Impact of pathogen co-detection on disease severity and clinical outcomes in children with Mycoplasma pneumoniae pneumonia

BACKGROUND: Although Mycoplasma pneumoniae pneumonia (MPP) is a leading cause of pediatric community-acquired pneumonia, the specific clinical impact of respiratory pathogen co-detection remains incompletely understood. METHODS: In this retrospective cohort study, we analyzed data from 3081 children hospitalized with confirmed MPP at a single center in China (January 2023-December 2024). Based on comprehensive respiratory pathogen testing, patients were classified into MPP mono-infection (n = 1173) or MPP co-detection (n = 1908) groups. Severe MPP (SMPP) was defined as a composite outcome per national guidelines. The primary outcome was the incidence of SMPP; secondary outcomes included specific complications, healthcare utilization, and costs. Stratified analysis by co-detection pattern (single virus, single bacterium, viral-bacterial, and multiple viruses) was performed. Multivariable logistic regression was used to assess the independent association of co-detection with SMPP, adjusting for sex, age, platelet count, C-reactive protein (CRP) level, and D-dimer level. RESULTS: The co-detection rate was 61.9% (1908/3081). Among co-detected cases, single-viral detection was most common (41.8%), followed by viral-bacterial detection (19.1%). Adenovirus (33.5%) and rhinovirus (32.1%) were the predominant single viruses. The co-detection group exhibited a significantly higher incidence of SMPP (51.8% vs. 47.3%, P = 0.018), higher total hospitalization costs, longer hospital stays, and longer durations of cough and fever (all P < 0.001). Stratified analysis revealed that the viral-bacterial co-detection subtype consistently exhibited the most severe outcomes. After adjusting for sex, age, platelet count, CRP level, and D-dimer level, pathogen co-detection was an independent risk factor for SMPP [adjusted odds ratio (OR) = 1.31; 95% confidence interval = 1.11-1.56; P = 0.002]. Elevated D-dimer levels (adjusted OR = 3.66) and older age were also significant independent predictors. CONCLUSIONS: Respiratory pathogen co-detection is prevalent in children with MPP and is independently associated with disease progression to SMPP (as defined by guideline criteria), prolonged hospitalization, and increased healthcare costs. The viral-bacterial co-detection pattern is associated with the greatest risk. These findings underscore the importance of comprehensive pathogen screening in the management of pediatric MPP.