MOLECULAR EPIDEMIOLOGY OF FLUOROQUINOLONE-RESISTANT ESCHERICHIA-COLI BLOOD-STREAM ISOLATES FROM PATIENTS ADMITTED TO EUROPEAN CANCER CENTERS

Previous reports have suggested an increasing incidence of highly fluo roquinolone-resistant Escherichia coli causing bacteremia among cancer patients on prophylactic therapy, We used genotyping by pulsed-field gel electrophoresis of chromosomal DNA digests and random amplified po lymorphic DNA fingerprinting to study clonal relationships among such isolates obtained at 10 cancer centers located across Europe and the M iddle East, Analysis by both methods indicated that isolates from diff erent centers were genotypically unrelated to each other, There were f ive centers from which more than one individual patient isolate was av ailable, and most demonstrated significant within-center genetic diver sity of strains. Strains shared among patients could be identified at two centers, At the center with the largest number of bloodstream isol ates from cancer patients available, fluoroquinolone-resistant control isolates from surgical patients and fluoroquinolone-susceptible contr ol isolates from patients admitted to medical services during the same time period were unrelated to resistant cancer patient isolates and t o each other as well. A substantial number of fluoroquinolone-resistan t isolates (19 of 58) were nontypeable by pulsed-field gel electrophor esis. Fluoroquinolone resistance was commonly associated with multiple antibiotic resistance to chemically unrelated antibacterial agents ir respective of the origin of the isolates.