author(s)
Asmaa H Abdullah, Ban N Nadhom and Hind H Al-Ammiri

abstract
This study was conducted to isolate Serratia marcescens from bovine mastitis for the first time in veterinary medicine field in Iraq and their susceptibility against antibiotics. One hundred and fifty samples from case of mastitic milk of cow were collected from College of University of Baghdad/College of Veterinary Medicine, University of Baghdad/College of Agriculture, Dora zone, Radhwanya zone and Abu-Ghraib zone. Cultured by selective and differential media then Gram stain were done. After purification of cultured bacteria biochemical tests were done and confirmed by API 20 E System and RapID^TM ONE System kit. Results showed that 6 (4%) samples out of 150 samples were positive for Serratia marcescens and it’s the first time to isolate in veterinary medicine field. The resistance of these isolates against antibiotics Gentamycin (30 mg), Imipenem (10 mg),Ciprofloxacin (5 mg),Nalidixic acid (30 mg), Ampicillin (10 mg), Cefotaxime (30 mcg), Amikacin (30 mg), Chloramphenicol (30 mg), Tetracyclin (10 mg) and Amoxicillin-Clavulanic acid (20/10 mg) were studied. The results showed that Serratia marcescens were resistant 100% to Ampicillin, Imipenem and Tetracyclin, 66.66% to Cefotaxime and susceptible 100% to Ciprofloxacin, 83.33% to Gentamycin, 66.66% to Chloramphenicol and 50% to Nalidixic acid. While Intermediate 83.33% to Amoxicillin-Clavulanic acid, 50% to Nalidixic acid and 33.33% to Chloramphenicol and Cefotaxime.