Abstract:
INTRODUCTION : Extended spectrum beta-lactamase (ESBL) producing Escherichia
coli have become widespread among food producing animals. These strains serve
as a reservoir of antibiotic resistance genes (ARGs) and act as a possible source of
infection to humans as transmission can occur by direct or indirect contact.
METHODS : This study investigated the faecal carriage of ESBL producing and
colistin resistant E. coli in poultry over a 2-year period (2017-2019) from
Zimbabwe. A total of 21 ESBL positive isolates from poultry cloacal specimens
were selected for whole genome sequencing from animal E. coli isolates biobanked
at the National Microbiology Reference laboratory using phenotypic
susceptibility testing results from the National Escherichia coli Surveillance
Program to provide representation of different geographical regions and year of
isolation. Cloacal swabs were collected from 3000 broiler live birds from farm 1
and fromfarm2, 40 backyard chickens and 10 duckswere sampled. Antimicrobial
susceptibility and ESBL testing were performed as per Clinical Laboratory
Standards Institute guidelines. Whole genome sequencing of ESBL producing
isolates was used to determine sequence types (STs), ARGs, and phylogroups.
RESULTS : Twenty-one of the included E. coli isolates were confirmed as ESBL
producers. Three defined sequence type clonal complexes (CCs) were identified
(ST10CC, ST155CC and ST23CC), with ST10CC associated with the most antibiotic
resistant profile. The ESBL phenotype was linked to the presence of either
cefotaximase-Munich-14 (CTX-M-14) or CTX-M-79. Plasmid mediated quinolone
resistant determinants identified were qnrB19 and qnrS1 and one ST10CC isolate
from farm 1 broiler chickens harbored a mobile colistin resistance gene (mcr-1).
Phylogenetic groups most identified were B1, A and unknown.
DISCUSSIONS : The avian ESBL producing E. coli belonged to a diverse group of
strains. The detection of several ARGs highlights the importance of
implementing enhanced control measures to limit the spread in animals,
environment, and humans. This is the first report of mcr-1 in Zimbabwe,
which further underscores the importance of the One Health approach to
control the spread and development of AMR.
