Antimicrobial Resistance Profile Characterization of Enterococcus Species Isolated from Aquaculture Environment

Aquaculture environments can become reservoirs of antibiotic-resistant strains of faecal bacteria including enterococci which are capable of contributing to the spread of antimicrobial resistance in the marine environment. The aim of this study was to characterize the antimicrobial resistance profile of Enterococcus species from various aquacultures (fish ponds) in Benin City, Edo State. A total of 376 water samples were obtained from four different fish ponds between February and July, 2015 and were investigated for the presence of Enterococcus species using standard culture based methods. The antimicrobial susceptibility profiles of the isolates were determined by using Kirby-Bauer disc diffusion method. From the 376 water samples analyzed for the presence of enterococci isolates, 100 isolates each from Enterococcus faecalis and Enterococcus faecium were isolated from the four fish ponds investigated. The mean enterococal counts from the four fish ponds investigated ranged from 4±0.01 × 102 to 12±0.17×102 cfu/ml. Statistical analysis reveals that there was a significant difference observed in the mean enterococcal counts obtained from the four different fish ponds in the study (p< 0.05). The distribution of the enterococcal isolates in the study from February to July reveals that 50 isolates from each pond were characterized. Statistical analysis also reveals that there was a significant difference observed in the distribution of the enterococcal isolates from the fish ponds (p< 0.05). High level resistance was observed against six antibiotics used in the study such that 15 enterococcal isolates displayed marked resistance to the action of trimethoprim, chloramphenicol, erythromycin, oxytetracycline, sulfamethoxazole, and ciprofloxacin. Adherence to adequate and proper use of manure products and frequent discharge of water from fish pond will reduce the high level of antimicrobial resistance in Enterococcus species isolated from fish ponds and also reduce the potential risk to human health.