Determination of antimicrobial resistance profiles of Edwardsiella species isolated from fish sold in markets around Kampala

Abstract

Edwardsiella tarda, causes zoonoses in humans and is vectored by fish, hence a serious threat to aquaculture sector globally. However, there is limited information on its antibiotic susceptibility in fish sold on Ugandan market. This study was conducted to establish stock and determine the antimicrobial resistance profiles of Edwardsiella tarda isolated from fish sold around Kampala from selected markets. A total of 30 fish samples (14 Nile Tilapia and 16 African catfish) were randomly collected from three different markets around Kampala (Bwaise, Kalerwe, and Wandegeya), between 1st and 30th March 2024. Edwardsiella tarda was phenotypically identified basing on colony morphology and conventional biochemical tests and thereafter characterized by Polymerase Chain Reaction using species-specific primers. Two Edwardsiella tarda isolates were phenotypically identified using conventional biochemical tests. However, only one isolate was successfully resuscitated and subjected to Polymerase Chain Reaction but was negative for the Edwardsiella tarda target gene. The isolates exhibited low levels of antibiotic resistance as they were resistant only to Oxacillin by Disc Susceptibility Testing method. Unlike some previous research, resistance to one antibiotic was encountered in this study. Finally, the isolate from this study shall contribute to future research in epidemiological cut-off point establishment.