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Williams P, Hill P, Bonev B, Chan WC. Quorum-sensing, intra- and inter-species competition in the staphylococci. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001381. [PMID: 37578829 PMCID: PMC10482373 DOI: 10.1099/mic.0.001381] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 07/31/2023] [Indexed: 08/15/2023]
Abstract
In Gram-positive bacteria such as Staphylococcus aureus and the coagulase-negative staphylococci (CoNS), the accessory gene regulator (agr) is a highly conserved but polymorphic quorum-sensing system involved in colonization, virulence and biofilm development. Signalling via agr depends on the interaction of an autoinducing peptide (AIP) with AgrC, a transmembrane sensor kinase that, once phosphorylated activates the response regulator AgrA. This in turn autoinduces AIP biosynthesis and drives target gene expression directly via AgrA or via the post-transcriptional regulator, RNAIII. In this review we describe the molecular mechanisms underlying the agr-mediated generation of, and response to, AIPs and the molecular basis of AIP-dependent activation and inhibition of AgrC. How the environment impacts on agr functionality is considered and the consequences of agr dysfunction for infection explored. We also discuss the concept of AIP-driven competitive interference between S. aureus and the CoNS and its anti-infective potential.
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Affiliation(s)
- Paul Williams
- Biodiscovery Institute and School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Phil Hill
- School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, LE12 5RD, UK
| | - Boyan Bonev
- Biodiscovery Institute and School of Life Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Weng C. Chan
- School of Pharmacy, Biodiscovery Institute, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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2
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Polaske TJ, West KHJ, Zhao K, Widner DL, York JT, Blackwell HE. Chemical and biomolecular insights into the Staphylococcus aureus agr quorum sensing system: Current progress and ongoing challenges. Isr J Chem 2023; 63:e202200096. [PMID: 38765792 PMCID: PMC11101167 DOI: 10.1002/ijch.202200096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Indexed: 03/19/2023]
Abstract
Staphylococcus aureus is a ubiquitous bacterium that has become a major threat to human health due to its extensive toxin production and tremendous capacity for antibiotic resistance (e.g., MRSA "superbug" infections). Amid a worsening antibiotic resistance crisis, new strategies to combat this deadly microbe that remove the selective pressure of traditional approaches are in high demand. S. aureus utilizes an accessory gene regulator (agr) quorum sensing network to monitor its local cellular population and trigger a devastating communal attack, like an invading horde, once a threshold cell density has been reached. The role of the agr system in a range of disease types is still being unraveled. Herein, we discuss the present-day biochemical understanding of agr along with unresolved details, describe its connection to the progression of infection, and review how chemical strategies have been implemented to study and intercept this signaling pathway. This research is illuminating the potential of agr as an anti-virulence target in S. aureus and should inform the study of similar, yet less studied, agr systems in related bacterial pathogens.
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Affiliation(s)
- Thomas J. Polaske
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Korbin H. J. West
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Ke Zhao
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Danielle L. Widner
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Jordan T. York
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
| | - Helen E. Blackwell
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706 USA
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Otto M. Critical Assessment of the Prospects of Quorum-Quenching Therapy for Staphylococcus aureus Infection. Int J Mol Sci 2023; 24:ijms24044025. [PMID: 36835436 PMCID: PMC9958572 DOI: 10.3390/ijms24044025] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 02/04/2023] [Accepted: 02/08/2023] [Indexed: 02/19/2023] Open
Abstract
Staphylococcus aureus is an important pathogen that causes a high number of infections and is one of the leading causes of death in hospitalized patients. Widespread antibiotic resistance such as in methicillin-resistant S. aureus (MRSA) has prompted research into potential anti-virulence-targeted approaches. Targeting the S. aureus accessory gene regulator (Agr) quorum-sensing system, a master regulator of virulence, is the most frequently proposed anti-virulence strategy for S. aureus. While much effort has been put into the discovery and screening for Agr inhibitory compounds, in vivo analysis of their efficacy in animal infection models is still rare and reveals various shortcomings and problems. These include (i) an almost exclusive focus on topical skin infection models, (ii) technical problems that leave doubt as to whether observed in vivo effects are due to quorum-quenching, and (iii) the discovery of counterproductive biofilm-increasing effects. Furthermore, potentially because of the latter, invasive S. aureus infection is associated with Agr dysfunctionality. Altogether, the potential of Agr inhibitory drugs is nowadays seen with low enthusiasm given the failure to provide sufficient in vivo evidence for their potential after more than two decades since the initiation of such efforts. However, current Agr inhibition-based probiotic approaches may lead to a new application of Agr inhibition strategies in preventing S. aureus infections by targeting colonization or for otherwise difficult-to-treat skin infections such as atopic dermatitis.
