Genetic Characterization of Enterobacter hormaechei Co-Harboring bla NDM-1 and mcr-9 Causing Upper Respiratory Tract Infection

• Published in: Infection and drug resistance Vol. 15; pp. 5035 - 5042
• Main Authors: Liu, Huiqiong, Wang, Dao, Tang, Miaomiao, Jia, Peisheng, Huo, Yufeng, Wei, Erhu, Xu, Hao, Chi, Xiaohui, Wang, Huaili
• Format: Journal Article
• Language: English
• Published: 01.01.2022
• ISSN: 1178-6973; 1178-6973
• DOI: 10.2147/IDR.S367073

PurposeWith the spread of multiple drug-resistant bacteria, bla NDM-1 and mcr-9 have been detected in various bacteria worldwide. However, the simultaneous detection of bla NDM-1 and mcr-9 in Enterobacter hormaechei has been rarely reported. This study identified an E. hormaechei strain carrying both bla NDM-1 and mcr-9. We investigated the genetic characteristics of these two resistance genes in detail, elucidating various potential mechanisms by which they may be transmitted. MethodsBacterial genomic features and possible origins were assessed by whole-genome sequencing (WGS) with Illumina and PacBio platforms and phylogenetic analysis. Subsequent investigations were performed, including antimicrobial susceptibility testing and multilocus sequence typing (MLST). ResultsWe isolated an E. hormaechei strain DY1901 carrying both bla NDM-1 and mcr-9 from the sputum sample. Susceptibility testing showed that the isolate was multidrug-resistant. Multiple antibiotic resistance genes and virulence genes are widely distributed in DY1901. S1-PFGE, Southern blotting, and plasmid replicon typing showed that DY1901 carried four plasmids. The plasmid carrying mcr-9 was 259Kb in size and belonged to IncHI2, while the plasmid carrying bla NDM-1 was 45Kb in length and belonged to IncX3. ConclusionThe E. hormaechei strain isolated in this study has a broad antibiotic resistance spectrum, posing a challenge to clinical treatment. Plasmids carrying mcr-9 are fusion plasmids, and those taking NDM are widely disseminated in China, suggesting that we should conduct routine genomic surveillance on such plasmids to curb the spread of drug-resistant bacteria in the region.