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.
ABSTRACT
Objective To analyze the drug resistance phenotype and genetic background of New Delhi metallo-β-lactamase (NDM)-producing bacterial strains in Lishui area of Zhejiang province.Methods The imipenem-resistant Enterobacteriaceae strains were isolated from January 2012 to December 2016 in Lishui Municipal Central Hospital of Zhejiang Province.Mrieux Vitek 2 Compact system was used to identified strains and PCR was used to screen for blaNDMgene.Susceptibility was detected by K-B method and MICs were obtained by Vitek 2 with GN13 cards.Plasmids typing was carried out by DNA sequencing of the replication initiator with the transconjugates as templates.The blaNDMgenetic contexts were detected by PCR and complete genome sequencing.Results A total of 102 strains of carbapenem-resistant enterobacteria (CRE), mainly Escherichia coli and Enterobacter cloacae, were isolated, of which 15 were positive for blaNDMwith a positive detection rate of 14.7%.The resistance rate to β-lactam antibiotics was 100%, and the resistance rates to aztreonam, compound sulfamethoxazole , tobramycin and gentamicin were all ＞80%;and the resistance rate to quinolones was ＞50%.Among the 15 NDM-producing strains , 12 strains were positive for Hodge test, and 2 strains of Enterobacter cloacae and 1 strain of Escherichia coli were negative. There were 11 strains of blaNDM-1and 4 strains of blaNDM-1.A variety of plasmid types such as IncX 3, IncFIIγ and IncA/C were detected, and 4 blaNDM-5genes were located in the IncX3 plasmid.Four blaNDMsurrounding gene structures were found, of which 8 blaNDM-1genes were located in ISAb125-hyp-blaNDM-1-bleMBL-TrpF-DsbC-IS26, while blaNDM-5was located in IS3000-IS5-blaNDM-5-bleMBL-TrpF-DsbC-IS26 structure, and the former was reported for the first time in China.Conclusion NDM-producing bacterial strains in Lishui area are prevalent at a low level and have high sensitivity to fosfomycin and polymyxin .The blaNDMgene may have multiple sources, but IncX3 plasmid is still the main source for gene transfer.Some new types of blaNDM-1 gene structure have been also found in this study.