Characterization of Non-O157 Escherichia coli from Cattle Faecal Samples in the North-West Province of South Africa

Emmanuel W Bumunang; Tim A McAllister; Rahat Zaheer; Rodrigo Ortega Polo; Kim Stanford; Robin King; Yan D Niu; Collins N Ateba

doi:10.3390/microorganisms7080272

Characterization of Non-O157 Escherichia coli from Cattle Faecal Samples in the North-West Province of South Africa

Microorganisms. 2019 Aug 20;7(8):272. doi: 10.3390/microorganisms7080272.

Authors

Emmanuel W Bumunang^{1

2

3}, Tim A McAllister⁴, Rahat Zaheer², Rodrigo Ortega Polo², Kim Stanford³, Robin King⁵, Yan D Niu⁶, Collins N Ateba⁷

Affiliations

¹ Department of Microbiology, Faculty of Natural and Agricultural Sciences, North-West University, Mafikeng Campus, Private Bag X2046, Mmabatho 2735, South Africa.
² Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB T1J 4B1, Canada.
³ Alberta Agriculture and Forestry, Lethbridge, AB T1J 4V6, Canada.
⁴ Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, AB T1J 4B1, Canada. tim.mcallister@canada.ca.
⁵ Alberta Agriculture and Forestry, Edmonton, AB T6H 4P2, Canada.
⁶ Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada. dongyan.niu@ucalgary.ca.
⁷ Department of Microbiology, Faculty of Natural and Agricultural Sciences, North-West University, Mafikeng Campus, Private Bag X2046, Mmabatho 2735, South Africa. collins.ateba@nwu.ac.za.

Abstract

Escherichia coli are commensal bacteria in the gastrointestinal tract of mammals, but some strains have acquired Shiga-toxins and can cause enterohemorrhagic diarrhoea and kidney failure in humans. Shiga-toxigenic E. coli (STEC) strains such as E. coli O157:H7 and some non-O157 strains also contain other virulence traits, some of which contribute to their ability to form biofilms. This study characterized non-O157 E. coli from South African cattle faecal samples for their virulence potential, antimicrobial resistance (AMR), biofilm-forming ability, and genetic relatedness using culture-based methods, pulsed-field gel electrophoresis (PFGE), and whole genome sequencing (WGS). Of 80 isolates screened, 77.5% (62/80) possessed Shiga-toxins genes. Of 18 antimicrobials tested, phenotypic resistance was detected against seven antimicrobials. Resistance ranged from 1.3% (1/80) for ampicillin-sulbactam to 20% (16/80) for tetracycline. Antimicrobial resistance genes were infrequently detected except for tetA, which was found in 31.3% (25/80) and tetB detected in 11.3% (9/80) of isolates. Eight biofilm-forming associated genes were detected in STEC isolates (n = 62) and two non-STEC strains. Prevalence of biofilm genes ranged from 31.3% (20/64) for ehaA^β passenger to 100% for curli structural subunit (csgA) and curli regulators (csgA and crl). Of the 64 STEC and multi-drug resistant isolates, 70.3% (45/64) and 37.5% (24/64) formed strong biofilms on polystyrene at 22 and 37 °C, respectively. Of 59 isolates screened by PFGE, 37 showed unique patterns and the remaining isolates were grouped into five clusters with a ≥90% relatedness. In silico serotyping following WGS on a subset of 24 non-O157 STEC isolates predicted 20 serotypes comprising three novel serotypes, indicating their diversity as potential pathogens. These findings show that North West South African cattle harbour genetically diverse, virulent, antimicrobial-resistant and biofilm-forming non-O157 E. coli. Biofilm-forming ability may increase the likelihood of persistence of these pathogens in the environment and facilitate their dissemination, increasing the risk of cross contamination or establishment of infections in hosts.

Keywords: PFGE; WGS; antibiotic resistance; biofilm; cattle; non-O157 Escherichia coli; virulence genes.

Grants and funding

98983/National Research Foundation of South Africa