Objectives

Sputum culture is an insensitive method for the diagnosis of pulmonary aspergillosis. Growth of the organism allows identification of the causative species and susceptibility testing, both of which can inform treatment choices. The current practice is to culture an aliquot of diluted sputum. We assessed the value of culturing large volumes of unprocessed sputum, a method that we have termed high-volume culture (HVC).

Methods

Specimens were processed by conventional culture (using an aliquot of homogenized, diluted sputum on Sabouraud agar at 37°C and 45°C for up to 5 days) and HVC (using undiluted sputum on Sabouraud agar at 30°C for up to 14 days). A separate specimen was tested by quantitative real-time PCR. Antifungal susceptibility testing was performed by the EUCAST standard.

Results

We obtained sputum specimens from 229 individuals with the following conditions: chronic pulmonary aspergillosis (66.8%, 153/229), allergic bronchopulmonary aspergillosis (25.3%, 58/229) and Aspergillus bronchitis (7.9%, 18/229). Individuals with invasive pulmonary aspergillosis were not included. The positivity rate of conventional culture was 15.7% (36/229, 95% CI 11.6%–21.0%) and that of HVC was 54.2% (124/229, 95% CI 47.7%–60.5%) (p < 0.001). The higher positivity rate of HVC was demonstrated regardless of administration of antifungal treatment. Quantitive real-time PCR had an overall positivity rate of 49.2% (65/132, 95% CI 40.9%–57.7%), comparable to that of HVC.

Conclusion

Detection of Aspergillus spp. in sputum is greatly enhanced by HVC. HVC allows for detection of azole-resistant isolates that would have been missed by conventional culture. This method can be performed in any microbiology laboratory without the need for additional equipment.

中文翻译：

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大容量培养和实时定量PCR检测痰中的曲霉菌。

目标

痰培养是诊断肺曲霉病的一种不灵敏的方法。生物体的生长可以确定致病菌种和药敏试验，这两者都可以为治疗选择提供依据。目前的做法是培养一份稀释的痰。我们评估了培养大量未经处理的痰的价值，这种方法被我们称为高容量培养（HVC）。

方法

通过常规培养（在37°C和45°C下在Sabouraud琼脂上匀浆，稀释的痰等分试样最多5天）和HVC（在30°C下在Sabouraud琼脂上使用未稀释的痰液长达14天）对样品进行处理）。通过定量实时PCR测试单独的样品。通过EUCAST标准进行抗真菌药敏试验。

结果

我们从229名患有以下情况的个体获得了痰标本：慢性肺曲霉菌病（66.8％，153/229），过敏性支气管肺曲霉菌病（25.3％，58/229）和曲霉菌性支气管炎（7.9％，18/229）。不包括有侵袭性肺曲霉病的个体。常规培养的阳性率为15.7％（36 / 229，95％CI 11.6％–21.0％），而HVC的阳性率为54.2％（124/229，95％CI 47.7％–60.5％）（p <0.001）。无论是否使用抗真菌治疗，均显示出HVC的阳性率更高。实时定量PCR的总体阳性率为49.2％（65 / 132，95％CI为40.9％–57.7％），与HVC相当。

结论

曲霉属的检测。HVC可大大增强痰液中的胆固醇。HVC可以检测常规培养可能遗漏的抗唑类分离株。此方法可以在任何微生物实验室中进行，而无需其他设备。