Detection of Enterotoxin Genes in Staphylococcus Aureus Isolated From Cow Milk

Abstract

Staph. aureus is considered one of the main causes of food poisoning and clinical infections in different hosts. So this work intended to investigate the occurrence of enterotoxin genes and antibiotics susceptibility of Staph aureus isolated from raw and local pasteurized milk. To realize this, 125 samples of raw milk and 75 samples of local pasteurized milk were obtained from supermarkets, dairy shops and farms in Sohag Province, Egypt. These samples were subjected to bacteriological examination. The result showed that 68 out of 125 raw milk samples and 37 out of 75 local pasteurized milk samples were positive for Staphylococcus spp. on mannitol salt agar. Biochemical scheme supposed that 18 isolates of raw milk samples and 8 isolates of local pasteurized milk samples were positive for staph aureus. PCR by using nuc gene specific primer, discriminated the existence of Staph aureus DNA in 15 isolates out of 18 isolates of raw milk samples, while 7 isolates out of 8 isolates of local pasteurized milk samples showed a postive bands at 267bp. Staphylococcal enterotoxin genes were detected in 53.33% and 42.86% of Staph aureus isolates from raw and local pasteurized milk, respectively. sea and sed genes were detected in most isolates of Staph aureus while none of these isolates harbored seb and see genes. sec gene could be detected only in the raw milk isolates. The antibiotics sensitivity profile of enterotoxigenic Staph aureus was showed a high percentage of resistance to penicillin and tetracycline while all isolates were fully susceptible to vancomycin.