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Lam NM, Tsang TF, Qu J, Tsang MW, Tao Y, Kan CH, Zou Q, Chan KH, Chu AJ, Ma C, Yang X. Development of a luciferase-based Gram-positive bacterial reporter system for the characterization of antimicrobial agents. Appl Environ Microbiol 2024; 90:e0071724. [PMID: 39016615 PMCID: PMC11337827 DOI: 10.1128/aem.00717-24] [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: 04/21/2024] [Accepted: 06/24/2024] [Indexed: 07/18/2024] Open
Abstract
Mechanistic investigations are of paramount importance in elucidating the modes of action of antibiotics and facilitating the discovery of novel drugs. We reported a luciferase-based reporter system using bacterial cells to unveil mechanisms of antimicrobials targeting transcription and translation. The reporter gene Nluc encoding NanoLuciferase (NanoLuc) was integrated into the genome of the Gram-positive model organism, Bacillus subtilis, to generate a reporter strain BS2019. Cellular transcription and translation levels were assessed by quantifying the amount of Nluc mRNA as well as the luminescence catalyzed by the enzyme NanoLuc. We validated this system using three known inhibitors of transcription (rifampicin), translation (chloramphenicol), and cell wall synthesis (ampicillin). The B. subtilis reporter strain BS2019 successfully revealed a decline in Nluc expression by rifampicin and NanoLuc enzyme activity by chloramphenicol, while ampicillin produced no observable effect. The assay was employed to characterize a previously discovered bacterial transcription inhibitor, CUHK242, with known antimicrobial activity against drug-resistant Staphylococcus aureus. Production of Nluc mRNA in our reporter BS2019 was suppressed in the presence of CUHK242, demonstrating the usefulness of the construct, which provides a simple way to study the mechanism of potential antibiotic candidates at early stages of drug discovery. The reporter system can also be modified by adopting different promoters and reporter genes to extend its scope of contribution to other fields of work. IMPORTANCE Discovering new classes of antibiotics is desperately needed to combat the emergence of multidrug-resistant pathogens. To facilitate the drug discovery process, a simple cell-based assay for mechanistic studies is essential to characterize antimicrobial candidates. In this work, we developed a luciferase-based reporter system to quantify the transcriptional and translational effects of potential compounds and validated our system using two currently marketed drugs. Reporter strains generated in this study provide readily available means for identifying bacterial transcription inhibitors as prospective novel antibacterials. We also provided a series of plasmids for characterizing promoters under various conditions such as stress.
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Affiliation(s)
- Nga Man Lam
- Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong Special Administrative Region, China
| | - Tsz Fung Tsang
- Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong Special Administrative Region, China
| | - Jiayi Qu
- Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong Special Administrative Region, China
| | - Man Wai Tsang
- Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong Special Administrative Region, China
| | - Yuan Tao
- Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong Special Administrative Region, China
| | - Cheuk Hei Kan
- Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong Special Administrative Region, China
| | - Qingyu Zou
- Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong Special Administrative Region, China
| | - King Hong Chan
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region, China
| | - Adrian Jun Chu
- Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong Special Administrative Region, China
| | - Cong Ma
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region, China
| | - Xiao Yang
- Department of Microbiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong Special Administrative Region, China
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Balogh H, Anthony A, Stempel R, Vossen L, Federico VA, Valenzano GZ, Blackledge MS, Miller HB. Novel Anti-virulence Compounds Disrupt Exotoxin Expression in MRSA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.15.594412. [PMID: 38798408 PMCID: PMC11118326 DOI: 10.1101/2024.05.15.594412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Hemolysins are lytic exotoxins expressed in most strains of S. aureus , but hemolytic activity varies between strains. We have previously reported several novel anti-virulence compounds that disrupt the S. aureus transcriptome, including hemolysin gene expression. This report delves further into our two lead compounds, loratadine and a structurally related brominated carbazole, and their effects on hemolysin production in MRSA. To gain understanding into how these compounds affect hemolysis, we analyzed these exotoxins at the DNA, RNA, and protein level after in vitro treatment. While lysis of red blood cells varied between strains, DNA sequence variation did not account for it. We hypothesized that our compounds would modulate gene expression of multiple hemolysins in a laboratory strain and a clinically relevant hospital-acquired strain of MRSA, both with SCC mec type II. RNA-seq analysis of differential gene expression in untreated and compound-treated cultures revealed hundreds of differentially expressed genes, with a significant enrichment in genes involved in hemolysis. The brominated carbazole and loratadine both displayed the ability to reduce hemolysis in the laboratory strain, but displayed differential activity in a hospital-acquired strain. These results corroborate gene expression studies as well as western blots of alpha hemolysin. Together, this work suggests that small molecules may alter exotoxin production in MRSA, but that the directionality and/or magnitude of the difference is likely strain-dependent.
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Wang J, Meng Y, Zhang R, Yan H, Xu G, Zhu Y, Xie Z, Jiang S. Coagulase-negative staphylococci are the main causes of bacterial meningitis in duck. Poult Sci 2024; 103:103592. [PMID: 38447309 PMCID: PMC11067754 DOI: 10.1016/j.psj.2024.103592] [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: 01/24/2024] [Revised: 02/17/2024] [Accepted: 02/22/2024] [Indexed: 03/08/2024] Open
Abstract
Since September 2018, serious meningitis has been found on some breeding-duck farms in Shandong Province, China. A large number of ducks exhibit severe neurological symptoms. The ducks were randomly selected for laboratory testing. Duck brain samples were collected using standard sterile techniques, and the staphylococci isolates were detected in 404 (70.14%) out of 576 brain samples. A total of 525 coagulase-negative staphylococci (CoNS) strains were isolated, including 6 species: Staphylococcus sciuri (S. sciuri) (67.24%, 353/525), Staphylococcus epidermidis (S. epidermidis) (9.71%, 51/525), Staphylococcus saprophyticus (S. saprophyticus) (8.38%, 44/525), Staphylococcus lentus (S. lentus) (7.62%, 40/525), Staphylococcus haemolyticus (S. haemolyticus) (2.48%, 13/525), and Staphylococcus xylosus (S. xylosus) (4.57%, 24/525). Mixed strain infections were detected in 121 (29.95%) infected presentations. The antimicrobial susceptibility testing indicated that 40.38% of the isolates exhibited multi-drug resistance, and 53.90% of the strains were methicillin-resistant strains by amplification of the methicillin resistance gene (mecA) gene. Through experimental reproduction of the disease, we determined that the CoNS strains were the leading pathogens causing bacterial meningitis in ducks. Although these CoNS strains does not directly cause the death of sick ducks, they still cause large economic losses due to the retarded growth and development of the sick ducks, lower feed returns, and lower grades of processed duck products. The results of this study will contribute to our understanding of the epidemiology and pathogenesis of CoNS and be helpful in the prevention and treatment of the infection.
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Affiliation(s)
- Jingyu Wang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Tai'an 271018, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Tai'an 271018, China
| | - Yu Meng
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Tai'an 271018, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Tai'an 271018, China
| | - Ruihua Zhang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Tai'an 271018, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Tai'an 271018, China
| | - Hui Yan
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Tai'an 271018, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Tai'an 271018, China
| | - Guige Xu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Tai'an 271018, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Tai'an 271018, China
| | - Yanli Zhu
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Tai'an 271018, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Tai'an 271018, China
| | - Zhijing Xie
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Tai'an 271018, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Tai'an 271018, China
| | - Shijin Jiang
- Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Tai'an 271018, China; Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Tai'an 271018, China; Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Tai'an 271018, China.
