Occurrence of the Gene in the -Harboring Plasmids: Adverse Clinical Impact for Direct Tracking of KPC-Producing by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been used for the direct detection of KPC-producing isolates by analysis of the 11,109 Da mass peak representing the P019 protein. In this study, we evaluate the presence of the 11,109 Da mass peak in a collection of 435 unduplicated Klebsiella pneumoniae clinical isolates. The prevalence of the P019 peak in the K. pneumoniae isolates was 49.2% (32/65). The 11,109 Da mass peak was not observed in any of the other carbapenemase (319) or noncarbapenemase producers (116). Computational analysis of the presence of the gene was performed in the aforementioned carbapenemase-producing K. pneumoniae isolates fully characterized by whole-genome sequencing (WGS) and in a further collection of 1,649 K. pneumoniae genomes included in EuSCAPE. Herein, we have demonstrated that the gene is not exclusively linked to the pKpQil plasmid but that it is present in the following plasmids: IncFIB(K)/IncFII(K)/ColRNAI, IncFIB(pQil), IncFIB(pQil)/ColRNAI, IncFIB(pQil)/IncFII(K), IncFIB(K)/IncFII(K), and IncX3. In addition, we have proven the independent movement of the Tn and the IS, of which the gene is a component. The absence of the gene was obvious in Col440I, Col(pHAD28), IncFIB(K)/IncX3/IncFII(K), and IncFIB(K)/IncFII(K) plasmids. In addition, we also observed another plasmid in which neither Tn nor IS was found, IncP6. In the EuSCAPE, the occurrence of varied from 0% to 100% among the different geographical locations. The adverse clinical impact of the diminished prevalence of the gene within the plasmid encoding KPC-producing Klebsiella pneumoniae puts forward the need for reconsideration when applying this technique in a clinical setting.