Multiple-Antibiotic Resistance in Salmonella enterica Serovars Isolated in Iran Harboring Class 1 Integrons

Aims: This research was carried out to detect the content and distribution of class 1 integrons in multidrug resistant Salmonella isolates. Materials and Methods: Eighty four clinical isolates of Salmonella serovars were subjected to molecular detection of class 1 integrons following the antimicrobial susceptibility test using disk diffusion method and MIC determination. Results: Eleven isolates (13.1%) which were resistant to at least 4 groups of antimicrobial agents Original Research Article Rajaei et al.; BMRJ, 5(2): 186-193, 2015; Article no.BMRJ.2015.020 187 considered as MDR (multidrug resistant) Salmonella serovars. The intI1 gene and internal variable regions (IVRs) of class 1 integron were detected in 50 (59.5%) and 35 (70%) of Salmonella clinical isolates respectively. Analysis of the sequence data revealed four gene cassette arrays including the dhfr7 (0.8 kb), aadA1 (1kb), blaP1 (1.2 kb), dhfr1-aadA1 (1.6 kb) with eight IVR distribution patterns. Conclusion: Detection of class 1 integron carrying gene cassettes which confer resistance to different classes of antibiotics such as aminoglycosides, s-lactams and trimethoprim confirms that integron-mediated antimicrobial gene cassettes are prevalent in Salmonella serovars isolated in