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Affiliation(s)
- Michael Otto
- Pathogen Molecular Genetics Section, Laboratory of Bacteriology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20814, USA
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4
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Staphylococcus aureus Genomic Analysis and Outcomes in Patients with Bone and Joint Infections: A Systematic Review. Int J Mol Sci 2023; 24:ijms24043234. [PMID: 36834650 PMCID: PMC9967247 DOI: 10.3390/ijms24043234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 01/31/2023] [Accepted: 02/02/2023] [Indexed: 02/09/2023] Open
Abstract
Many studies have been published assessing the association between the presence of S. aureus genes and outcomes in patients with bone and joint infections (BJI), but it is not known if they have had similar findings. A systematic literature review was performed. All available data on studies in Pubmed between January 2000 to October 2022 reporting the genetic characteristics of S. aureus and the outcomes of BJIs were analyzed. BJI included prosthetic joint infection (PJI), osteomyelitis (OM), diabetic foot infection (DFI), and septic arthritis. Because of the heterogeneity of studies and outcomes, no meta-analysis was performed. With the search strategy, 34 articles were included: 15 articles on children and 19 articles on adults. In children, most BJI studied were OM (n = 13) and septic arthritis (n = 9). Panton Valentine leucocidin (PVL) genes were associated with higher biological inflammatory markers at presentation (n = 4 studies), more febrile days (n = 3), and more complicated/severe infection (n = 4). Other genes were reported anecdotally associated with poor outcomes. In adults, six studies reported outcomes in patients with PJI, 2 with DFI, 3 with OM, and 3 with various BJI. Several genes were associated with a variety of poor outcomes in adults, but studies found contradictory results. Whereas PVL genes were associated with poor outcomes in children, no specific genes were reported similarly in adults. Additional studies with homogenous BJI and larger sample sizes are needed.
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Turner AB, Gerner E, Firdaus R, Echeverz M, Werthén M, Thomsen P, Almqvist S, Trobos M. Role of sodium salicylate in Staphylococcus aureus quorum sensing, virulence, biofilm formation and antimicrobial susceptibility. Front Microbiol 2022; 13:931839. [PMID: 35992652 PMCID: PMC9384861 DOI: 10.3389/fmicb.2022.931839] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 07/06/2022] [Indexed: 01/01/2023] Open
Abstract
The widespread threat of antibiotic resistance requires new treatment options. Disrupting bacterial communication, quorum sensing (QS), has the potential to reduce pathogenesis by decreasing bacterial virulence. The aim of this study was to investigate the influence of sodium salicylate (NaSa) on Staphylococcus aureus QS, virulence production and biofilm formation. In S. aureus ATCC 25923 (agr III), with or without serum, NaSa (10 mM) downregulated the agr QS system and decreased the secretion levels of alpha-hemolysin, staphopain A and delta-hemolysin. Inhibition of agr expression caused a downregulation of delta-hemolysin, decreasing biofilm dispersal and increasing biofilm formation on polystyrene and titanium under static conditions. In contrast, NaSa did not increase biofilm biomass under flow but caused one log10 reduction in biofilm viability on polystyrene pegs, resulting in biofilms being twice as susceptible to rifampicin. A concentration-dependent effect of NaSa was further observed, where high concentrations (10 mM) decreased agr expression, while low concentrations (≤0.1 mM) increased agr expression. In S. aureus 8325-4 (agr I), a high concentration of NaSa (10 mM) decreased hla expression, and a low concentration of NaSa (≤1 mM) increased rnaIII and hla expression. The activity of NaSa on biofilm formation was dependent on agr type and material surface. Eight clinical strains isolated from prosthetic joint infection (PJI) or wound infection belonging to each of the four agr types were evaluated. The four PJI S. aureus strains did not change their biofilm phenotype with NaSa on the clinically relevant titanium surface. Half of the wound strains (agr III and IV) did not change the biofilm phenotype in the 3D collagen wound model. In addition, compared to the control, ATCC 25923 biofilms formed with 10 mM NaSa in the collagen model were more susceptible to silver. It is concluded that NaSa can inhibit QS in S. aureus, decreasing the levels of toxin production with certain modulation of biofilm formation. The effect on biofilm formation was dependent on the strain and material surface. It is suggested that the observed NaSa inhibition of bacterial communication is a potential alternative or adjuvant to traditional antibiotics.
