ABSTRACT
Carbapenem-resistant Klebsiella pneumoniae (CRKP) is highly prevalent and poses a great health challenge due to the lack of effective treatments. Klebsiella pneumoniae carbapenemase-2 (KPC-2), encoded by blaKPC-2 gene, is one of the major contributors to carbapenem resistance in CRKP. In China and other Asian regions, Tn1721 and plasmid IncFⅡ are the main vectors for blaKPC-2 transfer between Kpn ST11 strains, which lack clustered regularly interspaced short palindromic repeats (CRISPR) and restriction-modification (R-M) systems. The structure of transposons has a significant impact on the transposition frequency of blaKPC-2, which may be related to the different transposition patterns of transposons. The prevalence advantage of blaKPC-2 in Kpn ST11 strains is highly associated with the immune deficiency in Kpn ST11. By acquiring a re-engineered CRISPR-Cas3 system via conjugation, the high-risk IncFⅡ plasmid can be successfully cleaved and ST11 CRKP can regain antibiotic sensitivity, which provides a promising approach for clinical treatment and prevention of CRKP.
ABSTRACT
Objective To investigate the carbapenem-resistant mechanism of one strain of Klebsiella pneumoniae( KPN) and one strain of Pseudomonas aeruginosa( PAE) .Methods The identity of the isolates was confirmed by using MALDI-TOF mass spectrometry, 16S rDNA and special gene amplification .The minimum inhibitory concentrations (MICs) of the antimicrobial agents were determined by VITEK 2 Compact System .CarbaNP Antimicrobial susceptibility testing , plasmid extraction, electroporation experiment , PCR amplification, and cloning and sequencing were carried out to analyze the en-coding gene of β-lactamases.Results The types of β-lactamases of the KPN were blaKPC-2 and blaSHV, confirmed by se-quencing of the PCR products , and that of the PAE were blaKPC-2 .Only blaKPC-2 was displayed in both transformants .All of the results of CarbaNP were type A .Conclusion Both strains of KPN and PAE resisting to carbapenem produce a plasmid-mediated carbapenemase blaKPC-2 , which belongs to Bush group 2f, class A β-lactamase.The extended-spectrum β-lacta-mases gene encoding blaSHV of the KPN might be located in the chromosome or not in the plasmid carrying with blaKPC-2 .