Class 1 integrons in ciprofloxacin-resistant Escherichia coli strains from two Dutch hospitals.
A significant increase in the isolation frequency of ciprofloxacin-resistant Escherichia coli was observed in the haematology departments of two university hospitals in The Netherlands. Amplified fragment length polymorphism analysis revealed that this increase was not caused by the emergence of unique ciprofloxacin-resistant clones. Determination of the presence of class 1 integrons indicated that 81% of the ciprofloxacin-resistant isolates contained an intI1 gene, compared with 11% of the ciprofloxacin-susceptible isolates (p<0.0001). The quinolone resistance gene qnrA was not present in any of the integrons characterised and could not be detected using dot-blot hybridisation of total DNA. In addition, conjugation experiments showed that ciprofloxacin resistance was not co-transferred with class 1 integrons. Ciprofloxacin-resistant isolates harboured mutations in the gyrA gene, which are known to encode ciprofloxacin resistance. In conclusion, an association was observed between ciprofloxacin resistance and the presence of class 1 integrons, which could not be explained by the currently known genetic determinants of quinolone resistance.
Mooij
M J
MJ
Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, The Netherlands.
Schouten
I
I
Vos
G
G
Van Belkum
A
A
Vandenbroucke-Grauls
C M J E
CM
Savelkoul
P H M
PH
Schultsz
C
C
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology*; D003227:Conjugation, Genetic; D016172:DNA Fingerprinting; D027081:DNA Gyrase / Q000235:genetics; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics; D022761:Gene Transfer, Horizontal; D006402:Hematologic Diseases / Q000150:complications; D006761:Hospitals; D006801:Humans; D007297:Inpatients; D019426:Integrases / Q000235:genetics; D032023:Integrons; D009426:Netherlands; D009693:Nucleic Acid Hybridization; D011110:Polymorphism, Genetic
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C485384:Qnr protein, E coli; D002939:Ciprofloxacin; D019426:Integrases; C115006:integron integrase IntI1; D027081:DNA Gyrase