Bacteriological Assessment and Antibiotic Susceptibility Profile of Bacteria Recovered from <i>Clarias gariepinus</i> Selected from Various Fish Farms in Anambra North Senatorial Zones in Anambra State, Nigeria

Abstract

Fishes are cheap sources of protein and are commonly reared in artificial pond in Nigeria. Bacterial infested fishes have been a serious public health concern. This study was aimed at isolating and identifying bacteria associated with the internal organs (gills, liver, guts) of Clarias gariepinus (African Catfish) in fish ponds in Anambra North Senatorial zones in Anambra State, Nigeria, and to determine the seasonal bacterial load of the organs and antibiotic susceptibility profile of the isolates to conventional antibiotics. A total of 720 African catfish were sampled from randomly selected fish farms during rainy and dry seasons. Bacteria isolates inoculated on Blood and Nutrient agar plates were identified based on morphological and biochemical characteristics. Susceptibility of the isolates to antibiotics was carried out using the Kirby-Bauer disc diffusion method. Isolates from the fish organs include species of Vibrio, Aeromonas, Pseudomonas, Lactobacillus, Staphylococcus, Microbacterium, Serratia, Proteus, Bacillus, Streptococcus, Citrobacter and Micrococcus . Results also revealed that there was significant difference (p value < 0.05) in the bacterial load recovered from the fish organs, during rainy and dry seasons. Bacillus sp. was the most abundant gram positive bacterium in the organs of the fish samples during the rainy and dry season, while Citrobacter sp., a gram negative organism, was relatively abundant in the liver and gut. Percentage susceptibility of the bacteria to antibiotics was highest with vancomycin (100%) and least with erythromycin (75.0%). The most susceptible isolates were species of Staphylococcus, Microccoccus and Microbacterium while Bacillus sp. was the most resistant bacterium. This study has shown that high bacteria load are found in the internal organs of the fish and a good number of the bacteria are resistant to some of the antibiotics tested. There is, therefore, need for adherence to proper sanitary measures to avoid bacterial contamination of fish.