Bacterial meningitis

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Contents

Introduction

Meningitis means inflammation of the meninges – the membranes covering the brain and spinal cord. Bacterial Meningitis is the most serious form of meningitis and can be rapidly fatal unless treated.

General Symptoms and signs

Inflammation of the meninges explains the classic symptoms of meningitis, which include:

  • Headache
  • Neck stiffness
  • Pain on stretching the sciatic nerve
  • Dislike of bright lights (photophobia)
  • Irritability

These signs are rarely found in children and can be vague in the elderly. The difficulty is that in the early stages, the illness appears much the same as a simple benign "flu like" illness. The diagnosis can be difficult and doctors who have missed it in their own children. Meningitis can be caused by a variety of organisms, including bacteria and viruses.

The most common bacterial causes are:

In Neonates meningitis can be due to other organisms. Other rarer causes include

Meningococcal Meningitis

Meningitis and Meningococcal disease remain relatively uncommon: a GP is unlikely to see a case more often than once every few years, and may never see one. The onset of illness is usually abrupt and in addition to the symptoms described above patients may present with more vague symptoms such as:[1]

  • Fever
  • Malaise
  • Unexplained vomiting
  • Back or joint pains
  • Headache
  • Confusion
  • Rash
  • Cold mottled peripheries

The early signs and symptoms of meningococcal disease are non-specific, and similar to those that arise in pyrexia of any origin. Meningism (a syndrome which may include headache, photophobia, neck stiffness, sciatic nerve irritability) only occurs in meningitis (not in septicaemia), and is, in any case, uncommon in younger children.

It is vital for patients – and especially their carers – to be alert for the deterioration that may occur rapidly in a patient thought to have only a relatively minor illness because:

i)the disease is uncommon but serious;
ii)the early signs and symptoms are common but non-specific; and
iii)deterioration may be rapid.

In cases of flu-like illness, patients and their carers should always be advised of the possibility of more serious disease, and of what action to take if they suspect meningococcal disease. GPs might like to consider leaving information, such as a credit-card sized list of the signs and symptoms of meningitis and septicaemia from one of the meningitis charities.

In meningococcal septicaemia, circulatory failure is an important – and may be a relatively early - sign, so it is important to measure pulse and blood pressure, especially in children.

Please take particular note that the commonly expressed view that the rash is of the sort that does not fade on pressure may be misleading. In 60% of cases, the initial rash is of a maculopapular nature, and it resembles a measles rash. (Measles is now an extremely rare disease). A skin rash that does not fade under pressure (i.e., a petechial or haemorrhagic rash) does occur in meningococcal infection - however it is a feature that reflects advancing illness, and is due to bacterial disruption of small blood vessels and subsequent leakage of blood into the subcutaneous tissues.

Chemoprophylaxis of contacts may be required.

Pneumococcal Meningitis

Tends to be found in older patients. Associated with spread from the middle ear or sinuses through fractures. It is seen in the extremes of age, in the elderly and babies. Splenectomy is a risk factor. The typical symptoms of Meningitis become present but can easily be missed in the elderly as a confused patient unless a lumbar puncture is done and the presence of CSF full of polymorphs, with low sugar and gram positive diplococci is found.

Treatment is with benzylpenicillin, cefotazime or chloramphenicol.

Late sequaelae include cranial nerve palsies and mortlaity is 10-20%

Chemoprophylaxis of contacts is NOT required.

Haemophilus Meningitis

Caused by Haemophilus Influenzae, and mostly seen in children under 5. Gram Negative bacillus. Treat with cefotaxime or chloramphenicol. Chemoprophylaxis may be required.

