Molecular Detection of Antimicrobial Resistance Gene Cassettes Associated with Class 2 Integron in Salmonella Serovars Isolated in Iran
Bahareh Rajaei
Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran and Department of Stem Cells, Division of Nanobiomaterials and Tissue Engineering, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran.
Nahid Sepehri Rad
Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran
Farzad Badmasti
Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran
Mohamad Reza Razavi
Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran
Mohammad Reza Aghasadeghi
Department of Hepatitis and AIDS, Pasteur Institute of Iran, Tehran, Iran.
Raheleh Saboohi
Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran.
Taraneh Rajaei
Department of biotechnology, Pasteur Institute of Iran, Tehran, Iran.
Arfa Moshiri
Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran and Department of Biotechnology, School of Allied Sciences, Tehran University of Medical Sciences, Tehran, Iran
Mehdi Nejati
Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran.
Ahmad Reza Bahremand
Department of Mycobacteriology and Lung Research, Pasteur Institute of Iran, Tehran, Iran.
Seyed Davar Siadat *
Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran. and Department of Mycobacteriology and Lung Research, Pasteur Institute of Iran, Tehran, Iran.
*Author to whom correspondence should be addressed.
Abstract
Aim:Salmonella is an important food-borne pathogen in humans and a broad range of animals. Antimicrobial resistance in Salmonella spp. is a serious health problem in human and veterinary medicine worldwide. The aim of this study was to detect integrons, the natural recombination systems that can be transferred in companion with mobile genetic elements and play a major role in spreading antibiotic resistance genes in clinical isolates.
Place and Duration of Study:Salmonella clinical isolates were provided by a number of institutes and hospitals over the country through the years 2008-2009.
Methodology: Antimicrobial susceptibility testing and serotyping were carried out for eighty four epidemiologically unrelated clinical isolates of Salmonella serovars collected from different provinces of Iran through the years 2008-2009. PCR assays were carried out to detect intI2 gene (integrase I attributed to class 2 integron) and internal variable regions (IVRs) of class 2 integron. These sequences were deposited in EMBL/GenBank database (www.ncbi.nlm.nih.gov).
Results: Eleven isolates (13.1%) which were resistant to at least 4 groups of antimicrobial agents were considered as MDR (multidrug resistant) Salmonella serovars. PCR assays detected intI2 gene (integrase I attributed to class 2 integron) and internal variable regions (IVRs) of class 2 integron in Fourteen (16.7%) and eleven (78.6%) of Salmonella clinical isolates respectively. Analysis of the sequence data revealed 3 gene cassette arrays deposited in Genbank databases including the dhfrA1 (0.75 kb), dfrA14- lsp (1 kb), dhfrA1-sat2-aadA1 (3 kb) with three IVR distribution patterns. An artifact PCR product of 2 kb was reported in this study to be amplified together with IVRs of class 2 integrons which was associated with the fhuE- ptsG genes.
Conclusions: Presence of MDR Salmonella serovars demonstrates that antimicrobial selection pressure is widespread in our clinical settings. Detection of class 2 integron carrying gene cassettes which confer resistance to different classes of antibiotics such as aminoglycosides, and trimethoprim confirms that integron-mediated antimicrobial gene cassettes are prevalent in Salmonella serovars isolated in Iran.
Keywords: Salmonella, class 2 integron, gene cassettes, multidrug resistance (MDR).