Pathogenesis

Pathogenesis

Colonies of a gram-positive pathogen of the oral cavity,Actinomyces sp.

In the classical sense, six gram-positive genera are typically pathogenic in humans. Two of these, Streptococcus andStaphylococcus, are cocci (sphere-shaped). The remaining organisms are bacilli (rod-shaped) and can be subdivided based on their ability to form spores. The non-spore formers are Corynebacterium and Listeria (a coccobacillus), whereasBacillus and Clostridium produce spores.^[16] The spore-forming bacteria can again be divided based on their respiration:Bacillus is a facultative anaerobe, while Clostridium is an obligate anaerobe.^[17] Also, Rathybacter, Leifsonia, andClavibacter are three gram-positive genera that cause plant disease.

Orthographic note

The adjectives 'gram-positive' and 'gram-negative' are named after Hans Christian Gram; as eponymous adjectives, they are conventionally written in lowercase.^[18][19][20]