Abstract
About 144 moribund of the common carp were examined were brought to the laboratory for examination after an epizootic of citrobacteriosis on cultivated in floating cages at Al-Hilla river, during the period December 2017- November 2018. The bacterium was identified by Vitek II system. The fish displayed dark color and hyperemia of the mouth. The possible etiologic agent was identified by Vitek II system as Citrobacter spp. Citrobacter species were identified with a different percentage in common carp, which are C. freundi, C. amalonaticus and C. braakii. Antibiotic susceptibility test of 12 antibiotics, which are piperacillin/tazobactan, amikacin, cefazolin, gentamicin, cefoxitin, ciprofloxacin, ceftazidime, levofloxacin, cefepime, tigecycline, imipenem and trimethoprim/sulfamethoxazoleby) showed variable resistances for Aeromonas species. Aeromonas species were identified and examined for antibiotic susceptibility using the Vitek II system. The results indicate that the bacteria sensitive to Minimum Inhibitory Concentration (MIC) of levofloxacin (< = 0.12 μg/ml), imipenem and ciprofloxacin (< = 0. 25 μg/ml), but resistant to cefazolin (> = 64 μg/ml) and trimethoprim/sulfamethoxazole (40 μg/ml).