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Goc A, Sumera W, Rath M, Niedzwiecki A. Inhibition of α-hemolysin activity of Staphylococcus aureus by theaflavin 3,3'-digallate. PLoS One 2023; 18:e0290904. [PMID: 37651426 PMCID: PMC10470925 DOI: 10.1371/journal.pone.0290904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 08/17/2023] [Indexed: 09/02/2023] Open
Abstract
The ongoing rise in antibiotic resistance, and a waning of the introduction of new antibiotics, has resulted in limited treatment options for bacterial infections, including these caused by methicillin-resistant Staphylococcus aureus, leaving the world in a post-antibiotic era. Here, we set out to examine mechanisms by which theaflavin 3,3'-digallate (TF3) might act as an anti-hemolytic compound. In the presented study, we found that TF3 has weak bacteriostatic and bactericidal effects on Staphylococcus aureus, and strong inhibitory effect towards the hemolytic activity of its α-hemolysin (Hla) including its production and secretion. A supportive SPR assay reinforced these results and further revealed binding of TF3 to Hla with KD = 4.57×10-5 M. Interestingly, TF3 was also able to protect human primary keratinocytes from Hla-induced cell death, being at the same time non-toxic for them. Further analysis of TF3 properties revealed that TF3 blocked Hla-prompting immune reaction by inhibiting production and secretion of IL1β, IL6, and TNFα in vitro and in vivo, through affecting NFκB activity. Additionally, we observed that TF3 also markedly attenuated S. aureus-induced barrier disruption, by inhibiting Hla-triggered E-cadherin and ZO-1 impairment. Overall, by blocking activity of Hla, TF3 subsequently subdued the inflammation and protected the epithelial barrier, which is considered as beneficial to relieving skin injury.
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Affiliation(s)
- Anna Goc
- Department of Infectious Diseases, Dr. Rath Research Institute, San Jose, California, United States of America
| | - Waldemar Sumera
- Department of Infectious Diseases, Dr. Rath Research Institute, San Jose, California, United States of America
| | - Matthias Rath
- Department of Infectious Diseases, Dr. Rath Research Institute, San Jose, California, United States of America
| | - Aleksandra Niedzwiecki
- Department of Infectious Diseases, Dr. Rath Research Institute, San Jose, California, United States of America
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Pivard M, Caldelari I, Brun V, Croisier D, Jaquinod M, Anzala N, Gilquin B, Teixeira C, Benito Y, Couzon F, Romby P, Moreau K, Vandenesch F. Complex Regulation of Gamma-Hemolysin Expression Impacts Staphylococcus aureus Virulence. Microbiol Spectr 2023; 11:e0107323. [PMID: 37347186 PMCID: PMC10434192 DOI: 10.1128/spectrum.01073-23] [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: 03/15/2023] [Accepted: 05/25/2023] [Indexed: 06/23/2023] Open
Abstract
Staphylococcus aureus gamma-hemolysin CB (HlgCB) is a core-genome-encoded pore-forming toxin that targets the C5a receptor, similar to the phage-encoded Panton-Valentine leucocidin (PVL). Absolute quantification by mass spectrometry of HlgCB in 39 community-acquired pneumonia (CAP) isolates showed considerable variations in the HlgC and HlgB yields between isolates. Moreover, although HlgC and HlgB are encoded on a single operon, their levels were dissociated in 10% of the clinical strains studied. To decipher the molecular basis for the variation in hlgCB expression and protein production among strains, different regulation levels were analyzed in representative clinical isolates and reference strains. Both the HlgCB level and the HlgC/HlgB ratio were found to depend on hlgC promoter activity and mRNA processing and translation. Strikingly, only one single nucleotide polymorphism (SNP) in the 5' untranslated region (UTR) of hlgCB mRNA strongly impaired hlgC translation in the USA300 strain, leading to a strong decrease in the level of HlgC but not in HlgB. Finally, we found that high levels of HlgCB synthesis led to mortality in a rabbit model of pneumonia, correlated with the implication of the role of HlgCB in severe S. aureus CAP. Taken together, this work illustrates the complexity of virulence factor expression in clinical strains and demonstrates a butterfly effect where subtle genomic variations have a major impact on phenotype and virulence. IMPORTANCE S. aureus virulence in pneumonia results in its ability to produce several virulence factors, including the leucocidin PVL. Here, we demonstrate that HlgCB, another leucocidin, which targets the same receptors as PVL, highly contributes to S. aureus virulence in pvl-negative strains. In addition, considerable variations in HlgCB quantities are observed among clinical isolates from patients with CAP. Biomolecular analyses have revealed that a few SNPs in the promoter sequences and only one SNP in the 5' UTR of hlgCB mRNA induce the differential expression of hlgCB, drastically impacting hlgC mRNA translation. This work illustrates the subtlety of regulatory mechanisms in bacteria, especially the sometimes major effects on phenotypes of single nucleotide variation in noncoding regions.
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Affiliation(s)
- Mariane Pivard
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, Lyon, France
| | - Isabelle Caldelari
- Architecture et Réactivité de l’ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Virginie Brun
- Université Grenoble Alpes, Inserm, CEA, UMR BioSanté U1292, CNRS, CEA, Grenoble, France
- Université Grenoble Alpes, CEA, LETI, Clinatec, Grenoble, France
| | | | - Michel Jaquinod
- Université Grenoble Alpes, Inserm, CEA, UMR BioSanté U1292, CNRS, CEA, Grenoble, France
| | | | - Benoît Gilquin
- Université Grenoble Alpes, Inserm, CEA, UMR BioSanté U1292, CNRS, CEA, Grenoble, France
- Université Grenoble Alpes, CEA, LETI, Clinatec, Grenoble, France
| | - Chloé Teixeira
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, Lyon, France
| | - Yvonne Benito
- Institut des Agents Infectieux, Hospices Civils de Lyon, Lyon, France
- Centre National de Référence des Staphylocoques, Hospices Civils de Lyon, Lyon, France
| | - Florence Couzon
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, Lyon, France
| | - Pascale Romby
- Architecture et Réactivité de l’ARN, Université de Strasbourg, CNRS, IBMC, Strasbourg, France
| | - Karen Moreau
- CIRI, Centre International de Recherche en Infectiologie, Université de Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, 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 UMR5308, ENS de Lyon, Lyon, France
- Institut des Agents Infectieux, Hospices Civils de Lyon, Lyon, France
- Centre National de Référence des Staphylocoques, Hospices Civils de Lyon, Lyon, France
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Abdulmanea AA, Alharbi NS, Somily AM, Khaled JM, Algahtani FH. The Prevalence of the Virulence Genes of Staphylococcus aureus in Sickle Cell Disease Patients at KSUMC, Riyadh, Saudi Arabia. Antibiotics (Basel) 2023; 12:1221. [PMID: 37508317 PMCID: PMC10416153 DOI: 10.3390/antibiotics12071221] [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: 06/20/2023] [Revised: 07/12/2023] [Accepted: 07/18/2023] [Indexed: 07/30/2023] Open
Abstract
Staphylococcus aureus in the blood of sickle cell disease (SCD) patients may result in a significant increase in morbidity and mortality. S. aureus strains contain various virulence characteristics, including the ability to create a variety of toxins and develop drug resistance. The current study sought to assess the prevalence of S. aureus in SCD patients and to identify the pathogen's virulence characteristics. Between 2017 and 2021, blood samples and data were collected at King Saud University Medical City (KSUMC) in Riyadh, Saudi Arabia. The Vitek system PCR and gene sequencing methods were used for identification, antibiotic resistance patterns, and genetic analysis. During the study period, 47 S. aureus blood isolates (methicillin-resistant S. aureus (MRSA) 41.6% and non-MRSA 58.4%) were isolated from 2406 SCD patients. The prevalence percentages of virulence genes (finbB, sdrC, sdrD, icaA, coa, nuc, hlg, hla, finbA, clfA, efb, pvl, agr, spa, seb, sea, sec, tst, and sed) among all the isolates from the SCD patients compared with non-SCD patients (control group) were as follows: (100% vs. 100%), (100% vs. 100%), (100% vs. 100%), (100% vs. 87.5%), (100% vs. 81.3%), (100% vs. 100%), (100% vs. 100%), (100% vs. 100%), (97.9% vs. 81.3%), (97.9% vs. 100%), (97.9% vs. 87.5%), (54.3% vs. 56.3%), (46.8% vs. 75%), (42.6% vs. 43.8%), (27.7% vs. 0%), (25.5% vs. 12.5%), (12.8% vs. 6.3%), (4.3% vs. 12.5%), and (4.3% vs. 0%). Regarding the resistance genes (plaZ, mecA, ermA, ermC, tetK, tetM, and ermB) of the S. aureus strains isolated from the SCD patients compared with non-SCD patients (control group), the prevalence percentages were as follows: (100% vs. 100%), (100% vs. 56.3%), (0% vs. 31.3%), (31.9% vs. 18.8%), (40.4% vs. 25%), (0% vs. 0%), and (0% vs. 0%). As for the antibiotic (ampicillin, penicillin, amoxicillin, cefazolin, imipenem, oxacillin, erythromycin, tetracycline, azithromycin, ciprofloxacin, moxifloxacin, and levofloxacin) resistance of the S. aureus strains isolated from the SCD patients compared with non-SCD patients (control group), the prevalence percentages were as follows: (100% vs. 100%), (97.9% vs. 100%), (72.3% vs. 25%), (68.1% vs. 37.5%), (68.1% vs. 25%), (66% vs. 25%), (36.2% vs. 18.8%), (23.4% vs. 12.5%), (19.1% vs. 12.5%), (17% vs. 12.5%), (14.9% vs. 25%), and (10.6% vs. 18.7%). This study concluded that several virulence genes were present in the S. aureus strains recovered from the SCD patients at KSUMC, with all the isolates containing the finbB, sdrC, sdrD, icaA, coa, nuc, hlg, and hla genes.
