Antibiotic Resistance and Virulence of Extraintestinal Pathogenic Escherichia coli (ExPEC) Vary According to Molecular Types

Yitao Duan,Zhenzhe Wu,Shuangqing Liu,Liyang Zheng,Daqing Mao,Yi Luo,Yang Cao,Hongqiang Ren,Siyuan Zhu,Huihui Gao

doi:10.3389/fmicb.2020.598305

Abstract

Extraintestinal pathogenic Escherichia coli (ExPEC) can cause many human extraintestinal infections. Resistance and virulence of ExPEC are inextricably linked to its phylogenetic background. However, studies on type-specific distribution of resistance and virulence and the connection between resistance/virulence and molecular typing are lacking. Here, 411 ExPEC strains were collected and characterized using antimicrobial susceptibility testing and molecular typing. Among these, 74 representative strains were selected for whole genome sequencing and the Galleria mellonella killing assay. CH40-30-ST131, CH37-27-ST405, CH40-41-ST131, and CH13-5-ST12 isolates had high resistance rates to all antimicrobials tested. BlaCTX–M played a significant role in the β-lactam resistance of ExPEC isolates. CH14-64-ST1193, CH40-30-ST131, and CH35-27-ST69 isolates were highly virulent in the G. mellonella model. Virulence factors (VFs) involved in adherence (papB, papI, papX, and fimA), autotransporter (sat), invasion (aslA, kpsD), iron uptake (except for entD), or toxin (senB) might be responsible for pathogenicity in vivo. Specific antibiotic resistance genes (ARGs) or VFs were prevalent in specific types of strains, including papB, papI, fimA, sat, kpsD, senB, and aerobactin genes in CH14-64-ST1193 isolates; blaCTX–M–15, aac(6′)-Ib-cr, papB, papI, sat, iucA, iucB, iucC, chuT, chuX, and shuU in CH40-30-ST131 isolates; tetB in CH35-27-ST69 and CH13-5-ST12 isolates. Type distribution also differed by VF score. CH37-27-ST405 and CH26-5-ST38 isolates carried more ARGs and VFs indicating that they had a high resistance and virulence potential. This study demonstrates the type-specific distribution of resistance and virulence thus providing a basis for further research, prevention and treatment of ExPEC infections.

Highlights

Extraintestinal pathogenic Escherichia coli (ExPEC) is one of the most common bacterial pathogens isolated from clinical specimens
According to the phylogenetic groups and sequence type (ST) of 74 sequenced strains sampled from the 411 ExPEC isolates (Supplementary Table S1), we could infer some CH-ST correlations with phylogenetic groups of the different strains in the cohort, including CH1464-ST1193, CH40-30-ST131, CH40-41-ST131, CH38-27-ST95, and CH13-5-ST12 belonging to group B2; CH35-27-ST69 and CH37-27-ST405, and CH26-5-ST38 belonging to group D; CH11-54 belonging to group F; and ST648 belonging to group A
CH typing based on the sequencing of two loci is faster and cheaper than the standard seven-locus Multilocus sequence typing (MLST), and specific CH types correspond to specific STs with 95% accuracy (Roer et al, 2018)

Summary

Introduction

Extraintestinal pathogenic Escherichia coli (ExPEC) is one of the most common bacterial pathogens isolated from clinical specimens. It causes urinary tract infection, bacteremia, neonatal meningitis, and other infections at non-intestinal sites (Biran and Ron, 2018). With the exception of ST131 isolates, there are less studies on the characterization of antibiotic resistance and virulence of ExPEC belonging to other molecular types. The study shows that antibiotic resistance and virulence of ExPEC strains differ according to molecular types. It provides a basis for further research targeting prevention and treatment

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Results

Conclusion