Emergency action for suspected cases of Bacterial meningitis

  • Rapid admission to hospital is a priority when meningococcal disease or indeed any form of bacterial meningitis is suspected
  • All general practitioners should carry benzylpenicillin and give it while arranging the transfer of the case to hospital; admitting hospital doctors should ask if this has been done. The only contraindication is a history of penicillin anaphylaxis. In these instances chloramphenicol (if available) may be given by injection (1.2g for adults, 25mg/kg for children under 12 years), but urgent transfer to hospital is the most important measure.
  • Immediate dose of benzylpenicillin for suspected meningococcal infections:
  • Adults and children aged 10 years or over: 1200mg
  • Children aged 1 to 9 years: 600mg
  • Children aged under 1 year: 300mg
  • This dose should be given as soon as possible, ideally by intravenous injection. Intramuscular injection is likely to be less effective in shocked patients due to reduced tissue perfusion, but should be used if a vein cannot be found. On arrival in hospital of a suspected case, doctors should take blood for culture and give benzylpenicillin (or a suitable alternative) immediately if this has not already been done.

There is no evidence to support the use of corticosteroids before admission or in tuberculosis meningitis. After admission is slightly more complex with:

  • In children in industralised society beneficial[2]
  • In children in non-industralised society likely to be ineffective or harmful[3]
  • In adults in industralised society with:
    • Gram negative/meningococcal meningitis likely to be ineffective or harmful
    • Pneumococcal meningitis beneficial
    • Haemophilus meningitis beneficial[4][5].
  • In non-industrial society adults unlikely to be benefical although some evidence for benefit limited to those with definitive bacterial meningitis (proven)

Anaphylaxis following injection of penicillin is rare (0.002% of exposed patients). Cross reactivity between penicillin and cephalosporin allergy occurs in between 2% and 10% of cases

Investigations

All cases of suspected meningitis must be assessed and managed without delay. Acute (taken a.s.a.p. after admission)

  • Blood for culture
  • EDTA or citrated blood for PCR (0.5 - 2 ml)
  • CSF for culture, PCR and microscopy (whenever available)†
  • Clotted blood specimen or serum, for acute serology (0.5 - 2 ml)
  • Oro- or nasopharyngeal (ideally post-nasal or per-nasal), swab for culture.
  • Rash aspirate for microscopy and culture (if this investigation identified as useful locally).

Convalescent (10 to 28 days)*

  • Clotted blood for serology (0.5 - 2 ml)
  • EDTA blood if not already obtained

Optional Taking throat swabs from family members before prophylaxis may help to identify the causative organism, especially when the case is under 5 years of age. Counselling is advised before swabbing to forestall feelings of guilt by explaining that the intention is to identify the strain causing illness in the case since other family members may have picked it up.

Clinical Sequelae

For those who survive the initial illness long term damage may persist. Hearing impairment is relatively common, so audiological follow-up of all cases of meningitis is recommended. Typical after effects in young children are those that may arise after a young child has been admitted to hospital for any illness. They include:

  • Babyish behaviour, being extra clingy
  • Temper tantrums
  • Forgetting skills they have recently learned
  • Bed-wetting
  • Disturbed sleep, nightmares.

Typical after effects in children and adults include:

  • Tiredness
  • Headaches
  • Difficulty concentrating
  • Short-term memory loss
  • Clumsiness and/¬or giddiness or balance problems
  • Depression, temper tantrums, aggression, or mood swings
  • Learning difficulties and falling behind in some areas of school work
  • Deafness and/¬or tinnitus (ringing in the ears)
  • Sore or stiff joints
  • Eyesight problems
  • Brain damage, possibly causing epilepsy

Survivors of meningococcal septicaemia commonly make a complete recovery. In some, however, the clotting disorders caused by the disease may cause gangrene. Sufferers may have to have skin grafts, or even have limbs, fingers, or toes amputated.

Case definitions

LogoWarningBox4.pngNotification. Meningitis, and meningococcal disease without meningitis, are notifiable diseases. ALL cases (meningococcal disease or meningitis of any aetiology) should be notified ON SUSPICION, not just confirmed or probable cases.

The public health action required depends on the case definition (possible, probable, or confirmed); regardless of whether a case is an isolated case or part of a cluster.

Meningitis Prevention

Meningitis prevention

External links

References