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Affiliation(s)
- Adel A. Abdulmanea
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; (N.S.A.); (J.M.K.)
| | - Naiyf S. Alharbi
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; (N.S.A.); (J.M.K.)
| | - Ali M. Somily
- Department of Pathology, College of Medicine, King Saud University and King Saud University Medical City, P.O. Box 2925, Riyadh 11451, Saudi Arabia;
| | - Jamal M. Khaled
- Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; (N.S.A.); (J.M.K.)
| | - Farjah H. Algahtani
- Department of Hematology, College of Medicine, King Saud University and King Saud University Medical City, P.O. Box 2925, Riyadh 11451, Saudi Arabia;
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Cella MA, Coulson T, MacEachern S, Badr S, Ahmadi A, Tabatabaei MS, Labbe A, Griffiths MW. Probiotic disruption of quorum sensing reduces virulence and increases cefoxitin sensitivity in methicillin-resistant Staphylococcus aureus. Sci Rep 2023; 13:4373. [PMID: 36928453 PMCID: PMC10020441 DOI: 10.1038/s41598-023-31474-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 03/13/2023] [Indexed: 03/18/2023] Open
Abstract
Therapies which target quorum sensing (QS) systems that regulate virulence in methicillin-resistant Staphylococcus aureus (MRSA) are a promising alternative to antibiotics. QS systems play a crucial in the regulation of MRSA antibiotic resistance, exotoxin production, antioxidant protection and immune cell evasion, and are therefore attractive therapeutic targets to reduce the virulence of a pathogen. In the present work the the effects of bioactive peptides isolated from two strains of lactic acid bacteria were tested against antibiotic resistance, carotenoid production, resistance to oxidative killing and biofilm structure in two clinical MRSA isolates. The results obtained from fractional-inhibitory concentration assays with bulk and semi-purified bioactive molecules showed a significant synergistic effect increasing cefoxitin mediated killing of MRSA. This was coupled to a six-fold decrease of the major membrane pigment staphyloxanthin, and a 99% increase in susceptibility to oxidative stress mediated killing. Real-time quantitative PCR analysis of the QS-genes agrA and luxS, showed differential expression between MRSA strains, and a significant downregulation of the hemolysin gene hla. Light microscopy and scanning electron microscopy revealed alteration in biofilm formation and clustering behavior. These results demonstrate that bioactive metabolites may be effectively applied in tandem with beta-lactam antibiotics to sensitize MRSA to cefoxitin. Moreover, these results shown that several key QS-controlled virulence mechanisms are diminished by probiotic metabolites.
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Affiliation(s)
- Monica Angela Cella
- Department of Mechanical Engineering, École de Technologie Supérieure (ÉTS), Montreal, QC, H3C 1K3, Canada
| | | | | | - Sara Badr
- Department of Mechanical Engineering, École de Technologie Supérieure (ÉTS), Montreal, QC, H3C 1K3, Canada
| | - Ali Ahmadi
- Department of Mechanical Engineering, École de Technologie Supérieure (ÉTS), Montreal, QC, H3C 1K3, Canada
| | | | - Alain Labbe
- MicroSintesis Inc., Victoria, PE, COA 2G0, Canada.
| | - Mansel William Griffiths
- Canadian Research Institute for Food Safety, University of Guelph, Guelph, ON, N1G 2W1, Canada
- Food Science Department, University of Guelph, Guelph, ON, N1G 2W1, Canada
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The survival of epidemic and sporadic MRSA on human skin mimics is determined by both host and bacterial factors. Epidemiol Infect 2022; 150:e203. [PMID: 36382385 PMCID: PMC9987022 DOI: 10.1017/s0950268822001765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Bacterial survival on, and interactions with, human skin may explain the epidemiological success of MRSA strains. We evaluated the bacterial counts for 27 epidemic and 31 sporadic MRSA strains on 3D epidermal models based on N/TERT cells (NEMs) after 1, 2 and 8 days. In addition, the expression of antimicrobial peptides (hBD-2, RNase 7), inflammatory cytokines (IL-1β, IL-6) and chemokine IL-8 by NEMs was assessed using immunoassays and the expression of 43 S. aureus virulence factors was determined by a multiplex competitive Luminex assay. To explore donor variation, bacterial counts for five epidemic and seven sporadic MRSA strains were determined on 3D primary keratinocyte models (LEMs) from three human donors. Bacterial survival was comparable on NEMs between the two groups, but on LEMs, sporadic strains showed significantly lower survival numbers compared to epidemic strains. Both groups triggered the expression of immune factors. Upon interaction with NEMs, only the epidemic MRSA strains expressed pore-forming toxins, including alpha-hemolysin (Hla), gamma-hemolysin (HlgB), Panton-Valentine leucocidin (LukS) and LukED. Together, these data indicate that the outcome of the interaction between MRSA and human skin mimics, depends on the unique combination of bacterial strain and host factors.
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Ziesemer S, Kuhn SO, Hahnenkamp A, Gerber M, Lutjanov E, Gruendling M, Hildebrandt JP. Staphylococcus aureus Alpha-Toxin in Deep Tracheal Aspirates—Preliminary Evidence for Its Presence in the Lungs of Sepsis Patients. Toxins (Basel) 2022; 14:toxins14070450. [PMID: 35878188 PMCID: PMC9320683 DOI: 10.3390/toxins14070450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 06/20/2022] [Accepted: 06/29/2022] [Indexed: 02/05/2023] Open
Abstract
The pore forming alpha-toxin (hemolysin A, Hla) of Staphylococcus aureus (S. aureus) is a major virulence factor with relevance for the pathogenicity of this bacterium, which is involved in many cases of pneumonia and sepsis in humans. Until now, the presence of Hla in the body fluids of potentially infected humans could only be shown indirectly, e.g., by the presence of antibodies against Hla in serum samples or by hemolysis testing on blood agar plates of bacterial culture supernatants of the clinical isolates. In addition, nothing was known about the concentrations of Hla actually reached in the body fluids of the infected hosts. Western blot analyses on 36 samples of deep tracheal aspirates (DTA) isolated from 22 hospitalized sepsis patients using primary antibodies against different epitopes of the Hla molecule resulted in the identification of six samples from five patients containing monomeric Hla (approx. 33 kDa). Two of these samples showed also signals at the molecular mass of heptameric Hla (232 kDa). Semiquantitative analyses of the samples revealed that the concentrations of monomeric Hla ranged from 16 to 3200 ng/mL. This is, to our knowledge, the first study directly showing the presence of S. aureus Hla in samples of airway surface liquid in human patients.
