AUTHOR=He Juan , Li Cui , Cui Pengfei , Wang Hongning 

TITLE=Detection of Tn7-Like Transposons and Antibiotic Resistance in Enterobacterales From Animals Used for Food Production With Identification of Three Novel Transposons Tn6813, Tn6814, and Tn6765

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.02049

DOI=10.3389/fmicb.2020.02049

ISSN=1664-302X

ABSTRACT=<p><italic>Enterobacterales</italic> are widely distributed in the gastro-intestinal system of animals and may cause opportunistic infections. Worse still, multidrug-resistant <italic>Enterobacterales</italic> also poses a serious threat to public health. Tn<italic>7</italic>-like transposons have been found in several species of the <italic>Enterobacterales</italic> order and play an important role in dissemination of antibiotic resistance. This study aimed to investigate the distribution and genetic characterization of Tn<italic>7</italic>-like transposons in <italic>Enterobacterales</italic> isolates from food animals and their association with antibiotic resistance. <italic>Enterobacterales</italic> isolated from the samples were identified and classified according to the 16S rDNA sequence. Tn<italic>7</italic>-like transposons and associated integrons were detected by polymerase chain reaction (PCR) and sequencing. The antibiotic resistance of each Tn<italic>7</italic>-like transposon positive isolate was detected according to the Kirby-Bauer disk diffusion method. Then, six representative strains were selected to study the genetic environment by whole-genome sequencing (WGS). In total, we isolated 377 Tn<italic>7</italic>-like transposons positive strains of <italic>Enterobacterales</italic>. Class 2 integrons were detected in 99.5% of the isolates, and there were high frequency mutation sites especially in base 535, a stop mutation. Many isolates (54.9%) were multidrug-resistant and observed high resistance rates to trimethoprim/sulfamethoxazole and streptomycin. Among these strains, we found three new types of Tn<italic>7</italic>-like transposons, named Tn<italic>6813</italic>, Tn<italic>6814</italic>, and Tn<italic>6765</italic>. This is the first comprehensive survey that shows Tn<italic>7</italic>-like transposons in <italic>Enterobacterales</italic> from animals used for food production in different regions of China. This study also provides an insight into the horizontal transfer of resistance genes associated with Tn<italic>7</italic>-like transposons.</p>