Propionibacterium spp. are best described as which of the following?

Propionibacterium spp. are best described as which of the following?

• A. Non-spore-forming, Gram-positive bacilli
• B. Spore-forming, Gram-positive bacilli
• C. Non-spore-forming, Gram-negative bacilli
• D. Spore-forming, Gram-negative bacilli

Answer: (A)

Propionibacterium species are Gram-positive rod-shaped bacteria that do not form spores. This combination—Gram-positive plus non-spore-forming—is why the best description is non-spore-forming, Gram-positive bacilli. They are commonly part of the skin’s normal flora and are typically anaerobic, which helps place them within the non-spore-forming, Gram-positive bacilli category. They are not Gram-negative, and they do not form spores, so descriptions calling them Gram-negative or spore-forming would not fit. This contrasts with spore-forming Gram-positive bacilli like Bacillus and Clostridium and with Gram-negative rods, which Propionibacterium is not.

Propionibacterium species are Gram-positive rod-shaped bacteria that do not form spores. This combination—Gram-positive plus non-spore-forming—is why the best description is non-spore-forming, Gram-positive bacilli. They are commonly part of the skin’s normal flora and are typically anaerobic, which helps place them within the non-spore-forming, Gram-positive bacilli category. They are not Gram-negative, and they do not form spores, so descriptions calling them Gram-negative or spore-forming would not fit. This contrasts with spore-forming Gram-positive bacilli like Bacillus and Clostridium and with Gram-negative rods, which Propionibacterium is not.