Diagnostic value of cytokine detection in children with Mycoplasma pneumoniae pneumonia complicated by bacterial or viral co-infections

Abstract Background To evaluate the diagnostic value of cytokine levels in paediatric patients with Mycoplasma pneumoniae pneumonia (MPP) complicated by bacterial or viral infections, to enhance early detection and treatment strategies. Methods A retrospective analysis was conducted on 145 paediatric patients with MPP at Fujian Children’s Hospital between October 2023 and April 2024. The patients were categorised into three groups: MPP only, MPP with bacterial co-infection, and MPP with viral co-infection. Clinical and laboratory data were analysed. Diagnostic accuracy was assessed using receiver operating characteristic (ROC) curves. Machine learning models with Boruta feature selection and 5-fold cross-validation were applied for co-infection classification. Statistical significance was set at P < 0.05. Results Significant differences were observed between groups. The bacterial co-infection group had higher white blood cell and platelet counts and elevated levels of interferon-alpha, interleukin-1 beta, interleukin-6, and tumour necrosis factor-alpha (all P < 0.05). The viral co-infection group had lower interleukin-12P70 levels, longer fever and cough durations, and higher lactate dehydrogenase levels (all P < 0.05). Correlation analysis showed strong associations between white blood cells, platelets, and proinflammatory cytokines. ROC analysis of single parameters showed modest discrimination: for bacterial co-infections the best single marker was interferon-alpha with an AUC of 0.774 (95% CI 0.649–0.899), whereas for viral co-infections the best was lactate dehydrogenase with an AUC of 0.684 (95% CI 0.563–0.806). In contrast, machine learning models achieved higher performance, reaching an AUC of 0.868 (95% CI 0.772–0.964; SVM) for bacterial co-infections and 0.753 (95% CI 0.636–0.870; LightGBM) for viral co-infections. Conclusion The combination of clinical data, laboratory parameters and cytokine profiles may improve the early diagnostic accuracy of MPP with bacterial or viral co-infections in some patients, and potentially guide optimised treatment strategies.