The Emergence and Molecular Characteristics of New Delhi Metallo β-Lactamase-Producing Escherichia coli From Ducks in Guangdong, China

This study aimed to determine the prevalence and transmission characteristics of New Delhi metallo β-lactamase (NDM)-producing Escherichia coli from ducks in Guangdong, China. In this study, a total of 28 NDM-producing E. coli isolates were recovered from 88 unduplicated diseased duck samples (31.8%) from veterinary clinics in Guangzhou, Foshan, Qingyuan, and Huizhou. Two variants, bla(NDM−1) and bla(NDM−5), were detected and the latter was present in 89.6% of the isolates (25/28). Multilocus sequence typing (MLST) analysis indicated that these E. coli isolates possessed six distinct STs, and ST156 was the most prevalent followed by ST648, ST746, ST354, ST10, and ST162. In addition, phylogenomic analysis found that two of the isolates that were recovered from a single sample possessed different genomes, and the bla(NDM)-carrying IncX3 plasmids may be horizontal transfer between E. coli isolates in the intestinal tracts of ducks. Whole-genome sequencing (WGS) analysis further revealed that bla(NDM) co-existed with other 25 types of antimicrobial resistance genes (ARGs), of which 16 ARGs were highly prevalent with detection rates >50%, and a high incidence of coproducing bla(NDM) and mcr-1 E. coli isolates (22/88, 25.0%) was detected in ducks. This study underscores the importance of surveillance for bla(NDM)-harboring microbes in ducks.