Identification of edwardsiella tarda isolated from tilapia nilotica (oreochromis niloticus)‎ by polymerase chain reaction (PCR)‎. the effect of garlic oil and different antimicrobials on the identified organism in vitro

Abstract EN

Edwardsiella tarda is considered as a serious pathogen of fish and it is also important due to its zoonotic aspects as infected fish processed for human consumption is a source of gastroenteritis and meningitis.

One hundred and thirty samples of cultured apparently healthy Nile tilapia were collected from private farms in Alexandria governorate and examined bacteriologically to isolate Edwardsiella tarda.

E.

tarda could be isolated from the kidney, liver, spleen, muscles and intestinal contents of examined fish with in a percentage of 3.

9 %.

The five isolates of E.

tarda were identified morphologically and biochemically then subjected to confirmation by conventional Polymerase Chain Reaction (PCR) with the amplification product of 415 bp using gyrB gene as a taxonomic marker.

Pathogenicity test of the isolate and histopathological examination of the experimentally infected fish were carried out.

In vitro, sensitivity test of the isolate against antimicrobials and garlic oil showed that it was resistant to garlic oil, Neomycin, Nitrofurantoin, Streptomycin, Tetracycline, Amoxicillin, Ampicillin/ sulbactam and Colistin; and sensitive to Chlormphenicol, Enerofoxacin, Flumequine Gentamycin ; while antimicrobials combined with garlic oil revealed that garlic oil decreased the potencies of antimicrobials.

proper aquarium hygiene, appropriate regulations of physical conditions in the aquarium are recommended and fish must be cooked sufficiently before eating to protect human health from such hazards.