title: Analysis of drug resistance determinants in Klebsiella pneumoniae isolates from a tertiary-care hospital in Beijing, China.
abstract: BACKGROUND
  The rates of multidrug-resistant (MDR), extensively drug-resistant (XDR) and pandrug-resistant (PDR) isolates among Enterobacteriaceae isolates, particularly Klebsiella pneumoniae, have risen substantially worldwide.
  
  
  RESULTS
  To better understand the molecular mechanisms of drug resistance in K. pneumoniae, we analyzed the drug resistance determinants for K. pneumoniae isolates collected from the 306 Hospital, a tertiary-care hospital in Beijing, China, for the period of September 1, 2010-October 31, 2011. Drug susceptibility testing, PCR amplification and sequencing of the drug resistance determinants were performed. Conjugation experiments were conducted to examine the natural ability of drug resistance to disseminate among Enterobacteriaceae strains using a sodium azide-resistant Escherichia coli J53 strain as a recipient. Among the 223 consecutive non-repetitive K. pneumoniae isolates included in this study, 101 (45.3%) were extended-spectrum beta-lactamases (ESBLs) positive. The rates of MDR, XDR, and PDR isolates were 61.4% (n = 137), 22.0% (n = 49), and 1.8% (n = 4), respectively. Among the tested drug resistance-associated genes, the following ones were detected at relatively high rates bla(CTX-M-10) (80, 35.9%), aacC2 (73, 32.7%), dhfr (62, 27.8%), qnrS (58, 26.0%), aacA4 (57, 25.6%), aadA1 (56, 25.1%). Results from conjugation experiments indicate that many of the drug resistance genes were transmissible.
  
  
  CONCLUSIONS
  Our data give a "snapshot" of the complex genetic background responsible for drug resistance in K. pneumoniae in China and demonstrate that a high degree of awareness and monitoring of those drug resistance determinants are urgently needed in order to better control the emergence and transmission of drug-resistant K. pneumoniae isolates in hospital settings.
authors.affiliation: Chinese Academy of Sciences Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.forename: Yong
authors.initials: Y
authors.lastname: Yi
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Patrick C Y
authors.initials: PC
authors.lastname: Woo
authors.forename: Lin
authors.initials: L
authors.lastname: Tan
authors.forename: Hua
authors.initials: H
authors.lastname: Jing
authors.forename: George F
authors.initials: GF
authors.lastname: Gao
authors.forename: Cui Hua
authors.initials: CH
authors.lastname: Liu
mesh_terms: D001483:Base Sequence; D002681:China; D017931:DNA Primers; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000235:genetics; D008826:Microbial Sensitivity Tests; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D062606:Tertiary Care Centers
chemical_list: D017931:DNA Primers