Rapid emergence of ciprofloxacin-resistant enterobacteriaceae containing multiple gentamicin resistance-associated integrons in a Dutch hospital

In a hematology unit in the Netherlands, the incidence of ciprofloxacin-res istant Enterobacter cloacae and Escherichia coli increased from <0.5% to 20 .7% and <0.5% to 64%, respectively, from 1996 to 1999. Clonal spread of sin gle genotypes of both ciprofloxacin-resistant E. coli and Enterobacter cloa cae from patient to patient was documented by pulsed-field gel electrophore sis and random amplification of polymorphic DNA. In addition, genetically h eterogeneous strains were isolated regularly. Integrons associated with gen tamicin resistance were detected in Enterobacter cloacae and E. coli strain s. Integron-containing E. coli were detected in all hematology wards. In co ntrast, in Enterobacter cloacae strains two integron types were encountered only in the isolates from one ward. Although in all patients identical ant ibiotic regimens were used for selective decontamination, we documented cle ar differences with respect to the nosocomial emergence of ciprofloxacin-re sistant bacterial strains and gentamicin resistance-associated integrons.