Emergence and Characterization of a Novel IncP-6 Plasmid Harboring blaKPC–2 and qnrS2 Genes in Aeromonas taiwanensis Isolates

Abstract

The dissemination of <i>Klebsiella pneumoniae</i> carbapenemases (KPCs) among Gram-negative bacteria is an important threat to global health. However, KPC-producing bacteria from environmental samples are rarely reported. This study aimed to elucidate the underlying resistance mechanisms of three carbapenem-resistant <i>Aeromonas taiwanensis</i> isolates recovered from river sediment samples. Pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS) analysis indicated a close evolutionary relationship among <i>A. taiwanensis</i> isolates. S1-PFGE, Southern blot and conjugation assays confirmed the presence of <i>bla</i> _KPC- ₂ and <i>qnrS2</i> genes on a non-conjugative plasmid in these isolates. Plasmid analysis further showed that pKPC-1713 is an IncP-6 plasmid with a length of 53,205 bp, which can be transformed into DH5α strain and mediated carbapenems and quinolones resistance. The plasmid backbone of p1713-KPC demonstrated 99% sequence identity to that of IncP-6-type plasmid pKPC-cd17 from <i>Aeromonas</i> spp. and IncP-6-type plasmid: 1 from <i>Citrobacter freundii</i> at 74% coverage. A 14,808 bp insertion sequence was observed between <i>merT</i> gene and hypothetical protein in p1713-KPC, which include the quinolone resistance <i>qnrS2</i> gene. Emergence of plasmid-borned <i>bla</i> _KPC and <i>qnrS2</i> genes from <i>A. taiwanensis</i> isolates highlights their possible dissemination into the environment. Therefore, potential detection of such plasmids from clinical isolates should be closely monitored.