Co-infections of two carbapenemase-producing Enterobacter hormaechei clinical strains isolated from the same diabetes individual in China
Manlin Ding, Jiao Shi, Ahmad Ud Din, Yao Liu, Feiyang Zhang, Xiangjin Yan, Qin Li, Jiawei Bai, Wenbi Chen, Yingshun Zhou
Abstract
Introduction. Since mcr-1 was first reported in China, there have been ten variants of MCR appearing nationwide so far. Multidrug-resistant Enterobacteriaceae bacteria carrying both NDM and MCR have become a serious threat to global public health. Hypothesis/Gap Statement. The genetic structure of mcr-9 needs to be better understood in order to better prevent and control the transmission of drug-resistant genes. Aims. The aim of this study was to characterize the presence of two Enterobacter hormaechei isolates, which carries bla NDM-5 CME2 and the coexistence of mcr-9 and bla NDM-1 strain CMD2, which were isolated from a patient with diabetes in Sichuan, China. Methodology. The microbroth dilution method was used for antibiotic susceptibility. Conjugation experiment was used to investigate the transferability of bla NDM-1 , bla NDM-5 and mcr-9 . Whole-genome sequencing was performed on Illumina HiSeq platform. The ability of biofilm formation was detected by crystal-violet staining, the virulence of the bacteria was measured by Galleria mellonella killing assay. Results. bla NDM-5 carrier CME2 and CMD2 with bla NDM-1 and mcr-9 were resistant to carbapenems, β-lactam, aminoglycoside, quinolone and tetracycline, while CMD2 was also resistant to colistin. Conjugation assay and plasmid replicon typing further demonstrated that both bla NDM-1 and bla NDM-5 were respectively present on the self-transferrable IncX3 plasmid, mcr-9 was located on the self-transferrable IncHI2 plasmid. Through the analysis of mcr-9 gene context, the structure was DUF4942-rcnR-rcnA-copS -IS 903-mcr-9-wbuC-qseC-qseB-IS1R -Δ silR -IS 903 , bla NDM-1 context was IS 3000 -ΔIS Aba125 -IS 5-bla NDM-1 - ble-trpF-groS-groL-insE -ΔIS 26 structure, bla NDM-5 structure was IS 3000-bla NDM-5 - ble-trpF-dsbC -ΔIS 26-umuD -IS Kox3-tnpR-parA . Biofilm formation of CME2 was stronger than CMD2. There was no significant difference in virulence between the two strains. Conclusion. This study reveals two multiple drug-resistant E. hormaechei isolates from diabetes patient samples. E. hormaechei carrying two NDM-resistant genes is already a serious threat, where MCR is an important cause of treatment failure in bacterial infections. This study is a reminder not only to prevent infection in patients with diabetes, but also to constantly monitor the epidemic and spread of the drug-resistant gene.