AUTHOR=Liao Feng , Mo Zhishuo , Chen Meiling , Pang Bo , Fu Xiaoqing , Xu Wen , Jing Huaiqi , Kan Biao , Gu Wenpeng 

TITLE=Comparison and Evaluation of the Molecular Typing Methods for Toxigenic Vibrio cholerae in Southwest China

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.00905

DOI=10.3389/fmicb.2018.00905

ISSN=1664-302X

ABSTRACT=<p><italic>Vibrio cholerae</italic> O1 strains taken from the repository of Yunnan province, southwest China, were abundant and special. We selected 70 typical toxigenic <italic>V. cholerae</italic> (69 O1 and one O139 serogroup strains) isolated from Yunnan province, performed the pulsed field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and MLST of virulence gene (V-MLST) methods, and evaluated the resolution abilities for typing methods. The <italic>ctxB</italic> subunit sequence analysis for all strains have shown that cholera between 1986 and 1995 was associated with mixed infections with El Tor and El Tor variants, while infections after 1996 were all caused by El Tor variant strains. Seventy <italic>V. cholerae</italic> obtained 50 PFGE patterns, with a high resolution. The strains could be divided into three groups with predominance of strains isolated during 1980s, 1990s, and 2000s, respectively, showing a good consistency with the epidemiological investigation. We also evaluated two MLST method for <italic>V. cholerae</italic>, one was used seven housekeeping genes (<italic>adk</italic>, <italic>gyrB</italic>, <italic>metE</italic>, <italic>pntA</italic>, <italic>mdh</italic>, <italic>purM</italic>, and <italic>pyrC</italic>), and all the isolates belonged to ST69; another was used nine housekeeping genes (<italic>cat</italic>, <italic>chi</italic>, <italic>dnaE</italic>, <italic>gyrB</italic>, <italic>lap</italic>, <italic>pgm</italic>, <italic>recA</italic>, <italic>rstA</italic>, and <italic>gmd</italic>). A total of seven sequence types (STs) were found by using this method for all the strains; among them, <italic>rstA</italic> gene had five alleles, <italic>recA</italic> and <italic>gmd</italic> have two alleles, and others had only one allele. The virulence gene sequence typing method (<italic>ctxAB</italic>, <italic>tcpA</italic>, and <italic>toxR</italic>) showed that 70 strains were divided into nine STs; among them, <italic>tcpA</italic> gene had six alleles, <italic>toxR</italic> had five alleles, while <italic>ctxAB</italic> was identical for all the strains. The latter two sequences based typing methods also had consistency with epidemiology of the strains. PFGE had a higher resolution ability compared with the sequence based typing method, and MLST used seven housekeeping genes showed the lower resolution power than nine housekeeping genes and virulence genes methods. These two sequence typing methods could distinguish some epidemiological special strains in local area.</p>