in vitro and in vivo models of mastitis. Vet Res 2019; 50:49. [PMID: 31221210 PMCID: PMC6585048 DOI: 10.1186/s13567-019-0664-9] [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: 03/21/2019] [Accepted: 05/25/2019] [Indexed: 01/23/2023] Open
Abstract
An ethanolic extract from Rhodomyrtus tomentosa leaves (RTL) was studied as a natural alternative to control Staphylococcus aureus, which is an important pathogen responsible for bovine mastitis. The minimal inhibitory concentrations (MICs) of the RTL extract and of rhodomyrtone, a pure compound isolated from the plant, were determined by a microdilution method. Rhodomyrtone and the RTL extract exhibited antibacterial activity against S. aureus, including its persistent phenotype (SCV: small-colony variant) and a biofilm hyperproducer strain, with MICs of 0.25–0.5 and 8–16 µg/mL, respectively. Time-kill kinetics showed a strong bactericidal activity for both the RTL extract- and rhodomyrtone-treated bacteria at 2 × MIC as early as 4 h post-exposure. An additive effect of the extract at 0.5 × MIC was observed in a combination with oxytetracycline or pirlimycin against S. aureus by showing a 64- to 128-fold reduction in antibiotic MICs. Moreover, the RTL extract significantly decreased the number of intracellular SCVs inside bovine mammary epithelial cells. However, the extract or its combination with pirlimycin only slightly improved the activity of pirlimycin against the bacterial colonization of mouse mammary glands. In vitro MICs determined in the presence of casein indicated that the limited activity of the RTL extract in the murine model of mastitis could be linked to neutralization of active components by milk proteins. While the RTL extract showed interesting antibacterial properties in vitro, to be considered as an alternative to antibiotics in dairy farms, formulation studies are needed to cope with the observed reduction of activity in vivo.
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Affiliation(s)
- Auemphon Mordmuang
- Department of Microbiology and Excellence Research Laboratory on Natural Products, Faculty of Science and Natural Product Research Center of Excellence, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand.,School of Medicine, Walailak University, Tha Sala, Nakhon Si Thammarat, 80160, Thailand
| | - Eric Brouillette
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada
| | - Supayang Piyawan Voravuthikunchai
- Department of Microbiology and Excellence Research Laboratory on Natural Products, Faculty of Science and Natural Product Research Center of Excellence, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand.
| | - François Malouin
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada.
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21
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Alreshidi MM, Dunstan RH, Macdonald MM, Smith ND, Gottfries J, Roberts TK. Amino acids and proteomic acclimation of Staphylococcus aureus when incubated in a defined minimal medium supplemented with 5% sodium chloride. Microbiologyopen 2019; 8:e00772. [PMID: 30739392 PMCID: PMC6562129 DOI: 10.1002/mbo3.772] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 10/31/2018] [Accepted: 10/31/2018] [Indexed: 11/06/2022] Open
Abstract
Staphylococcus aureus is a versatile bacterium that can adapt to survive and grow in a wide range of salt concentrations. This study investigated whether the cells could mount a response to survive a challenge of 5% NaCl in a minimal incubation medium that would not support cell replication. Cells were grown in liquid culture, washed and then incubated for 90 min at 37°C in a medium that contained only glycine and glucose as substrates in PBS plus trace elements. The control cells were compared with a treatment group which was incubated with an additional 5% NaCl. Significantly more glycine was taken up by the cells exposed to 5% NaCl compared with control cells, and both groups consumed 99% of the glucose supplied. The NaCl treated cells had significantly higher cytoplasmic levels of proline and glutamic acid as well as lower levels of alanine and methionine compared with the controls (p < 0.05). The levels of the two major cytoplasmic amino acids, aspartic acid and glycine, remained constant in control and treated cells. Proteomic analyses revealed that 10 proteins showed differential responses between the control and treatment groups. The reductions in proteins were primarily associated with processes of protein biosynthesis, pathogenicity, and cell adhesion. Since cell numbers remained constant during the incubation period in minimal medium, it was concluded that there was no cell division to support population growth. The results provided evidence that the cells in the minimal medium exposed to the NaCl treatment underwent in situ homeostatic changes to adjust to the new environmental conditions. It was proposed that this represented a phenotypic shift to form cells akin to small colony variants, with lower metabolic rates and lower levels of key proteins associated with pathogenicity.
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Affiliation(s)
- Mousa M. Alreshidi
- Department of Biology, College of ScienceUniversity of HailHailSaudi Arabia
| | - R. Hugh Dunstan
- Metabolic Research Group, Faculty of ScienceSchool of Environmental and Life SciencesCallaghanNew South WalesAustralia
| | - Margaret M. Macdonald
- Metabolic Research Group, Faculty of ScienceSchool of Environmental and Life SciencesCallaghanNew South WalesAustralia
| | - Nathan D. Smith
- Analytical and Biomolecular Research Facility (ABRF)University of NewcastleCallaghanNew South WalesAustralia
| | - Johan Gottfries
- Department of ChemistryGothenburg UniversityGothenburgSweden
| | - Tim K. Roberts
- Metabolic Research Group, Faculty of ScienceSchool of Environmental and Life SciencesCallaghanNew South WalesAustralia
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22
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Min KB, Min JY. Nasal colonization with methicillin-resistant Staphylococcus aureus associated with elevated homocysteine levels in the general US adults. Medicine (Baltimore) 2019; 98:e15499. [PMID: 31045837 PMCID: PMC6504329 DOI: 10.1097/md.0000000000015499] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Given the emergence of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) as a global health threat, understanding the risk factors for MRSA infection in the community may be a reasonable strategy to prevent it. We investigated the associations between serum homocysteine levels and prevalence of nasal colonization with S aureus and MRSA among United States adults. We conducted a cross-sectional analysis of a nationally representative sample of 7832 adults (20 years or older). The main outcome variables were nasal colonization with S aureus and MRSA. Percentages of colonization with S aureus and MRSA were calculated by the quartiles of serum homocysteine. A total of 7832 of 2051 subjects (26.2%) were culture positive for S aureus, 98 (4.8%) of whom had nasal colonization with MRSA. In comparison with subjects having the lowest serum homocysteine, the odds of nasal colonization with MRSA were significantly higher in those with the highest homocysteine (odds ratio, 3.09; 95% confidence interval, 1.11-8.61) in multivariate analysis, adjusted for all confounding variables. By contrast, homocysteine elevation was not significantly associated with S aureus colonization. Nasal colonization with MRSA in the general community was significantly associated with increases in serum homocysteine levels.