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Affiliation(s)
- Adam Benedict Turner
- Department of Biomaterials, University of Gothenburg, The Sahlgrenska Academy, Gothenburg, Sweden
- Center for Antibiotic Resistance Research (CARe), University of Gothenburg, Gothenburg, Sweden
| | - Erik Gerner
- Department of Biomaterials, University of Gothenburg, The Sahlgrenska Academy, Gothenburg, Sweden
- Center for Antibiotic Resistance Research (CARe), University of Gothenburg, Gothenburg, Sweden
- Mölnlycke Health Care AB, Gothenburg, Sweden
| | - Rininta Firdaus
- Department of Biomaterials, University of Gothenburg, The Sahlgrenska Academy, Gothenburg, Sweden
- Center for Antibiotic Resistance Research (CARe), University of Gothenburg, Gothenburg, Sweden
| | - Maite Echeverz
- Microbial Pathogenesis Research Unit, Public University of Navarre, Pamplona, Spain
| | - Maria Werthén
- Department of Biomaterials, University of Gothenburg, The Sahlgrenska Academy, Gothenburg, Sweden
- Center for Antibiotic Resistance Research (CARe), University of Gothenburg, Gothenburg, Sweden
| | - Peter Thomsen
- Department of Biomaterials, University of Gothenburg, The Sahlgrenska Academy, Gothenburg, Sweden
| | | | - Margarita Trobos
- Department of Biomaterials, University of Gothenburg, The Sahlgrenska Academy, Gothenburg, Sweden
- Center for Antibiotic Resistance Research (CARe), University of Gothenburg, Gothenburg, Sweden
- *Correspondence: Margarita Trobos,
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Genomic Study on Blood Culture Isolates From Patients With Staphylococcus Infection-associated Glomerulonephritis. Kidney Int Rep 2022; 7:2264-2278. [PMID: 36217522 PMCID: PMC9546744 DOI: 10.1016/j.ekir.2022.07.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 06/05/2022] [Accepted: 07/11/2022] [Indexed: 11/23/2022] Open
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Montagut EJ, Acosta G, Albericio F, Royo M, Godoy-Tena G, Lacoma A, Prat C, Salvador JP, Marco MP. Direct Quantitative Immunochemical Analysis of Autoinducer Peptide IV for Diagnosing and Stratifying Staphylococcus aureus Infections. ACS Infect Dis 2022; 8:645-656. [PMID: 35175740 PMCID: PMC8922274 DOI: 10.1021/acsinfecdis.1c00670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An immunochemical strategy to detect and quantify AIP-IV, the quorum sensing (QS) signaling molecule produced by Staphylococcus aureus agr type IV, is reported here for the first time. Theoretical calculations and molecular modeling studies have assisted on the design and synthesis of a suitable peptide hapten (AIPIVS), allowing to obtain high avidity and specific antibodies toward this peptide despite its low molecular weight. The ELISA developed achieves an IC50 value of 2.80 ± 0.17 and an LOD of 0.19 ± 0.06 nM in complex media such as 1/2 Tryptic Soy Broth. Recognition of other S. aureus AIPs (I-III) is negligible (cross-reactivity below 0.001%), regardless of the structural similarities. A pilot study with a set of clinical isolates from patients with airways infection or colonization demonstrates the potential of this ELISA to perform biomedical investigations related to the role of QS in pathogenesis and the association between dysfunctional agr or the agr type with unfavorable clinical outcomes. The AIP-IV levels could be quantified in the low nanomolar range in less than 1 h after inoculating agr IV-genotyped isolates in the culture broth, while those genotyped as I-III did not show any immunoreactivity after a 48 h growth, pointing to the possibility to use this technology for phenotyping S. aureus. The research strategy here reported can be extended to the rest of the AIP types of S. aureus, allowing the development of powerful multiplexed chips or point-of-care (PoC) diagnostic devices to unequivocally identify its presence and its agr type on samples from infected patients.
