Which statement about daptomycin's suitability for pneumonia is correct?

Which statement about daptomycin's suitability for pneumonia is correct?

• A. Inactivated by pulmonary surfactant; active against Gram-positive organisms including MRSA and VRE.
• B. Active against Gram-negative bacteria including Pseudomonas.
• C. Effective for pneumonia and skin infections equally.
• D. Binds to iron and inhibits protein synthesis.

Answer: (A)

Daptomycin’s suitability for pneumonia hinges on two points: it is inactivated by pulmonary surfactant, and it is active mainly against Gram-positive organisms (like MRSA and VRE). Because surfactant in the lungs neutralizes the drug, it isn’t effective for treating pneumonia. Yet it remains a potent agent against Gram-positive pathogens, acting by calcium-dependent binding to the bacterial cell membrane, causing rapid depolarization and death without lysis. This mechanism explains its lack of activity against Gram-negative bacteria such as Pseudomonas, which have an outer membrane that daptomycin cannot readily cross. Consequently, daptomycin isn’t used for pneumonia and is instead used for complicated skin/soft tissue infections and bacteremia caused by Gram-positive organisms. The statement about binding iron and inhibiting protein synthesis is inaccurate for this drug.

Daptomycin’s suitability for pneumonia hinges on two points: it is inactivated by pulmonary surfactant, and it is active mainly against Gram-positive organisms (like MRSA and VRE). Because surfactant in the lungs neutralizes the drug, it isn’t effective for treating pneumonia. Yet it remains a potent agent against Gram-positive pathogens, acting by calcium-dependent binding to the bacterial cell membrane, causing rapid depolarization and death without lysis. This mechanism explains its lack of activity against Gram-negative bacteria such as Pseudomonas, which have an outer membrane that daptomycin cannot readily cross. Consequently, daptomycin isn’t used for pneumonia and is instead used for complicated skin/soft tissue infections and bacteremia caused by Gram-positive organisms. The statement about binding iron and inhibiting protein synthesis is inaccurate for this drug.