Molecular Characteristics of ST1193 Clone among Phylogenetic Group B2 Non-ST131 Fluoroquinolone-Resistant Escherichia coli

Abstract

<b>Objectives:</b> Sequence type 1193 is emerging as a new, virulent and resistant lineage among fluoroquinolone resistant <i>Escherichia coli</i> (FQ^r<i>E. coli</i>). In this study, we investigated the prevalence and molecular characteristics of this clone isolated from a Chinese university hospital. <b>Methods:</b> 73 phylogenetic group B2-FQ^r-non-ST131 isolates were collected from August 2014 and August 2015 at a Chinese university hospital. Isolates were screened for ST1193 by multilocus sequence typing. <i>E. coli</i> ST1193 then underwent lactose fermentation determination, susceptibility testing, virulence genotyping, PCR-based O typing, pulsed-field gel electrophoresis (PFGE) and FQ^r mechanism analysis. <b>Results:</b> Of 73 B2-FQ^r-non ST131 <i>E. coli</i> isolates, 69.9% (<i>n</i> = 51) were ST1193. 90.2% (46/51) of ST1193 isolates were O75 serotype and 96.1% (49/51) of the ST1193 isolates were lactose non-fermenters. 35 clusters were identified by PFGE. ST1193 isolates exhibited a set of 3 conserved mutations defining quinolone-resistance determining region substitutions (<i>gyrA</i> S83L, D87N, and <i>parC</i> S80I). The most frequent VF genes detected in these <i>E. coli</i> ST1193 isolates were <i>fyuA</i> (yersiniabactin, 96.1%), <i>fimH</i> (type 1 fimbriae, 94.1%), <i>iutA</i> (iron uptake gene, 90.2%), <i>kpsMT II</i> (group II capsule, 90.2%), <i>kpsK1</i> (K1 capsule, 86.3%) and PAI. <b>Conclusion:</b> ST1193 lineage accounts for the majority of group B2-FQ^r-non-ST131 <i>E. coli</i> clinical isolates. Most of the ST1193 are serotype O75 and lactose non-fermenting. Strategic surveillance and control schemes are needed in the future for this newly emerging clone of <i>E. coli</i>: B2-FQ^r-ST1193.