Analysis of Integrons and Associated Gene Cassettes in Clinical Isolates of Escherichia coli

Background and Objective: Horizontal transfer of integrons is the most successful transfer of antimicrobial resistance genes and the emergence of multi-drug resistance strains. The aim of the present study was to investigate the prevalence of class I and II integrons and their gene cassette assortments and antibiotic resistance profile in Escherichia coli strains isolated from diarrheal and urine specimens. Materials and Methods: In this cross-sectional study ۲۰۰ E. coli isolates were collected from the clinical urine and stool specimens. After identification of isolates by biochemical tests, the antibiotic susceptibility test (disk diffusion method) was done according to CLSI advice against ۱۳ antibiotics. DNA extraction was performed and class ۱ and ۲ integrons and associated gene cassettes were determined using PCR method. Results: The highest resistance was found against erythromycin (۹۶.۵%) and %۹۸.۵ of isolates were susceptible to imipenem. Out of ۲۰۰ isolates, class ۱ integron was detected in ۱۸۱ (۹۰.۵%) isolates and ۷۸.۵% of these isolates were positive for the gene cassettes. Also, class ۲ integron was detected in ۱۵ (۷.۵%) isolates and ۲% of them were positive for the gene cassettes. Dihydrofolate reductase (dfrA) and aminoglycoside adenyl transferase (aad) gene cassettes were found most frequently in intI۱ positive isolates. Conclusion: These results indicate that class ۱ integrons are widespread among E. coli isolates. Therefore, appropriate surveillance and control measures are essential to prevent further spread of integron producing isolates. References ۱- Goossensa H, Grabeind B. Prevalence and antimicrobial susceptibility data for extended- spectrum β- lactamas and AmpC- producing Enterobacteriaceaefrom the MYSTIC program in Europe and United States (۱۹۹۷- ۲۰۰۴). Diag Microbiol Infect Dis. ۲۰۰۵ ۵۳: ۲۵۷-۶۴. ۲- Foxman B. Epidemiology of urinary tract infections: incidence, morbidity and economic costs. 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Keywords:

Keywords: Escherichia coli , Integron , Gene cassette , Antibiotic resistance