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Affiliation(s)
- Kyoung-Bok Min
- Department of Preventive Medicine, Seoul National University College of Medicine
| | - Jin-Young Min
- Institute of Health and Environment, Seoul National University, Seoul, Republic of Korea
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23
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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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24
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Woods PW, Haynes ZM, Mina EG, Marques CNH. Maintenance of S. aureus in Co-culture With P. aeruginosa While Growing as Biofilms. Front Microbiol 2019; 9:3291. [PMID: 30687276 PMCID: PMC6333908 DOI: 10.3389/fmicb.2018.03291] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 12/18/2018] [Indexed: 12/11/2022] Open
Abstract
Bacterial biofilms are found in various environmental niches and are mostly comprised by two or more bacterial species. One such example, are the mixed species bacterial biofilms found in chronic lung infections of cystic fibrosis (CF) patients, which include the Staphylococcus aureus and Pseudomonas aeruginosa bacterial species. S. aureus is one of the CF lung initial colonizers and is assumed to be abrogated when P. aeruginosa becomes established, eliminating its involvement as the infection evolves. Common models used in research do not mimic the actual progression of the mixed species biofilms thus, in this work we developed an in vitro model, where S. aureus biofilms establish prior to the introduction of P. aeruginosa, simulating a state that is phenotypically more similar to the one found in CF lungs. Overall our results demonstrate that S. aureus is not outcompeted, and that timing of inoculation and bacterial concentration affect the final bacterial ratio and quorum sensing related gene expression during the dual species biofilm development.
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Affiliation(s)
- Paul W Woods
- Department of Biological Sciences, Binghamton University, Binghamton, NY, United States.,Binghamton Biofilm Research Center, Binghamton University, Binghamton, NY, United States
| | - Zane M Haynes
- Department of Biological Sciences, Binghamton University, Binghamton, NY, United States.,Binghamton Biofilm Research Center, Binghamton University, Binghamton, NY, United States
| | - Elin G Mina
- Department of Biological Sciences, Binghamton University, Binghamton, NY, United States.,Binghamton Biofilm Research Center, Binghamton University, Binghamton, NY, United States
| | - Cláudia N H Marques
- Department of Biological Sciences, Binghamton University, Binghamton, NY, United States.,Binghamton Biofilm Research Center, Binghamton University, Binghamton, NY, United States
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25
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Sato T, Kawamura M, Furukawa E, Fujimura S. Screening method for trimethoprim/sulfamethoxazole-resistant small colony variants of Staphylococcus aureus. J Glob Antimicrob Resist 2018; 15:1-5. [PMID: 29857058 DOI: 10.1016/j.jgar.2018.05.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 05/08/2018] [Accepted: 05/13/2018] [Indexed: 10/16/2022] Open
Abstract
OBJECTIVES Trimethoprim/sulfamethoxazole (SXT) is used to treat Staphylococcus aureus infections. However, the effect of treatment with SXT is sometimes not sufficient and there are patients whose treatment has to be prolonged. There are few reports of isolated strains of SXT-resistant S. aureus, but it is possible that some resistant strains cannot be detected by current testing methods We have therefore developed a tool to identify these resistant strains. METHODS The mutant selection window (MSW) of SXT for 40 clinical isolates of S. aureus, including 20 methicillin-resistant S. aureus (MRSA), was determined. The optimum concentration of SXT and thymidine in agar for detecting SXT-resistant small colony variants (SCVs) of S. aureus was investigated. RESULTS The MSW50 and MSW90 of SXT, presented as a multiple of the minimum inhibitory concentration (MIC), were 16× MIC and >256× MIC, respectively. SCVs were detected within the MSW in 32 (80%) of the 40 clinical isolates studied. To maintain the morphology of SCVs, the most suitable concentrations of SXT and thymidine for screening were 4mg/L and 0.01μg/mL, respectively. All 32 SCVs were resistant to SXT (MIC >32mg/L). The sensitivity and specificity of this screening method was 100% and 88.9%, respectively. CONCLUSIONS SXT-resistant SCVs are not usually detected by routine laboratory tests performed in hospitals. However, the screening test described here can easily distinguish SXT-resistant SCVs among S. aureus isolated from specimens. This newly developed screening test could become an important tool to prevent inappropriate use of SXT.
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Affiliation(s)
- Takumi Sato
- Division of Clinical Infectious Diseases and Chemotherapy, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi Prefecture 981-8558, Japan
| | - Masato Kawamura
- Division of Clinical Infectious Diseases and Chemotherapy, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi Prefecture 981-8558, Japan
| | - Emiko Furukawa
- Division of Clinical Infectious Diseases and Chemotherapy, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi Prefecture 981-8558, Japan
| | - Shigeru Fujimura
- Division of Clinical Infectious Diseases and Chemotherapy, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi Prefecture 981-8558, Japan.
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Tomatidine Is a Lead Antibiotic Molecule That Targets Staphylococcus aureus ATP Synthase Subunit C. Antimicrob Agents Chemother 2018; 62:AAC.02197-17. [PMID: 29610201 DOI: 10.1128/aac.02197-17] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 03/27/2018] [Indexed: 12/20/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of deadly hospital-acquired infections. The discovery of anti-Staphylococcus antibiotics and new classes of drugs not susceptible to the mechanisms of resistance shared among bacteria is imperative. We recently showed that tomatidine (TO), a steroidal alkaloid from solanaceous plants, possesses potent antibacterial activity against S. aureus small-colony variants (SCVs), the notoriously persistent form of this bacterium that has been associated with recurrence of infections. Here, using genomic analysis of in vitro-generated TO-resistant S. aureus strains to identify mutations in genes involved in resistance, we identified the bacterial ATP synthase as the cellular target. Sequence alignments were performed to highlight the modified sequences, and the structural consequences of the mutations were evaluated in structural models. Overexpression of the atpE gene in S. aureus SCVs or introducing the mutation found in the atpE gene of one of the high-level TO-resistant S. aureus mutants into the Bacillus subtilis atpE gene provided resistance to TO and further validated the identity of the cellular target. FC04-100, a TO derivative which also possesses activity against non-SCV strains, prevents high-level resistance development in prototypic strains and limits the level of resistance observed in SCVs. An ATP synthesis assay allowed the observation of a correlation between antibiotic potency and ATP synthase inhibition. The selectivity index (inhibition of ATP production by mitochondria versus that of bacterial ATP synthase) is estimated to be >105-fold for FC04-100.
