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Related Subjects: |Adrenal Physiology |Addisons Disease

In cases of suspected meningococcal meningitis/septicaemia antibiotics should be given immediately preferably before referral to hospital, and if in the hospital before lumbar puncture

About

• Acute bacterial meningitis has a mortality of 70-100% if untreated
• Treat on clinical suspicion alone with Cefotaxime or Ceftriaxone.
• Do not await test results. Always consider Listeria in older or pregnant patients.
• Delayed treatment increases mortality and morbidity
• Difficulty is those with an atypical presentation

Aetiology

• Bacterial infection in the subarachnoid space
• Pneumococcus/Meningococcus/HiB all capsulated
• Gives protection from neutrophil phagocytosis
• Colonise nasopharynx and secrete IgA protease
• Damages mucous lining and allows attachment and cell entry

Pathology

• Purulent exudate in the subarachnoid space
• Loss of cerebral autoregulation
• Localised Thrombophlebitis and vasogenic oedema
• Arterial/venous thrombosis and infarction
• Protein levels rise - affect CSF flow

Causes in the immunocompromised

• Defective polymorphs : Gram negative bacilli, candida, aspergillus
• Defective antibodies (Haem malignancies) : pneumococcus, haemophilus
• Defective Cell mediate immunity (AIDs/post transplant): Listeria, cryptococcus, nocardia, aspergillus, toxoplasma, CMV, TB, Varicella
• Asplenia/Sickle cell : pneumococcus, haemophilia

Causes: many adults with meningitis have no pathogen detected

Causes in those > 50

• Streptococcus pneumoniae
• Neisseria meningitidis
• Listeria monocytogenes
• Gram negative bacilli.

When to consider diagnosis of Meningitis

• If ANY of the following are present: Headache, Fever, Altered Consciousness, Neck Stiffness, Rash, Seizures, Shock

Clinical

• Recent chest infection, craniotomy, rhinorrhoea
• Petechiae (non-blanching) - hands and feet and conjunctiva
• Neck stiffness suggests meningeal irritation, resists passive neck flexion
• Kernig's sign; patient supine with the thigh flexed back to abdomen and knee flexed. Pain elicited on straightening the knee.
• Brudzinski's sign: supine and flexing neck causes flexion of hips and knees
• Signs may be muted in the young and elderly or immunocompromised
• Atypical - delirium, stroke-like, falls, unexplained fever
• Nausea, vomiting, photophobia, seizures
• With progression - VI nerve palsy, papilloedema, reduced level of consciousness, decerebrate posturing, falling heart rate, increasing BP.

Complications

• Seizures, Stroke from vessel arterial/venous thrombosis
• Hyponatraemia, Raised ICP, Hydrocephalus
• Cerebral abscess/empyema, Cerebral herniation

Investigations

• FBC, U&E, LFTS, CRP, Glucose
• CT scan if any suggestion of raised ICP or focal signs or reduced level of consciousness or papilloedema or immunocompromised or elderly or recent seizure
• Blood cultures should be taken immediately and antibiotics commenced. Family physicians may treat on suspicion prior to cultures being done. Take as soon as possible after.
• Nose and throat swab for meningococcal culture
• HIV should be included in the differential diagnosis of all cases of meningitis.
• CSF analysis is very useful for diagnosis confirmation and detecting an organism. Very high protein and low glucose are bad prognostic predictors. LP contraindicated if suspected coagulopathy. Send for
  • Glucose (with concurrent plasma glucose)
  • CSF protein
  • CSF lactate (if prior antibiotics have not been given)
  • Microscopy, culture and sensitivities
  • Meningococcal and Pneumococcal PCR
  • Enteroviral, Herpes Simplex and Varicella Zoster PCR
  • Consider investigations for TB meningitis
• Biopsy of petechial skin lesions can reveal organisms

