Transfer of antibiotic resistance between commensal and pathogenic members of the Enterobacteriaceae under ileal conditions

Aim: To determine the rate of antibiotic resistance transmission between commensal and pathogenic representatives of the Enterobacteriaceae. Methods and Results: Through the use of a validated in vitro simulation of the porcine ileum, the transmission of antibiotic resistance was detected between commensal Escherichia coli, E. coli O157 and Salmonella spp. Countable transconjugant populations arose readily and, in one example, proved capable of indefinite persistence. Conclusions: Genetic material conferring antibiotic resistance is readily transmissible between members of the Enterobacteriaceae under ileal conditions. Recipient phenotype influences the persistence of multi-resistant transconjugants. Significance and Impact of the Study: The observation that the conjugal transmission of antibiotic resistance is commonplace under ileal conditions impacts primarily on the risk of food contamination by multi-resistant bacteria. The establishment of a multi-resistant transconjugant population as a dominant member of the microflora maintains a genetic reservoir of antimicrobial resistance.