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Affiliation(s)
- Sabine Ziesemer
- Animal Physiology and Biochemistry, University of Greifswald, Felix Hausdorff-Strasse 1, D-17489 Greifswald, Germany; (S.Z.); (E.L.)
| | - Sven-Olaf Kuhn
- Department of Anesthesiology, University Hospital Greifswald, Ferdinand Sauerbruch-Strasse, D-17475 Greifswald, Germany; (S.-O.K.); (A.H.); (M.G.); (M.G.)
| | - Anke Hahnenkamp
- Department of Anesthesiology, University Hospital Greifswald, Ferdinand Sauerbruch-Strasse, D-17475 Greifswald, Germany; (S.-O.K.); (A.H.); (M.G.); (M.G.)
| | - Manuela Gerber
- Department of Anesthesiology, University Hospital Greifswald, Ferdinand Sauerbruch-Strasse, D-17475 Greifswald, Germany; (S.-O.K.); (A.H.); (M.G.); (M.G.)
| | - Elvira Lutjanov
- Animal Physiology and Biochemistry, University of Greifswald, Felix Hausdorff-Strasse 1, D-17489 Greifswald, Germany; (S.Z.); (E.L.)
| | - Matthias Gruendling
- Department of Anesthesiology, University Hospital Greifswald, Ferdinand Sauerbruch-Strasse, D-17475 Greifswald, Germany; (S.-O.K.); (A.H.); (M.G.); (M.G.)
| | - Jan-Peter Hildebrandt
- Animal Physiology and Biochemistry, University of Greifswald, Felix Hausdorff-Strasse 1, D-17489 Greifswald, Germany; (S.Z.); (E.L.)
- Correspondence: ; Tel.: +49-(0)3834-4204295
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10
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Karuppiah V, Seralathan M. Quorum sensing inhibitory potential of vaccenic acid against Chromobacterium violaceum and methicillin-resistant Staphylococcus aureus. World J Microbiol Biotechnol 2022; 38:146. [PMID: 35759150 DOI: 10.1007/s11274-022-03335-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 06/10/2022] [Indexed: 11/25/2022]
Abstract
Quorum sensing (QS) is a potential target for inhibiting bacterial antibiotic resistance and associated pathogenicity. The present study aimed to investigate vaccenic acid anti-QS and antibiofilm potential against Chromobacterium violaceum and methicillin-resistant Staphylococcus aureus (MRSA). In the broth microdilution method, we determined the minimum inhibitory concentration (MIC) of vaccenic acid against C. violaceum and MRSA. Then, we determined the vaccenic acid anti-QS potential against C. violaceum via a violacein inhibition assay. Vaccenic acid at a sub-MIC concentration significantly inhibited violacein pigment production. Vaccenic acid also inhibits C. violaceum and MRSA biofilm formation at sub-MIC concentrations. The effect of vaccenic acid antivirulence potential was evaluated by phenotypic virulence assays. The results showed that vaccenic acid at a sub-MIC concentration significantly inhibited the virulence production of C. violaceum (chitinase and motility) and MRSA (hemolysin and staphyloxanthin production). Quantitative PCR analysis revealed the downregulation of QS associated genes upon vaccenic acid treatment. This resulted in the downregulation of genes involved in QS mechanisms such as cviI, cviR, and SarA and pigment production such as vioB and crtM. The results of the present study suggest that vaccenic acid is a promising agent to combat C. violaceum and MRSA.
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Affiliation(s)
- Vijayakumar Karuppiah
- Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai, Cuddalore, Tamil Nadu, 608 502, India.
- PAR Life Sciences and Research Private Limited, Woraiyur, Trichy, Tamil Nadu, 620003, India.
| | - Muhilvannan Seralathan
- PAR Life Sciences and Research Private Limited, Woraiyur, Trichy, Tamil Nadu, 620003, India
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11
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Diversity and pathogenesis of Staphylococcus aureus from bovine mastitis: current understanding and future perspectives. BMC Vet Res 2022; 18:115. [PMID: 35331225 PMCID: PMC8944054 DOI: 10.1186/s12917-022-03197-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 03/03/2022] [Indexed: 11/10/2022] Open
Abstract
Staphylococcus aureus is a leading cause of bovine mastitis worldwide. Despite some improved understanding of disease pathogenesis, progress towards new methods for the control of intramammary infections (IMI) has been limited, particularly in the field of vaccination. Although herd management programs have helped to reduce the number of clinical cases, S. aureus mastitis remains a major disease burden. This review summarizes the past 16 years of research on bovine S. aureus population genetics, and molecular pathogenesis that have been conducted worldwide. We describe the diversity of S. aureus associated with bovine mastitis and the geographical distribution of S. aureus clones in different continents. We also describe studies investigating the evolution of bovine S. aureus and the importance of host-adaptation in its emergence as a mastitis pathogen. The available information on the prevalence of virulence determinants and their functional relevance during the pathogenesis of bovine mastitis are also discussed. Although traits such as biofilm formation and innate immune evasion are critical for the persistence of bacteria, the current understanding of the key host-pathogen interactions that determine the outcome of S. aureus IMI is very limited. We suggest that greater investment in research into the genetic and molecular basis of bovine S. aureus pathogenesis is essential for the identification of novel therapeutic and vaccine targets.
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12
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Increased Risk of Thrombocytopenia and Death in Patients with Bacteremia Caused by High Alpha Toxin-Producing Methicillin-Resistant Staphylococcus aureus. Toxins (Basel) 2021; 13:toxins13100726. [PMID: 34679019 PMCID: PMC8537302 DOI: 10.3390/toxins13100726] [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] [Received: 08/10/2021] [Revised: 10/08/2021] [Accepted: 10/09/2021] [Indexed: 01/25/2023] Open
Abstract
Alpha toxin (Hla) is a major virulence factor of Staphylococcus aureus that targets platelets but clinical data on Hla pathogenesis in bacteremia (SAB) is limited. We examined the link between in vitro Hla activity and outcome. Study isolates obtained from 100 patients with SAB (50 survivors; 50 non-survivors) were assessed for in vitro Hla production by Western immunoblotting in a subset of isolates and Hla activity by hemolysis assay in all isolates. Relevant demographics, laboratory and clinical data were extracted from patients' medical records to correlate Hla activity of the infecting isolates with outcome. Hla production strongly correlated with hemolytic activity (rs = 0.93) in vitro. A trend towards higher hemolytic activity was observed for MRSA compared to MSSA and with high-risk source infection. Significantly higher hemolytic activity was noted for MRSA strains isolated from patients who developed thrombocytopenia (median 52.48 vs. 16.55 HU/mL in normal platelet count, p = 0.012) and from non survivors (median 30.96 vs. 14.87 HU/mL in survivors, p = 0.014) but hemolytic activity of MSSA strains did not differ between patient groups. In vitro Hla activity of MRSA strains obtained from patients with bacteremia is significantly associated with increased risk for thrombocytopenia and death which supports future studies to evaluate feasibility of bedside phenotyping and therapeutic targeting.
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Wei J, Cheng X, Zhang Y, Gao C, Wang Y, Peng Q, Luo P, Yang L, Zou Q, Zeng H, Gu J. Identification and application of a neutralizing epitope within alpha-hemolysin using human serum antibodies elicited by vaccination. Mol Immunol 2021; 135:45-52. [PMID: 33873093 DOI: 10.1016/j.molimm.2021.03.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/08/2021] [Accepted: 03/31/2021] [Indexed: 11/15/2022]
Abstract
Staphylococcus aureus (SA), especially the methicillin-resistant variant (MRSA), is becoming a serious threat to human health in hospitals and communities, making the development of an effective vaccine urgent. Alpha-hemolysin (Hla) is a key virulence factor and also a good target for the development of SA vaccines. However, the epitopes in Hla recognized by human immunity are not characterized in detail, which hinders the design of epitope-based human vaccines against SA. In this study, we collected sera from volunteers in a phase 1b clinical trial of a novel recombinant five-antigen SA vaccine (NCT03966040). Using a Luminex-based assay, we characterized the human serologic response against Hla, and identified Hla121-138 as a neutralizing epitope. In addition, we successfully produced ferritin nanoparticles carrying the neutralizing Hla121-138 epitope (EpNP) in E. coli. EpNP presented as homogenous nanoparticles in aqueous solution. Immunization with EpNP elicited potent hemolysis-neutralizing antibodies and conferred significant protection in a mouse model of SA skin infection. Our data suggest that EpNP, carrying the neutralizing epitope Hla121-138, is a good candidate for a vaccine against SA.