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Idelevich EA, Kriegeskorte A, Schleimer N, Peters G, von Eiff C, Becker K. In Vitro Susceptibility of Clinical Staphylococcus aureus Small-Colony Variants to β-Lactam and Non-β-Lactam Antibiotics. Antimicrob Agents Chemother 2018; 62:e02532-17. [PMID: 29378720 PMCID: PMC5913952 DOI: 10.1128/aac.02532-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 01/19/2018] [Indexed: 02/08/2023] Open
Abstract
The Staphylococcus aureus small-colony variant (SCV) phenotype has been associated with relapsing and antibiotic-refractory infections. However, little is known about the activities of antibiotics on clinical SCVs. Here, we demonstrated that SCVs without detectable auxotrophies were at least as susceptible to most β-lactam and non-β-lactam antibiotics in vitro as their corresponding clonally identical strains with a normal phenotype. After prolonged incubation, a regrowth phenomenon has been observed in gradient diffusion inhibition zones irrespective of the strains' phenotype.
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Affiliation(s)
- Evgeny A Idelevich
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - André Kriegeskorte
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Nina Schleimer
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Georg Peters
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Christof von Eiff
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Karsten Becker
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
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Nagar SD, Aggarwal B, Joon S, Bhatnagar R, Bhatnagar S. A Network Biology Approach to Decipher Stress Response in Bacteria Using Escherichia coli As a Model. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2018; 20:310-24. [PMID: 27195968 DOI: 10.1089/omi.2016.0028] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The development of drug-resistant pathogenic bacteria poses challenges to global health for their treatment and control. In this context, stress response enables bacterial populations to survive extreme perturbations in the environment but remains poorly understood. Specific modules are activated for unique stressors with few recognized global regulators. The phenomenon of cross-stress protection strongly suggests the presence of central proteins that control the diverse stress responses. In this work, Escherichia coli was used to model the bacterial stress response. A Protein-Protein Interaction Network was generated by integrating differentially expressed genes in eight stress conditions of pH, temperature, and antibiotics with relevant gene ontology terms. Topological analysis identified 24 central proteins. The well-documented role of 16 central proteins in stress indicates central control of the response, while the remaining eight proteins may have a novel role in stress response. Cluster analysis of the generated network implicated RNA binding, flagellar assembly, ABC transporters, and DNA repair as important processes during response to stress. Pathway analysis showed crosstalk of Two Component Systems with metabolic processes, oxidative phosphorylation, and ABC transporters. The results were further validated by analysis of an independent cross-stress protection dataset. This study also reports on the ways in which bacterial stress response can progress to biofilm formation. In conclusion, we suggest that drug targets or pathways disrupting bacterial stress responses can potentially be exploited to combat antibiotic tolerance and multidrug resistance in the future.
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Affiliation(s)
- Shashwat Deepali Nagar
- 1 Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , New Delhi, India
| | - Bhavye Aggarwal
- 1 Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , New Delhi, India
| | - Shikha Joon
- 1 Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , New Delhi, India .,2 Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University , New Delhi, India
| | - Rakesh Bhatnagar
- 2 Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University , New Delhi, India
| | - Sonika Bhatnagar
- 1 Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology , New Delhi, India
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Guay I, Boulanger S, Isabelle C, Brouillette E, Chagnon F, Bouarab K, Marsault E, Malouin F. Tomatidine and analog FC04-100 possess bactericidal activities against Listeria, Bacillus and Staphylococcus spp. BMC Pharmacol Toxicol 2018; 19:7. [PMID: 29439722 PMCID: PMC5812199 DOI: 10.1186/s40360-018-0197-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 01/30/2018] [Indexed: 02/07/2023] Open
Abstract
Background Tomatidine (TO) is a plant steroidal alkaloid that possesses an antibacterial activity against the small colony variants (SCVs) of Staphylococcus aureus. We report here the spectrum of activity of TO against other species of the Bacillales and the improved antibacterial activity of a chemically-modified TO derivative (FC04–100) against Listeria monocytogenes and antibiotic multi-resistant S. aureus (MRSA), two notoriously difficult-to-kill microorganisms. Methods Bacillus and Listeria SCVs were isolated using a gentamicin selection pressure. Minimal inhibitory concentrations (MICs) of TO and FC04–100 were determined by a broth microdilution technique. The bactericidal activity of TO and FC04–100 used alone or in combination with an aminoglycoside against planktonic bacteria was determined in broth or against bacteria embedded in pre-formed biofilms by using the Calgary Biofilm Device. Killing of intracellular SCVs was determined in a model with polarized pulmonary cells. Results TO showed a bactericidal activity against SCVs of Staphylococcus aureus, Bacillus cereus, B. subtilis and Listeria monocytogenes with MICs of 0.03–0.12 μg/mL. The combination of an aminoglycoside and TO generated an antibacterial synergy against their normal phenotype. In contrast to TO, which has no relevant activity by itself against Bacillales of the normal phenotype (MIC > 64 μg/mL), the TO analog FC04–100 showed a MIC of 8–32 μg/mL. Furthermore, FC04–100 showed a strong bactericidal activity against L. monocytogenes SCVs in kill kinetics experiments, while TO did not. The addition of FC04–100 (4 μg/mL) to a cefalexin:kanamycin (3:2) combination improved the activity of the combination by 32 fold against cefalexin and kanamycin-resistant MRSA strains. In combination with gentamicin, FC04–100 also exhibited a strong bactericidal activity against biofilm-embedded S. aureus. Also, FC04–100 and TO showed comparable intracellular killing of S. aureus SCVs. Conclusions Chemical modifications of TO allowed improvement of its antibacterial activity against prototypical S. aureus and of its bactericidal activity against L. monocytogenes. Antibacterial activities against such prominent pathogens could be useful to prevent Listeria contamination in the food chain or as treatment for MRSA infections.
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Affiliation(s)
- Isabelle Guay
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada
| | - Simon Boulanger
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada
| | - Charles Isabelle
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada
| | - Eric Brouillette
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada
| | - Félix Chagnon
- Département de pharmacologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, 3001, 12 th avenue Nord, Sherbrooke, QC, J1H 5N4, Canada
| | - Kamal Bouarab
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada
| | - Eric Marsault
- Département de pharmacologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, 3001, 12 th avenue Nord, Sherbrooke, QC, J1H 5N4, Canada.
| | - François Malouin
- Centre d'Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, J1K 2R1, Canada.
