Which organism is commonly implicated in pediatric atypical pneumonia in school-age children?

• A. Haemophilus influenzae
• B. Adenovirus
• C. Streptococcus pneumoniae
• D. Mycoplasma pneumoniae

Answer: (D)

Atypical pneumonia in school-age children is most often caused by Mycoplasma pneumoniae. This organism lacks a cell wall, so it doesn’t respond to beta-lactam antibiotics and can’t be easily seen on Gram stain or routine culture. Clinically it tends to produce a gradual onset with a dry, nonproductive cough, low-grade fever, and malaise, and chest X-rays often show diffuse interstitial or patchy infiltrates rather than a single lobar consolidation. It also tends to occur in school settings, with potential outbreaks. Because of the lack of a cell wall, macrolide antibiotics are preferred for treatment. In contrast, Haemophilus influenzae is more common in younger children with typical bacterial pneumonia; Adenovirus can cause pneumonia but is not the classic picture for school-age atypical cases; Streptococcus pneumoniae is the most common cause of pneumonia overall in younger children and presents with a more acute, lobar picture. Thus, Mycoplasma pneumoniae best fits the pattern of pediatric atypical pneumonia in school-age children.