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Affiliation(s)
- Enrique-J. Montagut
- Nanobiotechnology for Diagnostics (Nb4D), Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC) of the Spanish Council for Scientific Research (CSIC), 08750 Barcelona, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid Spain
| | - Gerardo Acosta
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid Spain
- Multivalent Systems for Nanomedicine (MS4N), Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC) of the Spanish Council for Scientific Research (CSIC), 08750 Barcelona, Spain
| | - Fernando Albericio
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid Spain
- Multivalent Systems for Nanomedicine (MS4N), Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC) of the Spanish Council for Scientific Research (CSIC), 08750 Barcelona, Spain
- Department of Organic Chemistry, Faculty of Chemistry, University of Barcelona, 08028 Barcelona, Spain
- School of Chemistry and Physics, University of KwaZulu-Natal, 4000 Durban, South Africa
| | - Miriam Royo
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid Spain
- Multivalent Systems for Nanomedicine (MS4N), Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC) of the Spanish Council for Scientific Research (CSIC), 08750 Barcelona, Spain
| | - Gerard Godoy-Tena
- Servei de Microbiologia, Hospital Universitari Germans Trias i Pujol, Institut d’Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
| | - Alicia Lacoma
- Servei de Microbiologia, Hospital Universitari Germans Trias i Pujol, Institut d’Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- CIBER de Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
| | - Cristina Prat
- Servei de Microbiologia, Hospital Universitari Germans Trias i Pujol, Institut d’Investigació Germans Trias i Pujol, Universitat Autònoma de Barcelona, 08916 Badalona, Spain
- CIBER de Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, 3584 Utrecht, the Netherlands
| | - Juan-Pablo Salvador
- Nanobiotechnology for Diagnostics (Nb4D), Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC) of the Spanish Council for Scientific Research (CSIC), 08750 Barcelona, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid Spain
| | - María-Pilar Marco
- Nanobiotechnology for Diagnostics (Nb4D), Department of Surfactants and Nanobiotechnology, Institute for Advanced Chemistry of Catalonia (IQAC) of the Spanish Council for Scientific Research (CSIC), 08750 Barcelona, Spain
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28029 Madrid Spain
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Raghuram V, Alexander AM, Loo HQ, Petit RA, Goldberg JB, Read TD. Species-Wide Phylogenomics of the Staphylococcus aureus Agr Operon Revealed Convergent Evolution of Frameshift Mutations. Microbiol Spectr 2022; 10:e0133421. [PMID: 35044202 PMCID: PMC8768832 DOI: 10.1128/spectrum.01334-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 01/03/2022] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is a prominent nosocomial pathogen that causes several life-threatening diseases, such as pneumonia and bacteremia. S. aureus modulates the expression of its arsenal of virulence factors through sensing and integrating responses to environmental signals. The agr (accessory gene regulator) quorum sensing (QS) system is a major regulator of virulence phenotypes in S. aureus. There are four agr specificity groups each with a different autoinducer peptide sequence encoded by the agrD gene. Although agr is critical for the expression of many toxins, paradoxically, S. aureus strains often have nonfunctional agr activity due to loss-of-function mutations in the four-gene agr operon. To understand patterns in agr variability across S. aureus, we undertook a species-wide genomic investigation. We developed a software tool (AgrVATE; https://github.com/VishnuRaghuram94/AgrVATE) for typing and detecting frameshift mutations in the agr operon. In an analysis of over 40,000 S. aureus genomes, we showed a close association between agr type and S. aureus clonal complex. We also found a strong linkage between agrBDC alleles (encoding the peptidase, autoinducing peptide itself, and peptide sensor, respectively) but not agrA (encoding the response regulator). More than 5% of the genomes were found to have frameshift mutations in the agr operon. While 52% of these frameshifts occurred only once in the entire species, we observed cases where the recurring mutations evolved convergently across different clonal lineages with no evidence of long-term phylogenetic transmission, suggesting that strains with agr frameshifts were evolutionarily short-lived. Overall, genomic analysis of agr operon suggests evolution through multiple processes with functional consequences that are not fully understood. IMPORTANCE Staphylococcus aureus is a globally pervasive pathogen that produces a plethora of toxic molecules that can harm host immune cells. Production of these toxins is mainly controlled by an active agr quorum-sensing system, which senses and responds to bacterial cell density. However, there are many reports of S. aureus strains with genetic changes leading to impaired agr activity that are often found during chronic bloodstream infections and may be associated with increased disease severity. We developed an open-source software called AgrVATE to type agr systems and identify mutations. We used AgrVATE for a species-wide genomic survey of S. aureus, finding that more than 5% of strains in the public database had nonfunctional agr systems. We also provided new insights into the evolution of these genetic mutations in the agr system. Overall, this study contributes to our understanding of a common but relatively understudied means of virulence regulation in S. aureus.