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30
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The Electron Transport Chain Sensitizes Staphylococcus aureus and Enterococcus faecalis to the Oxidative Burst. Infect Immun 2017; 85:IAI.00659-17. [PMID: 28993457 DOI: 10.1128/iai.00659-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 09/28/2017] [Indexed: 12/16/2022] Open
Abstract
Small-colony variants (SCVs) of Staphylococcus aureus typically lack a functional electron transport chain and cannot produce virulence factors such as leukocidins, hemolysins, or the antioxidant staphyloxanthin. Despite this, SCVs are associated with persistent infections of the bloodstream, bones, and prosthetic devices. The survival of SCVs in the host has been ascribed to intracellular residency, biofilm formation, and resistance to antibiotics. However, the ability of SCVs to resist host defenses is largely uncharacterized. To address this, we measured the survival of wild-type and SCV S. aureus in whole human blood, which contains high numbers of neutrophils, the key defense against staphylococcal infection. Despite the loss of leukocidin production and staphyloxanthin biosynthesis, SCVs defective for heme or menaquinone biosynthesis were significantly more resistant to the oxidative burst than wild-type bacteria in human blood or the presence of purified neutrophils. Supplementation of the culture medium of the heme-auxotrophic SCV with heme, but not iron, restored growth, hemolysin and staphyloxanthin production, and sensitivity to the oxidative burst. Since Enterococcus faecalis is a natural heme auxotroph and cause of bloodstream infection, we explored whether restoration of the electron transport chain in this organism also affected survival in blood. Incubation of E. faecalis with heme increased growth and restored catalase activity but resulted in decreased survival in human blood via increased sensitivity to the oxidative burst. Therefore, the lack of functional electron transport chains in SCV S. aureus and wild-type E. faecalis results in reduced growth rate but provides resistance to a key immune defense mechanism.
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31
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Hosseinkhan N, Mousavian Z, Masoudi-Nejad A. Comparison of gene co-expression networks in Pseudomonas aeruginosa and Staphylococcus aureus reveals conservation in some aspects of virulence. Gene 2017; 639:1-10. [PMID: 28987343 DOI: 10.1016/j.gene.2017.10.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 09/23/2017] [Accepted: 10/03/2017] [Indexed: 12/13/2022]
Abstract
Pseudomonas aeruginosa and Staphylococcus aureus are two evolutionary distant bacterial species that are frequently isolated from persistent infections such as chronic infectious wounds and severe lung infections in cystic fibrosis patients. To the best of our knowledge no comprehensive genome scale co-expression study has been already conducted on these two species and in most cases only the expression of very few genes has been the subject of investigation. In this study, in order to investigate the level of expressional conservation between these two species, using heterogeneous gene expression datasets the weighted gene co-expression network analysis (WGCNA) approach was applied to study both single and cross species genome scale co-expression patterns of these two species. Single species co-expression network analysis revealed that in P. aeruginosa, genes involved in quorum sensing (QS), iron uptake, nitrate respiration and type III secretion systems and in S. aureus, genes associated with the regulation of carbon metabolism, fatty acid-phospholipids metabolism and proteolysis represent considerable co-expression across a variety of experimental conditions. Moreover, the comparison of gene co-expression networks between P. aeruginosa and S. aureus was led to the identification of four co-expressed gene modules in both species totally consisting of 318 genes. Several genes related to two component signal transduction systems, small colony variants (SCVs) morphotype and protein complexes were found in the detected modules. We believe that targeting the key players among the identified co-expressed orthologous genes will be a potential intervention strategy to control refractory co-infections caused by these two bacterial species.
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Affiliation(s)
- Nazanin Hosseinkhan
- Basic and Molecular Epidemiology of Gastrointestinal Disorders Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
| | - Zaynab Mousavian
- Department of Computer Science, School of Mathematics, Statistics, and Computer Science, University of Tehran, Tehran, Iran; Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Ali Masoudi-Nejad
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
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Côté-Gravel J, Brouillette E, Obradović N, Ster C, Talbot BG, Malouin F. Characterization of a vraG Mutant in a Genetically Stable Staphylococcus aureus Small-Colony Variant and Preliminary Assessment for Use as a Live-Attenuated Vaccine against Intrammamary Infections. PLoS One 2016; 11:e0166621. [PMID: 27855187 PMCID: PMC5113970 DOI: 10.1371/journal.pone.0166621] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 11/01/2016] [Indexed: 12/14/2022] Open
Abstract
Staphylococcus aureus is a leading cause of bovine intramammary infections (IMIs) that can evolve into difficult-to-treat chronic mastitis. To date, no vaccine formulation has shown high protective efficacy against S. aureus IMI, partly because this bacterium can efficiently evade the immune system. For instance, S. aureus small colony variants (SCVs) have intracellular abilities and can persist without producing invasive infections. As a first step towards the development of a live vaccine, this study describes the elaboration of a novel attenuated mutant of S. aureus taking advantage of the SCV phenotype. A genetically stable SCV was created through the deletion of the hemB gene, impairing its ability to adapt and revert to the invasive phenotype. Further attenuation was obtained through inactivation of gene vraG (SACOL0720) which we previously showed to be important for full virulence during bovine IMIs. After infection of bovine mammary epithelial cells (MAC-T), the double mutant (ΔvraGΔhemB) was less internalized and caused less cell destruction than that seen with ΔhemB and ΔvraG, respectively. In a murine IMI model, the ΔvraGΔhemB mutant was strongly attenuated, with a reduction of viable counts of up to 5-log10 CFU/g of mammary gland when compared to the parental strain. A complete clearance of ΔvraGΔhemB from glands was observed whereas mortality rapidly (48h) occurred with the wild-type strain. Immunization of mice using subcutaneous injections of live ΔvraGΔhemB raised a strong immune response as judged by the high total IgG titers measured against bacterial cell extracts and by the high IgG2a/IgG1 ratio observed against the IsdH protein. Also, ΔvraGΔhemB had sufficient common features with bovine mastitis strains so that the antibody response also strongly recognized strains from a variety of mastitis associated spa types. This double mutant could serve as a live-attenuated component in vaccines to improve cell-mediated immune responses against S. aureus IMIs.
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Affiliation(s)
- Julie Côté-Gravel
- Centre d’Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Eric Brouillette
- Centre d’Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Nataša Obradović
- Centre d’Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Céline Ster
- Centre d’Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Brian G. Talbot
- Centre d’Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - François Malouin
- Centre d’Étude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
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Clinical Significance and Pathogenesis of Staphylococcal Small Colony Variants in Persistent Infections. Clin Microbiol Rev 2016; 29:401-27. [PMID: 26960941 DOI: 10.1128/cmr.00069-15] [Citation(s) in RCA: 217] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Small colony variants (SCVs) were first described more than 100 years ago for Staphylococcus aureus and various coagulase-negative staphylococci. Two decades ago, an association between chronic staphylococcal infections and the presence of SCVs was observed. Since then, many clinical studies and observations have been published which tie recurrent, persistent staphylococcal infections, including device-associated infections, bone and tissue infections, and airway infections of cystic fibrosis patients, to this special phenotype. By their intracellular lifestyle, SCVs exhibit so-called phenotypic (or functional) resistance beyond the classical resistance mechanisms, and they can often be retrieved from therapy-refractory courses of infection. In this review, the various clinical infections where SCVs can be expected and isolated, diagnostic procedures for optimized species confirmation, and the pathogenesis of SCVs, including defined underlying molecular mechanisms and the phenotype switch phenomenon, are presented. Moreover, relevant animal models and suggested treatment regimens, as well as the requirements for future research areas, are highlighted.
