An anaerobic culture reveals colonies with a double zone of hemolysis on SBA plate. There was no growth on plates incubated aerobically. The Gram stain of that organism was a boxcar-shaped, gram-positive bacillus. What organism is this?

Question

Quizplus · Accepted Answer

The presence of double zone hemolysis and a boxcar-shaped, gram-positive bacillus are characteristic of Clostridium perfringens. The lack of growth on aerobic incubation supports its anaerobic nature. C. difficile, C. ramosum, and C. clostridioiforme may also be anaerobic and gram-positive, but they do not typically display double zone hemolysis.

An Anaerobic Culture Reveals Colonies with a Double Zone of Hemolysis