Purpose: The purpose of this study was to investigate the prevalence and antimicrobial resistance of Enterobacteriaceae recovered from shell eggs, collected at small-scale poultry farms and farmers’ markets.
Methods: Shell eggs (n=504) were collected and two eggs were constituted to make 252 composite samples. Enterobacteriaceae were enumerated by using violet red bile glucose agar plates and identified through biochemical tests and PCR. Antimicrobial susceptibility to 13 antimicrobial agents was determined by Kirby-Bauer’s disc diffusion method and results interpreted by CLSI interpretative values.
Results: Of a total of 252 composite eggs (shells, egg contents), 30 (11.9%), 23 (9.1%), and 29 (11.5%) egg shells alone and 13 (5.2%), 20 (7.9%), and 12 (4.8%) egg contents alone were positive for Escherichia coli, Enterobacter spp, and Serratia spp, respectively. The prevalence of Salmonella was 3.6% on the egg shells and none in the egg contents. Enterobacteriaceae level on shell eggs (4.4±2.0 log CFU/egg shell) was significantly higher (P≤ 0.05) in shell eggs from poultry farms than found on egg shells from farmers’ market (2.1±1.3 log CFU/egg shell). Out of the 134 Enterobacteriaceae isolates tested, resistance to erythromycin (80.6%), ampicillin (61.9%), tetracycline (50.7 %), and streptomycin (45.5 %) was observed.
Significance: Our results suggest that shell eggs from small-scale poultry farms and farmers’ markets may be contaminated with antibiotic resistant foodborne and commensal bacteria. These observations also underline the need to educate the public on the risks from mishandling raw eggs and consumption of undercooked eggs or egg products.