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Alreshidi MM, Dunstan RH, Gottfries J, Macdonald MM, Crompton MJ, Ang CS, Williamson NA, Roberts TK. Changes in the Cytoplasmic Composition of Amino Acids and Proteins Observed in Staphylococcus aureus during Growth under Variable Growth Conditions Representative of the Human Wound Site. PLoS One 2016; 11:e0159662. [PMID: 27442022 PMCID: PMC4956324 DOI: 10.1371/journal.pone.0159662] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 07/05/2016] [Indexed: 11/18/2022] Open
Abstract
Staphylococcus aureus is an opportunistic pathogen responsible for a high proportion of nosocomial infections. This study was conducted to assess the bacterial responses in the cytoplasmic composition of amino acids and ribosomal proteins under various environmental conditions designed to mimic those on the human skin or within a wound site: pH6-8, temperature 35–37°C, and additional 0–5% NaCl. It was found that each set of environmental conditions elicited substantial adjustments in cytoplasmic levels of glutamic acid, aspartic acid, proline, alanine and glycine (P< 0.05). These alterations generated characteristic amino acid profiles assessed by principle component analysis (PCA). Substantial alterations in cytoplasmic amino acid and protein composition occurred during growth under conditions of higher salinity stress implemented via additional levels of NaCl in the growth medium. The cells responded to additional NaCl at pH 6 by reducing levels of ribosomal proteins, whereas at pH 8 there was an upregulation of ribosomal proteins compared with the reference control. The levels of two ribosomal proteins, L32 and S19, remained constant across all experimental conditions. The data supported the hypothesis that the bacterium was continually responding to the dynamic environment by modifying the proteome and optimising metabolic homeostasis.
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Affiliation(s)
- Mousa M. Alreshidi
- Metabolic Research Group, Faculty of Science and Information Technology, School of Environmental and Life Sciences, Department of Biology, University Drive, Callaghan, 2308, NSW, Australia
- Department of Biology, College of Science, University of Ha’il, P.O. 2440, Hail, Saudi Arabia
| | - R. Hugh Dunstan
- Metabolic Research Group, Faculty of Science and Information Technology, School of Environmental and Life Sciences, Department of Biology, University Drive, Callaghan, 2308, NSW, Australia
- * E-mail:
| | - Johan Gottfries
- Department of Chemistry and Molecular Biology, Gothenburg University, Sweden
| | - Margaret M. Macdonald
- Metabolic Research Group, Faculty of Science and Information Technology, School of Environmental and Life Sciences, Department of Biology, University Drive, Callaghan, 2308, NSW, Australia
| | - Marcus J. Crompton
- Metabolic Research Group, Faculty of Science and Information Technology, School of Environmental and Life Sciences, Department of Biology, University Drive, Callaghan, 2308, NSW, Australia
| | - Ching-Seng Ang
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia
| | - Nicholas A. Williamson
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia
| | - Tim K. Roberts
- Metabolic Research Group, Faculty of Science and Information Technology, School of Environmental and Life Sciences, Department of Biology, University Drive, Callaghan, 2308, NSW, Australia
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Resilience in the Face of Uncertainty: Sigma Factor B Fine-Tunes Gene Expression To Support Homeostasis in Gram-Positive Bacteria. Appl Environ Microbiol 2016; 82:4456-4469. [PMID: 27208112 DOI: 10.1128/aem.00714-16] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Gram-positive bacteria are ubiquitous and diverse microorganisms that can survive and sometimes even thrive in continuously changing environments. The key to such resilience is the ability of members of a population to respond and adjust to dynamic conditions in the environment. In bacteria, such responses and adjustments are mediated, at least in part, through appropriate changes in the bacterial transcriptome in response to the conditions encountered. Resilience is important for bacterial survival in diverse, complex, and rapidly changing environments and requires coordinated networks that integrate individual, mechanistic responses to environmental cues to enable overall metabolic homeostasis. In many Gram-positive bacteria, a key transcriptional regulator of the response to changing environmental conditions is the alternative sigma factor σ(B) σ(B) has been characterized in a subset of Gram-positive bacteria, including the genera Bacillus, Listeria, and Staphylococcus Recent insight from next-generation-sequencing results indicates that σ(B)-dependent regulation of gene expression contributes to resilience, i.e., the coordination of complex networks responsive to environmental changes. This review explores contributions of σ(B) to resilience in Bacillus, Listeria, and Staphylococcus and illustrates recently described regulatory functions of σ(B).
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Day M. Yeast petites and small colony variants: for everything there is a season. ADVANCES IN APPLIED MICROBIOLOGY 2016; 85:1-41. [PMID: 23942147 DOI: 10.1016/b978-0-12-407672-3.00001-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The yeast petite mutant was first found in the yeast Saccharomyces cerevisiae. The colony is small because of a block in the aerobic respiratory chain pathway, which generates ATP. The petite yeasts are thus unable to grow on nonfermentable carbon sources (such as glycerol or ethanol), and form small anaerobic-sized colonies when grown in the presence of fermentable carbon sources (such as glucose). The petite phenotype results from mutations in the mitochondrial genome, loss of mitochondria, or mutations in the host cell genome. The latter mutations affect nuclear-encoded genes involved in oxidative phosphorylation and these mutants are termed neutral petites. They all produce wild-type progeny when crossed with a wild-type strain. The staphylococcal small colony variant (SCV) is a slow-growing mutant that typically exhibits the loss of many phenotypic characteristics and pathogenic traits. SCVs are mostly small, nonpigmented, and nonhaemolytic. Their small size is often due to an inability to synthesize electron transport chain components and so cannot generate ATP by oxidative phosphorylation. Evidence suggests that they are responsible for persistent and/or recurrent infections. This chapter compares the physiological and genetic basis of the petite mutants and SCVs. The review focuses principally on two representatives, the eukaryote S. cerevisiae and the prokaryote Staphylococcus aureus. There is, clearly, commonality in the physiological response. Interestingly, the similarity, based on their physiological states, has not been commented on previously. The finding of an overlapping physiological response that occurs across a taxonomic divide is novel.
