Prevalence and antibiotic susceptibility pattern of Escherichia coli O157:H7 isolated from harvested fish at Lake Hayq and Tekeze dam, Northern Ethiopia

Fisheries play a significant role in food security, livelihood, and source of income in developing countries. Although fish are a healthy source of protein, they can also spread diseases caused by pathogenic micro-organisms they may harbor. Epidemiology of foodborne pathogens is not well studied in Ethiopia. To address this issue to some extent, a cross-sectional study with a simple random sampling approach was conducted from October 2017 to May 2018 with the objectives of to isolate and estimate the prevalence of Escherichia coli O157: H7 in fish, and to evaluate the antimicrobial susceptibility pattern of the isolates in selected Lakes of Northern Ethiopia. All the microbial identification and isolation procedures were conducted based on ISO 6887-3:2017 recommendations. Antimicrobial susceptibility test was also performed following the standard procedure of Kirby-Bauer disk diffusion protocol. From the total 410 fish samples examined, six (1.46%) of them were found contaminated with Shiga toxin-producing Escherichia coli O157: H7 strain. The organism was isolated from landing sites (5/293) and local retail markets (1/75). Besides, Escherichia coli O157: H7 was isolated from filleted fish (5/214) and whole fish (1/125); however, it was not isolated from samples of ready to eat fish and working environments of restaurants. The antibiotic susceptibility test revealed that the isolates were resistant to Ampicillin and Streptomycin disks. However, Ciprofloxacin, Gentamicin and Nalidixic acid were found effective in inhibiting the growth of all of the isolates. Since pathogenic Escherichia coli strain was detected from fish, raw and undercooked fish consumption in Ethiopia may result in contracting infections. The occurrence of such pathogenic organisms in fish indicates the need for intervention by stakeholders. Supports like freezers, generators, the establishment of fish processing plants and on job training about proper fish handling practices may play a tremendous role in decreasing the level of contamination of fish in Ethiopia.