AUTHOR=Xu Yanmei , Bai Xiangning , Jin Yujuan , Hu Bin , Wang Hong , Sun Hui , Fan Ruyue , Fu Shanshan , Xiong Yanwen 

TITLE=High Prevalence of Virulence Genes in Specific Genotypes of Atypical Enteropathogenic Escherichia coli

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=7

YEAR=2017

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2017.00109

DOI=10.3389/fcimb.2017.00109

ISSN=2235-2988

ABSTRACT=<p>Atypical enteropathogenic <italic>Escherichia coli</italic> (aEPEC) strains are emerging enteropathogens that have been detected worldwide. A collection of 228 aEPEC strains (121 from diarrheal patients, 27 from healthy carriers, 47 from animals and 33 from raw meats) were investigated for serotypes, virulence gene profiles and phylogenetic relationships. Sixty-six O serogroups were identified. Serogroup O51 was the most prevalent, followed by O119, O26 and O76. For the 20 virulence genes detected, statistically significant differences were observed in the overall prevalence of <italic>efa1</italic> (<italic>lifA</italic>), <italic>nleB, nleE, set</italic>/<italic>ent, paa</italic>, and <italic>ehxA</italic> genes among strains from diarrheal patients, healthy carriers, animals and raw meats, respectively. Strains from diarrheal patients had significantly higher levels of <italic>efa1</italic> (<italic>lifA</italic>) (29.8 vs. 0%, <italic>P</italic> = 0.0002), <italic>nleB</italic> (41.3 vs. 7.4%, <italic>P</italic> = 0.0004), <italic>nleE</italic> (43.8 vs. 7.4%, <italic>P</italic> = 0.0002) and <italic>set/ent</italic> (41.3 vs. 7.4%, <italic>P</italic> = 0.0004) genes than strains obtained from healthy carriers. The <italic>paa</italic> gene was identified more often in isolates from raw meats (63.6 vs. 14.8%, <italic>P</italic> &lt; 0.0001), animals (42.6 vs. 14.8%, <italic>P</italic> &lt; 0.0122), and diarrheal patients (36.4 vs. 14.8%, <italic>P</italic> &lt; 0.0225) than in strains obtained from healthy carriers. The <italic>ehxA</italic> gene was detected more frequently in strains from raw meats than in strains from diarrheal patients (27.3 vs. 2.5%, <italic>P</italic> = 0.0000) and healthy carriers (27.3 vs. 7.4%, <italic>P</italic> = 0.0474). The phylogenetic marker, <italic>yjaA</italic>, was more frequently observed in strains among healthy carriers than in diarrheal patient strains. Among the 228 aEPEC strains, 79 sequence types (STs) were identified. The prominent STs, which comprised strains carrying the four OI-122 genes and <italic>lpfA</italic>, were ST40, ST328, and ST29. Overall, the results indicate that aEPEC strains isolated in China are highly heterogeneous. aEPEC strains that are potentially more pathogenic appear to be related to specific STs or clonal complexes and serotypes. The high prevalence of diarrhea-associated genes in animal or raw meat strains suggests a zoonotic transmission pathway for potentially human pathogenic aEPEC.</p>