Coinfection Patterns of Mycoplasma pneumoniae with Other Respiratory Pathogens in Children.

Mycoplasma pneumoniae (MP) is a frequent cause of pediatric pneumonia, but the clinical relevance of respiratory coinfections remains incompletely defined. We conducted a retrospective cohort study of 192 hospitalized children with multiplex RT-PCR-confirmed MP infection between April 2023 and November 2025. Patients were classified as MP monoinfection (123/192, 64.1%), MP with viral coinfection (34/192, 17.7%), or MP with bacterial/mixed coinfection (35/192, 18.2%) and children with coinfection were younger than those with MP infection alone, with median ages of 6.5 years (IQR 1-11) in the viral coinfection group and 5 years (IQR 1-7) in the bacterial/mixed coinfection group, compared with 11 years (IQR 7-14) in children with MP alone (p < 0.001). Respiratory failure occurred in 36% of children with MP infection alone, 65% of those with viral coinfection, and 31% of those with bacterial/mixed coinfection. In adjusted logistic regression, viral coinfection was independently associated with higher odds of respiratory failure relative to MP infection alone (aOR 3.37, 95% CI 1.49-7.94; p = 0.004), whereas bacterial/mixed coinfection was not (aOR 0.85, 95% CI 0.35-2.03; p = 0.725). In multinomial regression, increasing age was inversely associated with both viral coinfection (RRR 0.86, 95% CI 0.79-0.94; p < 0.001) and bacterial/mixed coinfection (RRR 0.79, 95% CI 0.72-0.87; p < 0.001). In negative binomial regression, evidence for longer hospitalization in the viral coinfection group was weaker and imprecise (IRR 1.16, 95% CI 0.99-1.37; p = 0.069). Fibrinogen differed across etiologic groups, with the lowest values in bacterial/mixed coinfection (p = 0.004). In this hospitalized pediatric cohort, MP coinfection was more frequent in younger children, and viral co-detection showed the clearest association with respiratory failure. These findings should be interpreted in the context of the retrospective design, modest subgroup sizes, and the limitations of upper-airway multiplex PCR co-detection.