Mycoplasmal pneumonia is different from pneumococcal pneumonia in that:

• A. Mycoplasmal pneumonia is caused by bacteria that lack a cell wall.
• B. Mycoplasmal pneumonia typically produces a thick, rust-colored sputum.
• C. Mycoplasmal pneumonia is treated effectively with penicillin.
• D. Mycoplasmal pneumonia is caused by Streptococcus pneumoniae.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the causative agents of both types of pneumonia. Mycoplasmal pneumonia is caused by Mycoplasma pneumoniae, a type of bacteria that is unique because it lacks a cell wall. Pneumococcal pneumonia, on the other hand, is caused by Streptococcus pneumoniae, which has a typical bacterial cell wall.
2. Step 2: Recognize the significance of the cell wall in bacterial classification and treatment. The absence of a cell wall in Mycoplasma makes it resistant to antibiotics like penicillin, which target cell wall synthesis.
3. Step 3: Compare the clinical features. Pneumococcal pneumonia often produces thick, rust-colored sputum due to blood in the mucus, whereas Mycoplasmal pneumonia usually causes a milder, atypical pneumonia without this characteristic sputum.
4. Step 4: Review treatment options. Since Mycoplasma lacks a cell wall, antibiotics that inhibit cell wall synthesis (like penicillin) are ineffective. Instead, treatments typically involve antibiotics that target other bacterial processes, such as protein synthesis inhibitors.
5. Step 5: Summarize the key difference: Mycoplasmal pneumonia is caused by bacteria without a cell wall, which affects both its clinical presentation and treatment, distinguishing it from pneumococcal pneumonia caused by Streptococcus pneumoniae.