Carbapenem-Resistant Klebsiella pneumoniae in Southwest China: Molecular Characteristics and Risk Factors Caused by KPC and NDM Producers

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection has attracted worldwide concern and became a serious challenge for clinical treatment. The aims of this study were to evaluate the molecular characteristics and risk factors for CRKP infection. Methods: All the CRKP strains were screened for antimicrobial resistance genes, virulence genes, and integron by polymerase chain reaction (PCR). Plasmid typing was performed by plasmid conjugation assay and PCR-based replicon typing (PBRT). The genetic environments of bla(KPC-2) and bla(NDM-1 )were analyzed by using overlapping PCR and molecular typing was performed by multi-locus sequence typing (MLST). Risk factors for CRKP infection were analyzed by logistic regression model. Results: All the 66 CRKP isolates were multidrug-resistant, but all of them were susceptible to tigecycline and polymyxin B. Among the CRKP isolates, 42 bla(KPC-2)-positive strains were identified carrying IncFII plasmids. Meanwhile, 24 bla(NDM)-positive strains were found on lncX3 plasmids, including 20 bla(NDM-1) isolates and 4 bla(NDM-5) isolates. Most of CRKP isolates contained several virulence genes and the class I integron (intl1). The genetic environments of bla(KPC-2) and bla(NDM-1) revealed that the conserved regions (tnpA-tnpR-IS kpn8-bla(KPC-2)) and (bla(NDM-1)-ble(MBL)-trpF-tat) were associated with the dissemination of KPC-2 and NDM-1. ST11 was the most common type in this work. Hematological disease, tracheal cannula, and use of beta-lactams and beta-lactamase inhibitor combination were identified as independent risk factors for CRKP infection. Conclusion: This study established the resistance pattern, molecular characteristics, clonal relatedness, and risk factors of CRKP infection. The findings of the novel strain that co-harboring bla(ND)(M-)(5) and bla(IMP-4), and the novel ST4495 indicated that the brand-new types have spread in Southwest China, emphasizing the prevent and control the further dissemination of CRKP isolates are highly needed.

Automated summary

This study evaluated the molecular characteristics and risk factors of CRKP infection, revealing different genetic environments of KPC-2 and NDM-1 genes on various plasmids, as well as common risk factors like hematological disease and tracheal cannula usage. The detection of novel strains and the need for preventive measures against further dissemination of CRKP isolates were emphasized.