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.
Highlights
IntroductionAureus was occurred through the infection of the mammary gland or by bad sanitary conditions, during or after milking, and these happened by human activity who responsible for the contamination (Rehman et al, 2014)
Milk is an imperative food because it is rich by various essential components including proteins, vitamins, and minerals it considers a nutritive media for many microorganisms such as Staph. aureus which mainly criminalized in food poisoning cases (Pandey et al, 2014), because it can adapt to grow in various types of foods and secreting enterotoxins (Balaban and Rasooly,2000)
The data postulated in Table (3) and Fig (3&4) revealed that enterotoxin genes were detected in 8 out of 15 Staph. aureus isolates (53.33%) from raw milk samples and 3 out of 7 Staph. aureus isolates (42.86%) from local pasteurized milk samples, sea and sed genes were detected in most Staph. aureus isolates, sec gene could be detected only in the raw milk isolates while seb and see genes were not detected in any Staph. aureus isolates from both raw and local pasteurized milk
Summary
Aureus was occurred through the infection of the mammary gland or by bad sanitary conditions, during or after milking, and these happened by human activity who responsible for the contamination (Rehman et al, 2014). Staphylococcal enterotoxins resists the majority of proteolytic enzymes and remains their action in gastrointestinal tract. They are highly heat resistant toxin (Sutejo et al, 2017), they keep their activities even after pasteurization (Ralln et al, 2008).The SEs toxins resulting in nausea, brutal vomiting, abdominal pain and occasionally diarrhea (Rosengren et al, 2013). Aureus usually carried out by traditional methods but these methods were discomfit and time consuming. In the last 10 years, unrestricted detection methods using molecular techniques, suth as polymerase chain reaction (PCR) method multiplex PCR was proven as one of the most suitable way for sensitive and fast detection of pathogenic bacteria in food (Shawish and Al-Humam, 2016 and Kim et al, 2017)
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