Prevalence of Septicemia and Red Mouth Disease Caused by Aeromonas sobria at Sahl El-Housinia Fish Farm

Abstract

The present study was carried out to isolate, identify and perform a trial for treatment of Aeromonas sobria ; the etiological agent responsible for signs of septicemia with redness and hemorrhage of mouth in cultured Oreochromis niloticus and mullet species. A total of 312 Oreochromis niloticus (30-65 g) and 158 mullet species (200-300 g) were collected a live from a private fish farm at Sahl El-Housinia, Sharkia Governorate, Egypt. Bacteriological examination of samples from gills, kidney, intestine, liver and spleen was carried out. Molecular identification, pathogenicity and in vitro antibiotic sensitivity of the isolated strains as well as in vivo trials of treatment were performed. The naturally infected fishes were characterized by signs of septicemia with redness of mouth and different parts of the body. Aeromonas sobria prevalence in Oreochromis niloticus (35.89%) was higher than that in mullet species (20.88%). Antibiotic sensitivity test on PCR confirmed isolates (n=3) that were highly pathogenic revealed that Aeromonas sobria was highly sensitive to enrofloxacin. The trial treatment of experimentally infected Oreochromis niloticus with 0.2 ml (9x10 8 CFU/ml) of 24 hrs virulent Aeromonas sobria broth culture using enrofloxacin (2 mg/l for 5 days as medical water bath) revealed better health condition and improvement in the signs of infection and levels of the alanine aminotransferase, aspartate aminotransferase and creatinine. Histopathological findings of liver, kidney and intestine confirmed the results of serum biochemical analysis where lesions were alleviated to normal indicating improvement in the health condition due to the efficacy of enrofloxacin treatment. In conclusion, the use of enrofloxacin as a medical water bath by 2 mg/l for five days revealed good results but must be used under restrictions to avoid bacterial resistance to the antibiotic.