Abstract

Integrons, which are short sequences of deoxyribonucleic acid (DNA) like transposes have the capability of transferring genes of antibiotic resistance to other bacteria. Studies have revealed that these elements could bear the extended spectrum beta lactamase (ESBL), genes that are transmitted to many strains of bacteria especially Enterobacteriaceae members. The aim of this study was to determine prevalence of integron elements and gene groups encoding ESBLs in Escherichia coli, and Klebsiella pneumoniae isolated from urine specimens. In total 5000 specimen were collected from children with urinary tract infection (UTI) referred to Mofid children hospital in Tehran, during the 6 month study period by consecutive sampling. The 100 confirmed isolates ofE. coli and 50 K. pneumoniae were tested for susceptibility to different antimicrobial drugs like cefotaxime, ceftriaxone, cefpodoxime, aztreonam, ceftazidime, cefpodoxime plus clavulanate antibiotic susceptibility testing was performed by disk diffusion method and E-test method were used for detection MIC. ESBL positive bacteria were preserved in -70°C freezers and finally polymerase chain reaction (PCR) performed on them. The gene groups studied for presences of ESBLs were CTX, TEM, SHV and Int. Thirty isolates of E. coli were positive for ESBL; the frequency of gene groups was as follows: CTX (24), TEM (26), SHV (15), and Int (12). In the 19 isolated stains of K. pneumonia positive for ESBL, the frequency of gene groups was: CTX (18), TEM (18), SHV (15) and Int (10). The prevalence of class 1 Integrons was 52% in non-outbreak E. coli isolates and 48% in K. pneumoniae isolates from patients in our study. Less than half of the selected isolates from patients' samples that we tested were positive for class 1 Integron. 48% of K. pneumoniae and 54% of E. coli strains possessed Integron and ESBL genes concomitantly.

Key words: Integron, extended –spectrum β-lactmase (ESBLs), PCR, Escherichia coli,Klebsiella Pneumoniae.