Molecular epidemiology of Klebsiella pneumoniae blaKPC gene in Lishui from 2010 to 2016

Abstract

Objective To investigate the distribution of blaKPC gene in Lishui and to analyze the molecular epidemiological characteristics of Klebsiella pneumoniae (K.pneumoniae) blaKPC gene. Methods From 2010 to 2016, all of the non-repetitive K. pneumoniae carbapenemase (KPC)-producing isolates in Lishui Municipal Central Hospital were collected. They were identified with VITEK 2 Compact system and typed by multilocus sequence typing (MLST). Plasmids were classified based on the DNA sequences of replication initiators. Transposons were detected by PCR. Locations of blaKPC gene were verified through complete sequencing of the plasmids by next-generation sequencing (NGS). Results A total of 125 strains were collected. K. pneumoniae strains accounted for 88.8% (111) and among them, 103 were ST11 type. IncF plasmids were detected in 48.6% of K. pneumoniae strains and most of them carried mutant Tn1721/Tn4401 chimera (48/54 isolates). Untypable plasmids were discovered in 50.5% of isolated strains and most of them were positive for the wild-type chimera (54/56 isolates). IncF-positive strains isolated during the period of 2011 and 2013 accounted for 94.4%, followed by a dramatic decrease. However, 76.8% of the strains harboring untypable plasmids were isolated from 2014 to 2016 and the number increased year by year. Conclusion K. pneumoniae of ST11 type was the main cause of blaKPC gene dissemination in Lishui area. Strains carrying the IncF plasmids integrated with the mutant Tn1721/Tn4401 chimera and the untypable plasmids with the wild-type chimera were prevalent before and after 2014, respectively. Key words: Klebsiella pneumoniae; blaKPC gene; Molecular epidemiology; Plasmid; Transposon