Overview
Macrococcus is a genus of bacteria recognized as a distinct group closely related to the staphylococci. Members are spherical (coccoid) cells that are generally larger than typical staphylococci and are most often isolated from the skin and mucous membranes of animals. For taxonomic summaries and authoritative listings see taxonomic resources.
Key characteristics
Typical laboratory and physiological features include:
- Gram-positive cell wall structure and spherical morphology (coccoid).
- Catalase-positive and oxidase-positive reactions, distinguishing them from many related genera.
- Non-motile and non–spore-forming; colonies are usually pale and relatively large.
Identification in the laboratory
Macrococcus isolates are detected using routine microbiological approaches: Gram stain, catalase and oxidase tests, and growth characteristics on common media. Modern identification often uses mass spectrometry (MALDI-TOF) or sequence-based methods for definitive species assignment. Practical protocols and diagnostic guidance are available from clinical and laboratory manuals (laboratory methods).
Habitat and ecology
These bacteria are primarily commensals of animals, especially on skin, hair and in the nasal cavity. They have been recovered from domestic mammals and occasionally from food-related environments. One well-known species is Macrococcus caseolyticus, which has been reported from animal-derived samples.
Clinical and applied importance
Macrococcus species are generally considered nonpathogenic in humans but can act as opportunistic agents in animals. They are of interest to veterinary microbiologists and public-health researchers because some isolates harbor antimicrobial-resistance determinants, making them relevant to surveillance of resistance in animal-associated bacteria (clinical relevance).
Taxonomic history and distinctions
The genus was established after genetic and phenotypic studies showed consistent differences from Staphylococcus. Key distinguishing features include larger cell size and the combination of catalase- and oxidase-positive reactions. For more on Gram staining and related classification criteria see reference material.