Frequency and Diversity of Hybrid Escherichia coli Strains Isolated from Urinary Tract Infections.

Júllia A S Nascimento,Tânia A T Gomes,Ana Carolina M Santos,Tiago B Valiatti,Rodrigo Cayô,Ana C Gales,José F Santos-Neto,Fernanda F Santos

doi:10.3390/microorganisms9040693

Júllia A S Nascimento, Tânia A T Gomes + Show 6 more

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https://doi.org/10.3390/microorganisms9040693

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Journal: Microorganisms	Publication Date: Mar 27, 2021
Citations: 20	License type: CC BY 4.0

Affiliation: Universidade Federal de São Paulo

Abstract

(1) Background: Hybrid uropathogenic Escherichia coli (UPEC) strains carry virulence markers of the diarrheagenic E. coli (DEC) pathotypes, which may increase their virulence potential. This study analyzed the frequency and virulence potential of hybrid strains among 452 UPEC strains. (2) Methods: Strains were tested for the DEC virulence diagnostic genes’ presence by polymerase chain reaction (PCR). Those carrying at least one gene were classified as hybrid and further tested for 10 UPEC and extraintestinal pathogenic E. coli (ExPEC) virulence genes and phylogenetic classification. Also, their ability to produce hemolysis, adhere to HeLa and renal HEK 293T cells, form a biofilm, and antimicrobial susceptibility were evaluated. (3) Results: Nine (2%) hybrid strains were detected; seven of them carried aggR and two, eae, and were classified as UPEC/EAEC (enteroaggregative E. coli) and UPEC/aEPEC (atypical enteropathogenic E. coli), respectively. They belonged to phylogroups A (five strains), B1 (three), and D (one), and adhered to both cell lineages tested. Only the UPEC/EAEC strains were hemolytic (five strains) and produced biofilm. One UPEC/aEPEC strain was resistant to third-generation cephalosporins and carried blaCTX-M-15. (4) Conclusions: Our findings contribute to understanding the occurrence and pathogenicity of hybrid UPEC strains, which may cause more severe infections.

Highlights

Escherichia coli is a commensal microorganism of the gastrointestinal tract of mammals
This study aimed to analyze the frequency of hybrid uropathogenic E. coli (UPEC) strains among E. coli strains recovered from patients with urinary tract infections (UTIs) and characterize molecularly and phenotypically their virulence background
The presence of eae in isolates devoid of bfpB and stx is the diagnostic marker of aEPEC

Summary

Introduction

Escherichia coli is a commensal microorganism of the gastrointestinal tract of mammals. Some E. coli strains can be considered pathogenic due to the acquisition of different virulence-encoding genes during their evolution, which allowed them to cause intestinal or extraintestinal infections [1]. According to the body site of infection and their virulence markers, these pathogens can be divided into two different groups called diarrheagenic (DEC) and extraintestinal pathogenic (ExPEC) E. coli. Unlike DEC, the ExPEC pathotypes were defined by isolation source, share different sets of virulence factors (VFs), and pathogenic strains to humans are pathogenic to animals and vice-versa [5,6]. More than 50 VFs were described as playing a role in ExPEC pathogenesis [7,8].

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