Multiple ESBL-producing Escherichia coli sequence types carrying quinolone and aminoglycoside resistance genes circulating in companion and domestic farm animals in Mwanza, Tanzania, harbor commonly occurring plasmids

Abstract

The increased presence of extended-spectrum beta-lactamase (ESBL)-producing bacteria in humans, animals, and their surrounding environments is of global concern. Currently there is limited information on ESBL presence in rural farming communities worldwide. We performed a cross-sectional study in Mwanza, Tanzania, involving 600 companion and domestic farm animals between August/September 2014. Rectal swab/cloaca specimens were processed to identify ESBL-producing Enterobacteriaceae. We detected 130 (21.7%) animals carrying ESBL-producing bacteria, the highest carriage being among dogs and pigs [39.2% (51/130) and 33.1% (43/130), respectively]. The majority of isolates were Escherichia coli [93.3% (125/134)] and exotic breed type [OR (95%CI) = 2.372 (1.460 3.854), p-value < 0.001] was found to be a predictor of ESBL carriage among animals. Whole-genome sequences of 25 ESBL-producing E. coli were analyzed for phylogenetic relationships using multi-locus sequence typing (MLST) and core genome comparisons. Fourteen different sequence types were detected of which ST617 (7/25), ST2852 (3/25), ST1303 (3/25) were the most abundant. All isolates harbored the blaCTX-M-15 allele, 22/25 carried strA and strB, 12/25 aac(6)-lb-cr, and 11/25 qnrS1. Antibiotic resistance was associated with IncF, IncY, as well as non-typable plasmids. Eleven isolates carried pPGRT46-related plasmids, previously reported from isolates in Nigeria. Five isolates had plasmids exhibiting 85 99% homology to pCA28, previously detected in isolates from the US. Our findings indicate a pan-species distribution of ESBL-producing E. coli clonal groups in farming communities and provide evidence for plasmids harboring antibiotic resistances of regional and international impact.