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Affiliation(s)
- Jinning Wei
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, PR China
| | - Xin Cheng
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, PR China
| | - Yi Zhang
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, PR China
| | - Chen Gao
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, PR China
| | - Ying Wang
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, PR China
| | - Qi Peng
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Ping Luo
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, PR China
| | - Liuyang Yang
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, PR China; Medical Laboratory Center, First Medical Center of Chinese PLA General Hospital, No. 28 Fuxing Road, Haidian District, Beijing, 100853, China
| | - Quanming Zou
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, PR China
| | - Hao Zeng
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, PR China.
| | - Jiang Gu
- National Engineering Research Center of Immunological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing, 400038, PR China.
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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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Vlaeminck J, Raafat D, Surmann K, Timbermont L, Normann N, Sellman B, van Wamel WJB, Malhotra-Kumar S. Exploring Virulence Factors and Alternative Therapies against Staphylococcus aureus Pneumonia. Toxins (Basel) 2020; 12:toxins12110721. [PMID: 33218049 PMCID: PMC7698915 DOI: 10.3390/toxins12110721] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/12/2020] [Accepted: 11/15/2020] [Indexed: 12/13/2022] Open
Abstract
Pneumonia is an acute pulmonary infection associated with high mortality and an immense financial burden on healthcare systems. Staphylococcus aureus is an opportunistic pathogen capable of inducing S. aureus pneumonia (SAP), with some lineages also showing multidrug resistance. Given the high level of antibiotic resistance, much research has been focused on targeting S. aureus virulence factors, including toxins and biofilm-associated proteins, in an attempt to develop effective SAP therapeutics. Despite several promising leads, many hurdles still remain for S. aureus vaccine research. Here, we review the state-of-the-art SAP therapeutics, highlight their pitfalls, and discuss alternative approaches of potential significance and future perspectives.
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Affiliation(s)
- Jelle Vlaeminck
- Laboratory of Medical Microbiology, Vaccine and Infectious Diseases Institute, University of Antwerp, 2610 Antwerp, Belgium; (J.V.); (L.T.)
| | - Dina Raafat
- Department of Immunology, Institute of Immunology and Transfusion Medicine, University Medicine Greifswald, 17475 Greifswald, Germany; (D.R.); (N.N.)
- Department of Microbiology and Immunology, Faculty of Pharmacy, Alexandria University, Alexandria 21521, Egypt
| | - Kristin Surmann
- Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, 17475 Greifswald, Germany;
| | - Leen Timbermont
- Laboratory of Medical Microbiology, Vaccine and Infectious Diseases Institute, University of Antwerp, 2610 Antwerp, Belgium; (J.V.); (L.T.)
| | - Nicole Normann
- Department of Immunology, Institute of Immunology and Transfusion Medicine, University Medicine Greifswald, 17475 Greifswald, Germany; (D.R.); (N.N.)
| | - Bret Sellman
- Microbiome Discovery, Microbial Sciences, BioPharmaceuticals R & D, AstraZeneca, Gaithersburg, MD 20878, USA;
| | - Willem J. B. van Wamel
- Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Center Rotterdam, 3015 Rotterdam, The Netherlands;
| | - Surbhi Malhotra-Kumar
- Laboratory of Medical Microbiology, Vaccine and Infectious Diseases Institute, University of Antwerp, 2610 Antwerp, Belgium; (J.V.); (L.T.)
- Correspondence: ; Tel.: +32-3-265-27-52
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16
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Silence as a way of niche adaptation: mecC-MRSA with variations in the accessory gene regulator (agr) functionality express kaleidoscopic phenotypes. Sci Rep 2020; 10:14787. [PMID: 32901059 PMCID: PMC7479134 DOI: 10.1038/s41598-020-71640-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 08/19/2020] [Indexed: 11/09/2022] Open
Abstract
Functionality of the accessory gene regulator (agr) quorum sensing system is an important factor promoting either acute or chronic infections by the notorious opportunistic human and veterinary pathogen Staphylococcus aureus. Spontaneous alterations of the agr system are known to frequently occur in human healthcare-associated S. aureus lineages. However, data on agr integrity and function are sparse regarding other major clonal lineages. Here we report on the agr system functionality and activity level in mecC-carrying methicillin resistant S. aureus (MRSA) of various animal origins (n = 33) obtained in Europe as well as in closely related human isolates (n = 12). Whole genome analysis assigned all isolates to four clonal complexes (CC) with distinct agr types (CC599 agr I, CC49 agr II, CC130 agr III and CC1943 agr IV). Agr functionality was assessed by a combination of phenotypic assays and proteome analysis. In each CC, isolates with varying agr activity levels were detected, including the presence of completely non-functional variants. Genomic comparison of the agr I-IV encoding regions associated these phenotypic differences with variations in the agrA and agrC genes. The genomic changes were detected independently in divergent lineages, suggesting that agr variation might foster viability and adaptation of emerging MRSA lineages to distinct ecological niches.
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17
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Verdú-Expósito C, Romanyk J, Cuadros-González J, TesfaMariam A, Copa-Patiño JL, Pérez-Serrano J, Soliveri J. Study of susceptibility to antibiotics and molecular characterization of high virulence Staphylococcus aureus strains isolated from a rural hospital in Ethiopia. PLoS One 2020; 15:e0230031. [PMID: 32163464 PMCID: PMC7067403 DOI: 10.1371/journal.pone.0230031] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Accepted: 02/19/2020] [Indexed: 11/20/2022] Open
Abstract
We characterised 80 Staphylococcus aureus strains isolated from human patients with SSTIs at a rural hospital in Ethiopia. Susceptibility to antibiotic of all strains was tested. The MLST method was used to type and a phylogenetic analysis was conducted employing the sequences of 7 housekeeping genes. PCR amplification was used to investigate the presence of the following virulence genes in all strains: hla (α-haemolysin), tstH (toxic shock syndrome toxin), luk PV (Panton-Valentine leukocidin), fnbA (fibronectin binding protein A) and mecA (methicillin resistance). Most of the strains were resistant to penicillin and ampicillin, but only 3 strains were resistant to oxacillin, and 1 of them was a true MRSA. The MLST results showed a high diversity of sequence types (ST), 55% of which were new, and ST152 was the most prevalent. A phylogeny study showed that many of the new STs were phylogenetically related to other previously described STs, but bore little relationship to the only ST from Ethiopia described in the database. Virulence gene detection showed a high prevalence of strains encoding the hla, fnbA and pvl genes (98.77%, 96.3% and 72.84%, respectively), a low prevalence of the tst gene (13.58%) and a markedly low prevalence of MRSA (1.25%). S. aureus strains isolated from patients in a rural area in Ethiopia showed low levels of antibiotic resistance, except to penicillin. Moreover, this study reveals new STs in Eastern Africa that are phylogenetically related to other previously described STs, and confirm the high prevalence of the pvl gene and the low prevalence of MRSA on the continent.
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Affiliation(s)
- Cristina Verdú-Expósito
- Department of Biomedicine and Biotechnology, University of Alcalá, Alcalá de Henares, Madrid, Spain
| | - Juan Romanyk
- Microbiology Service, Hospital Universitario Príncipe de Asturias, Alcalá-Meco, Alcalá de Henares, Madrid, Spain
| | - Juan Cuadros-González
- Microbiology Service, Hospital Universitario Príncipe de Asturias, Alcalá-Meco, Alcalá de Henares, Madrid, Spain
| | - Abraham TesfaMariam
- Department of General Medicine, Gambo General Rural Hospital, West-Arsi, Ethiopia
| | - José Luis Copa-Patiño
- Department of Biomedicine and Biotechnology, University of Alcalá, Alcalá de Henares, Madrid, Spain
| | - Jorge Pérez-Serrano
- Department of Biomedicine and Biotechnology, University of Alcalá, Alcalá de Henares, Madrid, Spain
| | - Juan Soliveri
- Department of Biomedicine and Biotechnology, University of Alcalá, Alcalá de Henares, Madrid, Spain
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Hua X, Jia Y, Yang Q, Zhang W, Dong Z, Liu S. Transcriptional Analysis of the Effects of Gambogic Acid and Neogambogic Acid on Methicillin-Resistant Staphylococcus aureus. Front Pharmacol 2019; 10:986. [PMID: 31572177 PMCID: PMC6753875 DOI: 10.3389/fphar.2019.00986] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 07/31/2019] [Indexed: 11/13/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) infection is a major threat to human health, as this bacterium has developed resistance to a variety of conventional antibiotics. This is especially true of MRSA biofilms, which not only exhibit enhanced pathogenicity but also are resistant to most antibiotics. In this work, we demonstrated that two natural products with antitumor activity, namely, gambogic acid (GA) and neogambogic acid (NGA), have significant inhibitory activity toward MRSA. GA and NGA can not only effectively inhibit planktonic MRSA strains in vivo and in vitro, but also have strong inhibitory effects on MRSA biofilms formation. By transcriptome sequencing, Q-RT-PCR and PRM, we found that GA and NGA could reduce the expression of S. aureus virulence factors by inhibiting the saeRS two-component, thus achieving inhibition of MRSA. We found that GA and NGA had anti-MRSA activity in vivo and in vitro and identified saeRS to be the target, indicating that saeRS inhibitors may be used to treat biofilm-related infections.
