大肠埃希菌、肺炎克雷伯菌质粒β-内酰胺酶检测

目的了解大肠埃希菌和肺炎克雷伯菌产质粒β-内酰胺酶的类型、检测方法及耐药性. 方法用NCCLS确证试验检测超广谱β-内酰胺酶,根据表型、纸片协同试验及头孢西丁三相试验检测AmpC酶. 结果 835株大肠埃希菌和肺炎克雷伯菌,共检测出产超广谱β-内酰胺酶菌株220株,大肠埃希菌和肺炎克雷伯菌总ESBLs发生率为26%;根据头孢西丁三相试验结果,表现为产AmpC酶的菌株共有36株,检出率为4.31%,表型鉴别高产AmpC酶,表现为产AmpC酶的菌株共有37株,检出率为4.43%,与头孢西丁三相试验符合率为97.3%;纸片协同试验表现为产AmpC酶的为32株,检出率为3.83%,与头孢西丁三相试验符合率为88.9%. 结论大肠埃希菌和肺炎克雷伯菌产超广谱β-内酰胺酶为主;表型筛选法检测AmpC酶结果可靠、方法简便,易于在临床实验室中推广应用.

Detection of Plasmid Mediated Beta-lactamases in Escherichia coli and Klebsiella pneumoniae Isolates

OBJECTIVE To determine plasmid mediated beta-lactamase in Escherichia coli and Klebsiella pneumoniae isolates, and to evaluate relative detection methods. METHODS Extended broad spectrum beta-lactamases were determined by using confirmatory test recommended by NCCLS. AmpC enzymes were detected with phenotype observation, sheet paper cooperation test and cefoxitin triphase assay. RESULTS The presence of extended spectrum beta-lactamases (ESBLs) in 835 E.coli and 128 K.pneumoniae strains was determined. ESBLs were detected in 220 strains (26%). AmpC beta-lactamases were detected in 36(4.31%) strains by cefoxitin triphase test, 37(4.43%) strains by no phenotypic test, 32 (3.83%)strains by sheet paper cooperation test. The results of phenotypic test and sheet paper cooperation test were similar to those of cefoxitin triphase test. The coincidence rate was 97.3% and 88.9%, respectively. CONCLUSIONS The mainly beta-lactamases produced by E. coli and K. pneumoniae were ESBLs. The phenotypic screening methods for the detection of AmpC enzyme were simple, reliable and could be used in clinical laboratory.