Bacterial diseases outbreaks in some freshwater fish farms in Kafr El-Sheikh, Egypt

Abstract

ABSTRACT Bacterial fish diseases are one of the challenges facing the aquaculture industry and lead to tremendous economic losses. After surveying the infected farms understudy from April 2018 to November 2019, we collected 480 samples from 12 tilapia and carp farms experiencing mortalities in Kafr El-Sheikh region of Egypt with major aquaculture production. Clinically, hemorrhages, exophthalmia, and ulceration were the most common symptoms. We then determined the frequency, bacteriological and molecular identity, antibiotic sensitivity, pathogenicity, and histopathological characteristics of pathogens. For molecular identification was used a set of specific primers (16S rRNA, 16SPSEflu, and Sin-1b). Our results showed that Aeromonas hydrophila, Pseudomonas fluorescens, and Streptococcus iniae were the most important causes. Antibiotic sensitivity test revealed that all isolates were highly sensitive to ciprofloxacin. Additionally, naturally and experimentally infected fish are the same in pathognomonic signs. Overall, a valuable tool for diagnosis is the combination of both bacteriological and molecular examination. Besides, choosing the best antibiotics by sensitivity test helps avoid drug resistance phenomenon.