Mycoplasma pneumoniae and Chlamydophila pneumoniae in children with community-acquired pneumonia in Thailand.

Background: The prevalence of community-acquired pneumonia (CAP) caused by atypical pathogens in Thai children is unknown.
Objective: To examine the prevalence of Mycoplasma pneumoniae and Chlamydophila pneumoniae infections in paediatric patients (aged 2-15 years) with CAP in three academic hospitals using standardised laboratory techniques. The characteristics of atypical pneumonia were also compared with other causes of CAP.
Methods: Diagnosis of current infection was based on a four-fold or more rise in antibody serum samples or persistently high antibody titres together with the presence of mycoplasmal or chlamydial DNA in secretions.
Results: Of 245 patients with CAP, 17.5% of cases were caused by atypical pathogens (M. pneumoniae 14.3%, C. pneumoniae 2.8% and co-infection 0.4%). We also found atypical pathogens in young children aged 2-5 years. The clinical and laboratory findings did not distinguish atypical pneumonia from other CAPs. Segmental or lobar consolidation on chest X-rays was more common in atypical pneumonia, while dyspnoea was more prominent in other CAPs.
Conclusion: Our data show a high prevalence of M. pneumoniae and C. pneumoniae in Thai children with CAP, including in children aged 2-5 years.