AUTHOR=Zhu Zhichen , Wu Shuhua , Zhu Jie , Wang Tao , Wen Yicheng , Yang Chengcheng , Lv Jinnan , Zhang Haifang , Chen Liang , Du Hong 

TITLE=Emergence of Aeromonas veronii strain co-harboring blaKPC–2, mcr-3.17, and tmexC3.2-tmexD3.3-toprJ1b cluster from hospital sewage in China

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1115740

DOI=10.3389/fmicb.2023.1115740

ISSN=1664-302X

ABSTRACT=<sec><title>Introduction</title><p>The raise of multi-drug resistant bacteria involving carbapenem, colistin, or tigecycline resistance constitutes a threat to public health, which partly results from the transmission of corresponding mobile resistance genes, such as <italic>bla</italic><sub>KPC</sub> and <italic>bla</italic><sub>NDM</sub> for carbapenem, <italic>mcr</italic> for colistin, and <italic>tmexCD-toprJ</italic> gene cluster for tigecycline. Herein, we described the emergence of an <italic>Aeromonas veronii</italic> strain HD6454 co-harboring <italic>bla</italic><sub>KPC–2</sub>, <italic>mcr-3.17</italic>, and <italic>tmexC3.2-tmexD3.3-toprJ1b</italic> gene cluster from hospital sewage.</p></sec><sec><title>Methods</title><p>Whole genome sequencing (WGS) was used to determine the genome sequence of HD6454, and the detailed genomic analysis of genetic elements or regions carrying key antimicrobial resistance genes (ARGs) from HD6454 were performed. Cloning experiment was conducted to confirm the function of key ARGs in mediating antimicrobial resistance. Conjugation experiment was conducted to determine the mobility of the plasmid.</p></sec><sec><title>Results</title><p>The results showed that this strain belonged to a novel sequence type (ST) variant ST1016, and carried 18 important ARGs. Among them, the <italic>bla</italic><sub>KPC–2</sub> was carried by non-self-transmissible IncP-6 plasmid, while <italic>tmexC3.2-tmexD3.3-toprJ1b</italic> gene cluster and <italic>mcr-3.17</italic> were carried by integrative and mobilizable element (IME) or IME-related region in chromosome. The <italic>mcr-3.17</italic>, <italic>mcr-3.6</italic>, and <italic>mcr-3-like3</italic> genes were further inferred to originate from IMEs of <italic>Aeromonas</italic> species. Additionally, for the first time, the <italic>mcr-3.17</italic> was confirmed to confer low-level resistance to colistin under inducible expression, while <italic>tmexC3.2-tmexD3.3-toprJ1b</italic> gene cluster was confirmed to confer low-level resistance to tigecycline.</p></sec><sec><title>Discussion</title><p>This is the first report of a strain co-harboring <italic>bla</italic><sub>KPC–2</sub>, <italic>mcr-3.17</italic>, and <italic>tmexC3.2-tmexD3.3-toprJ1b</italic> gene cluster. Although the resistance and/or mobility of these ARGs are limited in this strain, the emergence of this multiple important ARGs-carrying strain deserves further attention.</p></sec>