评估纸片扩散法与 Vitek2-compact GN13测定肠杆菌科细菌体外药敏及 ESBLs 可靠性的研究

Evaluation of the capabilities of disc diffusion and Vitek2-compact GN13 methods for testing antimi-crobial susceptibility and screening of ESBLs Enterobacteriaceae clinical isolates

目的：评估纸片扩散法与Vitek2-compact GN13测定肠杆菌科细菌体外药敏及ESBLs的可靠性。方法本研究选取了2011—2012年从21家医院腹腔感染患者中分离的93株肠杆菌科细菌。分别采用纸片扩散法、Vitek2-compact GN13、微量肉汤稀释法测定其对氨苄西林-舒巴坦、哌拉西林-他唑巴坦、厄他培南、头孢他啶、头孢曲松、头孢吡肟、亚胺培南、阿米卡星、环丙沙星和左氧氟沙星的体外敏感性。以微量肉汤稀释法作为参考方法，分别评估纸片扩散法、Vitek2-compact GN13与参考方法的分类一致率（ CA％）。利用PCR及测序法，在大肠埃希菌、肺炎克雷伯菌、产酸克雷伯菌和奇异变形杆菌中筛选超广谱β-内酰胺酶（ ESBLs）耐药基因，评估纸片扩散法与Vitek2-compact GN13表型确证试验筛选ESBLs的敏感性、特异性、阳性预测值和阴性预测值。结果纸片扩散法和Vitek2-compact GN13与参考方法的一致率均＞90％；但在使用Vitek2-compact GN13测定厄他培南、氨苄西林-舒巴坦、头孢他啶和头孢吡肟时，会出现一定比例的大错误（ ME，3．2％）和极大错误（ VME，2．2％）。此外，纸片扩散法和Vitek2-compact GN13对产ESBLs菌株测定的敏感性、特异性、阳性预测值、阴性预测值分别为96．7％（29／30）、100％（20／20）、100％（30／30）和95％（19／20）。结论无论是纸片扩散法还是Vitek2-compact GN13，对肠杆菌科细菌体外药敏及ESBLs的测定均比较可靠。但在采用Vitek2-compact GN13测定厄他培南、氨苄西林-舒巴坦、头孢他啶和头孢吡肟时，应注意可能出现ME及VME。

Objective To evaluate the capabilities of disc diffusion and Vitek2-compact GN13 methods for testing antimicrobial susceptibility of screening ESBLs （ extended-spectrumβ-lactamase） in En-terobacteriaceae clinical isolates.Methods A total of 93 Enterobacteriaceae strains were isolated from pa-tients with intra-abdominal infections in 21 hospitals during 2011 to 2012.The in vitro minimum inhibition concentration （ MIC ） values of ampicillin-sulbactam, piperacillin-tazobactam, ertapenem, ceftazidime, ceftriaxone, cefepime, imipenem, amikacin, ciprofloxacin and levofloxacin were determined by disc diffu-sion, Vitek2-compact GN13 and broth microdilution methods, respectively.Categorical agreement （ CA ） rates of disc diffusion and Vitek2-compact GN13 methods were determined by using broth microdilution meth-od as the reference method.The genes encoding ESBLs were screened in Escherichia coli （E.coli）, Kleb-siella pneumoniae （K.pneumonia）, Klebsiella oxytoca （K.oxytoca） and Proteus mirabilis （P.mirabilis） strains by using PCR analysis and gene sequencing.Disc diffusion and Vitek2-compact GN13 methods were used for the phenotypic confirmatory test of ESBLs and the sensitivity, specificity, positive predictive value and negative predictive value of the two tests were evaluated.Results The CA values of disc diffusion and Vitek2-compact GN13 methods for the 10 antibiotics were all 〉90% as compared with broth microdilution method.The major error （ME） rate for ertapenem was 3.2%and the very major error （VME） rates for am- picillin-sulbactam, ceftazidime and cefepime tests were all 2.2% by using Vitek2-compact GN13 method. The sensitivity, specificity, positive predictive value and negative predictive value of disc diffusion and Vitek2-compact GN13 methods in the phenotypic confirmatory test of ESBLs were 96.7%（29/30）, 100%（20/20）, 100%（30/30） and 95%（19/20）, respectively.Conclusion Both disc diffusion and Vitek2-compact GN13 methods could be used for testing the antimicrobial susceptibility and the detection of ESBLs in Enterobacteriaceae clinical isolates with the advantage of accuarcy.Attention should be paid to the posibil-lity of oaurance of ME and VME when testing ertapenem, ampicillin-sulbactam, ceftazidime and cefepime by using Vitek2-compact GN13 method.