PCR Primers for the Detection of Staphylococcal Enterotoxins K, L, and M and Survey of Staphylococcal Enterotoxin Types in Staphylococcus aureus Isolates from Food Poisoning Cases in Taiwan

Abstract

Staphylococcal enterotoxins (SEs) are important causative agents in gastroenteritidis and food poisoning cases. They are serologically grouped into five major classical types, i.e., SEA, SEB, SEC, SED, and SEE. In addition, new SEs, such as SEG through SEM, have recently been identified and characterized. In an attempt to survey the distribution of classical and new SEs in organisms responsible for staphylococcal infections in Taiwan, we developed PCR primers for the genes that define the SEK, SEL, and SEM types. Bacterial strains other than sek, sel, and sem Staphylococcus aureus, including strains of other Staphylococcus species, did not generate any false-positive results when examined with these primers. The expression potential for the sek, sel, and sem types were also determined by reverse transcription-PCR. Together with the PCR primers specific for the classical SEs and other new SEs, including SEG, SEH, SEI, and SEJ, we surveyed the SE genes in S. aureus strains isolated from food poisoning cases. For 147 S. aureus isolates originating from food poisoning cases, 109 (74.1%) were positive for one or more SE genes. Of them, the major classical enterotoxin type was sea (28.6%), followed by seb (20.4%), sec (8.2%), and sed (2.0%). For the new SE types, sei (30.6%) was detected the most often, followed by sek (18.4%), sem (12.9%), and sel (8.2%). Also, 64 (43.5%) of the total bacterial strains had more than one enterotoxin gene.

Antibiotic Resistance and Molecular Analysis of Staphylococcus aureus Isolated from Cow's Milk and Dairy Products in Northeast Brazil

“…However, the predominance of pulsotypes (A, B, C, and I) that harbor SE genes supports the theory that superantigenic toxins are important for pathogenesis of the udder (5,15). In our study, the seg + sei combination, with or without other genes, was the most prevalent (48.9%) and was often detected in strains isolated from cases of food poisoning (6,8,42). The involvement of staphylococcal enterotoxin H in staphylo coccal food poisoning has been proposed because it was detected in foods responsible for two outbreaks (23,25).…”

Molecular analysis of Staphylococcus aureus pathogenicity islands (SaPI) and their superantigens combination of food samples

“…Furthermore, as described earlier, staphylococcal diseases related to SAg, such as foodpoisoning and TSST-1, may result from a complex phenotype caused by multiple toxins (Orwin et al, 2001). Considering this data, however, it should be reminded that S. aureus strains with high isolation frequency and high enterotoxin productivity does not mean that these strains cause a high number of food-poisoning cases or outbreaks (Cihang et al, 2006).…”

“…However, 6 S. aureus strains with the tst gene were detected without sec and sell, because the latter are encoded on SaPI2 (Novick et al, 2010). Cihang et al (2006) analysed S. aureus isolates from foodpoisoning cases in Taiwan and found strains were positive for at least one SE or tst gene. Our results showed that SaPI4 did not contain any superantigen gene and this finding is in full agreement with Argudin et al (2010) and Novick et al (2010).…”

Enterotoxigenic coagulase positive Staphylococcus in milk and milk products, lben and jben, in northern Morocco

“…The PCR mixture consisted of 0.25 µl of primer 1 (100 pmol /µl), 0.25µl of primer 2 (100 pmol/µl), 2 µl of deoxynucleoside triphosp hate (2.5 mmol/liter), 2.5 µl of 10 x thermophilic buffer, 1. [25] d [26] Germany) with the program shown in Table 1.…”