Abstract:
Staphylococcus aureus is one of the important pathogens involved in food related diseases and common community associated infections. This organism proliferates in food and causes food-borne illnesses. Milk serves as an ideal medium for growth of many microorganisms including Staphylococcus aureus.
This study was conducted to isolate Staphylococcus aureus from raw cow milk and studying its antibiotics susceptibility and was to detect the specific mecA gene in the Staphylococcus aureus isolates.
Two hundred raw cow milk samples were collected from four areas throughout Ghebaish locality under aseptic precautions and processed under standard bacteriological techniques. The samples were investigated for the presence of Staphylococci. The Baird Parker Agar and Mannitol salt Agar were
used as selective media for isolation. The presumptive isolates were identified on the basis of their morphological, cultural and biochemical characteristics. The sensitivity pattern of S. aureus with different antimicrobial agents was evaluated by disk diffusion method. Forty five (22%) Staphylococci isolates were obtained and confirmed by biochemical tests, 33 (73%) isolates were Staphylococcus aureus, 12 (26%) isolates were Staphylococcus epidermities.
The results of sensitivity test revealed high resistance of antibiotics used. The two organisms were showed resistant to Streptomycin (0%), Vancomycin (78% - 100%), methicillin (18% - 25%) and penicillin (100%).
Bacterial DNA was extracted from each isolate using boiling method. PCR was used to detect mecA gene. The results indicated 23 isolates were positive to mecA gene (69%).The mecA gene sequence of S. aureus showed high similarities with those recorded in gene bank.
It is concluded that, S. aureus appeared to be a major frequent bacterial contaminant of raw cow milk reflecting potential public health threat, the result of antibiotics sensitivity testing showed variable response, multi-drug resistance, Bacterial DNA extracted from Staphylococcus aureus reflected appearance of mecA gene which was responsible of resistance to methicillin. and it is recommended that the full dose treatment need be observed and ensured as well as raising awareness of sanitary behavior.
