Molecular characterization and PCR-based replicon typing of multidrug resistant Shigella sonnei isolates from an outbreak in Thimphu, BhutanReportar como inadecuado

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BMC Research Notes

, 7:95

First Online: 20 February 2014Received: 02 August 2013Accepted: 14 February 2014DOI: 10.1186-1756-0500-7-95

Cite this article as: Ruekit, S., Wangchuk, S., Dorji, T. et al. BMC Res Notes 2014 7: 95. doi:10.1186-1756-0500-7-95


BackgroundShigella species are an important cause of diarrhea in developing countries. These bacteria normally acquire their antibiotic resistance via several different mobile genetic elements including plasmids, transposons, and integrons involving gene cassettes. During a diarrhea surveillance study in Thimphu, Bhutan in June and July, 2011, Shigella sonnei were isolated more frequently than expected. This study describes the antibiotic resistance of these S. sonnei isolates.

MethodsA total of 29 S. sonnei isolates from Thimphu, Bhutan was characterized for antimicrobial susceptibility by disc diffusion assay and minimum inhibitory concentration MIC assay. All isolates were tested by pulsed-field gel electrophoresis PFGE with restriction enzyme Xba I and were tested for plasmid. The plasmid patterns and the PFGE patterns were analyzed by Bionumerics software. DNA sequencing was performed on amplified products for gyraseA gene and class 1 and class 2 integrons. S. sonnei isolates were classified for incompatibility of plasmids by PCR-based replicon typing PBRT.

ResultsThese S. sonnei were resistant to multiple drugs like ciprofloxacin, nalidixic acid, trimethoprim-sulfamethoxazole, streptomycin, and tetracycline but susceptible to azithromycin. All isolates had class 2 integrons dfrA1, sat1 and aadA1 genes. Two point mutations in Gyrase A subunit at position Ser83Leu and Asp87Gly were detected in these quinolone resistant isolates. The plasmid and PFGE patterns of S. sonnei isolates suggested a clonal relationship of the isolates. All isolates carried common ColE plasmid. ColE plasmid co-resided with B-O plasmid nine isolates or I1 plasmid one isolate.

ConclusionsThe characteristics of 29 S. sonnei isolates from Thimphu, Bhutan in June and July, 2011 are identical in PFGE, plasmid and resistance pattern. This study suggests that these recent S. sonnei isolates are clonally related and multidrug-resistant.

KeywordsShigella sonnei Multidrug resistance Bhutan Electronic supplementary materialThe online version of this article doi:10.1186-1756-0500-7-95 contains supplementary material, which is available to authorized users.

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Autor: Sirigade Ruekit - Sonam Wangchuk - Tshering Dorji - Kinzang Pem Tshering - Piyarat Pootong - Panida Nobthai - Oralak Seric


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