Which biochemical description best matches Clostridium tetani?

Which biochemical description best matches Clostridium tetani?

• A. It is nonmotile
• B. It produces gelatinase and indole positive but is nonproteolytic and H2S negative
• C. It is proteolytic
• D. It utilizes carbohydrates

Answer: (B)

Biochemical testing helps distinguish Clostridium species by what enzymes they produce and what substrates they can break down. Gelatinase production means the organism can hydrolyze gelatin, a specific proteolytic activity. Indole positivity shows it has tryptophanase and can convert tryptophan to indole. Hydrogen sulfide (H2S) negativity indicates it does not produce H2S in the test medium. The note of being nonproteolytic generally means it doesn’t degrade proteins like casein in milk agar, so most protein substrates aren’t broken down, while gelatinase is a more targeted proteolytic activity. This particular combination—gelatinase production with indole positivity, plus overall nonproteolytic behavior and lack of H2S production—matches the biochemical pattern used to identify Clostridium tetani in many lab keys, more so than descriptions implying other metabolic traits.

Biochemical testing helps distinguish Clostridium species by what enzymes they produce and what substrates they can break down. Gelatinase production means the organism can hydrolyze gelatin, a specific proteolytic activity. Indole positivity shows it has tryptophanase and can convert tryptophan to indole. Hydrogen sulfide (H2S) negativity indicates it does not produce H2S in the test medium. The note of being nonproteolytic generally means it doesn’t degrade proteins like casein in milk agar, so most protein substrates aren’t broken down, while gelatinase is a more targeted proteolytic activity. This particular combination—gelatinase production with indole positivity, plus overall nonproteolytic behavior and lack of H2S production—matches the biochemical pattern used to identify Clostridium tetani in many lab keys, more so than descriptions implying other metabolic traits.