Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands
Center of Expertise in Mycology Radboudumc/CWZ, Nijmegen, The Netherlands.
Antimicrob Agents Chemother. 2017 Nov 22;61(12). doi: 10.1128/AAC.01250-17. Print 2017 Dec.
Antifungal susceptibility testing is an essential tool for guiding therapy, although EUCAST and CLSI reference methods are often available only in specialized centers. We studied the performance of an agar-based screening method for the detection of azole resistance in cultures. The VIPcheck consists of four wells containing voriconazole, itraconazole, posaconazole, or a growth control. Ninety-six isolates were used. Thirty-three isolates harbored a known resistance mechanism: TR/L98H (11 isolates), TR/Y121F/T289A (6 isolates), TR (2 isolates), and 14 isolates with other gene point mutations. Eighteen resistant isolates had no -mediated azole resistance. Forty-five isolates had a wild-type (WT) azole phenotype. Four technicians and two inexperienced interns, blinded to the genotype/phenotype, read the plates visually after 24 h and 48 h and documented minimal growth, uninhibited growth, and no growth. The performance was compared to the EUCAST method. After 24 h of incubation, the mean sensitivity and specificity were 0.54 and 1.00, respectively, with uninhibited growth as the threshold. After 48 h of incubation, the performance mean sensitivity and specificity were 0.98 and 0.93, respectively, with minimal growth. The performance was not affected by observer experience in mycology. The interclass correlation coefficient was 0.87 after 24 h and 0.85 after 48 h. VIPcheck enabled the selection of azole-resistant colonies, with a mean sensitivity and specificity of 0.98 and 0.93, respectively. Uninhibited growth on any azole-containing well after 24 h and minimal growth after 48 h were indicative of resistance. These results indicate that the VIPcheck is an easy-to-use tool for azole resistance screening and the selection of colonies that require MIC testing.
抗真菌药敏试验是指导治疗的重要工具,尽管 EUCAST 和 CLSI 参考方法通常仅在专门中心提供。我们研究了基于琼脂的筛选方法在检测 培养物中唑类药物耐药性的性能。VIPcheck 由四个含有伏立康唑、伊曲康唑、泊沙康唑或生长对照的孔组成。使用了 96 个分离株。33 个分离株携带已知的耐药机制:TR/L98H(11 个分离株)、TR/Y121F/T289A(6 个分离株)、TR(2 个分离株)和 14 个具有其他 基因点突变的分离株。18 个耐药分离株没有 -介导的唑类药物耐药性。45 个分离株具有野生型(WT)唑类表型。四名技术员和两名没有经验的实习生在不知道基因型/表型的情况下对平板进行了 24 小时和 48 小时的视觉读数,并记录了最小生长、不受抑制的生长和无生长。将结果与 EUCAST 方法进行了比较。孵育 24 小时后,以不受抑制的生长为阈值,平均敏感性和特异性分别为 0.54 和 1.00。孵育 48 小时后,平均敏感性和特异性分别为 0.98 和 0.93,以最小生长为阈值。观察者在真菌学方面的经验并不影响性能。孵育 24 小时后的组内相关系数为 0.87,孵育 48 小时后的组内相关系数为 0.85。VIPcheck 能够选择唑类耐药 菌落,平均敏感性和特异性分别为 0.98 和 0.93。孵育 24 小时后在任何含唑类药物的孔中无抑制生长和孵育 48 小时后最小生长表明存在耐药性。这些结果表明,VIPcheck 是一种易于使用的唑类药物耐药性筛选工具,可用于选择需要 MIC 测试的菌落。