Characterization of edwardsiella species isolated from fish by using genomic DNA fingerprinting technique

الملخص EN

Nowadays, Edwardsiella is considered the most dangerous bacterial problem in cultured fish farms.

In this study, 100 diseased Nile tilapia (Oreochromis niloticus) and 100 diseased sea bass (Dicentrarchus labrax) were collected randomly from kafer El-sheikh cultured fish farms and also from Damietta Government during the period from May 2016 till May 2017.

All diseased fishes showed hemorrhages, all over the body surface accompanied by swelling of abdomen were observed clinically and post-mortem.

Liver, kidney and spleen samples were subjected to bacteriological examinations, for isolation of E.

tarda.

The suspected isolates were characterized morphologically and biochemically including microbact 24.

PCR technique was applied for detection of some virulence genes (etfA, etfD, gyerB genes) in E.

tarda isolates.

Total prevalence of well identified E.

tarda isolates was 12% in Oreochromis niloticus while 7% in Dicentrarchus labrax.

Most E.

tarda isolates were sensitive to ciprofloxacin, streptomycin chloramphenicol and gentamycin, conversely, most of isolates were resistant to tetracyclin, nalidixic acid, ampicillin, and sulphamethoxazole.

PCR results recorded that all recovered E.

tarda isolates contain gyerB at 415bp and etfD at 445 bp, while not all E.

tarda posses etfA at 415bp