The Relationship of Class I Integron Gene Cassettes and the Multidrug-Resistance in Extended -Spectrum β-Lactamase Producing Isolates of Escherichia coli

Abstract

Background: Integron is an important element in creating multi-drug resistant (MDR) bacteria. This study evaluated the relationship of class I integron and antibiotic resistance in extended-spectrum beta-lactamase producing (ESBL) isolates of Escherichia coli (E. coli). Methods: A total of 66 ESBL-producing E. coli were isolated from urinary tract infection in Kermanshah and their antimicrobial susceptibility was assessed. The incidence of class I integron was determined in isolates using PCR. The class I integron-associated gene cassettes were also verified by DNA sequencing. Data were analyzed using statistical methods. Results: Of 66 ESBL-producing isolates, 65 (98.5%) were MDR. The most prevalent antibiotic resistance of the isolates was observed for ampicillin (98.4%), ceftriaxone (98.4%), cefotaxime (95.4%), and co-trimoxazole (86.3%). The frequency of class I integron in isolates was 92.3%. The relationship between class I integron and resistance to streptomycin, co-trimoxazole, and ceftazidime was statistically significant. The genes encoding resistance to streptomycin and co-trimoxazole, as well as a gene encoding a protein with unknown function, were associated with class I integron. The most common gene cassette was dfrA17-aadA5. Conclusions: The results indicate a high prevalence of antibiotic resistance among ESBL-producing isolates to the antibiotics commonly used for the empirical treatment of urinary tract infections. The frequency of class I integron and associated gene cassettes involving resistance to antibiotics is high. There is a high percentage of MDR among the ESBL-producing isolates, which mostly contain gene cassettes. These findings suggest a strong association of integron and ESBL genes in the isolates.