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Affiliation(s)
- Vishnu Raghuram
- Microbiology and Molecular Genetics Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, Georgia, USA
| | - Ashley M. Alexander
- Population Biology, Ecology, and Evolution Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, Georgia, USA
| | - Hui Qi Loo
- Department of Biology, Emory University, Atlanta, Georgia, USA
| | - Robert A. Petit
- Division of Infectious Diseases, Department of Medicine, Emory University, Atlanta, Georgia, USA
| | - Joanna B. Goldberg
- Division of Pulmonary, Allergy and Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Timothy D. Read
- Division of Infectious Diseases, Department of Medicine, Emory University, Atlanta, Georgia, USA
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Impact of agr Functionality on the Outcome of Patients with Methicillin-Susceptible Staphylococcus aureus Bacteremia. Microbiol Spectr 2021; 9:e0011621. [PMID: 34378959 PMCID: PMC8552762 DOI: 10.1128/spectrum.00116-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Dysfunctional accessory gene regulator (agr) is associated with unfavorable outcomes in invasive methicillin-resistant Staphylococcus aureus infections. However, it is unknown whether this association persists in methicillin-susceptible Staphylococcus aureus bacteremia (MSSA-B). This study evaluated the association between agr dysfunction and mortality in patients with MSSA-B. This retrospective cohort study included MSSA-B patients (≥15 years) enrolled from June 2014 to June 2019 and retrospectively collected their demographic and clinical information. Stored causative strains were measured for agr functionality by δ-hemolysin production assays. Among 244 MSSA-B patients, 91 (37.3%) and 153 (62.7%) had dysfunctional and functional agr MSSA-B, respectively. Ninety-day mortality occurred in 18.7% and 17.6% dysfunctional and functional groups, respectively (P = 0.97). Kaplan-Meier analysis showed that mortality due to dysfunctional agr MSSA-B was not significantly higher (P = 0.82). Age, sites, the severity of infection, and comorbidity adjusted hazard ratio (aHR) of the dysfunctional group for 90-day mortality was 1.303 (95% confidence interval [CI], 0.698 to 2.436, P = 0.41). Mortality due to MSSA-B with sequential organ failure assessment (SOFA) scores of 2 to 5 was significantly higher in the dysfunctional group (P = 0.03), and the dysfunctional agr aHR for 90-day mortality was 3.260 (95% CI, 1.050 to 10.118, P = 0.04). The agr dysfunction of causative organisms can have a significant effect on the outcomes of MSSA-B in patients with moderate severity (SOFA scores 2 to 5). IMPORTANCE Few studies have examined the association between methicillin-susceptible Staphylococcus aureus (MSSA) infection and accessory gene regulator (agr) functionality. We evaluated the association between agr dysfunction and mortality in patients with MSSA bacteremia. Dysfunctional agr is associated with lower survival in MSSA bacteremia patients with moderately severe sequential organ failure assessment (SOFA) scores of 2 to 5. We found that the agr functionality of causative organisms may have an effect on patients’ outcomes in MSSA like in methicillin-resistant S. aureus.
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10
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Blicharz L, Rudnicka L, Czuwara J, Waśkiel-Burnat A, Goldust M, Olszewska M, Samochocki Z. The Influence of Microbiome Dysbiosis and Bacterial Biofilms on Epidermal Barrier Function in Atopic Dermatitis-An Update. Int J Mol Sci 2021; 22:ijms22168403. [PMID: 34445108 PMCID: PMC8395079 DOI: 10.3390/ijms22168403] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 07/31/2021] [Accepted: 08/02/2021] [Indexed: 12/13/2022] Open
Abstract
Atopic dermatitis (AD) is a common inflammatory dermatosis affecting up to 30% of children and 10% of adults worldwide. AD is primarily driven by an epidermal barrier defect which triggers immune dysregulation within the skin. According to recent research such phenomena are closely related to the microbial dysbiosis of the skin. There is growing evidence that cutaneous microbiota and bacterial biofilms negatively affect skin barrier function, contributing to the onset and exacerbation of AD. This review summarizes the latest data on the mechanisms leading to microbiome dysbiosis and biofilm formation in AD, and the influence of these phenomena on skin barrier function.
