ABSTRACT
Objecive To investigate the prevalence of NDM-type carbapenemases in the carbapenem-resistant Escherichia coli strains collected from Ruijin Hospital, Shanghai Jiaotong University School of Medicine. The epidemiological characteristics of NDM-type carbapenemase-producing isolates were analyzed.Methods Eighteen strains were collected from November 2013 to January 2015 in the clinical microbiology laboratory of Ruijin Hospital. All of them were resistant to imipenem or meropenem (inhibition zone diameter≤19 mm). The blaNDM gene was detected by PCR. The amplified products were subjected to sequencing analysis. Conjugation experiment was carried out to verify the transferability of plasmids. Multilocus sequence typing (MLST) and pulsed field gel electrophoresis (PFGE) were performed to analyze the molecular epidemiology.Results The blaNDM gene was identified in 6 strains, 4 of which had blaNDM-1-type and 2 had blaNDM-5-type carbapenemase gene. Three strains were positive in the conjugation experiment. MLST analysis showed that 6 NDM carbapenemase-producing isolates belonged to ifve sequence types, corresponding to five PFGE-DNA patterns (A-E). Two of these isolates shared the identical sequence type (ST5018) and nearly the same PFGE-DNA patterns (A1, A2).Conclusions NDM-type carbapenemase-producing E. coli is identified in this study. Most blaNDM-positive cases were sporadic. Plasmid might play an important role in the spread of blaNDM inE. coli. The blaNDM-5 type carbapenemase gene was first identified in Shanghai, to which more attention should be paid.
ABSTRACT
Objective To investigate the prevalence and main genotypes of carbapenemases in carbepenem‐resistant Enterobacteriaceae (CRE) .Methods A total of 114 strains of CRE were isolated in Shanghai Ruijin Hospital from May 2011 to June 2013 .The diameter of inhibition zone of imipemen or meropenem for these strains was not larger than 22 mm .PCR method was used to screen for the main carbapenemase genes (blaKPC ,blaIMP ,blaVIM ,blaOXA‐48 and blaNDM ) with previously described primers followed by nucleotide sequencing analysis . Conjugation experiments were performed to examine the transferability of plasmids .Pulsed‐field gel electrophoresis (PFGE) was used to show the relatedness of KPC‐2‐producing Enterobacteriaceae .Results Most of the 114 isolates were K lebsiella pneumoniae and Escherichia coli .Of the 114 isolates ,98 was positive for carbapenemases ,specifically ,78 blaKPC‐2‐positive ,15 blaIMP‐4‐positive ,2 blaIMP‐8‐positive ,1 positive for both blaKPC‐2 and blaIMP‐4 and 4 blaNDM‐1‐positive .None of the strains was positive for blaOXA‐48 or blaVIM .About 21 .4% (21/98) of the isolates were conjugated successfully .The 49 blaKPC‐2‐positive K .pneumoniae isolates were grouped into 12 types according to PFGE patterns .Majority (34/49) of these isolates belonged to the same type A .Conclusions BlaKPC‐2 was the primary epidemic genotype of Enterobacteriaceae in Ruijin Hospital ,followed by blaIMP‐4 .NDM‐1 carbapenemase was produced in 4 strains of CRE . Meanwhile , clonal spread of KPC‐2‐producing K . pneumoniae was observed in some departments of our hospital , such as surgical ICU , respiratory medicine and thoracic surgery . Appropriate measures should be taken timely and effectively to prevent the in‐hospital spread of resistant genes .