AUTHOR=Wang Lin , Shen Weiyi , Cai Jiachang 

TITLE=Mobilization of the blaKPC-14 gene among heterogenous plasmids in extensively drug-resistant hypervirulent Klebsiella pneumoniae

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1261261

DOI=10.3389/fmicb.2023.1261261

ISSN=1664-302X

ABSTRACT=<sec><title>Introduction</title><p>Ceftazidime/avibactam (CZA) is an effective alternative for the treatment of infections caused by KPC-producing carbapenem-resistant <italic>Klebsiella pneumoniae</italic> (CRKP). However, KPC variants with CZA resistance have been observed in clinical isolates, further limiting the treatment options of clinical use.</p></sec><sec><title>Methods</title><p>In this study, we isolated three KPC-14-producing CRKP from two patients in intensive care units without CZA therapy. The antimicrobial susceptibility was determined using the broth microdilution method. Three CRKP were subjected to whole-genome sequencing to analyze the phylogenetic relatedness and the carriage of antimicrobial resistance genes and virulence factors. Long-read sequencing was also performed to obtain the complete sequences of the plasmids. The horizontal transfer of the <italic>bla</italic><sub>KPC-14</sub> gene was evaluated by conjugation experiments.</p></sec><sec><title>Results</title><p>Three CRKP displayed resistance or reduced susceptibility to ceftazidime/avibactam, colistin, and tigecycline. Single-nucleotide polymorphism (SNP) analysis demonstrated the close phylogenetic distance between these strains. A highly similar IncFII/IncR plasmid encoding <italic>bla</italic><sub>KPC-14</sub> was shared by three CRKP, with <italic>bla</italic><sub>KPC-14</sub> located in an NTE<sub>KPC</sub>-Ib element with the core region of IS<italic>Kpn27</italic>- <italic>bla</italic><sub>KPC-14</sub>-IS<italic>Kpn6</italic>. This structure containing <italic>bla</italic><sub>KPC-14</sub> was also observed in another <italic>tet</italic>(A)-carrying plasmid that belonged to an unknown Inc-type in two out of three isolates. The horizontal transferability of these integrated plasmids to Escherichia coli EC600 was confirmed by the cotransmission of <italic>tet</italic>(A) and <italic>bla</italic><sub>KPC-14</sub> genes, but the single transfer of <italic>bla</italic><sub>KPC-14</sub> on the IncFII/IncR plasmid failed. Three CRKP expressed yersiniabactin and carried a hypervirulence plasmid encoding <italic>rmpA2</italic> and aerobactin-related genes, and were thus classified as carbapenem-resistant hypervirulent <italic>K. pneumoniae</italic> (hvKP).</p></sec><sec><title>Discussion</title><p>In this study, we reported the evolution of a mosaic plasmid encoding the <italic>bla</italic><sub>KPC-14</sub> gene via mobile elements in extensively drug-resistant hvKP. The <italic>bla</italic><sub>KPC-14</sub> gene is prone to integrate into other conjugative plasmids via the NTE<sub>KPC</sub>-Ib element, further facilitating the spread of ceftazidime/avibactam resistance.</p></sec>