The prevalence of macrolide-resistant Mycoplasma pneumoniae (MP) pneumonia has been rapidly increased. MP pneumonia is a risk factor for the development of post-infectious bronchiolitis obliterans (PIBO). The aim of the present study was to identify the risk factors for the development of PIBO after MP pneumonia in the era of increasing macrolide resistance of MP.

This retrospective study enrolled 150 children with a mean age of 6.0 years admitted to the hospital due to MP pneumonia between May 2019 and February 2020 at a tertiary hospital. The clinical, radiologic, and laboratory data were obtained using retrospective chart review.

Eighteen children (12%) were diagnosed with PIBO after MP pneumonia. PIBO was diagnosed after a mean duration of 100.0 days (range, 6–268 days) from symptom onset. The respiratory virus co-infection (adjusted odds ratio [aOR], 4.069; 95% confidence interval [95% CI], 1.224–13.523), adenovirus co-infection (aOR, 5.607; 95% CI, 1.801–17.454), longer duration between symptom onset and admission (aOR, 1.150; 95% CI, 1.020–1.298), higher levels of serum lactate dehydrogenase (LDH) at the time of admission (aOR, 1.001; 95% CI, 1.000–1.003), and poor response to stepwise treatment increased the risk for development of PIBO after MP pneumonia. However, macrolide resistance of MP was not associated with development of PIBO after MP pneumonia.

The present study suggests that respiratory virus co-infection, including adenovirus, poor response to the treatment of MP pneumonia, and higher levels of serum LDH, but not macrolide resistance of MP, are risk factors of PIBO after MP pneumonia.