Mycoplasma pneumoniae is associated with which features?

• A. Typical pneumonia with productive cough
• B. Atypical pneumonia with nonproductive cough and cold agglutinins
• C. Gram-positive cocci forming clusters
• D. Response to penicillin due to a rigid cell wall

Answer: (B)

Mycoplasma pneumoniae causes an atypical pneumonia, typically presenting with a dry, nonproductive cough and often cold agglutinins—IgM antibodies that cause RBC agglutination at cooler temperatures. A defining feature is that this organism lacks a cell wall, so it does not Gram stain and is resistant to beta-lactam antibiotics like penicillin, which target cell wall synthesis. This combination—atypical pneumonia with a nonproductive cough and cold agglutinins—best fits the scenario. In contrast, typical lobar pneumonia presents with a productive cough, Gram-positive cocci in clusters describe Staphylococcus aureus, and penicillin would not be effective due to the absence of a cell wall in Mycoplasma.