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Meningococcus

Last edited 4 Apr 2024

Meningococcal disease occurs as a result of infection with the bacterium Neisseria meningitides (1). The meningococcus is:

a gram negative coccus
globally endemic with periodic epidemics
the most common cause of pyogenic meningitis in the UK
predominantly a pathogen of children and young adults
most often seen in crowded communities such as army barracks

During epidemics close contacts of infected cases should be offered chemoprophylaxis.

Meningococci are divided into antigenically distinct groups according to the chemical composition of the polysaccharide capsule of the bacteria (2).

there are at least 13 serogroups, of which group B and C are the most common in the UK
but with the introduction of the Men C vaccine, serogroup C disease has reduced substantially with just 10 cases reported in the year 2009 (2)
other less common serogroups include A, Y, W135, 29E and Z.

Meningococcal bacteria colonise the nasopharynx of humans and are frequently harmless commensals

between 5% and 11% of adults and up to 25% of adolescents carry the bacteria without any signs or symptoms of the disease
- invasive disease does not develop in established meningococcal carriers (3)
transmission is by aerosol, droplets or direct contact with respiratory secretions of someone carrying the organism. Transmission usually requires either frequent or prolonged close contact
there is a marked seasonal variation in meningococcal disease, with peak levels in the winter months declining to low levels by late summer
incidence of meningococcal disease is highest in children aged one to five years followed by infants under one year of age
- next highest risk group is young people aged 15 to 19 years.

Immunisation is available against strains A and C of this bacteria, however strain B is the most often implicated in meningococcal meningitis.

Meningococcal infection may present as

meningitis - 15% of cases
septicaemia - 25% of cases
a combination of both meningitis and septicaemia - 60% of cases
less commonly, individuals may present with pneumonia, myocarditis, endocarditis, pericarditis, arthritis, conjunctivitis, urethritis, pharyngitis, and cervicitis (1)

Strongly suspect meningococcal disease in people with any of these red flag symptoms (4):

haemorrhagic, non-blanching rash with lesions larger than 2 mm (purpura)
rapidly progressive and/or spreading non-blanching petechial or purpuric rash
any symptoms and signs of bacterial meningitis, when combined with a non-blanching petechial or purpuric rash

do not rule out meningococcal disease just because a person does not have a rash

When looking for a rash:

check all over the body (including nappy areas), and check for petechiae in the conjunctivae
note that rashes can be hard to detect on brown, black or tanned skin (look for petechiae in the conjunctiva)
tell the person and their family members or carers to look out for any changes in the rash, because it can change from blanching to non-blanching

Be on heightened alert to the possibility of meningococcal disease in people with any of these risk factors:

missed meningococcal vaccinations
reduced or absent spleen function
complement deficiency or inhibition
they are a student in further or higher education, particularly if they are in large shared accommodation (such as halls of residence)
a family history of meningococcal disease
they have been in contact with someone with meningococcal disease, or have been in an area with an outbreak
a previous episode of meningococcal disease

The risk factor for recurrent meningococcal disease is primary or secondary immunodeficiency, including:

HIV
congenital complement deficiency or acquired inhibition
reduced or absent spleen function

If you suspect or strongly suspect meningococcal disease, transfer the person to hospital as an emergency (4)

For people with strongly suspected meningococcal disease, give intravenous or intramuscular ceftriaxone or benzylpenicillin as soon as possible outside of hospital, unless this will delay transfer to hospital (4)

For further details see NICE (March 2024). Meningitis (bacterial) and meningococcal disease: recognition, diagnosis and management

Click here for an example image of meningoccal septicaemia

Reference:

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Meningococcus

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