Superantigen gene profiles and presence of exfoliative toxin genes in community-acquired meticillin-resistant Staphylococcus aureus isolated from Chinese children

Wu, Dejing; Li, Xiangmei; Yang, Yonghong; Zheng, Yaojie; Deng, Li; Liu, Lan; Li, Changcong; Shang, Yunxiao; Zhao, Chuanqi; Yu, Sangjie; Shen, Xuzhuang

doi:10.1099/jmm.0.023465-0

Cited by 73 publications

(57 citation statements)

References 38 publications

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“…Several epidemiological studies have shown that sel-k is one of the most prevalent enterotoxin genes in clinical isolates of S. aureus (10,(12)(13)(14)(15)(16). Moreover, in several of these studies, SEl-K was significantly associated with CA-MRSA strains (10,15,16), which included USA300, USA400, and other clones.…”

Section: Discussionmentioning

confidence: 85%

“…Epidemiological studies have demonstrated the SEl-K-encoding genes to be among the most common SE genes in S. aureus clinical isolates (10-14). Additionally, SEl-K is the only SE gene to our knowledge that is significantly associated with community-acquired methicillin-resistant S. aureus (CA-MRSA) strains of several clonal lineages (10,15,16). Interestingly, the neighboring SEl-Q enterotoxin is not significantly associated with MRSA (10).…”

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confidence: 99%

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Detection and Measurement of Staphylococcal Enterotoxin-Like K (SEl-K) Secretion by Staphylococcus aureus Clinical Isolates

et al. 2014

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SEl-K is commonly present in more than half of all Staphylococcus aureus clinical isolates and is present in almost all USA300 community-acquired methicillin-resistant S. aureus (CA-MRSA) isolates. Sequencing of the sel-k gene in over 20 clinical isolates and comparative analysis with all 14 published sel-k sequences indicate that there are at least 6 variants of the sel-k gene, including one that is conserved among all examined USA300 strains. Additionally, we have developed a highly sensitive enzyme-linked immunosorbent assay (ELISA) that specifically detects and measures SEl-K protein in culture supernatants and biological fluids. Quantification of in vitro SEl-K secretion by various S. aureus isolates using this novel capture ELISA revealed detectable amounts of SEl-K secretion by all isolates, with the highest secretion levels being exhibited by MRSA strains that coexpress SEB. In vivo secretion was measured in a murine thigh abscess model, where similar levels of SEl-K accumulation were noted regardless of whether the infecting strain exhibited high or low secretion of SEl-K in vitro. We conclude that SEl-K is commonly expressed in the setting of staphylococcal infection, in significant amounts. SEl-K should be further explored as a target for passive immunotherapy against complicated S. aureus infection. Staphylococcus aureus can express a large and diverse repertoire of virulence factors, including many different surface proteins, enzymes, and secreted toxins (1). Among the most potent of these virulence factors are the members of a family of secreted, heatstable proteins known as enterotoxins. More than 20 staphylococcal enterotoxins (SEs) have been discovered that demonstrate superantigenic (SAg) properties against T cells (2, 3). Superantigens can activate 20% to 50% of the T cell population by bypassing the traditional pathway of major histocompatibility complex (MHC)-dependent presentation of antigens to T cell receptors (TCRs). Instead, superantigens bind simultaneously to MHC class II (MHC-II) and TCRs, outside their antigen-binding groove, resulting in an excessive inflammatory response that can lead to toxic shock, multiorgan failure, and death. Superantigens are also associated with other immune-mediated diseases, including Kawasaki disease, atopic dermatitis, and chronic rhinosinusitis (4).The classical superantigens toxic shock syndrome toxin 1 (TSST-1), SEA, and SEB have been extensively studied due to their causative roles in toxic shock syndrome and food poisoning (5). However, advancements in sequencing methodologies have enabled the discovery of many more SEs whose roles in pathogenesis remain unknown (6). One of these toxins, SEl-K, has been shown to exhibit superantigenic properties, including V␤-specific T cell activation, pyrogenicity, emesis, and lethality in primates (7-9). Epidemiological studies have demonstrated the SEl-K-encoding genes to be among the most common SE genes in S. aureus clinical isolates (10-14). Additionally, SEl-K is the only SE gene to our knowledge that is si...

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Section: Discussionmentioning

confidence: 85%

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confidence: 99%

Detection and Measurement of Staphylococcal Enterotoxin-Like K (SEl-K) Secretion by Staphylococcus aureus Clinical Isolates

et al. 2014

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“…S. aureus isolates (n5108) were selected randomly for PCR amplification of 30 genetic determinants. Amplification of super antigen genes (sea, seb, sed, see, seg, seh, sei, sej, sek, sem, sen, seo, sep, seq and tst), a glutathione peroxidase gene (bsaA) and a leukotoxin gene (lukE) were carried out as described previously by Diep et al (2006) and Wu et al (2011). Adhesin genes (clfA, clfB, cna, fnbA, sdrC, sdrD and sdrE) and other virulence factor genes (icaA and arcA) were amplified according to the method of Campbell et al (2008).…”

Section: Methodsmentioning

confidence: 99%

Phenotypic and molecular characterization of Staphylococcus aureus recovered from different clinical specimens of inpatients at a teaching hospital in Shanghai between 2005 and 2010

