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Molecular epidemiology and virulence of Escherichia coli O16:H5-ST131: comparison with H30 and H30-Rx subclones of O25b:H4-ST131.Molecular epidemiology and virulence of Escherichia coli O16:H5-ST131: comparison with H30 and H30-Rx subclones of O25b:H4-ST131.Dahbi G, Mora A, Mamani R, López C, Alonso MP, Marzoa J, Blanco M, Herrera A, Viso S, García-Garrote F, Tchesnokova V, Billig M, de la Cruz F, de Toro M, González-López JJ, Prats G, Chaves F, Martínez-Martínez L, López-Cerezo L, Denamur E, Blanco J. Int J2014-11-14T23:00:00Z<p style="text-align:justify;"><span class="ms-rteThemeForeColor-2-5" style="font-family:arial, helvetica, clean, sans-serif;font-size:1.0769em;font-weight:bold;">Abstract</span><br></p><div style="color:#000000;font-family:arial, helvetica, clean, sans-serif;text-align:justify;"><p style="margin-bottom:0.5em;font-size:1.04em;">The present study was carried out to evaluate the prevalence of the clonal subgroup O16:H5-ST131 and the H30 and H30-Rx subclones among E. coli isolates causing extraintestinal infections and to know their virulence potential. The ST131 clonal group accounted for 490 (16%) of the 2995 isolates obtained from clinical samples in five Spanish hospitals during the study period (2005-2012). Among those 490 ST131 isolates, 456 belonged to serotype O25b:H4, 27 to O16:H5 and seven were O-non-typeable:H4 (ONT:H4). All 27 O16:H5 isolates showed fimH41, whereas fimH30 and fimH22 alleles were the most frequently detected among O25b:H4 isolates. The majority (381/490; 78%) of ST131 isolates belonged to H30 subclone, and 302 of 381 (79%) H30 isolates belonged to the H30-Rx subclone. Of the 27 O16:H5 isolates, 48% produced CTX-M-14; however, none produced CTX-M-15. In contrast, 46% of O25b:H4 isolates produced CTX-M-15 while only 2% produced CTX-M-14. More than a half of the O16:H5 isolates (56%) showed the ExPEC status which was significantly more prevalent within O25b:H4 isolates (81%) (P<0.01), especially among H30-Rx (97%) isolates. In the present study, a modified virotype scheme was applied within which approximately half (52%) of the O16:H5 isolates showed the C1 specific virotype. Despite their low virulence-gene score (mean of virulence genes 6.4 versus 8.5 in O25b:H4 isolates), six out of the 10 O16:H5 isolates assayed showed high virulence in the mouse model of sepsis (killed 90-100% of mice challenged). Furthermore, four O16:H5 isolates of virotypes A and C1, carrying K2 variant of group II capsule, showed lethality at 24h. Thus, certain O16:H5 fimH41 isolates show a similar in vivo virulence to that reported with the highly virulent O25b:H4 H30-Rx isolates (Mora et al., PLOS ONE 2014, e87025), supporting their potential virulence for humans.<br></p></div><p>​<span style="color:#474f51;font-family:"yanone kaffeesatz";font-size:18px;background-color:#ffffff;">[</span><a href="" style="color:#ed391b;margin:0px;padding:0px;border:0px;font-stretch:inherit;font-size:18px;line-height:inherit;font-family:"yanone kaffeesatz";vertical-align:baseline;background-color:#ffffff;">pubmed</a><span style="color:#474f51;font-family:"yanone kaffeesatz";font-size:18px;background-color:#ffffff;">]</span><br></p>73