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Affiliation(s)
- Xin Hua
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
- College of Life Science, Northeast Forestry University, Harbin, China
| | - Yue Jia
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Qin Yang
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Wanjiang Zhang
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Zhimin Dong
- Innovation Team of Livestock and Poultry Epidemic Disease Prevention and Control, Tianjin Animal Science and Veterinary Research Institute, Tianjin, China
| | - Siguo Liu
- Division of Bacterial Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
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Selvaraj A, Jayasree T, Valliammai A, Pandian SK. Myrtenol Attenuates MRSA Biofilm and Virulence by Suppressing sarA Expression Dynamism. Front Microbiol 2019; 10:2027. [PMID: 31551964 PMCID: PMC6737500 DOI: 10.3389/fmicb.2019.02027] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 08/19/2019] [Indexed: 11/13/2022] Open
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a deleterious human pathogen responsible for severe morbidity and mortality worldwide. The pathogen has attained high priority in the World Health Organization (WHO) - Multidrug-resistant (MDR) pathogens list. Emerging MDR strains of S. aureus are clinically challenging due to failure in conventional antibiotic therapy. Biofilm formation is one of the underlying mechanisms behind the antibiotic resistance. Hence, attenuating biofilm formation has become an alternative strategy to control persistent infections. The current study is probably the first that focuses on the antibiofilm and antivirulence potential of myrtenol against MRSA and its clinical isolates. Myrtenol exhibited a concentration-dependent biofilm inhibition without causing any harmful effect on cell growth and viability. Further, microscopic analysis validated the biofilm inhibitory efficacy of myrtenol against MRSA. In addition, myrtenol inhibited the synthesis of major virulence factors including slime, lipase, α-hemolysin, staphyloxanthin and autolysin. Inhibition of staphyloxanthin in turn sensitized the MRSA cells to healthy human blood and hydrogen peroxide (H2O2). Notably, myrtenol treated cells were deficient in extracellular DNA (eDNA) mediated autoaggregation as eDNA releasing autolysis was impaired by myrtenol. Biofilm disruptive activity on preformed biofilms was observed at concentrations higher than minimum biofilm inhibitory concentration (MBIC) of myrtenol. Also, the non-cytotoxic effect of myrtenol on human peripheral blood mononuclear cell (PBMC) was evidenced by trypan blue and Alamar blue assays. Transcriptional analysis unveiled the down-regulation of global regulator sarA and sarA mediated virulence genes upon myrtenol treatment, which is well correlated with results of phenotypic assays. Thus, the results of the present study revealed the sarA mediated antibiofilm and antivirulence potential of myrtenol against MRSA.
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The Role of Streptococcal and Staphylococcal Exotoxins and Proteases in Human Necrotizing Soft Tissue Infections. Toxins (Basel) 2019; 11:toxins11060332. [PMID: 31212697 PMCID: PMC6628391 DOI: 10.3390/toxins11060332] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 06/04/2019] [Accepted: 06/10/2019] [Indexed: 12/31/2022] Open
Abstract
Necrotizing soft tissue infections (NSTIs) are critical clinical conditions characterized by extensive necrosis of any layer of the soft tissue and systemic toxicity. Group A streptococci (GAS) and Staphylococcus aureus are two major pathogens associated with monomicrobial NSTIs. In the tissue environment, both Gram-positive bacteria secrete a variety of molecules, including pore-forming exotoxins, superantigens, and proteases with cytolytic and immunomodulatory functions. The present review summarizes the current knowledge about streptococcal and staphylococcal toxins in NSTIs with a special focus on their contribution to disease progression, tissue pathology, and immune evasion strategies.
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Divyakolu S, Chikkala R, Ratnakar KS, Sritharan V. Hemolysins of <i>Staphylococcus aureus</i>—An Update on Their Biology, Role in Pathogenesis and as Targets for Anti-Virulence Therapy. ACTA ACUST UNITED AC 2019. [DOI: 10.4236/aid.2019.92007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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22
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Walther B, Klein KS, Barton AK, Semmler T, Huber C, Merle R, Tedin K, Mitrach F, Lübke-Becker A, Gehlen H. Equine Methicillin-Resistant Sequence Type 398 Staphylococcus aureus (MRSA) Harbor Mobile Genetic Elements Promoting Host Adaptation. Front Microbiol 2018; 9:2516. [PMID: 30405574 PMCID: PMC6207647 DOI: 10.3389/fmicb.2018.02516] [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: 06/08/2018] [Accepted: 10/02/2018] [Indexed: 12/31/2022] Open
Abstract
Continuing introduction of multi-drug resistant, zoonotic pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) in horse clinics challenges the biosafety of employees and animal patients. This study was aimed to determine the occurrence of mobile genetic elements facilitating survival in the early stages of invasive infection in different host species, including humans and horses, in MRSA carried by equine patients admitted to a large horse clinic. A total of 341 equine patients were investigated for carriage of MRSA by hygiene screening directly at hospital admission. MRSA were further investigated by antimicrobial susceptibility testing, whole-genome sequencing and genomic composition, including virulence factors involved in immune evasion and host adaption. From a total of 340 validated specimens from equine nostrils, 3.5% yielded positive results for MRSA. All MRSA were found to be closely related belonging to sequence type (ST) 398_t011 with up to four additional antimicrobial resistances. All MRSA harbored a specific Staphylococcal Pathogenicity Island (SaPIbov5) involved in facilitating survival in ruminant and equine plasma. Moreover, a β-hemolysin (hlb) converting ΦSa3 phage encoding the human-specific Immune Evasion Cluster (IEC) was present in 72% of the isolates. An equid-specific leukotoxin encoded by a further temperate phage (Saeq1) was only rarely detected (22%). Despite the absence of β-hemolysin production for all IEC-positive ST398, a prominent hemolysis zone was demonstrable on sheep blood agar. Thus, IEC might remain undetected among the ST398 lineage, since the presence of IEC is commonly associated with reduction of hemolysis in S. aureus belonging to other genetic backgrounds. Here we describe MRSA-ST398 harboring different mobile genetic elements encoding variants of immune evasion factors and toxins previously shown to contribute to S. aureus invasive diseases in specific host species or ecologic niches. We suggest these combinations contribute to the adaptation of MRSA belonging to ST398 with respect to epidemic spread across different habitats and hosts, and may therefore confer a host “generalist” phenotype.
