Antimicrobial resistance and genetic diversity of the SXT element in Vibrio cholerae from clinical and environmental water samples in northeastern Thailand

作者：Mala Wanida; Faksri Kiatichai; Samerpitak Kittipan; Yordpratum Uma****; Kaewkes Wanlop; Tattawasart Unchalee; Chomvarin Chariya^*

来源：Infection, Genetics and Evolution, 2017, 52: 89-95.

DOI：10.1016/j.meegid.2017.04.013

• Vibrio cholerae
• SXT element
• Antimicrobial resistance
• Clinical sample
• Environmental water sample

Multidrug resistance in V. cholerae has been increasing around the world including northeastern Thailand. The aquatic environment is a reservoir of V. cholerae and might be an important source of resistant strains. The aims of this study were to investigate the phylogenetic relationships of int(SXT) gene sequences from 31 clinical and 14 environmental V. cholerae 01 and non-01/non-0139 isolates and 11 sequences amplified directly from environmental water samples. We also amplified class 1 integrons, the SXT elements (targeting the int(SXT) gene) and antimicrobial resistance genes directly from water samples. Phylogenetic analysis displayed two major distinct clusters (clusters 1 and 2). Most V. cholerae 01 (19/20, 95%) and non-01/non-0139 isolates (8/ 11, 72.7%) from clinical sources, and all sequences obtained directly from water samples, belonged to cluster 1. Cluster 2 mostly comprised environmental non-01/non-0139 isolates (10/12, 83.3%). We successfully amplified the SXT elements directly from17.5% of water samples. Associated resistance genes were also amplified as follows: sul2 (41.3% of water samples), dfrAl (60%), dfr18 (33.8%), strB (70%) and tetA (2.5%). Class 1 integrons were not found in water samples, indicating that the SXT element was the major contributor of multidrug resistance determinants in this region. The SXT element and antimicrobial resistance genes could be transferred from clinical V. cholerae 01 to environmental V. cholerae non-01/non-0139 was demonstrated by conjugation experiment. These findings indicate that there may have been cross dissemination and horizontal gene transfer (HGT) of the SXT element harbored by V. cholerae 01 and non-01/non-0139 strains isolated from clinical and environmental water sources. Environmental water might be an important source of antimicrobial resistance genes in V. cholerae in this region. Direct detection of antimicrobial resistance genes in water samples can be used for monitoring the spread of such genes in the ecosystem.

• 出版日期2017-8