Antimicrobial resistance of Escherichia coli, Salmonella and enterococci isolated from surface of conventional broiler eggs, "Kampung" chicken eggs and carrying trays from wet markets in Selangor, Malaysia

Aims: Bacteria on chicken egg surfaces can be potential sources of food borne diseases. The aim of this study was to determine the prevalence of E. coli, Salmonella and enterococci on the surface of conventional broiler eggs, Kampung chicken eggs and carrying trays and to determine the antimicrobial resistant profile of these isolates. Methodology and results: Conventional broiler eggs, Kampung chicken eggs and carrying trays were sampled randomly from nine wet markets in Selangor, Malaysia. The surface of the eggs and carrying trays were swabbed and E. coli, Salmonella and enterococci were isolated using selective agars. Antimicrobial susceptibility testing (AST) was performed on the isolates against different antimicrobials via disk diffusion test. A large proportion of E. coli isolates (>50 of isolates from conventional broiler eggs and Kampung chicken eggs) was resistant to chloramphenicol and tetracycline whereas enterococci (>60 of isolates from conventional broiler eggs and Kampung chicken eggs) isolates were resistant to tetracycline and erythromycin. Salmonella isolates were found to be susceptible to all of the antimicrobials tested except for tetracycline. There was also presence of isolates showing multiple resistances in this study. E. coli isolates (8.8 ) from the surface of Kampung chicken eggs were resistant against 10 different antimicrobials whereas 17.8 of the enterococci isolates from the surface of Kampung chicken eggs were resistant to 11 different antimicrobials. Conclusion, significance and impact of study: The presence of multiple-antimicrobial resistant bacteria especially on the surface of Kampung chicken eggs that are ready to be sold to consumers is a serious concern. However, further study has to be conducted to determine the ultimate source of the bacterial contamination before specific food safety measures can be introduced