Molecular Detection of Antimicrobial Resistance Gene Cassettes Associated with Class 2 Integron in Salmonella Serovars Isolated in Iran.
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Date
2014-01
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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.
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Keywords
Salmonella, class 2 integron, gene cassettes, multidrug resistance (MDR)
Citation
Rajaei Bahareh, Siadat Seyed Davar, Rad Nahid Sepehri, Badmasti Farzad, Razavi Mohamad Reza, Aghasadeghi Mohammad Reza, Saboohi Raheleh, Rajaei Taraneh, Moshiri Arfa, Nejati Mehdi, Bahremand Ahmad Reza. Molecular Detection of Antimicrobial Resistance Gene Cassettes Associated with Class 2 Integron in Salmonella Serovars Isolated in Iran. British Microbiology Research Journal. 2014 Jan; 4(1): 132-141.