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Affiliation(s)
- Martin Day
- School of Biosciences, Cardiff University, Cardiff, United Kingdom.
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Johns BE, Purdy KJ, Tucker NP, Maddocks SE. Phenotypic and Genotypic Characteristics of Small Colony Variants and Their Role in Chronic Infection. Microbiol Insights 2015; 8:15-23. [PMID: 26448688 PMCID: PMC4581789 DOI: 10.4137/mbi.s25800] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 08/09/2015] [Accepted: 08/13/2015] [Indexed: 01/02/2023] Open
Abstract
Small colony variant (SCV) bacteria arise spontaneously within apparently homogeneous microbial populations, largely in response to environmental stresses, such as antimicrobial treatment. They display unique phenotypic characteristics conferred in part by heritable genetic changes. Characteristically slow growing, SCVs comprise a minor proportion of the population from which they arise but persist by virtue of their inherent resilience and host adaptability. Consequently, SCVs are problematic in chronic infection, where antimicrobial treatment is administered during the acute phase of infection but fails to eradicate SCVs, which remain within the host causing recurrent or chronic infection. This review discusses some of the phenotypic and genotypic changes that enable SCVs to successfully proliferate within the host environment as potential pathogens and strategies that could ameliorate the resolution of infection where SCVs are present.
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Affiliation(s)
- Benjamin E Johns
- Department of Biomedical Science, Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Kevin J Purdy
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Nicholas P Tucker
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
| | - Sarah E Maddocks
- Department of Biomedical Science, Cardiff School of Health Sciences, Cardiff Metropolitan University, Cardiff, UK
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Tuchscherr L, Bischoff M, Lattar SM, Noto Llana M, Pförtner H, Niemann S, Geraci J, Van de Vyver H, Fraunholz MJ, Cheung AL, Herrmann M, Völker U, Sordelli DO, Peters G, Löffler B. Sigma Factor SigB Is Crucial to Mediate Staphylococcus aureus Adaptation during Chronic Infections. PLoS Pathog 2015; 11:e1004870. [PMID: 25923704 PMCID: PMC4414502 DOI: 10.1371/journal.ppat.1004870] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 04/09/2015] [Indexed: 12/26/2022] Open
Abstract
Staphylococcus aureus is a major human pathogen that causes a range of infections from acute invasive to chronic and difficult-to-treat. Infection strategies associated with persisting S. aureus infections are bacterial host cell invasion and the bacterial ability to dynamically change phenotypes from the aggressive wild-type to small colony variants (SCVs), which are adapted for intracellular long-term persistence. The underlying mechanisms of the bacterial switching and adaptation mechanisms appear to be very dynamic, but are largely unknown. Here, we analyzed the role and the crosstalk of the global S. aureus regulators agr, sarA and SigB by generating single, double and triple mutants, and testing them with proteome analysis and in different in vitro and in vivo infection models. We were able to demonstrate that SigB is the crucial factor for adaptation in chronic infections. During acute infection, the bacteria require the simultaneous action of the agr and sarA loci to defend against invading immune cells by causing inflammation and cytotoxicity and to escape from phagosomes in their host cells that enable them to settle an infection at high bacterial density. To persist intracellularly the bacteria subsequently need to silence agr and sarA. Indeed agr and sarA deletion mutants expressed a much lower number of virulence factors and could persist at high numbers intracellularly. SigB plays a crucial function to promote bacterial intracellular persistence. In fact, ΔsigB-mutants did not generate SCVs and were completely cleared by the host cells within a few days. In this study we identified SigB as an essential factor that enables the bacteria to switch from the highly aggressive phenotype that settles an acute infection to a silent SCV-phenotype that allows for long-term intracellular persistence. Consequently, the SigB-operon represents a possible target to develop preventive and therapeutic strategies against chronic and therapy-refractory infections.
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Affiliation(s)
- Lorena Tuchscherr
- Institute of Medical Microbiology, Jena University Hospital, Jena, Germany
| | - Markus Bischoff
- Institute of Medical Microbiology and Hygiene, University of Saarland Medical Center, Homburg, Germany
| | - Santiago M. Lattar
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM UBA-CONICET) y Facultad de Medicina, University of Buenos Aires, Buenos Aires, Argentina
| | - Mariangeles Noto Llana
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM UBA-CONICET) y Facultad de Medicina, University of Buenos Aires, Buenos Aires, Argentina
| | - Henrike Pförtner
- Institute of Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Silke Niemann
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Jennifer Geraci
- Institute of Medical Microbiology, Jena University Hospital, Jena, Germany
| | - Hélène Van de Vyver
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Martin J. Fraunholz
- Department of Microbiology, Biocenter, University of Würzburg, Würzburg, Germany
| | - Ambrose L. Cheung
- Dartmouth Medical School, Hanover, New Hampshire, United States of America
| | - Mathias Herrmann
- Institute of Medical Microbiology and Hygiene, University of Saarland Medical Center, Homburg, Germany
| | - Uwe Völker
- Institute of Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Daniel O. Sordelli
- Instituto de Investigaciones en Microbiología y Parasitología Médica (IMPaM UBA-CONICET) y Facultad de Medicina, University of Buenos Aires, Buenos Aires, Argentina
| | - Georg Peters
- Institute of Medical Microbiology, University Hospital of Münster, Münster, Germany
| | - Bettina Löffler
- Institute of Medical Microbiology, Jena University Hospital, Jena, Germany
- * E-mail:
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Staphylococcus aureus adapts to oxidative stress by producing H2O2-resistant small-colony variants via the SOS response. Infect Immun 2015; 83:1830-44. [PMID: 25690100 PMCID: PMC4399076 DOI: 10.1128/iai.03016-14] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 02/10/2015] [Indexed: 12/30/2022] Open
Abstract
The development of chronic and recurrent Staphylococcus aureus infections is associated with the emergence of slow-growing mutants known as small-colony variants (SCVs), which are highly tolerant of antibiotics and can survive inside host cells. However, the host and bacterial factors which underpin SCV emergence during infection are poorly understood. Here, we demonstrate that exposure of S. aureus to sublethal concentrations of H2O2 leads to a specific, dose-dependent increase in the population frequency of gentamicin-resistant SCVs. Time course analyses revealed that H2O2 exposure caused bacteriostasis in wild-type cells during which time SCVs appeared spontaneously within the S. aureus population. This occurred via a mutagenic DNA repair pathway that included DNA double-strand break repair proteins RexAB, recombinase A, and polymerase V. In addition to triggering SCV emergence by increasing the mutation rate, H2O2 also selected for the SCV phenotype, leading to increased phenotypic stability and further enhancing the size of the SCV subpopulation by reducing the rate of SCV reversion to the wild type. Subsequent analyses revealed that SCVs were significantly more resistant to the toxic effects of H2O2 than wild-type bacteria. With the exception of heme auxotrophs, gentamicin-resistant SCVs displayed greater catalase activity than wild-type bacteria, which contributed to their resistance to H2O2. Taken together, these data reveal a mechanism by which S. aureus adapts to oxidative stress via the production of a subpopulation of H2O2-resistant SCVs with enhanced catalase production.
