Neisseria meningitidis, also simply known as meningococcus is a gram-negative bacterium best known for its role in meningitis. It only infects humans, there is no animal reservoir. It is the only form of bacterial meningitis to cause epidemics. Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Orders Alpha Proteobacteria    Caulobacterales - e. ... Genera Alysiella Aquaspirillum Catenococcus Chromobacterium Eikenella Formivibrio Iodobacter Kingella Microvirgula Neisseria Prolinoborus Simonsiella Vitreoscilla Vogesella The Neisseriaceae are a family of gram-negative, parasitic Proteobacteria, given their own order. ... Genera Alysiella Aquaspirillum Catenococcus Chromobacterium Eikenella Formivibrio Iodobacter Kingella Microvirgula Neisseria Prolinoborus Simonsiella Vitreoscilla Vogesella The Neisseriaceae are a family of gram-negative, parasitic Proteobacteria, given their own order. ... Neisseria is a genus of bacteria, included among the proteobacteria, a large group of gram-negative forms. ... In biology, binomial nomenclature is a standard convention used for naming species. ... Bacteria that are Gram-negative are not stained dark blue or violet by Gram staining, in contrast to Gram-positive bacteria. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Inferior view of a brain with meningitis caused by Haemophilus influenzae. ... An epidemic is a disease that appears as new cases in the population in a period of time at a rate (the number of new cases in the population during a specified period of time is called the incidence rate) that substantially exceeds what is expected, based on recent experence. ...

Clinical Presentations

Meningitis is the most well publicised condition. Whilst a non-specific illness initially, this can rapidly progress through fever, headache and neck stiffness to coma and death. The mortality is approximate 10% of cases. Suspicion of meningitis is a medical emergency and immediate medical assessment is recommended. Inferior view of a brain with meningitis caused by Haemophilus influenzae. ... Meningism is the triad of nuchal rigidity, photophobia (intolerance of bright light) and headache. ... In medicine, a coma (from the Greek koma, meaning deep sleep) is a profound state of unconsciousness, which may result from a variety of conditions including intoxication (drug, alcohol or toxins), metabolic abnormalities (hypoglycemia, hyperglycemia, ketoacidosis, etc. ... A medical emergency is an injury or illness that poses an immediate threat to a persons health or life which requires help from a doctor or hospital. ...

Septicaemia ("blood poisoning") has received much less public attention, but has been linked to infant deaths. Whilst there may be an absence of the classical meningitis symptoms, the presence of a non-blanchable purpuric rash is easily ignored by those not aware of its significance. Septicaemia carries an approximate 50% mortality rate over a few hours from initial onset. Anyone developing a rash that does not turn white ("non-blanching") if pressed with a glass in encouraged to attend a hospital casualty department as soon as possible. Sepsis (in Greek Σήψις) is a serious medical condition caused by a severe systemic infection leading to a systemic inflammatory response. ... Purpura is the appearance of purple discolorations on the skin caused by bleeding underneath the skin. ...

Waterhouse-Friderichsen syndrome a massive, usually bilateral, hemorrhage into the adrenal glands caused by fulminant infection. Waterhouse-Friderichsen syndrome is massive, usually bilateral, hemorrhage into the adrenal glands caused by fulminant meningococcemia. ...

UK policy is that any General Practitioner doctor seeing a suspected case of meningococcus meningitis or septicaemia should give intravenous antibiotics (benzylpenicillin) whilst hospital admission is sought. The possible reduction in subsequent microbiological confirmation of infection, due to starting treatment before testing, is offset by the reduced mortality. A general practitioner (GP) or family physician (FP) is a physician/doctor who provides primary care. ... Penicillin is a β-lactam antibiotic used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms. ...

Not all cases of a purpura-like rash are due to septicaemia, but the other causes also need prompt investigation (eg ITP, a platelet disorder). Purple discolorations on the skin caused by bleeding underneath the skin. ... Idiopathic thrombocytopenic purpura is the condition of having a low platelet count (thrombocytopenia) of no known cause (idiopathic). ... A 250 ml bag of newly collected platelets. ...

Strains

There are many strains of meningococcus, clinically the most important are A, B, C and W135:

• A - occurs most often in sub-sahara Africa and vaccination is recommended prior to travel with the Men A&C vaccine.
• B - is the most lethal form, comprising 40% of UK cases. The changing nature of the B group has prevented formation of a general B vaccine in the UK. However there has been developed the vaccine MeNZB against a specific strain of group B meningococcus, currently being trialled in New Zealand.
• C - caused approximately 60% of UK cases before the introduction of successful vaccination programme for infants. Previously the unconguted C component of Men A&C was ineffective in those under 2 years. The development of a conjugated form (Men C conj) was needed to provoke infant immunity.
• W135 - is particularly a problem for those undergoing annual pilgrimage to Mecca. It is a requirement of Saudi Arabia that all those intending to go on Hajj have a certificate of Men W135 vaccination.

Those with impaired immunity may be at particular risk of meningococcus, e.g. those with nephrotic syndrome or splenectomy. In asplenia (removed or non-functioning spleen), vaccination is performed according to protocols. Vaccination is a term coined by Edward Jenner for the process of administering a weakened form of a disease to patients as a means of giving them immunity to a more serious form of the disease. ... MeNZB is a vaccine against meningococcal B meningitis, currently being trialed in high-risk areas in New Zealand. ... This article is about the holy city in Saudi Arabia. ... The Hajj or Haj (Arabic حَجّ Ḥaǧǧ) is the Pilgrimage to Mecca (or, Makkah) and is the fifth of the Five Pillars of Islam in Sunni Islam and is one of the Furū al-Dīn in Shia Islam. ... The procedure of splenectomy involves removal of the spleen by operative means. ... Asplenia refers to the absence (a-) of normal spleen function and is associated with some risks. ...

See also

• Meningitis