Evidence of Extensive Interspecies Transfer of Integron‐Mediated Antimicrobial Resistance Genes among Multidrug‐Resistant Enterobacteriaceae in a Clinical Setting

Abstract

Multidrug resistance in gram-negative bacteria appears to be primarily the result of the acquisition of resistance genes by horizontal transfer. To what extent horizontal transfer may be responsible for the emergence of multidrug resistance in a clinical setting, however, has rarely been investigated. Therefore, the integron contents of isolates collected during a nosocomial outbreak of genotypically unrelated multidrug-resistant Enterobacteriaceae were characterized. The integron was chosen as a marker of transfer because of its association with multiresistance. Some genotypically identical isolates harbored different integrons. Grouping patients carrying the same integron yielded 6 epidemiologically linked clusters, with each cluster representing a different integron. Several patients carried multiple species harboring the same integron. Conjugation experiments with these strains resulted in the transfer of complete resistance patterns at high frequencies (10(-2) to 10(-4)). These findings provide strong evidence that the horizontal transfer of resistance genes contributed largely to the emergence of multidrug-resistant Enterobacteriaceae in this clinical setting.

Integron-mediated Multidrug Resistance in a Global Collection of NontyphoidalSalmonellaentericaIsolates

“…data). Transfer of integrons between different bacterial species has been documented in the clinical setting, which poses a serious threat to containment of nosocomial infections (27). The existence of identical integrons in different types of bacteria and the ability of these integrons to be transferred in vivo indicates that many bacteria acquire integrons from a common pool.…”

Susceptibilities to Antimicrobials and Disinfectants in Salmonella Isolates Obtained from Poultry and Swine in Thailand

“…prepared by the whole cell lysate procedure [17]. PCR was performed using Eppendrof ® MasterMix (Eppendrof, Hamburg, Germany) according to the manufacturer's instructions.…”

In-feed antibiotic effects on the swine intestinal microbiome

“…For example, commensal bacteria of the human colon harbor antibiotic resistance genes and can transfer these genes to pathogens (17,18). In fact, horizontal gene transfer is largely the cause of multidrug resistance in Gram-negative bacteria (19). With the identification of antibiotic resistance genes in commensal bacteria in the human food-chain (20)(21)(22), the role of the gut microbiota as a reservoir of resistance genes for animal and food-borne pathogens needs to be explored.…”