Host- and Tissue-Specific Pathogenic Traits of Staphylococcus aureus

ABSTRACT Comparative genomics were used to assess genetic differences between Staphylococcus aureus strains derived from infected animals versus colonized or infected humans. A total of 77 veterinary isolates were genetically characterized by high-throughput amplified fragment length polymorphism (AFLP). Bacterial genotypes were introduced in a large AFLP database containing similar information for 1,056 human S. aureus strains. All S. aureus strains isolated from animals in close contact with humans (e.g., pet animals) were predominantly classified in one of the five main clusters of the AFLP database (cluster I). In essence, mastitis-associated strains from animals were categorized separately (cluster IVa) and cosegregated with bacteremia-associated strains from humans. Distribution of only 2 out of 10 different virulence genes differed across the clusters. The gene encoding the toxic shock syndrome protein (tst) was more often encountered among veterinary strains (P < 0.0001) and even more in the mastitis-related strains (P<0.0001) compared to human isolate results. The gene encoding the collagen binding protein (cna) was rarely detected among invasive human strains. The virulence potential, as indicated by the number of virulence genes per strain, did not differ significantly between the human- and animal-related strains. Our data show that invasive infections in pets and humans are usually due to S. aureus strains with the same genetic background. Mastitis-associated S. aureus isolated in diverse farm animal species form a distinct genetic cluster, characterized by an overrepresentation of the toxic shock syndrome toxin superantigen-encoding gene.

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Superantigen genes encoded by the egc cluster and SaPIbov are predominant among Staphylococcus aureus isolates from cows, goats, sheep, rabbits and poultry

Journal of Medical Microbiology ◽

10.1099/jmm.0.45863-0 ◽

2005 ◽

Vol 54 (4) ◽

pp. 401-411 ◽

Cited By ~ 79

Author(s):

Davida S Smyth ◽

Patrick J Hartigan ◽

William J Meaney ◽

J Ross Fitzgerald ◽

Claudia F Deobald ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Toxic Shock Syndrome ◽

T Cell Proliferation ◽

Animal Disease ◽

Toxic Shock ◽

Gene Encoding ◽

Animal Hosts ◽

Toxic Shock Syndrome Toxin ◽

Staphylococcal Toxic Shock Syndrome ◽

Encoding Genes

In recent years several new staphylococcal enterotoxins (SEs) have been described, which currently have largely unknown frequencies of occurrence and roles in human or animal disease. One hundred and ninety-one Staphylococcus aureus isolates from cows (99), goats (39), sheep (23), rabbits (15), chickens (15) and a cat (1) were screened for SE genes sea–see, seg–seo and seq and for the tst gene encoding staphylococcal toxic shock syndrome toxin-1 using multiplex PCRs and individual PCRs for the seb and sek genes. One hundred and ten isolates tested positive for at least one of these 16 superantigen (SAg)-encoding genes. There were statistically significant differences in the frequencies of some of these SAg genes between isolates from different animals. No strain possessed either the sea or see gene. The sec gene was present in 51 isolates, the sed gene in eight and the seb gene in one. The seh gene was found in four strains and the sek and seq genes together in one isolate. The most common combinations of genes were the egc cluster, bearing the seg, sei, sem, sen and seo genes, in 47 isolates, the sec, sel and tst gene combination typical of the SaPIbov pathogenicity island in 44 isolates, the egc cluster lacking the seg gene in 11 isolates, the sed and sej genes in nine isolates, and the sec and tst genes without the sel gene in seven isolates. The higher frequencies of the sec and tst genes together and the lower frequencies of the egc gene cluster among the SAg gene-positive sheep or goat isolates compared to bovine isolates were statistically significant. Of 36 bovine isolates that were mitogenic for human T lymphocytes, four were negative for the 16 SAg genes tested for, while a further 14 gave borderline results in the mitogenicity assay, 12 of which were SAg gene-negative. Twenty-nine strains lacking all the SAg genes did not induce T-cell proliferation. This survey indicates that novel SE genes seg, sei, sel, sem, sen and seo along with the sec and tst genes predominate in S. aureus from animal hosts. The mitogenicity assays indicate that further uncharacterized SAgs may be present in bovine isolates.

