الفهرس 
Cover Page Title in EnglishOnly 14 pages are availabe for public view
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Abstract
Mastitis is a serious problem in dairy farms not only for the associated economic losses but also because of its hazards of zoonotic diseases. S. aureus is considered one of the most important and widespread pathogens causing mastitis. The antimicrobial resistant poses a threat to human and animal health due to the antibiotic resistant bacteria carried by animals can enter human food chain through the consumption of meat or other animal products, through farm runoff water, and by other pathways, on the other hand food animals and food of animal origin are traded worldwide. Thus, the occurrence of antimicrobial resistance in one country is a serious problem for all countries. Consequently, antibiotic resistance genes, if transferred to human microflora, may reduce efficacy of treatment for infectious diseases. In this study the prevalence, virulence and antibiotic resistance of isolated S. aureus from clinical mastitis milk collected from different private and governmental farms located at El Bohera governorate was the aim. Bacteriological examination of 117 clinical mastitis milk samples yielded 33 isolates with an incidence of 28.2% were suspected to be staphylococci since these isolates showed pigmentation characteristics and were Gram-positive cocci. Ten isolates with an incidence of 30.3% out of the 33 suspected isolates produced black, shiny, convex colonies with entire margins and clear zones surrounding the colonies with or without an opaque zone after aerobic incubation of these isolates on Baired-Parker’s agar media for 24-48 hours at 37 oC. The observation of colonies made it possible provisional identification of S. aureus. Ten isolates with an incidence of 30.3% out of the 33 suspected isolates were positive for coagulase activity using the tube coagulase test (TCT) and slide coagulase test. Results detected the presence of pathogens. The test is inexpensive and easy to perform with limited laboratory facilities. PCR technique was used as confirmatory, rapid, sensitive and specific tool to detect S. aureus specific sequence gene (Sa), clumping factor A (clfA) gene, S. aureus protein A gene spa and Integron class -1 gene in 10 S. aureus bacteriologically positive samples. The technique used was PCR using specific primers. All isolates were positive for (Sa) and (clfA) gene, nine isolates were positive for spa gene and unfortunately, all isolate included in this study exhibited a negative PCR reaction with the Integron class -1 gene which need more studies. In vitro sensitivity of the S. aureus isolates to various antimicrobial agents revealed that among the 10 S. aureus isolates, one was resistance to all the antibiotics used in this study. Cephalothin (DF30), Ampicillin/sulbactam (SAM), Amoxicillin-Clavulanic acid (AMC30), Trimethoprime-Sulphamethaxole (SXT25µg) and Methicillin (DP5µg) were the most effective antibiotics for S. aureus strains. Susceptibility rates of S. aureus to these antibiotics were: 90% for Cephalothin (DF30), 80% for Ampicillin/sulbactam (SAM), for Methicillin (DP5µg and for Amoxicillin-Clavulanic acid (AMC30)) and 70% for trimethoprim-sulphamethoxazole (SXT25µg). Higher resistance was observed to Kanamycin (K30µg), Tetracycline (Te30µg), Erythromycin (E15µg), Cefotasime (CTX30µg), Cefoperazone (CEP75µg), Ampicillin (AMP10µg), Gentamicin (GN10µg), Amoxicillin (AX25µg) and Ciprofloxacin (CIP5µg), Susceptibility rates of S. aureus to these antibiotics were: 30, 30, 30, 40, 40, 40, 40, 40 and 50%, respectively.