Emergence of IMP-8-Producing Comamonas thiooxydans Causing Urinary Tract Infection in China

Abstract

The emergence of carbapenem resistance (CR) caused by hydrolytic enzymes called carbapenemases has become a major concern worldwide. So far, CR genes have been widely detected in various bacteria. However, there is no report of CR gene harboring <i>Comamonas thiooxydans</i>. We first isolated a strain of an IMP-8-producing <i>C. thiooxydans</i> from a patient with urinary tract infection in China. Species identity was determined using MALDI-TOF MS analysis and carbapenemase-encoding genes were detected using PCR. The complete genomic sequence of <i>C. thiooxydans</i> was identified using Illumina Novaseq and Oxford Nanopore PromethION. Antimicrobial susceptibility analysis indicated that the <i>C. thiooxydans</i> strain ZDHYF418 was susceptible to imipenem, intermediate to meropenem, and was resistant to aztreonam, fluoroquinolones, and aminoglycosides. The <i>bla</i> _<i>IMP-</i> ₈ gene was chromosomally located, and was part of a Tn402-like class 1 integron characterized by the following structure: <i>DDE-type integrase/transposase/recombinase-tniB-tniQ-recombinase family protein-aac(6')-Ib-cr-bla _<i>IMP-</i> ₈-intI1</i>. Phylogenetic analysis demonstrated that the closest relative of ZDHYF418 is <i>C. thiooxydans</i> QYY (accession number: CP053920.1). We detected 330 SNP differences between ZDHYF418 and <i>C. thiooxydans</i> QYY. Strain QYY was isolated from activated sludge in Jilin province, China in 2015. In summary, we isolated a strain of <i>C. thiooxydans</i> that is able to produce IMP-8 and a novel <i>bla</i> _<i>OXA</i> . This is the first time that a CR gene has been identified in <i>C. thiooxydans</i>. The occurrence of the strain needs to be closely monitored.