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MOLECULAR CHARACTERIZATION OF METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS ISOLATED FROM CLINICAL CASES IN EAST ALGERIA

Asian Journal of Pharmaceutical and Clinical Research ◽

10.22159/ajpcr.2017.v10i1.11856 ◽

2016 ◽

Vol 10 (1) ◽

pp. 59

Author(s):

Rahima Touaitia ◽

Soumia Bektache ◽

Nafissa Boutefnouchet ◽

Abdelghani Djahoudi ◽

Mohamed Bachtarzi

Keyword(s):

Staphylococcus Aureus ◽

Toxic Shock Syndrome ◽

Methicillin Resistant Staphylococcus Aureus ◽

Methicillin Resistance ◽

Meca Gene ◽

Toxic Shock ◽

Gene Encoding ◽

Methicillin Resistant ◽

Toxic Shock Syndrome Toxin ◽

Phenotypic Methods

ABSTRACTObjective: The purpose of this study is to investigate the methicillin resistance gene, and some virulence factors in methicillin-resistant Staphylococcusaureus (MRSA) isolates by polymerase chain reaction (PCR).Methods: This study has included 12 MRSA isolates. All isolates were previously identified as S. aureus by a standard microbiological procedure, anda detection of methicillin resistance was realized by phenotypic methods. Following genomic DNA extraction, the presence of gyrA, mecA, lukPV, andtst genes was analyzed by duplex PCR. All retained S. aureus species have been found to contain gyrA gene.Results: Ten stains have been found to harbor mecA gene indicating it’s responsibility for methicillin resistance in those strains. Among the 12 strains,six of which were found to be Panton-Valentine leukocidine positive while none of which has tst gene encoding the toxic shock syndrome toxin.Conclusion: The pathogenesis of MRSA infections is related to the expression of a wide variety of virulence factors.Keywords: Methicillin-resistant Staphylococcus aureus, Panton-Valentine leukocidine, Toxic shock syndrome toxin 1, Multidrug resistance, mecA.

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Temporal and Racial Differences Associated with Atopic Dermatitis Staphylococcus aureus and Encoded Virulence Factors

mSphere ◽

10.1128/msphere.00295-16 ◽

2016 ◽

Vol 1 (6) ◽

Cited By ~ 9

Author(s):

Joseph A. Merriman ◽

Elizabeth A. Mueller ◽

Michael P. Cahill ◽

Lisa A. Beck ◽

Amy S. Paller ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Atopic Dermatitis ◽

Gene Cluster ◽

Virulence Factors ◽

Toxic Shock Syndrome ◽

Enterotoxin Gene ◽

Toxic Shock ◽

Gene Encoding ◽

Content Type ◽

Toxic Shock Syndrome Toxin

ABSTRACT Monitoring pathogen emergence provides insight into how pathogens adapt in the human population. Secreted virulence factors, important contributors to infections, may differ in a manner dependent on the strain and host. Temporal changes of Staphylococcus aureus toxigenic potential, for example, in encoding toxic shock syndrome toxin 1 (TSST-1), contributed to an epidemic of TSS with significant health impact. This study monitored changes in atopic dermatitis (AD) S. aureus isolates and demonstrated both temporal and host infection differences according to host race based on secreted superantigen potential. The current temporal increase in enterotoxin gene cluster superantigen prevalence and lack of the gene encoding TSST-1 in AAs predict differences in infection types and presentations. Atopic dermatitis (AD) is an inflammatory skin condition strongly associated with Staphylococcus aureus colonization and infection. S. aureus strains shift in populations in ~10-year intervals depending on virulence factors. Shifts in S. aureus virulence factors may in part explain the racial differences observed in the levels of prevalence and severity of AD. AD S. aureus isolates collected from 2011 to 2014 (103 isolates) and in 2008 (100 isolates) were examined for the prevalence of genes encoding superantigens (SAgs). The strains from 2011 to 2014 were obtained from AD patients as a part of the National Institute of Allergy and Infectious Diseases (NIAID) Atopic Dermatitis Research Network (ADRN). The prevalence of SAg genes was investigated temporally and racially. The enterotoxin gene cluster (EGC) was more prevalent in the 2011–2014 AD isolates than in the 2008 AD isolates. The prevalences of virulence factor genes were similar in European American (EA) and Mexican American (MA) patients but differed in 6 of 22 SAg genes between EA and African American (AA) or MA and AA isolates; notably, AA isolates lacked tstH, the gene encoding toxic shock syndrome toxin 1 (TSST-1). The presence of tstH and sel-p (enterotoxin-like P) was associated with decreased clinical severity and increased blood eosinophils, respectively. The EGC is becoming more prevalent, consistent with the previously observed 10 years of cycling of S. aureus strains. Race-specific S. aureus selection may account for differences in virulence factor profiles. The lack of TSST-1-positive (TSST-1+) AD S. aureus in AA is consistent with the lack of AAs acquiring TSST-1-associated menstrual toxic shock syndrome (TSS). IMPORTANCE Monitoring pathogen emergence provides insight into how pathogens adapt in the human population. Secreted virulence factors, important contributors to infections, may differ in a manner dependent on the strain and host. Temporal changes of Staphylococcus aureus toxigenic potential, for example, in encoding toxic shock syndrome toxin 1 (TSST-1), contributed to an epidemic of TSS with significant health impact. This study monitored changes in atopic dermatitis (AD) S. aureus isolates and demonstrated both temporal and host infection differences according to host race based on secreted superantigen potential. The current temporal increase in enterotoxin gene cluster superantigen prevalence and lack of the gene encoding TSST-1 in AAs predict differences in infection types and presentations.

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