AUTHOR=Li Yingshan , Peng Kai , Yin Yi , Sun Xinran , Zhang Wenhui , Li Ruichao , Wang Zhiqiang 

TITLE=Occurrence and Molecular Characterization of Abundant tet(X) Variants Among Diverse Bacterial Species of Chicken Origin in Jiangsu, China

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.751006

DOI=10.3389/fmicb.2021.751006

ISSN=1664-302X

ABSTRACT=<p>Many novel tigecycline-inactivating enzymes encoded by <italic>tet</italic>(X) variants from different bacteria were discovered since the plasmid-mediated <italic>tet</italic>(X3) and <italic>tet</italic>(X4) genes conferring high-level resistance to tigecycline in Enterobacterales and <italic>Acinetobacter</italic> were reported. However, there have been no comprehensive studies of the prevalence of different <italic>tet</italic>(X) variants in poultry farms. In this study, we collected 45 chicken fecal samples, isolated <italic>tet</italic>(X)-positive strains, and performed antimicrobial susceptibility testing, conjugation assay, whole-genome sequencing, and bioinformatics analysis. A total of 15 <italic>tet</italic>(X)-bearing strains were isolated from 13 samples. Species identification and <italic>tet</italic>(X) subtyping analysis found that the 15 strains belonged to eight different species and harbored four different <italic>tet</italic>(X) variants. Genomic investigation showed that transmission of <italic>tet</italic>(X) variants was associated with various mobile genetic elements, and <italic>tet</italic>(X4) was the most prevalent variant transferred by conjugative plasmids. Meanwhile, we characterized a plasmid co-harboring <italic>tet</italic>(X6) and <italic>bla</italic><sub>OXA–58</sub> in <italic>Acinetobacter baumannii</italic>. In summary, we demonstrated that different <italic>tet</italic>(X) variants were widely disseminated in the chicken farming environment and dominated by <italic>tet</italic>(X4). This finding expands the understanding of the prevalence of <italic>tet</italic>(X) among different animal sources, and it was advocated to reduce the usage of antibiotics to limit the emergence and transmission of novel <italic>tet</italic>(X) variants in the poultry industry.</p>