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Affiliation(s)
- Leszek Blicharz
- Department of Dermatology, Medical University of Warsaw, 02-008 Warsaw, Poland; (L.R.); (J.C.); (A.W.-B.); (M.O.); (Z.S.)
- Correspondence:
| | - Lidia Rudnicka
- Department of Dermatology, Medical University of Warsaw, 02-008 Warsaw, Poland; (L.R.); (J.C.); (A.W.-B.); (M.O.); (Z.S.)
| | - Joanna Czuwara
- Department of Dermatology, Medical University of Warsaw, 02-008 Warsaw, Poland; (L.R.); (J.C.); (A.W.-B.); (M.O.); (Z.S.)
| | - Anna Waśkiel-Burnat
- Department of Dermatology, Medical University of Warsaw, 02-008 Warsaw, Poland; (L.R.); (J.C.); (A.W.-B.); (M.O.); (Z.S.)
| | - Mohamad Goldust
- Department of Dermatology, University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany;
| | - Małgorzata Olszewska
- Department of Dermatology, Medical University of Warsaw, 02-008 Warsaw, Poland; (L.R.); (J.C.); (A.W.-B.); (M.O.); (Z.S.)
| | - Zbigniew Samochocki
- Department of Dermatology, Medical University of Warsaw, 02-008 Warsaw, Poland; (L.R.); (J.C.); (A.W.-B.); (M.O.); (Z.S.)
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11
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Mahdally NH, George RF, Kashef MT, Al-Ghobashy M, Murad FE, Attia AS. Staquorsin: A Novel Staphylococcus aureus Agr-Mediated Quorum Sensing Inhibitor Impairing Virulence in vivo Without Notable Resistance Development. Front Microbiol 2021; 12:700494. [PMID: 34290689 PMCID: PMC8287904 DOI: 10.3389/fmicb.2021.700494] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/11/2021] [Indexed: 12/11/2022] Open
Abstract
The emergence of microbial resistance to the available antibiotics is a major public health concern, especially with the limited rate of developing new antibiotics. The utilization of anti-virulence agents is a non-conventional approach that can be used to combat microbial infection. In Staphylococcus aureus, many virulence factors are regulated by the Agr-mediated quorum sensing (QS). We developed a chemical compound that acts a potential Agr-inhibitor without reducing bacterial viability. The compound was designated staquorsin for Staphylococcus aureus QS inhibitor. In silico analyses confirmed the binding of staquorsin to the AgrA active site with an absolute binding score comparable to savirin, a previously described AgrA inhibitor. However, staquorsin turned out to be superior over savarin in not affecting the S. aureus viability in concentrations up to 600 μM. On the other hand, savirin inhibited S. aureus growth in concentrations as low as 25 μM. Moreover, staquorsin proved to be a potent inhibitor of the Agr system by inhibiting hemolysins, lipase production, and affecting biofilms formation and detachment. On the molecular level it significantly inhibited the effector transcript RNA III. In vivo testing, using the murine skin abscess model, confirmed the ability of staquorsin to modulate S. aureus virulence by effectively controlling the infection. Twenty passages of S. aureus in the presence of 40 μM staquorsin have not resulted in loss of activity as evidenced by maintaining its ability to reduce hemolysin production and RNA III transcript levels. In conclusion, we hereby describe a novel anti-virulence compound inhibiting the S. aureus Agr-system and its associated virulence factors. It is active both in vitro and in vivo, and its frequent use does not lead to the development of resistance. These findings model staquorsin as a promising drug candidate to join the fierce battle against the formidable pathogen S. aureus.
