Meningococcus, scientifically known as Neisseria meningitidis
## Morphology and Structure
Meningococcus is a gram-negative diplococcus, meaning it appears as pairs of spherical bacteria when viewed under a microscope[1]. The bacteria range in diameter from 0.6 to 1.0 μm, with adjacent sides often flattened where the pairs meet[1].
## Growth and Culture
N. meningitidis is an aerobic or facultative anaerobic organism[2]. This means it can grow in the presence of oxygen, but can also survive in environments with little to no oxygen. The bacteria are human-specific pathogens, exclusively infecting and colonizing humans[2].
## Capsule and Serotypes
A key feature of meningococcus is its polysaccharide capsule. Based on the unique composition of this capsule, at least 12 different serotypes of N. meningitidis have been identified[2]. The most clinically relevant serotypes are A, B, C, W, X, and Y, which are responsible for the majority of meningococcal infections worldwide[2].
## Virulence Factors
N. meningitidis possesses several virulence factors that aid in its pathogenicity:
1. Capsule: Helps the bacteria evade the host immune system
2. Pili: Assist in attachment to host cells
3. Outer membrane proteins: Contribute to adhesion and invasion
## Colonization and Transmission
Meningococcus typically colonizes the human nasopharynx. Up to 10% of the general population may carry the bacteria in their nose and throat without experiencing symptoms[2]. The bacteria spread through close contact with respiratory and throat secretions of infected individuals[1][3].
## Pathogenesis
Once N. meningitidis invades the bloodstream, it can cause severe infections including meningitis (infection of the meninges) and septicemia (bloodstream infection)[1][3]. The bacteria can also infect other sites, leading to conditions such as pneumonia, septic arthritis, and pericarditis[2].
Understanding the microbiology of meningococcus is crucial for developing effective prevention strategies, such as vaccines, and for guiding appropriate treatment approaches.
Citations:
[1] https://www.britannica.com/science/meningococcus
[2] https://www.ncbi.nlm.nih.gov/books/NBK549849/
[3] https://www.cdc.gov/meningococcal/about/index.html
[4] https://my.clevelandclinic.org/health/diseases/22442-meningococcal-disease
[5] https://www.health.state.mn.us/diseases/meningococcal/meningococcal.html
[6] https://www.cdc.gov/meningococcal/index.html
[7] https://www.ecdc.europa.eu/en/meningococcal-disease/factsheet