Abstract
Dystocia or birth difficulties may make the animals more prone to develop a case of metritis or endometritis due to uterine trauma and introduction of many bacterial strains into uterus. The objective of this study was to identify and characterize the main bacteria which would present in uterine samples of dairy cows during the first three weeks after parturition in dairy cows suffering from dystocia and those with normal birth. The obtained findings showed that E. coli was the most prevalent isolates throughout the three weeks, Staph.aureus was not reported in the first and second week but became more prominent in the third week. In addition, the combination of E. coli with Staph. aureus, and E.coli with streptococci is consistently observed throughout the three weeks. Other bacterial isolates, such as Trueperella pyogenes were detected in the first and third weeks, additionally, Micrococcus and Pseudomonas were detected in third week only. Regarding isolated bacteria, and based on antibiotics sensitivity test, Staphylococcus aureus was more sensitive to streptomycin and ciprofloxacin. On the other hand, E. coli show 100% sensitivity for imipenem, sulfamethoxazole and trimethoprim. Interestingly, both isolates showed 100% resistance to amoxiclav. Serodiagnosis of E. coli and presence of enterotoxins genes of Staph. aureus would confirm enterogenic origin of both of bacteria which indicate low hygienic measures. In conclusion, the prevalence of the isolated bacteria and bacterial combination besides persistence of theses bacteria till third week after parturition was more in cases suffered from dystocia than animals with normal birth. Antibiotic sensitivity test should be applied before administration of any antibiotics to the animals suffering from any uterine infection after parturition

Key words: Dystocia, E. coli, Staphylococcus aureus, Streptococci, Antibiotic sensitivity.