Characterization and Multiple Antibiotic Resistance of Bacterial Isolates Associated with Fish Aquaculture in Ponds and Rivers in Port Harcourt, Nigeria

Abstract

The transfer of resistant organisms through consumption of contaminated fish and shell fish poses a substantial risk of environmental contamination because of the practice of using medicated feeds to treat pens or cages. However, antibiotics used for animals either for therapy or prophylaxis can result in transfer of resistant genes from animals to humans and thereby establishing a reservoir of resistant microbes. This study was aimed at identifying bacterial isolates associated with fish pond aquaculture and their multiple resistance pattern to antibiotics. Samples of infected catfishes were collected from a fish pond in Aluu, Rivers state. The fishes were characterized by skin lesions which indicate the infection. Sterile swabs were used to swab the lesions on the skins of the fishes. The antibiotic sensitivity of the isolates was determined using the disc diffusion method. Standardized inoculums of the overnight grown broth cultures were spread on Mueller-Hinton agar plates using sterile swabs. The plates were dried at room temperature for 2 h before placing the antibiotic discs at equidistance and incubated for 24 h at 370C and the diameter of zone of inhibition was measured. Predominant bacterial isolates from the cultures of swabs from the skins of infected fishes on various media were characterized and identified as Escherichia coli, Pseudomonas putida, Salmonella sp, Shigella sp, Staphylococcus aureus, Enterobacter and Enterococcus fecalis. The results obtained for antibiotic sensitivity pattern of isolates show that most of the test isolates were resistant to the activities of Ceftazidine (CAZ), Cetriaxone (CRO), Cefotaxine (CTX), Cephalexin (CL) and Tetracycline (TC) while Gentamycin (CN) and Ciproflaxacin (CIP) were highly susceptible to most test isolates. The fact that transfers of resistant bacteria between aquatic animals and humans through consumption or handling of fish can pose a serious hazard to human health. Therefore the presence of multiple drug resistant bacteria from fish and fish handlers do not only poses risk of disease infection to fishes but also public health hazard to fish handlers and consumers in general.