Typical CSF Findings analysis

• CSF may look turbid
• Raised WCC(neutrophils , lymphocytes suggest Listeria or partially treated disease) > 1000/mm3
• Raised protein elevated (>0.45 g/litre)
• Low glucose usually reduced (<40% that of a parallel serum sample)
• Raised Opening CSF pressure.
• PCR and immune testing PCR for bacterial DNA, Latex agglutination to pneumococcus, meningococcus, influenzae, E.coli and Group B streptococci

Classical cerebrospinal fluid features for different causes of meningitis

Differential

• Viral meningitis, HSV encephalitis
• Rocky Mountain spotted fever in the USA
• SAH, Acute disseminated encephalomyelitis
• Cerebral abscess

Worrying signs: get Critical care help

• Rapidly progressing rash
• Poor peripheral perfusion capillary refill time >4 secs, oliguria or systolic BP <90mmHg
• Respiratory rate <8 or >30/min
• Pulse rate <40 or >140/min
• Acidosis pH<7.3 or Base excess worse than -5
• White blood cell count <4 x 10 9 /L
• Lactate >4 mmol/L
• Glasgow coma scale <12 or a drop of 2 points
• Poor response to initial fluid resuscitation

Reasons to Delay LP: If any of the following are present

• Signs of severe sepsis or rapidly evolving rash
• Infection at the site of needle
• Severe respiratory/cardiac compromise
• Significant bleeding risk
• Signs suggesting shift of brain compartments (CT scan before LP is warranted as long as patient is stable)
  • Focal neurological signs
  • Presence of papilloedema
  • Continuous or uncontrolled seizures
  • GCS < 12

Management

• Basic ABCs and resuscitation. IV access. Manage care in an HDU or ITU setting preferable admit patient inside room with appropriate droplet precautions
• Hypotension or severe sepsis: Fluid resuscitation with an initial bolus of 500ml of crystalloid given over 5-10 minutes as needed. Get critical care help.
• LP should be done within 1 hour if safe to do so. Reasons it might be unsafe are any signs of Space occupying lesion e.g. headache, fever, focal neurology and therefore needs CT. Avoid if suspected coagulopathy e.g. non-blanching rash.
• Antibiotics of choice PreHospital: If time before hospital admission, and there is non-blanching rash, give IV benzylpenicillin or cefotaxime, unless definite history of hypersensitivity. Ideally IV but IM if vein cannot be found. Benzylpenicillin (IV or IM) Age 10+ years: 1200 mg. Children 1 - 9 years: 600 mg. Children under 1 year: 300 mg or Cefotaxime (IV or IM) Age 12+ years: 1 gram Child under 12 years: 50mg/kg
• Antibiotics of choice In Hospital:
  • Ceftriaxone 2 g BD OR
  • Cefotaxime 2 g 6 hourly OR
  • Benzylpenicillin 2.4 g 4 hourly
  • If a true penicillin allergy then Chloramphenicol 25 mg/kg 6 hourly
  • Consider adding High dose IV Amoxicillin 2 g 4-6 hourly if Listeria possible (immunosuppression, alcohol, diabetics, pregnancy or age >50 years)
  • Consider adding IV Vancomycin 1g BD if Pseudomonas suspected
• Give Dexamethasone 0.15 mg/kg to (usually 10 mg IV stat and then QDS). This is then given for 4 days for suspected or confirmed bacterial meningitis
• Consider IV Aciclovir 10 mg/kg TDS initially if HSV Encephalitis still being considered in differential
• Treat with Rifampicin 600 mg BD PO for 2 days for the patient and contacts (see below). This helps get rid of nasopharyngeal carriage. It can however reduce the action of the OCP so alternative methods of contraception should be used. Their tears and urine may turn orange. Remove soft contact lenses which can become stained. Alternatives are Ciprofloxacin 500 mg single dose or Ceftriaxone 250 mg IM single dose.
• Inform the consultant in charge of communicable diseases notification by telephone of meningococcal disease confirmed.

Who needs Prophylaxis for Meningococcus

• People in same household or recently living there
• Sexual partners, those who share small office at work
• Those who do mouth to mouth resus on patient
• The patient when finished standard antibiotics
• School contacts if more than one case at school

References

• Acute Bacterial Meningitis Norfolk and Norwich