[NDM-1-producing Klebsiella pneumoniae in mainland China].
OBJECTIVE
To investigate the characteristics of New Delhi metallo-beta-lactamase-1 (NDM-1) gene of Klebsiella pneumoniae (K. pneumoniae) emerging in Hunan, and its relationship to antibiotic resistance.


METHODS
The clinical strain was isolated from a sputum sample of a child with severe pnemonia and toxic myocarditis who was admitted into a general hospital of Hunan Province. VITEK-2 compact instrument was used for bacterial identification and antibiotic susceptibility test. Modified Hodge test was used for the screening of carbapenemase. EDTA-synergy test and combination disk diffusion test were used for detection of metallo-β-lactamase (MBL). PCR was performed for amplification of NDM-1 genes and the positive products were sequenced and analyzed with BLAST. Conjugation was also performed to analyze mechanisms of antibiotic resistance. The results of antibiotic susceptibility tests were compared before and after conjugation.


RESULTS
The isolated strain was identified as K.pneumoniae. Modified Hodge test, EDTA-synergy test and combination disk diffusion test were all positive for the strain. The homology between gene sequence of PCR amplification products and NDM-1 gene FN396876.1 in the GenBank was 100%. Transconjugant DNA was used as template for the amplification of NDM-1 gene. The amplification products were sequenced and found to be the same as the NDM-1 gene amplification product of the donor strain. The MIC of transconjugant E.coli J53 (NDM-1) to all the β-lactams increased significantly compared with the recipient strain E.coli J53. The MIC of ertapenem and imipenem increased by more than 8 times, while the MIC of ceftazidime and ceftriaxone increased by more than 64 times.


CONCLUSIONS
This study first identified a strain of K. pneumoniae carrying NDM-1 in mainland China. NDM-1 gene can be transmitted among different strains and causes extensively drug-resistance to β-lactams.
Department of Clinical Laboratory, Xiangya Hospital, Central South University, Changsha 410008, China. zoumingxiang@126.com
Ming-Xiang
MX
Zou
Jing-Min
JM
Wu
Jun
J
Li
Qing-Ya
QY
Dou
Rong-Rong
RR
Zhou
Yuan
Y
Huang
Wen-En
WE
Liu
D001483:Base Sequence; D002681:China; D024881:Drug Resistance, Bacterial; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
D001618:beta-Lactamases; C552864:beta-lactamase NDM-1