[DHA-1 type cephalosporinase accompanied with SHV-12 prevailed in clinical isolates of Klebsiella pneumoniae].
OBJECTIVE
To study the prevalence, phenotype and genotype of the AmpC and ESBLs-producing clinical isolate of Klebsiella pneumoniae.


METHODS
The clinical isolates of Klebsiella pneumoniae were examined by standard disk diffusion susceptibility tests, three-dimensional methods, isoelectric focusing (IEF) and microdilution methods. The conjugation experiment, multiplex PCR and DNA sequencing methods were used for further analysis.


RESULTS
Four out of a total of 86 isolates tested were shown to be highly AmpC-producing by three-dimensional method. IEF showed that these strains produced a AmpC like beta-lactamase with a PI of 7.8, and DNA sequencing showed that the gene which expressed this AmpC like beta-lactamase was identical to DHA-1, a plasmid mediated cephalosporinase gene. These strains also produced an ESBL like beta-lactamase with a PI of 8.2 and the gene which expressed this beta-lactamase was identical to SHV-12. These strains were resistant not only to most of the third generation cephalosporins, but also to cefepime. However they were still susceptible to carbapenem.


CONCLUSIONS
Highly AmpC-producing DHA-1 accompanied with SHV-12 in Klebsiella pneumoniae was reported here for the first time. They result in a significant rise in antibiotic resistance, which is regarded as a great challenge for clinical antibiotic therapy.
Guan
Xi-zhou
XZ
Department of Respiratory Medicine, General Hospital of Chinese People's Liberation Army, Beijing 100853, China.
Liu
You-ning
YN
Luo
Yan-ping
YP
She
Dan-yang
DY
Zhou
Guang
G
Chen
Liang-an
LA
Xu
Ya-ping
YP
D001426:Bacterial Proteins / Q000235:genetics*; D002510:Cephalosporinase / Q000235:genetics*; D024881:Drug Resistance, Bacterial; D005798:Genes, Bacterial; D007711:Klebsiella pneumoniae / Q000201:enzymology* / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D001618:beta-Lactamases / Q000235:genetics*
D001426:Bacterial Proteins; D002510:Cephalosporinase; D001618:beta-Lactamases