Which pneumonia is often confused with a URI and may present with low-grade fever and wheezing?

• A. H influenza
• B. Pneumococcal pneumonia
• C. Mycoplasma
• D. Legionnaires

Answer: (C)

Atypical pneumonia from Mycoplasma pneumoniae often masquerades as a viral URI. It tends to affect school-age children and young adults with a gradual onset, low-grade fever, malaise, and a dry cough, and wheezing is common due to airway irritation. Because the illness is milder and lacks the abrupt high fever and focal chest findings of classic bacterial pneumonia, it can be mistaken for a URI in the early stages. On exam you may hear diffuse wheezes or crackles rather than a single lobar consolidation, and chest x-ray typically shows diffuse or interstitial markings rather than a localized infiltrate. The lack of a cell wall means beta-lactam antibiotics are ineffective, so treatment is with macrolides (or doxycycline in older patients, or a fluoroquinolone when appropriate). This combination of mild, URI-like presentation with wheeze and a gradual course is the hallmark of Mycoplasma pneumoniae.