Evidence of extensive interspecies transfer of integron-mediated antimicrobial resistance genes among multidrug-resistant Enterobacteriaceae in a clinical setting.
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.
Leverstein-van Hall
Maurine A
MA
Eijkman-Winkler Institute for Microbiology, Infectious Diseases, and Inflammation, University Medical Center Utrecht, 3508 GA Utrecht, The Netherlands. m.leversteinvhall@lab.azu.nl
Box
Adrienne T A
AT
Blok
Hetty E M
HE
Paauw
Armand
A
Fluit
Ad C
AC
Verhoef
Jan
J
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D004251:DNA Transposable Elements; D004196:Disease Outbreaks; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004755:Enterobacteriaceae / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology*; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D006801:Humans; D017720:Molecular Epidemiology; D009426:Netherlands / Q000453:epidemiology
D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements