Association Between Serum MPO-DNA and CCL26 Levels and Poor Prognosis in Children with Multidrug-Resistant Organism-Associated Pneumonia

Objective: To investigate serum myeloperoxidase-DNA (MPO-DNA) and C-C motif chemokine ligand 26 (CCL26) levels in pediatric multidrug-resistant organism (MDRO)-associated pneumonia and their association with 28-day prognosis. Methods: In this single-center prospective cohort study, 220 pediatric patients hospitalized for MDRO-associated pneumonia (February 2022–February 2025) were enrolled. Serum MPO-DNA, CCL26, C-reactive protein (CRP), and procalcitonin (PCT) were measured by ELISA within 24 h of admission. Patients were classified into good-prognosis (clinical improvement, ≥ 50% pulmonary lesion absorption, no severe complications) and poor-prognosis (treatment failure, severe complications, or death within 28 days) groups. Multivariable logistic regression and ROC analysis were performed. Results: Of 220 patients, 68 (30.9%) had poor prognosis. The poor-prognosis group showed significantly elevated CRP, PCT, MPO-DNA, and CCL26 (all P < 0.05). MPO-DNA and CCL26 were positively correlated (r = 0.507, P < 0.001). Multivariable analysis indicated elevated CRP (OR = 1.714, 95% CI: 1.389– 2.116), PCT (OR = 1.739, 95% CI: 1.497– 2.021), MPO-DNA (OR = 1.007, 95% CI: 1.003– 1.011), and CCL26 (OR = 1.002, 95% CI: 1.001– 1.004) as independent risk factors (all P < 0.05). ROC analysis showed AUC values for MPO-DNA, CCL26, and their combination of 0.799, 0.816, and 0.872, respectively, with the combined model significantly superior to either alone (all P < 0.05). Conclusion: Elevated serum MPO-DNA and CCL26 levels are associated with 28-day poor prognosis in pediatric MDRO pneumonia. Combined detection shows favorable discriminative performance. However, given the single-center design and lack of external validation, clinical utility requires further multicenter confirmation.