Antibiotic resistance patterns and characterization of class I integron in uropathogenic escherichia coli in Lebanon. (c2008)

Abstract

Improper monitoring of antibiotic usage has hastened the development of antimicrobial resistance among uropathogenic Escherichia coli (UPEC). The rapid dissemination of antibiotic-resistance is mediated by gene transfer mechanisms involving mobile genetic elements including the recently characterized gene cassettes in integrons. Integrons are conserved DNA sequences associated with multi-drug resistance. In this study the phenotypic resistance profiles and minimum inhibitory concentration of 18 currently used antibiotics were determined using the E-test on 50 UPEC isolates collected from two Lebanese hospitals. The isolates were additionally screened using real-time PCR. for the presence of the class I integron. The variable region (VR) was then amplified in plasmids extracted from isolates that carried the integrase gene. The majority of the isolates tested were found to be resistant to cephalothin (86%), ampicillin (72%) and amoxicillin-clavulinic acid (70%), while none were resistant to fosfomycin and only 2% to imipenem. Out of the 50 tested isolates, 26% of the isolates were resistant to ten or more of the tested antibiotics, while 48% harboured the class I integron integrase gene. Within the 24 class I integron positive isolates, 18 were positive for the plasmid VR with a size ranging from 0.75 kbp to 2.5 kbp. Interestingly, 8% of the isolates that were resistant to more than ten antibiotics were negative for the class I integron. Those isolates either carried an integron other than class I or had the genes dispersed in the genome. Isolates that were positive for the presence of the class I integron but gave a negative result in the plasmid VR PCR (n=6), had the VR PCR repeated on the whole DNA extract. None of those gave a positive result; indicating that the integron might be empty. This study represents the first report from Lebanon and the Arab world that characterizes the presence of class I integron in uropathogenic E. coli isolates, and provides basal information for future pursuit and comparison especially with respect to epidemiologic distribution, antimicrobial resistance and evolution of these important pathogens.