Antimicrobial Resistance in Salmonella and Escherichia coli Isolated from Commercial Shell Eggs

ABSTRACT The development of antimicrobial resis-tance in bacteria has become a global problem. Isolates of Salmonella and Escherichia coli recovered from shell egg samples, collected at 3 commercial plants, were analyzed for resistance to 16 antimicrobial agents (n = 990). Eggs were sampled by rinsing in a saline solution. Pooled sam-ples were preenriched in buffered peptone water and then selectively isolated using standard broths and agars. Salmonella-positive isolates were serogrouped immuno-logically before being serotyped. Enterobacteriaceae were enumerated from individual samples using violet red bile glucose agar plates. Escherichia coli were identified bio-chemically from presumptive Enterobacteriaceae isolates. Salmonella and generic E. coli antimicrobial-susceptibility testing was conducted using a semiautomated broth mi-crodilution system. More resistance was observed in th