Studies on antimicrobial resistance and virulence profiling of staphylococcus aureus recovered from milk and its public health impact /
دراسات على المقاومة لمضادات الميكروبات و سمات الضراوة لميكروب استافيلوكوكس أورياس المعزولة من الألبان وتأثيرها على الصحة العامة
Heba Sobhy Ibrahim Mahrous ; Supervised Khaled Farouk Mohamed Elamry , Ahmed Orabi Hassan Mohamed
- Cairo : Heba Sobhy Ibrahim Mahrous , 2020
- 94 P. : charts , facimiles ; 25cm
Thesis (Ph.D.) - Cairo University - Faculty of Veterinary Medicine - Department of Microbiology
Among common listed etiological agents causing contagious bovine mastitis, Staphylococcus aureus is topping the list. In addition, they are known to precipitately acquire resistance to accessible antimicrobial agents which in turn upsurge its public health risk and associated consequences. This study investigated S. aureus existence in raw milk samples gathered from 103 cows in dairy farms in Egypt, and disclosed its antimicrobial resistance profile, and related virulence/resistance-encoding genes. Conventional laboratory tests as well as the vitek2 compact system were used to determine and screen the isolates. S. aureus was isolated from (188) mastitis and (224) sub-clinically mastitis milk samples with an incidence of 50% (n=94) and 17.5% (n=39) respectively. Out of 133 positive S. aureus isolates, 69 were randomly selected and subjected to antimicrobial susceptibility testing using a vitek2 compact system whereas they were challenged with a set of 15 antibacterial agents commonly used in the medical and veterinary fields. In addition, 39 isolates were selected randomly and screened for sea, seb, sec, sed, and see enterotoxin-encoding genes by polymerase chain reaction (PCR). The tested isolates exhibited high resistance to Streptomycin, Penicillin-G, and Oxytetracycline while presented high sensitivity to Gentamycin, Amoxycillin +Clavulinic acid and fluoroquinolone antimicrobials (Enrofloxacin and Ciprofloxacin). According to the antimicrobial sensitivity test results, 8 isolates were selected and experienced further molecular typing techniques (PCR and hybridization) for detection of S. aureus virulence genes namely spa, hlg, coa, tst, nuc, clfA, as well as resistance genes blaZ and mecA. Spa gene was the most dominant virulence gene identified in the isolates (n=5), followed by coa and hlg (n=4), nuc and clfA (n=3) and the least detected gene was tst (n=2)