Objective: To evaluate the diagnostic performance of metagenomic next-generation sequencing (mNGS) using bronchoalveolar lavage fluid (BALF) in patients with ventilator-associated pneumonia (VAP).

Methods: BALF samples of 72 patients with VAP were collected from August 2018 to May 2020. The diagnostic performance of conventional testing (CT) and mNGS methods were compared based on bacterial and fungal examinations. The diagnostic value of mNGS for viral and mixed infections was also analyzed.

Results: The percentage of mNGS positive samples was significantly higher than that estimated by the CT method [odds ratio (OR), 4.33; 95% confidence interval (CI), 1.78–10.53; p < 0.001]. The sensitivity and specificity of mNGS for bacterial detection were 97.1% (95% CI, 93.2–101.0%) and 42.1% (95 CI, 30.7–53.5%), respectively, whereas the positive predictive value (PPV) and the negative predictive value (NPV) were 60.0% (95% CI, 48.7–71.3%) and 94.1% (95% CI, 88.7–99.6%), respectively. A total of 38 samples were negative for bacterial detection as determined by the CT method, while 22 samples were positive as shown by the mNGS method. Conflicting results were obtained for three samples between the two methods of bacterial detection. However, no significant differences were noted between the mNGS and CT methods (OR, 1.42; 95% CI, 0.68–2.97; p = 0.46) with regard to fungal infections. The sensitivity and specificity of mNGS were 71.9% (95% CI, 61.5–82.3%) and 77.5% (95% CI, 67.9–87.1%), respectively. mNGS exhibited a PPV of 71.9% (95% CI, 61.5–82.3%) and an NPV of 77.5% (95% CI, 67.9–87.1%). A total of 9 out of 40 samples were found positive for fungi according to mNGS, whereas the CT method failed to present positive results in these samples. The mNGS and CT methods produced conflicting results with regard to fungal detection of the two samples. A total of 30 patients were virus-positive using mNGS. Furthermore, 42 patients (58.3%) were identified as pulmonary mixed infection cases.

Conclusions: mNGS detection using BALF improved the sensitivity and specificity of bacterial identification in patients who developed VAP. In addition, mNGS exhibited apparent advantages in detecting viruses and identifying mixed infections.

目的：评价使用呼吸道相关性肺炎（VAP）的支气管肺泡灌洗液（BALF）进行宏基因组学新一代测序（mNGS）的诊断性能。

方法：收集2018年8月至2020年5月的72例VAP患者的BALF样本。通过细菌和真菌检查比较了常规检测（CT）和mNGS方法的诊断性能。还分析了mNGS对病毒和混合感染的诊断价值。

结果：mNGS阳性样品的百分比显着高于CT方法估计的百分比[几率（OR），4.33；95％置信区间（CI）为1.78–10.53；p<0.001]。mNGS对细菌检测的敏感性和特异性分别为97.1％（95％CI，93.2–101.0％）和42.1％（95 CI，30.7–53.5％），而阳性预测值（PPV）和阴性预测值（NPV）分别为60.0％（95％CI，48.7-71.3％）和94.1％（95％CI，88.7-99.6％）。如通过CT方法确定的，总共38个样品的细菌检测阴性，而通过mNGS方法显示的22个样品为阳性。在两种细菌检测方法之间的三个样品获得了矛盾的结果。但是，mNGS和CT方法之间没有显着差异（OR为1.42； 95％CI为0.68–2.97；p= 0.46）关于真菌感染。mNGS的敏感性和特异性分别为71.9％（95％CI，61.5-82.3％）和77.5％（95％CI，67.9-87.1％）。mNGS的PPV为71.9％（95％CI，61.5-82.3％）和NPV为77.5％（95％CI，67.9-87.1％）。根据mNGS，在40个样本中总共发现9个真菌阳性，而CT方法未能在这些样本中呈现阳性结果。对于两种样品的真菌检测，mNGS和CT方法产生了矛盾的结果。使用mNGS的30例患者均为病毒阳性。此外，有42例（58.3％）被确定为肺部混合感染病例。

结论：使用BALF进行mNGS检测可提高发生VAP的患者细菌鉴定的敏感性和特异性。另外，mNGS在检测病毒和识别混合感染方面显示出明显的优势。