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.