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Affiliation(s)
- Norhan H Mahdally
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Riham F George
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Mona T Kashef
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Medhat Al-Ghobashy
- Department of Analytical Chemistry, Faculty of Pharmacy, Cairo University, Cairo, Egypt.,School of Pharmacy, Newgiza University, Giza, Egypt
| | - Fathia E Murad
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Ahmed S Attia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
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Dehbashi S, Tahmasebi H, Zeyni B, Arabestani MR. Regulation of virulence and β-lactamase gene expression in Staphylococcus aureus isolates: cooperation of two-component systems in bloodstream superbugs. BMC Microbiol 2021; 21:192. [PMID: 34172010 PMCID: PMC8228909 DOI: 10.1186/s12866-021-02257-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 06/13/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA)-bloodstream infections (BSI) are predominantly seen in the hospital or healthcare-associated host. Nevertheless, the interactions of virulence factor (VFs) regulators and β-lactam resistance in MRSA-BSI are unclear. This study aims to characterize the molecular relationship of two-component systems of VFs and the expression of the β-lactamase gene in MRSA-BSI isolates. In this study, 639 samples were collected from BSI and identified by phenotypic methods. We performed extensive molecular characterization, including SCCmec type, agr type, VFs gene profiles determinations, and MLST on isolates. Also, a quantitative real-time PCR (q-RT PCR) assay was developed for identifying the gene expressions. RESULTS Ninety-one (91) S. aureus and 61 MRSA (67.0%) strains were detected in BSI samples. The presence of VFs and SCCmec genes in MRSA isolates were as follows: tst (31.4%), etA (18.0%), etB (8.19%), lukS-PVL (31.4%), lukF-PV (18.0%), lukE-lukD (16.3%), edin (3.2%), hla (16.3%), hlb (18.0%), hld (14.7%), hlg (22.9%), SCCmecI (16.3%), SCCmecII (22.9%), SCCmecIII (36.0%), SCCmecIV (21.3%), and SCCmecV (16.3%). Quantitative real-time PCR showed overexpression of mecRI and mecI in the toxigenic isolates. Moreover, RNAIII and sarA genes were the highest expressions of MRSA strains. The multi-locus sequence typing data confirmed a high prevalence of CC5, CC8, and CC30. However, ST30, ST22, and ST5 were the most prevalent in the resistant and toxigenic strains. CONCLUSION We demonstrated that although regulation of β-lactamase gene expressions is a significant contributor to resistance development, two-component systems also influence antibiotic resistance development in MRSA-BSI isolates. This indicates that resistant strains might have pathogenic potential. We also confirmed that some MLST types are more successful colonizers with a potential for MRSA-BSI.
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Affiliation(s)
- Sanaz Dehbashi
- Microbiology Department, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Hamed Tahmasebi
- School of Medicine, Shahroud University of Medical Sciences, Shahroud, Iran
| | - Behrouz Zeyni
- Microbiology Department, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Mohammad Reza Arabestani
- Microbiology Department, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran. .,Nutrition health Research center, Hamadan University of Medical Sciences, Hamadan, Iran.
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Avberšek J, Papić B, Kušar D, Erjavec V, Seme K, Golob M, Zdovc I. Feline Otitis Externa Caused by Methicillin-Resistant Staphylococcus aureus with Mixed Hemolytic Phenotype and Overview of Possible Genetic Backgrounds. Antibiotics (Basel) 2021; 10:antibiotics10050599. [PMID: 34070191 PMCID: PMC8158496 DOI: 10.3390/antibiotics10050599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/14/2021] [Accepted: 05/16/2021] [Indexed: 11/18/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of nosocomial infections in humans, but its importance in small animal practice is increasing. Here, we present a case of feline otitis externa (OE) caused by MRSA; both hemolytic and nonhemolytic variants with a stable phenotype were recovered from the external auditory canal after infection was detected by routine otoscopy. One isolate per variant underwent antimicrobial susceptibility testing (AST) by broth microdilution method, conventional spa typing and whole-genome sequencing (WGS). The results showed that both variants were genetically related and were of sequence type (ST) 1327, SCCmec type IV and spa type t005. AST and WGS showed that both isolates were resistant to β-lactams and sensitive to all tested non-β-lactam antibiotics. Both isolates were pvl-negative, but encoded several other virulence genes (aur, hlgABC, sak, scn, seg, sei, sem, sen, seo and seu). Genetic background of the mixed hemolytic phenotype was not identified; no differences in the agr locus or other regulatory regions were detected. Three single-nucleotide polymorphisms were identified but could not be associated with hemolysis. This well-documented case of MRSA infection in companion animals adds to the reports of MRSA infections with a mixed hemolytic phenotype.
