RESUMEN
Objective: To describe the frequency and impact of bacterial co-infections in children hospitalized with Mycoplasma pneumoniae pneumonia. Design: Retrospective, descriptive study. Setting: Tertiary-care hospital in Beijing, China. Participants: 8612 children admitted to Beijing Children's Hospital from June 2006 to June 2014. Methods: According to the testing results of etiology we divided the cases into pure M. pneumoniae infection group and mixed bacterial infection group. We analyzed clinical features, hospital expenses and differences between these two groups. Results: 173 (2%) of included children had bacterial co-infection. 56.2% of bacterial pathogens were identified as Streptococcus pneumoniae. Conclusion: The most common bacterium causing co-infection in children with M. pneumoniae pneumonia was S. pneumoniae.