Metagenomic next-generation sequencing for the diagnosis and evaluation of pediatric pleural effusion: a case series

Pleural effusion is a common symptom in children with respiratory diseases, with infections being the leading cause. Currently, the use of metagenomic next-generation sequencing (mNGS) for pleural effusion has not been fully evaluated in pediatric lung disease patients. Patients who had undergone mNGS for pleural effusion were included in the study. Patients were categorized into a clinically useful group and a not clinically useful group on the basis of their clinical data, laboratory results, and mNGS results. A total of 48 children were included in this study. The number of positive mNGS results was 32/48 (66.7%), which was greater than that of conventional tests (22/48 [45.8%]). The diagnostic concordance of mNGS for detecting bacterial infections was 62.5% (20/32) higher than that of conventional detection methods, which was 15.6% (5/32). However, the diagnostic concordance of mNGS in detecting mycoplasma infections (4/9 vs. 7/9) and tuberculosis infections (0/5 vs. 5/5) was lower than that of conventional detection methods. Compared with the not clinically useful group, the clinically useful group had a lower mean age (50.50 [IQR, 32.25, 102.50] vs. 98.00 [IQR, 60.00, 118.50] months, P = 0.019), a greater incidence of wheezing (n = 5/23 vs. n = 0/23, P = 0.018), a greater incidence of pulmonary consolidation (n = 15/23 vs. n = 8/23, P = 0.039), and a greater incidence of loculated pleural effusion (n = 5/23 vs. n = 0/23, P = 0.018). Additionally, the clinically useful group had a longer hospital stay (17.0 [IQR, 10.75, 25.0] vs. 12.0 [IQR, 6.75, 15.00] days, P = 0.011). Nevertheless, the rate of improvement after treatment was greater in the clinically useful group than in the not clinically useful group (100% vs. 73.9%, P = 0.009). mNGS has distinct diagnostic advantages, with more accurate bacterial identification in pediatric pleural effusion. Negative results may prompt exploration of non-infectious causes. However, pathogen-specific limitations should be considered.