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Affiliation(s)
- Birgit Walther
- Centre for Infection Medicine, Institute of Microbiology and Epizootics, Freie Universität Berlin, Berlin, Germany.,Advanced Light and Electron Microscopy (ZBS4), Robert Koch Institute, Berlin, Germany
| | - Katja-Sophia Klein
- Equine Clinic, Surgery and Radiology, Freie Universität Berlin, Berlin, Germany
| | - Ann-Kristin Barton
- Equine Clinic, Surgery and Radiology, Freie Universität Berlin, Berlin, Germany
| | - Torsten Semmler
- Microbial Genomics (NG1), Robert Koch Institute, Berlin, Germany
| | - Charlotte Huber
- Microbial Genomics (NG1), Robert Koch Institute, Berlin, Germany
| | - Roswitha Merle
- Institute for Veterinary Epidemiology and Biostatistics, Freie Universität Berlin, Berlin, Germany
| | - Karsten Tedin
- Centre for Infection Medicine, Institute of Microbiology and Epizootics, Freie Universität Berlin, Berlin, Germany
| | - Franziska Mitrach
- Faculty of Environment and Natural Sciences, Institute of Biotechnology, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany
| | - Antina Lübke-Becker
- Centre for Infection Medicine, Institute of Microbiology and Epizootics, Freie Universität Berlin, Berlin, Germany
| | - Heidrun Gehlen
- Equine Clinic, Surgery and Radiology, Freie Universität Berlin, Berlin, Germany
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23
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Zhang L, Gao J, Barkema HW, Ali T, Liu G, Deng Y, Naushad S, Kastelic JP, Han B. Virulence gene profiles: alpha-hemolysin and clonal diversity in Staphylococcus aureus isolates from bovine clinical mastitis in China. BMC Vet Res 2018; 14:63. [PMID: 29499697 PMCID: PMC5834907 DOI: 10.1186/s12917-018-1374-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Accepted: 02/14/2018] [Indexed: 12/20/2022] Open
Abstract
Background Staphylococcus aureus, a common cause of bovine mastitis, is known for its ability to acquire to antimicrobial resistance and to secrete numerous virulence factors that can exacerbate inflammation. In addition, alpha-hemolysin has an important role in S. aureus infections, diversity of the hla gene (that produces alpha-hmolysin) in S. aureus isolated from bovine mastitis has not been well characterized. The objective was, therefore, to determine diversity of virulence genes, hla gene sequences, and clonal profiles of S. aureus from bovine mastitis in Chinese dairy herds, and to evaluate inter-relationships. Results The antimicrobials resistance varies from as low as 1.9% (2/103) for CTX to as high as 76.7% (79/103) for penicilin in the 103 isolates and 46 (44.7%) S. aureus were determined as multi-resistant isolates with diverse resistance patterns. Thirty-eight virulence gene patterns (with variable frequencies) were identified in the 103 isolates and correlated with MLST types, indicating a great diversity. Although the hla gene also had great diversity (14 genotypes), Hla peptides were relatively more conserved. With 7 clonal complexes identified from 24 spa types and 7 MLST types. Regarding the letter, ST 97 was the dominant type in S. aureus from bovine mastitis in China. Furthermore, based on phylogenetic analysis, there was a distinct evolutionary relationship between the hla gene and MLST. Conclusion Multi-resistant S. aureus occurred in bovine mastitis with diverse resistance patterns. The diversity of virulence gene profiles, especially the hla gene and, their relationship with molecular types were reported for the first time in S. aureus from bovine mastitis, which will be useful for future studies on immunogenicity and vaccine development. In addition, based on the distinct evolutionary relationship between the hla gene and MLST types, we inferred that the hla gene has potential role for molecular typing of S. aureus. Electronic supplementary material The online version of this article (10.1186/s12917-018-1374-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Limei Zhang
- College of Veterinary Medicine, China Agricultural University, Yuan Ming Yuan West Road No. 2, Haidian District, Beijing, 100193, People's Republic of China
| | - Jian Gao
- College of Veterinary Medicine, China Agricultural University, Yuan Ming Yuan West Road No. 2, Haidian District, Beijing, 100193, People's Republic of China
| | - Herman W Barkema
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Tariq Ali
- College of Veterinary Medicine, China Agricultural University, Yuan Ming Yuan West Road No. 2, Haidian District, Beijing, 100193, People's Republic of China
| | - Gang Liu
- College of Veterinary Medicine, China Agricultural University, Yuan Ming Yuan West Road No. 2, Haidian District, Beijing, 100193, People's Republic of China
| | - Youtian Deng
- College of Veterinary Medicine, China Agricultural University, Yuan Ming Yuan West Road No. 2, Haidian District, Beijing, 100193, People's Republic of China
| | - Sohail Naushad
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - John P Kastelic
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada
| | - Bo Han
- College of Veterinary Medicine, China Agricultural University, Yuan Ming Yuan West Road No. 2, Haidian District, Beijing, 100193, People's Republic of China.
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Seilie ES, Bubeck Wardenburg J. Staphylococcus aureus pore-forming toxins: The interface of pathogen and host complexity. Semin Cell Dev Biol 2017; 72:101-116. [PMID: 28445785 DOI: 10.1016/j.semcdb.2017.04.003] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 03/22/2017] [Accepted: 04/18/2017] [Indexed: 12/20/2022]
Abstract
Staphylococcus aureus is a prominent human pathogen capable of infecting a variety of host species and tissue sites. This versatility stems from the pathogen's ability to secrete diverse host-damaging virulence factors. Among these factors, the S. aureus pore-forming toxins (PFTs) α-toxin and the bicomponent leukocidins, have garnered much attention for their ability to lyse cells at low concentrations and modulate disease severity. Although many of these toxins were discovered nearly a century ago, their host cell specificities have only been elucidated over the past five to six years, starting with the discovery of the eukaryotic receptor for α-toxin and rapidly followed by identification of the leukocidin receptors. The identification of these receptors has revealed the species- and cell type-specificity of toxin binding, and provided insight into non-lytic effects of PFT intoxication that contribute to disease pathogenesis.
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Affiliation(s)
- E Sachiko Seilie
- Department of Pediatrics, The University of Chicago, Chicago, IL 60637, United States; Department of Microbiology, The University of Chicago, Chicago, IL 60637, United States
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25
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Liu Y, Shi D, Guo Y, Li M, Zha Y, Wang Q, Wang J. Dracorhodin Perochlorate attenuates Staphylococcus aureus USA300 virulence by decreasing α-toxin expression. World J Microbiol Biotechnol 2016; 33:17. [PMID: 27900629 DOI: 10.1007/s11274-016-2129-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 08/14/2016] [Indexed: 01/08/2023]
Abstract
α-Toxin, a pore-forming toxin secreted by most Staphylococcus aureus, plays critical role in the pathogenesis associated with various infectious diseases. The USA300 which is a major international epidemic methicilin-resisrant S. aureus has spread rapidly to multiple countries and become an emerging public health concern. In this study, the in vitro efficacy of Dracorhodin Perochlorate (DP) against USA300 virulence was evaluated. Using susceptibility testing, immunoblots, rabbit blood haemolytic assay and real-time RT-PCR, we observed that the α-toxin production was decreased when USA300 was co-cultured with different sub-inhibitory concentration of DP. Further, the protective effect of DP against USA300-mediated injury of human alveolar epithelial cells (A549) and MH-S cells was evaluated by cytotoxicity assays, and the result revealed that DP, at final concentration of 16 µg/ml, is a potent antagonist for USA300-mediated cell damage. Importantly, those beneficial effects might partially correlate with hla and RNAIII suppression by DP, leading to the inhibition of α-toxin production in culture supernatant. Overall, these results suggest that DP could attenuate the virulence of USA300 by decreasing α-toxin production without inhibiting bacterial growth, and this compound may represent an ideal candidate for the development of anti-virulence agent combating S. aureus infection.
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Affiliation(s)
- Yumin Liu
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, China.,College of Animal Science and Technology, Changchun University of Science and Technology, Changchun, 130600, China
| | - Dongxue Shi
- Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, 130062, China
| | - Yan Guo
- Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, 130062, China
| | - Meng Li
- Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, 130062, China
| | - Yonghong Zha
- Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, 130062, China
| | - Quankai Wang
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130118, China.
| | - Jianfeng Wang
- Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, 130062, China.
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26
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Staphylococcus aureus Alpha-Toxin Is Conserved among Diverse Hospital Respiratory Isolates Collected from a Global Surveillance Study and Is Neutralized by Monoclonal Antibody MEDI4893. Antimicrob Agents Chemother 2016; 60:5312-21. [PMID: 27324766 PMCID: PMC4997823 DOI: 10.1128/aac.00357-16] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 06/14/2016] [Indexed: 12/13/2022] Open
Abstract
Staphylococcus aureus infections lead to an array of illnesses ranging from mild skin infections to serious diseases, such endocarditis, osteomyelitis, and pneumonia. Alpha-toxin (Hla) is a pore-forming toxin, encoded by the hla gene, that is thought to play a key role in S. aureus pathogenesis. A monoclonal antibody targeting Hla, MEDI4893, is in clinical development for the prevention of S. aureus ventilator-associated pneumonia (VAP). The presence of the hla gene and Hla protein in 994 respiratory isolates collected from patients in 34 countries in Asia, Europe, the United States, Latin America, the Middle East, Africa, and Australia was determined. Hla levels were correlated with the geographic location, age of the subject, and length of stay in the hospital. hla gene sequence analysis was performed, and mutations were mapped to the Hla crystal structure. S. aureus supernatants containing Hla variants were tested for susceptibility or resistance to MEDI4893. The hla gene was present and Hla was expressed in 99.0% and 83.2% of the isolates, respectively, regardless of geographic region, hospital locale, or age of the subject. More methicillin-susceptible than methicillin-resistant isolates expressed Hla (86.9% versus 78.8%; P = 0.0007), and S. aureus isolates from pediatric patients expressed the largest amounts of Hla. Fifty-seven different Hla subtypes were identified, and 91% of the isolates encoded an Hla subtype that was neutralized by MED4893. This study demonstrates that Hla is conserved in diverse S. aureus isolates from around the world and is an attractive target for prophylactic monoclonal antibody (MAb) or vaccine development.
