ABSTRACT
OBJECTIVE To investigate the prevalence of strains producing extended-spectrum ?-lactamases (ESBLs) and AmpC ?-lactamases in Pseudomonas aeruginosa,and to supply the laboratory evidence for antibiotic rational application in clinic. METHODS Totally 105 clinical isolates of P. aeruginosa were identified with VITEK-32. Drug sensitivities were determined by Kirby-Bauer methods. ESBLs were detected by double-disc synergy test,and cefoxitin three dimensional test was applied to filter AmpC positive strains. RESULTS Among 105 strains of P. aeruginosa,28 strains (26.7%) were AmpC enzymes positive,20 strains (19.0%) were ESBLs positive,and 5 strains(4.8%)were AmpC+ESBLs positive. The detective rate of producing AmpC ?-lactamases strains was higher than that of producing ESBLs strains. There was significant difference between them. CONCLUSIONS ESBLs and AmpC ?-lactamases are two main enzyme types conferring resistance to ?-lactam antibiotics in clinical isolates of P. aeruginosa. Imipenem can be the first choice for treating infections caused by P. aeruginosa producing ESBLs or AmpC ?-lactamases.
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OBJECTIVE To explore the drug-resistance,the existing forms,genotype,and transfer ways of extended spectrum ?-lactamases(ESBLs) and plasmid AmpC enzyme in Klebsiella pneumoniae.METHODS The drug sensitivity of K.pneumoniae to 17 antibiotics was done by slip-diffusion and microdilution methods.The genotype of two enzymes was assessed by PCR and sequencing.The transfer ways of K.pneumoniae drug-resistant gene were identified by transconjugants-test.RESULTS The ESBLs were mainly produced in 55 cefoxitin resistant K.pneumonia strains.The major genotypes of ESBLs and plasmid AmpC nzyme were CTX-M,MIR and DHA.These genes could be transferred from clinical isolates to recipient bacteria.CONCLUSIONS ESBLs as well as AmpC enzymes are the most important resistance mechanism in K.pneumoniae.The resistance could be transferred through the bacterial conjugation.
ABSTRACT
OBJECTIVE: To investigate the incidence rate of the ampC gene and AmpC enzyme of gram-negative(G-) bacterium in children,to analyze drug resistance of produced AmpC enzyme and un-produced AmpC enzyme strain.METHO_DS: 4 022 clinical G-isolates collected from 2002 to 2004 were identified and tested using K-B method.Selection 108 ESBLs bacterium,the ampC genes were amplified by PCR using common primers to AmpC and the AmpC enzymes were tested using the enzymatic rough extraction cefoxitin three-dimensional test.The drug resistance of bacterium produced AmpC enzymes were compared with the ones without AmpC enzymes.RESULTS: In 108 G-bacterium,the ampC genes positive bacterium were 70 strain(accounting for 64.8%),and 7 bacterium produced AmpC enzymes(accounting for 6.5%) were detected.The drug resistance of bacterium produced AmpC enzymes to ceftazidime(CAZ),ceftriaxone(CRO),piperacillin(PIP),ampicillin(AMP),aztreonam(ATM) were 85.7%,85.7%,71.4%,79.4%,79.4% respectively.The drug resistance of bacterium non-produced AmpC enzymes to CRO,PIP,gentamicin,AMP,ATM were 50.8%,55.6%,55.6%,70.3%,54.0% respectively,the drug resistance of bacterium to imipenem were the lowest,lower to ciprofloxacin.CONCLUSIONS: Detection rate of ampC gene were higher than AmpC-producing enzymes strains obviously,whereas the drug resistance to antibiotic of AmpC-producing enzymes strains were higher than non-producing enzymes strains.