Current perspectives on atypical pneumonia in children

Abstract

The major pathogens that cause atypical pneumonia are <i>Mycoplasma pneumoniae, Chlamydophila pneumoniae</i>, and <i>Legionella pneumophila</i>. Community-acquired pneumonia (CAP) caused by <i>M. pneumoniae</i> or <i>C. pneumoniae</i> is common in children and presents as a relatively mild and self-limiting disease. CAP due to <i>L. pneumophila</i> is very rare in children and progresses rapidly, with fatal outcomes if not treated early. <i>M. pneumoniae, C. pneumoniae</i>, and <i>L. pneumophila</i> have no cell walls; therefore, they do not respond to β-lactam antibiotics. Accordingly, macrolides, tetracyclines, and fluoroquinolones are the treatments of choice for atypical pneumonia. Macrolides are the first-line antibiotics used in children because of their low minimum inhibitory concentrations and high safety. The incidence of pneumonia caused by macrolide-resistant <i>M. pneumoniae</i> that harbors point mutations has been increasing since 2000, particularly in Korea, Japan, and China. The marked increase in macrolide-resistant <i>M. pneumoniae</i> pneumonia (MRMP) is partly attributed to the excessive use of macrolides. MRMP does not always lead to clinical nonresponsiveness to macrolides. Furthermore, severe complicated MRMP responds to corticosteroids without requiring a change in antibiotic. This implies that the hyper-inflammatory status of the host can induce clinically refractory pneumonia regardless of mutation. Empirical macrolide therapy in children with mild to moderate CAP, particularly during periods without <i>M. pneumoniae</i> epidemics, may not provide additional benefits over β-lactam monotherapy and can increase the risk of MRMP.