Class 1 integron-mediated antibiotic resistance in Salmonella enterica strains isolated in Tehran, Iran

Background and objectives: Salmonellae infection is one of the most important foodborne diseases. Antimicrobial drug resistance is increasing among Salmonella spp. and causes significant therapeutic problems in the treatment of diseases caused by this organisms. The aim of this study was to investigate the prevalence of class 1 integrons in Salmonella enterica and their relationship with antimicrobial resistance in clinical isolates from Iran during 2007-2009. Materials and Methods: Salmonella spp. strains were isolated from several hospitals in Tehran, Iran. The isolates were identified by standard biochemical tests and agglutination using specific antisera. The susceptibility of the isolates was determined according to the CLSI guidelines. Class 1 integrons were detected by PCR. Statistical comparisons of the frequency of resistance between integron-positive and integron-negative were made using Pearson χ2 test or the Fisher’s exact test. A P≤0.05 was intended as the level of statistical significance. Results: Class 1 integrons were detected in 39.1% of the strains. Integron-positive isolates represented seven different Salmonella enterica serotypes. All Salmonella isolates carrying class 1 integrons showed multiple drug resistance. Conclusion: Our findings showed that integrons class 1 were widely distributed among Salmonella enterica isolates. Surveillance and monitoring of antimicrobial drug resistance, including screening for integrons as likely indicators of drug resistance and acquisition of new resistance traits, are necessary steps in planning effective strategies for containing this phenomenon within foodborne infection organisms