AUTHOR=de Jesús Hernández-Díaz Lucio , Leon-Sicairos Nidia , Velazquez-Roman Jorge , Flores-Villaseñor Héctor , Guadron-Llanos Alma M. , Martinez-Garcia J. Javier , Vidal Jorge E. , Canizalez-Roman Adrián 

TITLE=A pandemic Vibrio parahaemolyticus O3:K6 clone causing most associated diarrhea cases in the Pacific Northwest coast of Mexico

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00221

DOI=10.3389/fmicb.2015.00221

ISSN=1664-302X

ABSTRACT=<p>Between September and October of 2004, more than 1230 cases of gastroenteritis due to pandemic O3:K6 strains of <italic>Vibrio parahaemolyticus</italic> (<italic>V. parahaemolyticus</italic>) were reported in the relatively small geographical area of Southern Sinaloa, a state located in Northwest Mexico. Since then, <italic>V. parahaemolyticus</italic>-associated gastroenteritis cases have gradually increased in prevalence spreading from south to north. The present study conducted an epidemiological surveillance of <italic>V. parahaemolyticus</italic> strains in both environmental and clinical samples along the Pacific coast of Sinaloa from 2011 to 2013. The genetic relatedness, serotype dominance and antibiotic resistance of isolates were investigated. A total of 46 strains were isolated from environmental samples (e.g., sediment, seawater and shrimp), whereas 249 strains were obtained from stools of patients with gastroenteritis. Nine different O serogroups and 16 serovars were identified. Serovars O3:K6 and O6:K46 were identified in both environmental and clinical strains. Whereas most environmental isolates carried the <italic>tdh</italic> gene (71.74%, 33/46), only three (6.52%) belonged to pandemic clones (O3:K6, O3:KUT and OUT:KUT). In contrast, 81.1% (202/249) of clinical isolates belonged to pandemic serotypes, with O3:K6 (<italic>tdh</italic>, <italic>toxRS/new</italic>, and/or <italic>orf8</italic>) representing the predominant serovar (97%, 196/202). This prevalence of pathogenic (<italic>tdh</italic> and/or <italic>trh</italic> positive) and O3:K6 pandemic <italic>V. parahaemolyticus</italic> isolates in this study were similar to those found from 2004 to 2010. As investigated by REP-PCR, genetic lineages of selected O3:K6 strains isolated in this study and some isolated earlier were nearly identical. Antimicrobial susceptibility testing showed that most strains (93.8%) were resistant to ampicillin but sensitive to <italic>chloramphenicol</italic> (98.8%). Multidrug resistance significantly increased from 8.6% (2004–2010) to 22.93% (2011–2013; <italic>p</italic> &lt; 0.05). Our data indicate that pandemic O3:K6 clone has endemically established in the Pacific Coast of Mexico.</p>