What test differentiates Cardiobacterium hominis from Actinobacillus spp.?

The indole test is pivotal in differentiating Cardiobacterium hominis from Actinobacillus species. Cardiobacterium hominis is known to produce indole, while most Actinobacillus species do not. This biochemical test helps in identifying whether or not the organism can convert tryptophan into indole, allowing microbiologists to distinguish between these two genera effectively.

While anaerobic incubation can be relevant for other aspects of microbial growth, and Gram staining provides information on cellular characteristics, it does not offer the specific biochemical insight needed to differentiate these two genera. The oxidase test is useful for identifying certain bacteria based on their respiratory capabilities, but it does not specifically distinguish between Cardiobacterium hominis and Actinobacillus species. Thus, the indole test serves as a key differentiator in this context.