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Krute CN, Carroll RK, Rivera FE, Weiss A, Young RM, Shilling A, Botlani M, Varma S, Baker BJ, Shaw LN. The disruption of prenylation leads to pleiotropic rearrangements in cellular behavior inStaphylococcus aureus. Mol Microbiol 2015; 95:819-32. [DOI: 10.1111/mmi.12900] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/03/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Christina N. Krute
- Department of Cell Biology, Microbiology & Molecular Biology; University of South Florida; Tampa FL USA
| | - Ronan K. Carroll
- Department of Biological Sciences; Ohio University; Athens OH USA
| | - Frances E. Rivera
- Department of Cell Biology, Microbiology & Molecular Biology; University of South Florida; Tampa FL USA
| | - Andy Weiss
- Department of Cell Biology, Microbiology & Molecular Biology; University of South Florida; Tampa FL USA
| | - Ryan M. Young
- Department of Chemistry; University of South Florida; Tampa FL USA
| | - Andrew Shilling
- Department of Chemistry; University of South Florida; Tampa FL USA
| | - Mohsen Botlani
- Department of Cell Biology, Microbiology & Molecular Biology; University of South Florida; Tampa FL USA
| | - Sameer Varma
- Department of Cell Biology, Microbiology & Molecular Biology; University of South Florida; Tampa FL USA
| | - Bill J. Baker
- Department of Chemistry; University of South Florida; Tampa FL USA
| | - Lindsey N. Shaw
- Department of Cell Biology, Microbiology & Molecular Biology; University of South Florida; Tampa FL USA
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Veh K, Klein R, Ster C, Keefe G, Lacasse P, Scholl D, Roy JP, Haine D, Dufour S, Talbot B, Ribon A, Malouin F. Genotypic and phenotypic characterization of Staphylococcus aureus causing persistent and nonpersistent subclinical bovine intramammary infections during lactation or the dry period. J Dairy Sci 2015; 98:155-68. [DOI: 10.3168/jds.2014-8044] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 09/24/2014] [Indexed: 11/19/2022]
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Hosseinkhan N, Zarrineh P, Masoudi-Nejad A. Analysis of Genome-scale Expression Network in Four Major Bacterial Residents of Cystic Fibrosis Lung. Curr Genomics 2014; 15:408-18. [PMID: 25435803 PMCID: PMC4245700 DOI: 10.2174/1389202915666140818205444] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 07/06/2014] [Accepted: 08/15/2014] [Indexed: 11/22/2022] Open
Abstract
In polymicrobial communities where several species co-exist in a certain niche and consequently the possibility of interactions among species is very high, gene expression data sources can give better insights in to underlying adaptation mechanisms assumed by bacteria. Furthermore, several possible synergistic or antagonistic interactions among species can be investigated through gene expression comparisons. Lung is one of the habitats harboring several distinct pathogens during severe pulmonary disorders such as chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF). Expression data analysis of these lung residents can help to gain a better understanding on how these species interact with each other within the host cells. The first part of this paper deals with introducing available data sources for the major bacteria responsible for causing lung diseases and their genomic relations. In the second part, the main focus is on the studies concerning gene expression analyses of these species.
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Affiliation(s)
- Nazanin Hosseinkhan
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Peyman Zarrineh
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Ali Masoudi-Nejad
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
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The Agr quorum-sensing system regulates fibronectin binding but not hemolysis in the absence of a functional electron transport chain. Infect Immun 2014; 82:4337-47. [PMID: 25092909 DOI: 10.1128/iai.02254-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Staphylococcus aureus is responsible for numerous chronic and recurrent infections, which are frequently associated with the emergence of small-colony variants (SCVs) that lack a functional electron transport chain. SCVs exhibit enhanced expression of fibronectin-binding protein (FnBP) and greatly reduced hemolysin production, although the basis for this is unclear. One hypothesis is that these phenotypes are a consequence of the reduced Agr activity of SCVs, while an alternative is that the lack of a functional electron transport chain and the resulting reduction in ATP production are responsible. Disruption of the electron transport chain of S. aureus genetically (hemB and menD) or chemically, using 2-n-heptyl-4-hydroxyquinoline N-oxide (HQNO), inhibited both growth and Agr activity and conferred an SCV phenotype. Supplementation of the culture medium with synthetic autoinducing peptide (sAIP) significantly increased Agr expression in both hemB mutant strains and S. aureus grown with HQNO and significantly reduced staphylococcal adhesion to fibronectin. However, sAIP did not promote hemolysin expression in hemB mutant strains or S. aureus grown with HQNO. Therefore, while Agr regulates fibronectin binding in SCVs, it cannot promote hemolysin production in the absence of a functional electron transport chain.
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Pförtner H, Burian MS, Michalik S, Depke M, Hildebrandt P, Dhople VM, Pané-Farré J, Hecker M, Schmidt F, Völker U. Activation of the alternative sigma factor SigB of Staphylococcus aureus following internalization by epithelial cells – An in vivo proteomics perspective. Int J Med Microbiol 2014; 304:177-87. [DOI: 10.1016/j.ijmm.2013.11.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Sharma P, Gupta SK, Rolain JM. Whole genome sequencing of bacteria in cystic fibrosis as a model for bacterial genome adaptation and evolution. Expert Rev Anti Infect Ther 2014; 12:343-55. [PMID: 24502835 DOI: 10.1586/14787210.2014.887441] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cystic fibrosis (CF) airways harbor a wide variety of new and/or emerging multidrug resistant bacteria which impose a heavy burden on patients. These bacteria live in close proximity with one another, which increases the frequency of lateral gene transfer. The exchange and movement of mobile genetic elements and genomic islands facilitate the spread of genes between genetically diverse bacteria, which seem to be advantageous to the bacterium as it allows adaptation to the new niches of the CF lungs. Niche adaptation is one of the major evolutionary forces shaping bacterial genome composition and in CF the chronic strains adapt and become less virulent. The purpose of this review is to shed light on CF bacterial genome alterations. Next-generation sequencing technology is an exciting tool that may help us to decipher the genome architecture and the evolution of bacteria colonizing CF lungs.
