Work

Clinical significance and discriminatory performance of the serum KL-6 level as a biomarker for severe Chlamydia pneumoniae infection in children

Year: 2026

Type: article

Abstract: Objective To characterize the expression and evaluate the clinical utility for assessing disease severity of the serum Krebs von den Lungen-6 (KL-6) level in children with mild and severe acute Chlamydia pneumoniae ( C. pneumoniae ) infection. Methods A total of 68 hospitalized children with acute lower respiratory tract infection caused by C. pneumoniae (48 mild cases and 20 severe cases) who were admitted to Children’s Hospital of Wujiang District from May 2024 to April 2025 were enrolled, with 19 healthy children included in the control group. Serum KL-6 levels, C. pneumoniae -IgM levels, and routine laboratory indicators were measured. The correlation between the KL-6 level and clinical features was analyzed, and discriminatory performance of the KL-6 level for identifying severe C. pneumoniae infection was assessed using ROC curves. Results Serum KL-6 levels were significantly higher in the severe group than in the mild group [303.00 (227.75, 328.25) U/mL vs. 146.50 (133.50, 164.25) U/mL, P < 0.001]. Binary logistic regression analysis indicated that KL-6 was independently associated with severe C. pneumoniae infection in children (P < 0.001), and the area under the curve (AUC) for differentiating severe infection from mild infection was 0.951 (95%CI=0.880-0.997, P<0.001). Further analysis revealed that the KL-6 level was positively correlated with the number of pulmonary lesions, the number of hospitalization days, and C. pneumoniae -IgM levels but not with other indicators. Conclusion The serum KL-6 level can effectively reflect the degree of pulmonary parenchymal injury in children with C. pneumoniae infection and can serve as an independent biomarker for severe C. pneumoniae infection. It demonstrates high discriminatory ability for identifying severe cases and may serve as an auxiliary biomarker for assessing pulmonary parenchymal injury.

Source: Frontiers in Cellular and Infection Microbiology

DOI: 10.3389/fcimb.2026.1791097