AUTHOR=Li Aijuan , Yu Runhao , Zhao Wenbo , Schwarz Stefan , Li Chenglong , Yao Hong , Du Xiang-Dang 

TITLE=Characterization of a genomic Island carrying the tet(X4) gene in porcine Acinetobacter towneri co-harboring plasmid-borne blaNDM−1 and blaOXA−58 genes

JOURNAL=Frontiers in Veterinary Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.1002149

DOI=10.3389/fvets.2022.1002149

ISSN=2297-1769

ABSTRACT=<p>Tigecycline and carbapenems are last-resort antimicrobial agents to treat serious infections caused by multi-drug resistant bacterial pathogens. However, the co-occurrence of tigecycline and carbapenem resistance determinants challenges the clinical efficacy of these antimicrobial agents. In this study, we report the co-existence of <italic>tet</italic>(X4), <italic>bla</italic><sub>NDM−1</sub> and <italic>bla</italic><sub>OXA−58</sub> genes in the porcine <italic>Acinetobacter towneri</italic> isolate 19110F47. Sequence analysis revealed that <italic>tet</italic>(X4) gene, along with the florfenicol resistance gene <italic>floR</italic>, was flanked by three copies of IS<italic>91</italic>-like elements, which can form three different translocatable units (TUs), and were located in a 41,098-bp multidrug resistance region (MDRR) within a novel 100,354-bp genomic island (GI) region. TUs comprising <italic>floR</italic>-<italic>vir</italic>D2-IS<italic>Vsa3, hp-abh-tet</italic>(X4)-IS<italic>Vsa3</italic> and <italic>virD2</italic>-<italic>floR</italic>-IS<italic>Vsa3</italic>-<italic>hp-abh</italic>-<italic>tet</italic>(X4)-IS<italic>Vsa3</italic> can be looped out from the chromosomal DNA and facilitate the transfer of the TU-based resistance genes into other plasmidic or chromosomal sites. In addition, the carbapenemase genes <italic>bla</italic><sub>NDM−1</sub> and <italic>bla</italic><sub>OXA−58</sub> were found on different non-conjugative multiresistance plasmids in this isolate, with the genetic contexts IS<italic>Aba125</italic>-<italic>bla</italic><sub>NDM−1</sub>-<italic>ble</italic><sub>MBL</sub>-<italic>tnpR</italic> and ΔIS<italic>Aba3-bla</italic><sub>OXA−58</sub><italic>-</italic>IS<italic>Aba3</italic>, respectively. The simultaneous occurrence of <italic>tet</italic>(X4), <italic>bla</italic><sub>NDM−1</sub> and <italic>bla</italic><sub>OXA−58</sub> in the same porcine <italic>A. towneri</italic> isolate emphasizes the importance of antimicrobial resistance surveillance in food-producing animals.</p>