الفهرس 
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Abstract
The objective of this study was to identify in general the predominant bacteria focusing on E.coli and Staph. aureus present in uterine samples collected from dairy cows during first three-week after parturition to determine their prevalence in cases of dystocia and normal birth. Therefore, uterine swab samples were collected from individual animals (n=108) for three consecutive weeks after parturition for bacterial isolation, characterization, detection of antibiotic sensitivity and enterotoxin gene of the isolated Staph. aureus.
The following results were obtained:
E. coli is the most prevalent isolate throughout the three weeks, with 25.7% in the first week, 40.62% in the second week, and 17.8% in the third week.
Staph. aureus not detected in the first and second week but becomes more prominent in third weeks, accounting for 10.7%. While Streptococci are present in the first and third weeks, accounting for 2.85% and 3.6% respectively.
The combination of E. coli with Staph. aureus is consistently observed, with 42.85% in the first week, 31.25% in the second week, and 46.4% in the third week. While the combination of E. coli with Streptococci is also seen, with 8.6% in the first week, 18.75% in the second week, and 10.7% in the third week.
Trueperella pyogenes was detected in the first and third weeks with a percent 5.7 and 3.6%, respectively; Micrococcus, and Pseudomonas were detected in third week only with an incidence level 3.6% for each organism.
Prevalence of isolated bacteria and bacterial combination was more in cases suffering from dystocia than animals of normal birth.
Persistence of these bacteria till third week after parturition was more cases suffered from dystocia than animals of normal birth.
Antimicrobial sensitivity of ten isolates of Staph. aureus revealed that Streptomycin and ciprofloxacin show 100% sensitivity followed by gentamycin (70%),while amoxiclav showing 100% resistance. All isolated Staphylococcus aureus strains were multidrug resistant with an AMR index ranging from 0.25 to 0.67.
It was found that 33.3% of examined Staph. aureus strains were MRSA ( resistant to both Oxacillin and cefoxitin).
Antimicrobial sensitivity of 12 isolates of E.coli revealed that Imipenem and (sulfamethoxazole + trimethoprim) show 100% sensitivity followed by gentamycin (83.3%). While Amoxiclav, penicillin and tylosin show 100% resistance. All isolated E.coli strains were AMR with an index ranging from 0.28 to 0.57.
Serology of E.coli shows that O44:K74 was the most prevalent serotype with level (60%), followed by O55: K59 (20%), and O25:K11 (20%).
Multiplex PCR for enterotoxins gene of biochemically identified Staph. aureus showed that Seb gene was present in 100% of examined isolated strains.