الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Bovine mastitis, which may be clinical or subclinical, is considered a serious threat in dairy industry as it causes huge economic losses in dairy herds. S. aureus is one of the major pathogens of clinical and subclinical bovine mastitis and represents an important public health hazard. The aim of study to study the incidence of S. aureus isolates, identify antibiotyping by detection antimicrobial resistant agents, patterns and genes recovered from bovine mastitic milk, moreover, determine the epidemiology of these isolates so identify the origin of S. aureus isolates involved in the etiology of the disease molecular methods were used. This promoted us to determine the genetic diversity of S. aureus so tracking the infection source and helping to take specific infection control measure. The aim of this study was to assess the diagnostic power of procalcitonin, sTREM-1 and IL-6 in detection of early infectious complications in liver transplant recipients and to study the relationship between these infective biomarkers and other clinical tests (C-reactive protein and white blood cells count). A total of 406 mastitic cow’s milk samples were examined by conventional methods but only 160 samples from both clinical and subclinical mastitis (66/100 and 94/306, respectively) were confirmed to be S. aureus. Recovered isolates confirmed to be S. aureus by PCR amplification to both nuc gene and coa gene. S. aureus strains exhibited different rate of resistance against antimicrobial classes. High rate of resistance was reported against vancomycin, penicillin, trimethoprim, and oxacillin in a rate of (93.75%), (86.25%), (60%) and (58.75%), respectively. A medium rate of resistance was observed to clindamycin (41.25%), ciprofloxacin (41.25%) and erythromycin (37.5%). On the other hand; S. aureus isolates displayed a low frequency of resistance to gentamicin (21.25%), ampicillin/sulbactam (20%) and chloramphenicol (18.75%). The multidrug-resistance to three or more classes of antimicrobials was detected in 108 isolates (67.5 %). This antimicrobials resistance represents an economic and public health hazard. Moreover, thirty-five antibiotypes were identified. Amplification of S. aureus antimicrobial resistance genes by using polymerase chain reaction revealed that 46 (28.75%) of isolates harbored mecA, 132 (82.5%) of isolates harbored blaZ and both genes were present in 40 (25%) of isolates. These genes causes failure of medications process so result in huge economic losses. On other hands, amplification S. aureus isolates against quinolones resistance genes (gyrA and gyrB) by using polymerase chain reaction cleared that all S. aureus isolates lack those genes. characterization of different virulence genes by PCR indicate varied result as out of 160 only three isolates (1.875%) were found to harbored tst, 95 (59.37%) possess hla gene and 89 (55.6%) of S. aureus strains were pvl positive. This high percentage of pvl gene investigation may indicate that the origin of bovine mastitis caused by S. aureus recovered isolates from different farms were from community acquired MRSA. Recovered S. aureus strains were characterized for sea 55 (34.38%), seb 9 (5.63%), and sec not identified. All recovered isolates produced only one SEs toxins. These observation suggest that consumption of bovine milk even properly pasteurized may contain one (or more) of SEs causing staphylococcal food poisoning.