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Affiliation(s)
- Poonam Sharma
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergents, CNRS-IRD, UMR 7278, IHU Méditerranée Infection, Faculté de Médecine et de Pharmacie, Aix-Marseille Université, 27 Bd Jean-Moulin, Marseille Cedex 05 13385, France
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Wong JK, Ranganathan SC, Hart E. Staphylococcus aureus in early cystic fibrosis lung disease. Pediatr Pulmonol 2013; 48:1151-9. [PMID: 23970476 DOI: 10.1002/ppul.22863] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 06/29/2013] [Indexed: 01/04/2023]
Abstract
Staphylococcus aureus: is a common bacterial organism infecting children with cystic fibrosis (CF). Emerging evidence suggests early lower airway infection with this organism in young children with CF results in the deterioration of lung function, poorer nutrition parameters and heightens the airway inflammatory response. Despite contributing significantly to the burden of early lung disease among this group, there are ongoing controversies in the management of S. aureus infection, and gaps in our understanding of exactly how this organism causes lung disease. To reduce the morbidity and mortality of early infection ongoing research is needed to: (i) understand the early host immune response that enables this pathogen to reside within the CF lung; (ii) determine if there are organism specific factors that are associated with CF lung disease; and (iii) clarify the utility of anti-staphylococcal antibiotic prophylaxis and/or eradication in the treatment of this patient population.
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Affiliation(s)
- John K Wong
- Department of Respiratory Medicine, Royal Children's Hospital, Melbourne, Australia; Murdoch Childrens Research Institute, Melbourne, Australia
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Harslund J, Frees D, Leifsson PS, Offenberg H, Rømer MU, Brünner N, Olsen JE. The role of Serpine-1 and Tissue inhibitor of metalloproteinase type-1 in early host responses to Staphylococcus aureus intracutaneous infection of mice. Pathog Dis 2013; 68:96-104. [PMID: 23776165 DOI: 10.1111/2049-632x.12055] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 05/30/2013] [Accepted: 06/08/2013] [Indexed: 11/30/2022] Open
Abstract
Staphylococcus aureus is a common cause of skin and soft tissue infections in animal and humans. In the current study, we hypothesized that early host responses to S. aureus infection leading to the recruitment of neutrophils and control of the bacterium at the site of infection depend on the expression of Serpine-1 and Tissue inhibitor of metalloproteinase type-1, two important endogenous proteinase inhibitors that possess regulatory properties on a variety of pathophysiological conditions. Using a mouse model of skin infection and single-gene and double-gene knockout mice, however, our observations showed that Serpine-1 and Tissue inhibitor of metalloprotease type-1 did not impact the number of bacteria accumulating at the site of infection. Double-gene knockout mice further had the same volume of accumulating host cells at the site of infection, while single Tissue inhibitor of metalloprotease type-1 knockout mice showed a decreased number of cells. Follow-up studies demonstrated changes in Serpine-1, Tissue inhibitor of metalloprotease type-1 and IL-6 plasma levels following challenge. In addition, double-gene knockout mice did not differ from wild-type mice in white blood cell, granulocyte and leucocyte counts, while single-gene genotypes differed in these phenotypes.
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Affiliation(s)
- Jakob Harslund
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
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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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Mitchell G, Fugère A, Pépin Gaudreau K, Brouillette E, Frost EH, Cantin AM, Malouin F. SigB is a dominant regulator of virulence in Staphylococcus aureus small-colony variants. PLoS One 2013; 8:e65018. [PMID: 23705029 PMCID: PMC3660380 DOI: 10.1371/journal.pone.0065018] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 04/22/2013] [Indexed: 12/21/2022] Open
Abstract
Staphylococcus aureus small-colony variants (SCVs) are persistent pathogenic bacteria characterized by slow growth and, for many of these strains, an increased ability to form biofilms and to persist within host cells. The virulence-associated gene expression profile of SCVs clearly differs from that of prototypical strains and is often influenced by SigB rather than by the agr system. One objective of this work was to confirm the role of SigB in the control of the expression of virulence factors involved in biofilm formation and intracellular persistence of SCVs. This study shows that extracellular proteins are involved in the formation of biofilm by three SCV strains, which, additionally, have a low biofilm-dispersing activity. It was determined that SigB activity modulates biofilm formation by strain SCV CF07-S and is dominant over that of the agr system without being solely responsible for the repression of proteolytic activity. On the other hand, the expression of fnbA and the control of nuclease activity contributed to the SigB-dependent formation of biofilm of this SCV strain. SigB was also required for the replication of CF07-S within epithelial cells and may be involved in the colonization of lungs by SCVs in a mouse infection model. This study methodically investigated SigB activity and associated mechanisms in the various aspects of SCV pathogenesis. Results confirm that SigB activity importantly influences the production of virulence factors, biofilm formation and intracellular persistence for some clinical SCV strains.
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Affiliation(s)
- Gabriel Mitchell
- Centre d'étude et de valorisation de la diversité microbienne, Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Alexandre Fugère
- Centre d'étude et de valorisation de la diversité microbienne, Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Karine Pépin Gaudreau
- Centre d'étude et de valorisation de la diversité microbienne, Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Eric Brouillette
- Centre d'étude et de valorisation de la diversité microbienne, Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Eric H. Frost
- Département de microbiologie et d'infectiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbooke, Quebec, Canada
| | - André M. Cantin
- Unité de recherche pulmonaire, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - François Malouin
- Centre d'étude et de valorisation de la diversité microbienne, Département de biologie, Faculté des sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
- * E-mail:
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50
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Grant SS, Hung DT. Persistent bacterial infections, antibiotic tolerance, and the oxidative stress response. Virulence 2013; 4:273-83. [PMID: 23563389 PMCID: PMC3710330 DOI: 10.4161/viru.23987] [Citation(s) in RCA: 213] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Certain bacterial pathogens are able to evade the host immune system and persist within the human host. The consequences of persistent bacterial infections potentially include increased morbidity and mortality from the infection itself as well as an increased risk of dissemination of disease. Eradication of persistent infections is difficult, often requiring prolonged or repeated courses of antibiotics. During persistent infections, a population or subpopulation of bacteria exists that is refractory to traditional antibiotics, possibly in a non-replicating or metabolically altered state. This review highlights the clinical significance of persistent infections and discusses different in vitro models used to investigate the altered physiology of bacteria during persistent infections. We specifically focus on recent work establishing increased protection against oxidative stress as a key element of the altered physiologic state across different in vitro models and pathogens.
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