The clinical presentation does not help distinguish M. pneumoniae pneumonia from that of any other bacterial etiology.

• Acute M. pneumoniae infection manifests as a nonspecific upper respiratory syndrome with pharyngitis, tracheobronchitis, and/or wheezing.
• Pneumonia develops in 3-13% of infected pts. The most common presenting symptom is a nonproductive cough. Headache, malaise, chills, and fever are common.
• On physical examination, ~80% of pts have wheezes or rales.
• Symptoms usually resolve in 2-3 weeks, and appropriate antimicrobial therapy significantly shortens the duration of clinical illness.
• Infection uncommonly results in critical illness and rarely causes death.
• Extrapulmonary manifestations of M. pneumoniae infection are relatively uncommon but include skin eruptions (e.g., erythema multiforme major, rashes), neurologic manifestations (e.g., encephalitis, Guillain-Barré syndrome, acute demyelinating encephalomyelitis), septic arthritis (particularly in pts with hypogammaglobulinemia), and hematologic manifestations (e.g., hemolytic anemia, coagulopathies).