Evaluation of the antimicrobial properties of african catfish skin mucus against Escherichia coli isolated from fish ponds in Keffi, Nasarawa State, Nigeria

Abstract

This study aimed to evaluate the antimicrobial activity of skin mucus extracted from African catfish (Clarias gariepinus) against multidrug-resistant Escherichia coli isolated from selected fish ponds in Keffi, Nasarawa State, Nigeria. The study was conducted at the Department of Microbiology Laboratory, Nasarawa State University, Keffi, between February 2024 and June 2024. Escherichia coli isolates were recovered from water samples collected from selected fish ponds using standard microbiological techniques. Antibiotic susceptibility testing was performed using the Kirby–Bauer disk diffusion method. Crude skin mucus extracts were concentrated to obtain a stock solution used for antimicrobial assays. Two fold serial dilutions were used for antimicrobial assays, twelve healthy African catfish weighing between 4–12 kg were evaluated for antimicrobial activity using agar well diffusion and broth microdilution assays. Data were analysed using one-way analysis of variance (ANOVA). Fifty Escherichia coli isolates were obtained from 100 water samples, representing a prevalence of 50%. High resistance was observed to ampicillin (80%), tetracycline (70%) and trimethoprim–sulfamethoxazole (76%), while gentamicin (64%) and nitrofurantoin (70%) showed higher effectiveness. Twelve isolates (24%) were identified as multidrug resistant. The mucus extract produced inhibition zones ranging from 0–4 mm, with some isolates showing no visible inhibition (0 mm). Mean inhibition zones were 0.6 mm for MDR isolates and 2.0 mm for susceptible isolates. Minimum inhibitory concentrations were high, indicating that large extract volumes (500–1000 µL equivalent) were required for inhibition, whereas ciprofloxacin showed significantly lower MIC values (0.125–0.5 µg/mL). Although the crude skin mucus of Clarias gariepinus demonstrated limited antibacterial activity against multidrug-resistant Escherichia coli, the findings indicate its potential as a source of antibacterial peptides, warranting further purification, characterization, and biotechnological application.