The Distribution of 18 Enterotoxin and Enterotoxin-Like Genes in Staphylococcus aureus Strains from Different Sources in East China

Abstract

The distribution of 18 staphylococcal enterotoxin (SE) or SE-like (SEl) genes in Staphylococcus aureus strains from different sources in east China was investigated. Among all 496 S. aureus strains, 291 strains carried one or more SE genes. The more frequently occurred genes were sea, seb, seg, selk, sell, selm, selo, and seq; the less frequent occurred genes were sec, selj, and ser. The classic SE genes and the enterotoxin gene cluster (egc) (seg, sei, selm, seln, selo, and/or selu) accounted for 25.67% and 61.68% of all detected genes, respectively. There were three gene clusters (egc, sea-sek-seq, and sed-sej-ser), of which the egc cluster was the important one that could generate novel complexes, and the sea-sek-seq cluster was a close relative to the hospital-acquired methicillin-resistant S. aureus. The SE gene distributions were different among strains of different sources and formed diverse toxin gene profiles. The human- and foodborne-origin strains harbored classic and novel SE and SEl genes, whereas animal-origin strains harbored egc and other novel SE and SEl genes mainly. The foodborne- and human-origin strains were the main dangerous factors of classic staphylococcal foodborne poisoning, whereas the strains (especially from animals) that carried egc and other novel genes mainly should be new potential dangerous factors for food safety.

Antimicrobial resistance and prevalence of CvfB, SEK and SEQ genes among Staphylococcus aureus isolates from paediatric patients with bloodstream infections

“…The prevalence of SEQ and SEK among the isolates in the present study was 34.0 and 35.8%, respectively, which represented similar frequencies to those previously reported (31.1 and 34.4%, respectively) for Korean patients with bacteraemia in intensive care units in 2001 and 2008 (28). Typically, genes of the SEA-SEK-SEQ cluster are present together in a phage φ3 genomic island (29)(30)(31) and are closely associated with the hospital-acquired MRSA SCCmec III clone (32)(33)(34)(35). In the present study, the presence of SEK + SEQ was only identified in MRSA isolates, which supported previous speculations.…”

Prevalence and Characterization of Staphylococcus aureus Cultured From Raw Milk Taken From Dairy Cows With Mastitis in Beijing, China

“…This finding is similar to those in previous reports from China and Australia, whereas the sed gene was mainly detected among isolates from raw milk samples in Poland (Rola et al, 2015 ; Song et al, 2015 ; McMillan et al, 2016 ; Liu et al, 2017 ). Meanwhile, another Chinese study reported that the seb gene was the most commonly detected (Cheng et al, 2016 ). Additionally, the prevalence rates of the sec gene from farm A (84.9%) was higher than from farm B (4.3%) ( p < 0.05).…”

“…Several studies examined for the presence of SEs genes among S. aureus cultured from raw milk and their food products (Asao et al, 2003 ; Song et al, 2015 ; Cheng et al, 2016 ; Liu et al, 2017 ). However, few reports assessed the enterotoxin producing capacity of these isolates in China.…”

Strain typing and characterization of virulence genes in clinicalStaphylococcus aureusisolates from Kenya

“…SEQ and SEK toxin genes were reported to significantly cooccur in Chinese MRSA isolates [73]. These toxins co-occur on genomic islands and have been associated with the HA SSC mec II clone [21,66]. CC 8 isolates have been reported to consistently bear SEQ, SEL and SEK toxin genes [19].…”