[The genotype and epidemiological feature of the Enterobacteriaceae carrying carbapenemase in China].
OBJECTIVE
To analyze the genotype and molecular epidemiology of carbapenem-resistant Enterobacteriaceae.


METHODS
A total of 201 carbapenem-resistant Enterobacteriaceae were isolated from 14 hospitals in 11 cities. The MICs of 14 antimicrobial drugs were detected using agar dilution method. Phenotypes of carbapenemase were screened using modified Hodge test and ethylene diamine tetraacetic acid (EDTA) test. Drug resistance genes were screened using PCR method. The strains carrying carbapenem resistance genes were confirmed by conjugation test. Homology analysis was carried out using pulsed-field gel electro-phoresis (PFGE) method and the epidemiological correlation is analyzed based on the Multilocus Sequence Typing (MLST) method in order to study the molecular epidemiology of carbapenem-resistant Enterobacteriaceae.


RESULTS
Fifty-three strains among 201 carbapenem-insensitive Enterobacteriaceae were detected positive carbapenem-resistant genes, among which included 33 Klebsiella pneumoniae, 9 Citrobacter freundii, 6 Escherichia coli and 5 Enterobacter cloacae. Among the 53 strains, 43 were from Beijing, 6 strains from Hangzhou, 3 strains from Nanjing and one from Fuzhou. Resistance genes-harboring plasmids were successfully transferred from 28 of 53 strains to Escherichia coli EC600. The PFGE spectrum showed that 33 Klebsiella pneumoniae were classified into three types, 9 Citrobacter freundii classified into four types, 5 Enterobacter cloacae classified into four types, while 6 Escherichia coli were the same type. Based on the results of MLST test, 29 Klebsiella pneumoniae strains producing KPC-2 type carbapenemase were all ST11, while among the four Klebsiella pneumonia carrying IMP-4 carbapenem resistant gene, three strains were ST876, one was ST147.


CONCLUSIONS
Carbapenem-resistant genes were detected only in hospitals from Beijing, Hangzhou, Nanjing and Fuzhou, and type KPC-2 was the most common, followed by IMP-4 and IMP-8. High homology of resistant strains could be related to horizontal transfer of carbapenemase genes, which should cause great concern.
Jixia
J
Zhang
Yingmei
Y
Liu
Hongbin
H
Chen
Bin
B
Cao
Huaying
H
Gao
Henan
H
Li
Department of Clinical Laboratory, Peking University People's Hospital, Beijing 100044, China. Email: whuibj@163.com.
Hui
H
Wang
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins; D015780:Carbapenems / Q000494:pharmacology; D002681:China / Q000453:epidemiology; D024881:Drug Resistance, Bacterial; D004755:Enterobacteriaceae / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology*; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D010957:Plasmids; D001618:beta-Lactamases
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D001618:beta-Lactamases; C063912:carbapenemase