Abstract:Objective To investigate the diagnostic value of next-generation sequencing (NGS) combined with serum galactomannan (GM) antigen test for severe pneumonia complicating fungal infection.Methods Between March 2020 and March 2023, a total of 148 patients with severe pneumonia admitted to the Emergency Intensive Care Unit of Daqing Longnan Hospital were included in this study. Bronchoalveolar lavage fluid was collected and subjected to microbial culture and NGS analysis. The serum GM antigen test was performed concurrently. With the results of microbial culture as the gold standard, the sensitivity and specificity of the serum GM antigen test and NGS on bronchoalveolar lavage fluid for diagnosing fungal infections in severe pneumonia were analyzed. The concordance of the serum GM antigen test and NGS on bronchoalveolar lavage fluid alone and their combination with the microbial culture was evaluated.Results Among 148 cases of severe pneumonia, 30 cases were complicated with fungal infections, including 10 cases of Pneumocystis, 8 cases of Candida albicans, 7 cases of Aspergillus, 1 case of Rhizopus, 3 cases of Pneumocystis with Candida albicans, and 1 case of Pneumocystis with Acinetobacter baumannii. The serum GM antigen test demonstrated that 28 cases were positive and 120 cases were negative, with a Kappa value of 0.700 for diagnosing fungal infections in comparison with the microbial culture. The NGS on bronchoalveolar lavage fluid showed that 34 cases were positive and 114 cases were negative, with a Kappa value of 0.841 for diagnosing fungal infections in comparison with the microbial culture. The combined detection via the serum GM antigen test and NGS on bronchoalveolar lavage fluid revealed that 30 cases were positive and 118 cases were negative, with a Kappa value of 0.916 for diagnosing fungal infections in comparison with the microbial culture. The sensitivities of the serum GM antigen test and NGS on bronchoalveolar lavage fluid alone and their combination for the diagnosis of severe pneumonia with fungal infection were 73.3% (95% CI: 0.538, 0.870), 93.3% (95% CI: 0.765, 0.988) and 93.3% (95% CI: 0.765, 0.988), with the specificities being 94.9% (95% CI: 0.888, 0.979), 94.9% (95% CI: 0.889, 0.979) and 98.3% (95% CI: 0.934, 0.997), and the areas under the curves (AUCs) being 0.841, 0.941 and 0.958.Conclusions The combination of the serum GM antigen test and NGS on bronchoalveolar lavage fluid exhibits great diagnostic efficacy for fungal infections in severe pneumonia, especially for common fungal species such as Pneumocystis, Candida albicans, and Aspergillus.