Rapid Emergence of Ciprofloxacin-Resistant Enterobacteriaceae Containing Multiple Gentamicin Resistance-Associated Integrons, the Netherlands

Abstract

In a hematology unit in the Netherlands, the incidence of ciprofloxacin-resistant 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 single genotypes of both ciprofloxacin-resistant E. coli and Enterobacter cloacae from patient to patient was documented by pulsed-field gel electrophoresis and random amplification of polymorphic DNA. In addition, genetically heterogeneous strains were isolated regularly. Integrons associated with gentamicin resistance were detected in Enterobacter cloacae and E. coli strains. Integron-containing E. coli were detected in all hematology wards. In contrast, in Enterobacter cloacae strains two integron types were encountered only in the isolates from one ward. Although in all patients identical antibiotic regimens were used for selective decontamination, we documented clear differences with respect to the nosocomial emergence of ciprofloxacin-resistant bacterial strains and gentamicin resistance-associated integrons.

Phylogenetic Background and Virulence Profiles of Fluoroquinolone‐Resistant ClinicalEscherichia coliIsolates from The Netherlands

“…Thirteen FQREC isolates collected in 1998-1999 from infected or colonized hematology ward patients in The Netherlands were analyzed [1]. The isolates represented 9 of the 16 distinct genotypes, as defined in a previous study using randomly amplified polymorphic DNA (RAPD) analysis, and constituted all available remaining FQREC isolates from that study [1].…”

“…Thirteen FQREC isolates collected in 1998-1999 from infected or colonized hematology ward patients in The Netherlands were analyzed [1]. The isolates represented 9 of the 16 distinct genotypes, as defined in a previous study using randomly amplified polymorphic DNA (RAPD) analysis, and constituted all available remaining FQREC isolates from that study [1]. Nineteen FQREC isolates newly collected in June and July 2002, from patients in the same hematology ward according to the same surveillance protocol, were similarly analyzed and were found to represent 16 distinct RAPD genotypes (A.v.B.…”

“…and C.v.d.S., unpublished data). Ciprofloxacin susceptibility was assessed by a broth microdilution assay [1], with MIC criteria of у4 mg/mL and р2 mg/mL, respectively, used to define resistance and susceptibility to ciprofloxacin. Archetypal ExPEC strains CFT073 (pyelonephritis), RS218 (neonatal meningitis), 536 (pyelonephritis), and CP9 (bacteremia), which are all fluoroquinolone susceptible, were used for reference [9].…”

“…To gain insights into this question, we analyzed representatives of 9 FQREC genotypes recently isolated from surveillance or clinical cultures from hematology ward patients in The Netherlands [1]. Specifically, we compared the Dutch FQREC isolates with fluoroquinolone-susceptible E. coli (FQSEC) from the same clinical setting, with selected archetypal ExPEC strains, and with members of the Escherichia coli Reference (ECOR) collection [6,8], according to phylogenetic background and extended virulence factor profile.…”

Integrons and β-lactamases—a novel perspective on resistance

“…Rapid and widespread emergence of resistance and more importantly similar patterns of resistance have been encountered in phylogenetically diverse Gram-negative clinical isolates on an increasing scale [1]. Apart from well-known bacterial methods of mutation, antibiotic genes are more frequently trapped in integron-borne cassettes, which provide an efficient means for capturing and exchanging various resistance genes [2]. To date four classes of integrons, each with distinct int genes, have been described in Gram-negative bacterial isolates [3][4][5], with class 1 integrons being most prevalent in clinical isolates, carrying single or multiple gene cassettes.…”