Gao_2026_Front.Microbiol_17_1842600

OBJECTIVE: This study aimed to compare pathogen detection rates between metagenomic next-generation sequencing (mNGS) and conventional microbiological culture in critically ill infants younger than 1 year of age, and to investigate the associations between mNGS positivity and clinical laboratory parameters. METHODS: We conducted a single-centre retrospective study including infants with severe infections admitted to the Children's Hospital of Soochow University between 1 January 2023 and 31 December 2025, who underwent both mNGS and conventional culture testing. Patients were classified into mNGS-positive and mNGS-negative groups, and clinical characteristics and laboratory findings were compared between groups. Candidate predictors of mNGS positivity were identified using least absolute shrinkage and selection operator (LASSO) regression, followed by multivariable logistic regression analysis. The predictive performance of key variables was evaluated using receiver operating characteristic (ROC) curve analysis. RESULTS: A total of 105 infants and 153 biological specimens were included. The overall mNGS positivity rate, as well as positivity rates across all specimen types except cerebrospinal fluid, were significantly higher than those of conventional culture (p < 0.05). LASSO regression identified eosinophil percentage, mean corpuscular haemoglobin (MCH), procalcitonin (PCT), cholinesterase, and serum calcium as candidate predictors of mNGS positivity. Multivariable logistic regression revealed that MCH (OR = 0.755, 95%CI: 0.657-0.869), cholinesterase (OR = 0.999, 95%CI: 0.999-1.000), and PCT (OR = 1.180, 95%CI: 1.050-1.320) were independently associated with mNGS positivity. ROC analysis demonstrated that MCH, cholinesterase, and PCT individually showed moderate discriminatory performance, whereas a combined model incorporating all three variables achieved substantially improved predictive performance (AUC = 0.842, 95%CI: 0.758-0.912), with a sensitivity of 87.2% and specificity of 81.6%. CONCLUSION: mNGS demonstrated superior pathogen detection compared with conventional culture in critically ill infants. MCH, cholinesterase, and PCT were independently associated with mNGS positivity, and a combined multi-marker model substantially improved the prediction of mNGS-positive cases.