The University of Manchester, 1.800 Stopford Building, Oxford Road, Manchester M13 9PT, United Kingdom.
Antimicrob Agents Chemother. 2011 Oct;55(10):4802-9. doi: 10.1128/AAC.00304-11. Epub 2011 Jul 18.
Aspergillus niger is a common clinical isolate. Multiple species comprise the Aspergillus section Nigri and are separable using sequence data. The antifungal susceptibility of these cryptic species is not known. We determined the azole MICs of 50 black aspergilli, 45 from clinical specimens, using modified EUCAST (mEUCAST) and Etest methods. Phylogenetic trees were prepared using the internal transcribed spacer, beta-tubulin, and calmodulin sequences to identify strains to species level and the results were compared with those obtained with cyp51A sequences. We attempted to correlate cyp51A mutations with azole resistance. Etest MICs were significantly different from mEUCAST MICs (P < 0.001), with geometric means of 0.77 and 2.79 mg/liter, respectively. Twenty-six of 50 (52%) isolates were itraconazole resistant by mEUCAST (MICs > 8 mg/liter), with limited cross-resistance to other azoles. Using combined beta-tubulin/calmodulin sequences, the 45 clinical isolates grouped into 5 clades, A. awamori (55.6%), A. tubingensis (17.8%), A. niger (13.3%), A. acidus (6.7%), and an unknown group (6.7%), none of which were morphologically distinguishable. Itraconazole resistance was found in 36% of the isolates in the A. awamori group, 90% of the A. tubingensis group, 33% of the A. niger group, 100% of the A. acidus group, and 67% of the unknown group. These data suggest that cyp51A mutations in section Nigri may not play as important a role in azole resistance as in A. fumigatus, although some mutations (G427S, K97T) warrant further study. Numerous cryptic species are found in clinical isolates of the Aspergillus section Nigri and are best reported as "A. niger complex" by clinical laboratories. Itraconazole resistance was common in this data set, but azole cross-resistance was unusual. The mechanism of resistance remains obscure.
黑曲霉是一种常见的临床分离株。多种曲霉被归入黑曲霉组，可通过序列数据进行区分。这些隐种的抗真菌药敏性尚不清楚。我们使用改良的 EUCAST（mEUCAST）和 Etest 方法，测定了 50 株黑色曲霉（其中 45 株来自临床标本）的唑类药物 MIC。我们使用内部转录间隔区、β-微管蛋白和钙调蛋白序列构建了系统发育树，以鉴定到种水平的菌株，并将结果与 cyp51A 序列的结果进行比较。我们试图将 cyp51A 突变与唑类药物耐药性相关联。Etest MIC 与 mEUCAST MIC 显著不同（P < 0.001），几何均值分别为 0.77 和 2.79mg/L。50 株分离株中有 26 株（52%）根据 mEUCAST（MICs > 8mg/L）判定为伊曲康唑耐药，对其他唑类药物的交叉耐药性有限。使用组合的β-微管蛋白/钙调蛋白序列，45 株临床分离株分为 5 个分支，即 Aspergillus awamori（55.6%）、A. tubingensis（17.8%）、A. niger（13.3%）、A. acidus（6.7%）和一个未知组（6.7%），它们在形态上无法区分。在 A. awamori 组中，36%的分离株对伊曲康唑耐药，在 A. tubingensis 组中，90%的分离株对伊曲康唑耐药，在 A. niger 组中，33%的分离株对伊曲康唑耐药，在 A. acidus 组中，100%的分离株对伊曲康唑耐药，在未知组中，67%的分离株对伊曲康唑耐药。这些数据表明，黑曲霉组中 cyp51A 突变在唑类药物耐药性中的作用可能不如在 A. fumigatus 中那么重要，尽管一些突变（G427S、K97T）值得进一步研究。在黑曲霉组的临床分离株中发现了许多隐种，临床实验室最好将其报告为“黑曲霉复合体”。本数据集常见伊曲康唑耐药，但唑类药物交叉耐药不常见。耐药机制尚不清楚。
