ANTIBIOGRAM OF SOME BACTERIA CONTAMINATING TILAPIA FISH AT EL-MANZALA LAKE IN PORT - SAID GOVERNORATE.

The antibacterial susceptibility of some bacterial isolates belonging to E. coli, coagulase positive  Staphylococcus aureus, Aeromonas hydrophila, Pseudomonas aeruginosa, Pseudomonas fluorescens and Vibrio anguillarum recovered from gills, skin, muscles and internal organs of Oreocochrormis niloticus fish was determined. Strains of these isolates were screened against ampicillin, chloramphenicol, oxytetrcycline, erythromicin, gentamicn, nalidixic acid, flumequine, neomycin, nitrofurantoin, penicillin and colistin using disc agar diffusion technique. High frequency of miultiresistant strains in bacterial population of fish towards several commonly used antibacterial agents was observed. Most isolates were generally sensitive to gentamicin, nalidixic acid, flumequine and nitrofurantoin. On contrary, all tested isolates were resistant to the two used β-lactam antibiotics. The remaining ‘drugs were effective but the level of activity was even lower than that. The antimicrobial assay of the isolates using minimum inhibitory concentration (MIC) revealed a high sensitivity of most isolates to gentamicin Its MIC against the tested strains ranged from 0.25 to 8ug/ml. Moderate sensitivity was observed in flumequine and nitrofurantoin. The incidences of drug-resistance bacteria and public health importance of existing microorganisms were discussed.