ISOLATION AND ANTIMICROBIAL SUSCEPTIBILITY PROFILE OF EDWARDSIELLA SPECIES AND ESCHERICHIA COLIO157:H7 FROM FISH HARVESTED FOR HUMAN CONSUMPTION FROM LAKE ABAYA AND GILEGEL GIBE-3 DAM, SOUTHERN, ETHIOPIA

Abstract

Edwardsiella species and pathogenic strains of Escherichia coli are members of the Enterobacteriaceae family that are frequently reported as causes of illness in fish and other mammals. A cross-sectional study was conducted from April 2022 to November2022 with the objectives of estimating the prevalence E. tarda, E. ictaluri, and E. coli O157:H7 in fish and determining the antimicrobial susceptibility pattern of the isolates. Thus, a total of 768 tissue samples comprising intestine, liver and kidney were collected from 256 apparently healthy fish originated from Lake Abaya and Gilegele gibe-3 dam, southern Ethiopia. Standard microbiological methods and procedure (ISO, 2003) were employed to isolate and identify target organisms using biochemical tests. The disc diffusion test was employed to determine the susceptibility pattern of isolates against seven standard antimicrobial discs. The findings were presented using descriptive statistics, while the association of categorical variables with the occurrence of bacterial species was computed using Chi-square and logistic regression analysis. The overall prevalence of E. coli O157:H7, E. tarda, and E. ictaluri among fishes were 14.1%, 8.6% and 4.7% respectively. Whereas, the overall prevalence of E. coli O157:H7, E. tarda, and E. ictaluri among organs (intestine, liver and kidney) were 5.34%, 4.01% and 1.95% respectively. The maturity of fish and Lake showed significant association (P<0.05) with the occurrence of E.tarda. Thus, immature fish and fishes from Gilgel-Gibe-3 had 2.6 (95%CI=1.0- 6.5) and 6.7 times (95%CI=1.3-35.7) respectively the odds of being positive to E. tarda than their counter categories. Resistance to tetracycline was noted in all of the isolates. All the isolates were 100% sensitive to gentamycin, sulfamethoxazole and trimethoprim. The results of the present study concluded that the intestines of fish have been found to be harboring E. tarda, E. ictaluri and E. coli O157:H7that may be a resident or transient microorganism. Moreover, the current findings create momentum for more research work to establish the occurrence and prevalence of E. tarda, E. ictaluri and E. coli O157:H7 in Lakes to determine cost effective measures that should be taken to reduce fish mortality.