Investigation of Class I Integron in Salmonella infantis and Its Association With Drug Resistance

BACKGROUND: Infection with non-typhoid Salmonella (NTS) is one of the most important health problems all over the world. Antimicrobial drug resistance is increasing among Salmonella infantis species. OBJECTIVES: The aim of this study was to investigate the frequency of presence of class 1 integrons in S. infantis species as well as its association with drug resistance. MATERIALS AND METHODS: This cross-sectional study was performed on 50 S. infantis isolated strains, collected from chicken samples between 2009-2011. These strains were identified by standard biochemical tests and serology. Antibiotic susceptibility profiles and minimum inhibitory concentration determination for 14 antibacterial agents were performed using micro dilution and disk diffusion methods. The detection of class 1 integron was performed by the PCR method. The demographic and microbiological data for the integron positive and negative isolates were compared by SPSS software. RESULTS: Eighteen out of 50 (36%) of isolated S. infantis species had intl gene. The isolated bacteria were sensitive to cefotaxime and ciprofloxacin (100%). Also isolates were resistant to nalidixic acid, tetracycline and streptomycin. All isolate with class 1 integron were multidrug resistant. CONCLUSIONS: The result of this study showed that due to increased level of drug resistance in S. infantis and the presence of class 1 integron in these strains, resistance can be transferred to other food borne pathogens.