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27
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den Reijer PM, Haisma EM, Lemmens-den Toom NA, Willemse J, Koning RA, Demmers JAA, Dekkers DHW, Rijkers E, El Ghalbzouri A, Nibbering PH, van Wamel W. Detection of Alpha-Toxin and Other Virulence Factors in Biofilms of Staphylococcus aureus on Polystyrene and a Human Epidermal Model. PLoS One 2016; 11:e0145722. [PMID: 26741798 PMCID: PMC4704740 DOI: 10.1371/journal.pone.0145722] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 12/07/2015] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND & AIM The ability of Staphylococcus aureus to successfully colonize (a)biotic surfaces may be explained by biofilm formation and the actions of virulence factors. The aim of the present study was to establish the presence of 52 proteins, including virulence factors such as alpha-toxin, during biofilm formation of five different (methicillin resistant) S. aureus strains on Leiden human epidermal models (LEMs) and polystyrene surfaces (PS) using a competitive Luminex-based assay. RESULTS All five S. aureus strains formed biofilms on PS, whereas only three out of five strains formed biofilms on LEMs. Out of the 52 tested proteins, six functionally diverse proteins (ClfB, glucosaminidase, IsdA, IsaA, SACOL0688 and nuclease) were detected in biofilms of all strains on both PS and LEMs. At the same time, four toxins (alpha-toxin, gamma-hemolysin B and leukocidins D and E), two immune modulators (formyl peptide receptor-like inhibitory protein and Staphylococcal superantigen-like protein 1), and two other proteins (lipase and LytM) were detectable in biofilms by all five S. aureus strains on LEMs, but not on PS. In contrast, fibronectin-binding protein B (FnbpB) was detectable in biofilms by all S. aureus biofilms on PS, but not on LEMs. These data were largely confirmed by the results from proteomic and transcriptomic analyses and in case of alpha-toxin additionally by GFP-reporter technology. CONCLUSION Functionally diverse virulence factors of (methicillin-resistant) S. aureus are present during biofilm formation on LEMs and PS. These results could aid in identifying novel targets for future treatment strategies against biofilm-associated infections.
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Affiliation(s)
- P. M. den Reijer
- Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The Netherlands
- * E-mail:
| | - E. M. Haisma
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
- Department of Dermatology, Leiden University Medical Center, Leiden, The Netherlands
| | - N. A. Lemmens-den Toom
- Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - J. Willemse
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - R. A. Koning
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - J. A. A. Demmers
- Proteomics Centre, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - D. H. W. Dekkers
- Proteomics Centre, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - E. Rijkers
- Proteomics Centre, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - A. El Ghalbzouri
- Department of Dermatology, Leiden University Medical Center, Leiden, The Netherlands
| | - P. H. Nibbering
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - W. van Wamel
- Department of Medical Microbiology and Infectious Diseases, Erasmus University Medical Center, Rotterdam, The Netherlands
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28
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Rao Q, Shang W, Hu X, Rao X. Staphylococcus aureus ST121: a globally disseminated hypervirulent clone. J Med Microbiol 2015; 64:1462-1473. [PMID: 26445995 DOI: 10.1099/jmm.0.000185] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Staphylococcus aureus is a leading cause of bacterial infections in hospitals and communities worldwide. With the development of typing methods, several pandemic clones have been well characterized, including the extensively spreading hospital-associated meticillin-resistant S. aureus (HA-MRSA) clone ST239 and the emerging hypervirulent community-associated (CA) MRSA clone USA300. The multilocus sequence typing method was set up based on seven housekeeping genes; S. aureus groups were defined by the sharing of alleles at ≥ 5 of the seven loci. In many cases, the predicted founder of a group would also be the most prevalent ST within the group. As a predicted founder of major S. aureus groups, approximately 90 % of ST121 strains was meticillin-susceptible S. aureus (MSSA). The majority of ST121 strains carry accessory gene regulator type IV, whereas staphylococcal protein A gene types for ST121 are exceptionally diverse. More than 90 % of S. aureus ST121 strains have Panton-Valentine leukocidin; other enterotoxins, haemolysins, leukocidins and exfoliative toxins also contribute to the high virulence of ST121 strains. Patients suffering from S. aureus ST121 infections often need longer hospitalization and prolonged antimicrobial therapy. In this review, we tried to summarize the epidemiology of the S. aureus clone ST121 and focused on the molecular types, toxin carriage and disease spectrum of this globally disseminated clone.
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Affiliation(s)
- Qing Rao
- Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing, PR China
| | - Weilong Shang
- Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing, PR China
| | - Xiaomei Hu
- Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing, PR China
| | - Xiancai Rao
- Department of Microbiology, College of Basic Medical Sciences, Third Military Medical University, Chongqing, PR China
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29
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Arya R, Ravikumar R, Santhosh RS, Princy SA. SarA based novel therapeutic candidate against Staphylococcus aureus associated with vascular graft infections. Front Microbiol 2015; 6:416. [PMID: 26074884 PMCID: PMC4447123 DOI: 10.3389/fmicb.2015.00416] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 04/20/2015] [Indexed: 12/03/2022] Open
Abstract
Staphylococcus aureus is a common pathogen seen in prosthetic vascular graft, leading to high morbidity and mortality. The virulence genes for severity of infections are under the control of global regulators. Staphylococcal accessory regulator A (SarA) a known master controller of biofilm formation is an attractive target for the drug development. A structure based screening of lead compounds was employed for the identification of novel small molecule inhibitors targeted to interact to the DNA binding domain of the transcriptional activator, SarA and hinder its response over the control of genes that up-regulate the phenotype, biofilm. The top-hit SarA selective inhibitor, 4-[(2,4-diflurobenzyl)amino] cyclohexanol (SarABI) was further validated in-vitro for its efficacy. The SarABI was found to have MBIC50value of 200 μg/ml and also down-regulated the expression of the RNA effector, (RNAIII), Hemolysin (hld), and fibronectin-binding protein (fnbA). The anti-adherence property of SarABI on S. aureus invasion to the host epithelial cell lines (Hep-2) was examined where no significant attachment of S. aureus was observed. The SarABI inhibits the colonization of MDR S. aureus in animal model experiment significantly cohere to the molecular docking studies and in vitro experiments. So, we propose that the SarABI could be a novel substitute to overcome a higher degree of MDR S. aureus colonization on vascular graft.
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Affiliation(s)
- Rekha Arya
- Quorum Sensing Laboratory, Centre for Research on Infectious Diseases, School of Chemical and Biotechnology, SASTRA University Thanjavur, India
| | - R Ravikumar
- Department of Chemistry, SASTRA University Thanjavur, India
| | - R S Santhosh
- Genetic Engineering Laboratory, Centre for Research on Infectious Diseases, School of Chemical and Biotechnology, SASTRA University Thanjavur, India
| | - S Adline Princy
- Quorum Sensing Laboratory, Centre for Research on Infectious Diseases, School of Chemical and Biotechnology, SASTRA University Thanjavur, India
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Arroliga AC, Velazco JF, Midturi JK, Ghamande SA. Back to the future: α-hemolysin activity on blood agar to predict ventilator-associated pneumonia caused by Staphylococcus aureus. Am J Respir Crit Care Med 2015; 190:1086-8. [PMID: 25398106 DOI: 10.1164/rccm.201410-1886ed] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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