[Mechanism of @entity2888 resistance in XXXX ].

@entity801 @entity2892 @entity2177 @entity5152 @entity798 @entity2893 @entity2888 @entity3064 @entity5505 @entity5646
OBJECTIVE: To investigate the mechanism of @entity2888 resistance in @entity3064 . METHODS: WHONET-5 software was used to analyze the trend of @entity2893 resistance in @entity3064 collected from 1999 to 2001 at Peking Union Medical College Hospital. Analytical isoelectric focusing was used to measure the pI of the beta-lactamase. Conjugation experiment was used to study the transfer of @entity2893 resistance and plasmid DNA was extracted and purified with Qiagen Plasmid Mini Kit. The homology of the isolates was determined by pulsed field gel electrophoresis (PFGE). Integrase genes and blaIMP-, blaVIM-, blaOXA- genes for resistant isolates were amplified and sequenced. RESULTS: @entity2892 resistance in A. baumannii was ranged from 1.8%-8.5%, but only 9 resistant isolates were viable. They were co-resistant to other @entity2888 , @entity5505 , @entity5646 , and @entity801 , and four isolates were resistant to @entity2177 . Impipenem resistance could not be transferred to susceptible strains. No plasmid was extracted. Each isolate produced TEM-1, AmpC, and two enzymes (pI 6.7, 6.0), which can not be inhibited by @entity5152 and @entity798 . Each isolate had class I intergase gene. Nine isolates were all negative for PCR of blaIMP- and blaVIM- genes, but positive for blaOXA-23 specific PCR. Sequencing found 100% homology with blaOXA-23. PFGE found 3 clones (A type: 5 isolates; B type: 3 isolates; C type: 1 isolate). Control isolates ( @entity2892 -susceptible, but @entity5505 , @entity2177 , and @entity801 resistant) were also A clone. CONCLUSIONS: Production of OXA-23 carbapenemase in A. baumannii was one of the main mechanisms of @entity2888 resistance at our hospital. It brings concern that @entity2892 -resistant clone has evoluted from nosocomial multiple-resistant strains.