Yan

et al. 2013

Journal of Medical Microbiology

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Staphylococcus aureus, including meticillin-sensitive and -resistant S. aureus (MSSA and MRSA, respectively), is associated with severe nosocomial human infections. This study aimed to investigate the molecular profile, including the dynamic changes and genotype/phenotype correlation, of S. aureus isolates recovered from different clinical specimens of inpatients with S. aureus infection over a 6-year span at a teaching hospital in Shanghai, China. Between 2005 and 2010, a random sample of 610 unique S. aureus isolates was collected from different clinical samples of inpatients with S. aureus infection for molecular and antibiotic susceptibility analysis. The results showed that, among the 610 S. aureus isolates, 20 sequence types (STs) determined by multi-locus sequence typing (primarily ST239, ST5, ST7, ST188 and ST398) and 52 spa types (primarily t002, t037, t030 and t601) were found. In total, 444 isolates (72.8 %) were MRSA and 166 (27.2 %) were MSSA. ST239-MRSA-III-spa t037 and ST5-MRSA-II-spa t002 were the predominant MRSA clones. From 2005 to 2010, spa t002, spa t037 and their corresponding STs (ST5 and ST239) were the most frequent clones among all of the S. aureus isolates and showed the most resistant phenotypes to various antibiotics. Generally, the different genotypes showed different drug resistance rates, but no isolates were resistant to vancomycin, teicoplanin or linezolid. The profiles of virulence and resistance genes differed by genetic background, with the ST239 and ST5 strains showing higher resistance rates to gentamicin, cefoxitin, ampicillin, cefazolin, erythromycin, clindamycin and levofloxacin than strains of other types. Moreover, the antiseptic resistance genes qacA/B were generally associated with these two types. The prevalence of STs was different among different clinical specimens and also changed by year. Recently (2009Recently ( -2010, the distribution of predominant MRSA clones decreased, whilst the prevalence of non-predominant MSSA clones increased, especially for the isolates causing bacteraemia. Continual monitoring of clinical isolates is necessary to develop and maintain an effective strategy against S. aureus infection in the hospital setting.

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“…DNA for polymerase chain reaction (PCR) was extracted as previously described (Wu et al, 2011) and immediately used for PCR or stored at -20°C. The presence of mecA was determined via PCR using a primer, as described elsewhere (Oliveira and de Lencastre, 2002).…”

Section: Detection Of Meca and Virulence And Erm Genesmentioning

confidence: 99%

Molecular analysis and frequency of Staphylococcus aureus virulence genes isolated from bloodstream infections in a teaching hospital in Tianjin, China

Hu²,

Ym³

et al. 2013

Genet. Mol. Res.

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ABSTRACT. Staphylococcus aureus is an important cause of bloodstream infections worldwide. We examined the prevalence of genes that encode erythromycin ribosome methylase and bacterial toxins in S. aureus collected from bloodstream infections. Sixty different S. aureus isolates were obtained from blood cultures of patients who were admitted to a Teaching Hospital in Tianjin from January 2006 to August 2011. The susceptibility of the isolates to 16 antibiotics was tested. Methicillin-resistant S. aureus (MRSA) was identified using the disk diffusion method with cefoxitin. PCR was used to detect genes that encode the staphylococcal enterotoxins, Panton-Valentine leukocidin, toxic shock syndrome toxin 1 and erythromycin ribosome methylase. Molecular analysis of the MRSA strains was done using pulsed-field gel electrophoresis (PFGE) and staphylococcal cassette chromosome mec (SCCmec) typing. The positivity rates of mecA, ermA, ermB, and ermC in the isolates were 13/60, 10/60, 18/60, and 18/60, respectively. Among the ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 12 (1): 646-654 (2013) Virulence genes of Staphylococcus aureus 647 60 isolates, 30 harbored enterotoxin genes, with sea as the most frequent toxin gene (33%), followed by sec (15%), sed (12%), and seb (5%). The see and tst genes were not found in any of the isolates. The pvl gene was detected in four strains. Eleven MRSA isolates were of the SCCmec type III; two MRSA isolates could not be determined through SCCmec typing. PFGE analysis of the 13 MRSA isolates produced 8 distinct pulsotypes. Virulence genes and erythromycin ribosome methylase genes were highly prevalent in these isolates. The PFGE results demonstrated that the MRSA spread through cloning, mainly involving SCCmec type III.

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Superantigen gene profiles and presence of exfoliative toxin genes in community-acquired meticillin-resistant Staphylococcus aureus isolated from Chinese children

Cited by 73 publications

References 38 publications

Detection and Measurement of Staphylococcal Enterotoxin-Like K (SEl-K) Secretion by Staphylococcus aureus Clinical Isolates

Detection and Measurement of Staphylococcal Enterotoxin-Like K (SEl-K) Secretion by Staphylococcus aureus Clinical Isolates

Phenotypic and molecular characterization of Staphylococcus aureus recovered from different clinical specimens of inpatients at a teaching hospital in Shanghai between 2005 and 2010

Molecular analysis and frequency of Staphylococcus aureus virulence genes isolated from bloodstream infections in a teaching hospital in Tianjin, China

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