Vitek-2药敏卡片检测MRSA的准确性评价

Accuracy evaluation of Vitek 2 card for determining MRSA

目的:评价Vitek2ASTP535药敏卡片测定金黄色葡萄球菌对苯唑西林敏感性的准确性。方法:对临床分离的菌株采用ASTP535药敏卡片和头孢西丁纸片测定对苯唑西林的耐药性,以PCR测定MecA基因为金标准,评价两种方法的准确性。结果:采用PCR共检测125株金黄色葡萄球菌,其中MecA基因阳性的耐甲氧西林金黄色葡萄球菌(Methicillin resistant Staphy lococcus aureus,MRSA)89株,mecA基因阴性的甲氧西林敏感金黄色葡萄球菌(Methicillin susceptive Staphy lococcus aureus,MSSA)36株,以此为标准,在89株MRSA中用Vitek-2ASTP535药敏卡片检测出81株,敏感度为91%,在36株MSSA中采用Vitek-2ASTP535药敏卡片检测出35株,特异性为97.2%;而采用头孢西丁纸片法检测出MRSA87株,敏感度为97.8%,检出MSSA36株,特异性为100%。结论:ASTP535药敏卡片测定金黄色葡萄球菌对苯唑西林的敏感性具有良好的灵敏度和特异性,准确性能满足临床需要,同时采用头孢西丁纸片法检测可进一步提高检测的准确性。

Objective：Evaluation the diagnostic accuracies of the automated Vitek 2 system for the detection of oxacillin resistance in Staphylococcus aureus strains.Methods：The susceptibility of Staphylococcus aureus to Oxacillin were determined by AST P535 card and cefoxitin disk diffusion tests.The validity of the two methods were evaluated by compared the results with the gold standard method of mecA gene determining by PCR.Results：The total 125 strains including 89 methicillin resistant Staphylococcus aureus（MRSA） with the positive mecA gene and 36 methicillin susceptive Staphylococcus aureus（MSSA） with the negative mecA gene.Of the 89 MRSA and 36 MSSA strains detected by PCR,81 strains of MRSA and 35 strains of MSSA were correctly detected by AST P535 cards and 87 strains of MRSA and 36 strains of MSSA were correctly detected by cefoxitin disk diffusion tests.The sensitivity and specificity for Vitek-2 AST P535 card and cefoxitin disk diffusion tests were 91%,97.5 and 97.8,100% respectively.Conclusions：Detection of methicillin resistance in Staphylococcus aureus strains by using AST P535 cards have good sensitivity and specificity with satisfactory results to addressing clinical diagnostics.Automated Vitek 2 system combined with cefoxitin disk diffusion tests can further improve the detective accuracies.