AUTHOR=Montso Peter Kotsoana , Mlambo Victor , Ateba Collins Njie 

TITLE=The First Isolation and Molecular Characterization of Shiga Toxin-Producing Virulent Multi-Drug Resistant Atypical Enteropathogenic Escherichia coli O177 Serogroup From South African Cattle

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=9

YEAR=2019

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2019.00333

DOI=10.3389/fcimb.2019.00333

ISSN=2235-2988

ABSTRACT=<p>Atypical enteropathogenic <italic>E. coli</italic> (aEPEC) is a group of diarrhoeagenic <italic>Escherichia coli</italic> with high diversity of serogroups, which lack the bundle-forming pili (BFP) and genes encoding for shiga toxins. The aim of this study was to isolate, identify and determine virulence and antibiotic resistance profiles of aEPEC O177 strains from cattle feces. A total of 780 samples were collected from beef and dairy cattle and analyzed for the presence of <italic>E. coli</italic> O177. One thousand two hundred and seventy-two (1272) presumptive isolates were obtained and 915 were confirmed as <italic>E. coli</italic> species. Three hundred and seventy-six isolates were positively confirmed as <italic>E. coli</italic> O177 through amplification of <italic>rmlB</italic> and <italic>wzy</italic> gene sequences using multiplex PCR. None of these isolates harbored <italic>bfpA</italic> gene. A larger proportion (12.74%) of the isolates harbored <italic>hlyA</italic> gene while 11.20, 9.07, 7.25, 2.60, and 0.63% possessed <italic>stx</italic><sub>2</sub>, <italic>stx</italic><sub>1</sub><italic>, eaeA, stx</italic><sub>2<italic>a</italic></sub>, and <italic>stx</italic><sub>2<italic>d</italic></sub>, respectively. Most of <italic>E. coli</italic> O177 isolates carried <italic>stx</italic><sub>2</sub>/<italic>hlyA</italic> (9.74%). Furthermore, 7.40% of the isolates harbored <italic>stx</italic><sub>1</sub>/<italic>stx</italic><sub>2</sub> while 7.09% possessed <italic>stx</italic><sub>1</sub>/<italic>stx</italic><sub>2</sub>/<italic>hlyA</italic> genes. Only one isolate harbored <italic>stx</italic><sub>1</sub>/<italic>stx</italic><sub>2</sub>/<italic>hly</italic>/<italic>eaeA</italic>/<italic>stx</italic><sub>2<italic>a</italic></sub><italic>/stx</italic><sub>2<italic>d</italic></sub> while 5.11% of the isolates harbored all the four major virulence genes <italic>stx</italic><sub>1</sub>/<italic>stx</italic><sub>2</sub>/<italic>hlyA</italic>/<italic>eaeA</italic>, simultaneously. Further analysis revealed that the isolates displayed varied antimicrobial resistance to erythromycin (63.84%), ampicillin (21.54%), tetracycline (13.37%), streptomycin (17.01%), kanamycin (2.42%), chloramphenicol (1.97%), and norfloxacin (1.40%). Moreover, 20.7% of the isolates exhibited different phenotypic multi-drug resistance patterns. All 73 isolates harbored at least one antimicrobial resistance gene. The <italic>aadA, streA, streB, erm</italic>, and <italic>tetA</italic> resistance genes were detected separately and/or concurrently. In conclusion, our findings indicate that environmental isolates of aEPEC O177 strains obtained from cattle in South Africa harbored virulence and antimicrobial resistance gene determinants similar to those reported in other shiga-toxin producing <italic>E. coli</italic> strains and suggest that these determinants may contribute to the virulence of the isolates.</p>