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Affiliation(s)
- Jana Avberšek
- Institute of Microbiology and Parasitology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana, Slovenia; (J.A.); (B.P.); (D.K.); (M.G.)
| | - Bojan Papić
- Institute of Microbiology and Parasitology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana, Slovenia; (J.A.); (B.P.); (D.K.); (M.G.)
| | - Darja Kušar
- Institute of Microbiology and Parasitology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana, Slovenia; (J.A.); (B.P.); (D.K.); (M.G.)
| | - Vladimira Erjavec
- Small Animal Clinic, Veterinary Faculty, University of Ljubljana, Cesta v Mestni log 47, SI-1000 Ljubljana, Slovenia;
| | - Katja Seme
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Ljubljana, Zaloška 4, SI-1000 Ljubljana, Slovenia;
| | - Majda Golob
- Institute of Microbiology and Parasitology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana, Slovenia; (J.A.); (B.P.); (D.K.); (M.G.)
| | - Irena Zdovc
- Institute of Microbiology and Parasitology, Veterinary Faculty, University of Ljubljana, Gerbičeva 60, SI-1000 Ljubljana, Slovenia; (J.A.); (B.P.); (D.K.); (M.G.)
- Correspondence: ; Tel.: +386-1-4779-158
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Genotypic and Phenotypic Characterization of Staphylococcus aureus Isolates from the Respiratory Tract in Mechanically-Ventilated Patients. Toxins (Basel) 2021; 13:toxins13020122. [PMID: 33562023 PMCID: PMC7915691 DOI: 10.3390/toxins13020122] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/03/2021] [Accepted: 02/03/2021] [Indexed: 12/17/2022] Open
Abstract
Staphylococcus aureus is a commensal and frequent colonizer of the upper respiratory tract. When mechanical ventilation disrupts natural defenses, S. aureus is frequently isolated from the lower airways, but distinguishing between colonization and infection is difficult. The objectives of this study were (1) to investigate the bacterial genome sequence in consecutive isolates in order to identify changes related to the pathological adaptation to the lower respiratory tract and (2) to explore the relationship between specific phenotypic and genotypic features with the patient’s study group, persistence of the clinical isolate and clinical outcome. A set of 94 clinical isolates were selected and corresponded to 34 patients that were classified as having pneumonia (10), tracheobronchitis (11) and bronchial colonization (13). Clinical strains were phenotypically characterized by conventional identification and susceptibility testing methods. Isolates underwent whole genome sequencing using Illumina HiSeq4000. Genotypic characterization was performed with an in-house pipeline (BacterialTyper). Genomic variation arising within-host was determined by comparing mapped sequences and de novo assemblies. Virulence factors important in staphylococcal colonization and infection were characterized using previously established functional assays. (1) Toxin production was assessed using a THP-1 cytotoxicity assay, which reports on the gross cytotoxicity of individual isolates. In addition, we investigated the expression of the major virulence factor, alpha-toxin (Hla) by Western blot. (2) Adhesion to the important extracellular matrix molecule, fibronectin, was determined using a standardized microtitre plate assay. Finally, invasion experiments using THP-1 and A539 cell lines and selected clinical strains were also performed. Repeated isolation of S. aureus from endotracheal aspirate usually reflects persistence of the same strain. Within-host variation is detectable in this setting, but it shows no evidence of pathological adaptation related to virulence, resistance or niche adaptations. Cytotoxicity was variable among isolates with 14 strains showing no cytotoxicity, with these latter presenting an unaltered Fn binding capacity. No changes on cytotoxicity were reported when comparing study groups. Fn binding capacity was reported for almost all strains, with the exception of two strains that presented the lowest values. Strains isolated from patients with pneumonia presented a lower capacity of adhesion in comparison to those isolated during tracheobronchitis (p = 0.002). Hla was detected in 71 strains (75.5%), with most of the producer strains in pneumonia and bronchial colonization group (p = 0.06). In our cohort, Hla expression (presence or absence) in sequential isolates was usually preserved (70%) although in seven cases the expression varied over time. No relationship was found between low cytotoxicity and intracellular persistence in invasion experiments. In our study population, persistent S. aureus isolation from airways in ventilated patients does not reflect pathological adaptation. There is an important diversity of sequence types. Cytotoxicity is variable among strains, but no association with study groups was found, whereas isolates from patients with pneumonia had lower adhesion capability. Favorable clinical outcome correlated with increased bacterial adhesion in vitro. Most of the strains isolated from the lower airways were Hla producers and no correlation with an adverse outcome was reported. The identification of microbial factors that contribute to virulence is relevant to optimize patient management during lower respiratory tract infections.
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