Infectious Disease

Meningitis

Bacteria reaching the subarachnoid space provoke an inflammatory response that raises intracranial pressure and injures cranial nerves, while meningococcal bloodstream invasion adds purpura, coagulopathy and shock.

In a nutshell

Bacterial meningitis and meningococcal disease are time-critical infections suspected from fever, headache, neck stiffness and altered consciousness, or a non-blanching rash. Give intravenous ceftriaxone 2 g every 12 hours within 1 hour of arrival.

Classic presentation

A university student with fever, severe headache, photophobia, neck stiffness and drowsiness, with rapidly spreading non-blanching petechiae on the trunk and conjunctivae.

Key points

Listeria monocytogenes is intrinsically resistant to cephalosporins, so ceftriaxone alone leaves a gap in people over 60, in pregnancy and in immunosuppression.
Cerebrospinal fluid polymerase chain reaction (PCR) stays positive for meningococcus for up to 96 hours after antibiotics start.
Antibiotic durations if recovered: meningococcal 5 days, pneumococcal 10, Haemophilus influenzae type b 7, group B streptococcus 14, coliforms and Listeria 21.
Test every adult with bacterial meningitis or meningococcal disease for HIV. Recurrence also means checking complement, spleen function and for a cerebrospinal fluid leak.
Ceftriaxone is incompatible with calcium-containing infusions and must not share a line with them.
Offer audiology within 4 weeks of being well enough, preferably before discharge, and book adult hospital review at 4 to 6 weeks.
Babies up to 28 days corrected gestational age are managed under NICE's neonatal infection guideline, not this pathway.
Cerebrospinal fluid results (cell count, protein, glucose) should be available within 4 hours of the lumbar puncture.

First-line investigation

Lumbar puncture for cerebrospinal fluid cell count, protein, paired glucose ratio, Gram stain, culture and polymerase chain reaction (PCR), if safe and not delaying antibiotics.

Management

Recognise, transfer and treat within the hour

Treat as an emergency: transfer, alert the hospital that a senior decision maker is needed, run ABCDE (airway, breathing, circulation, disability, exposure). Do not wait for proof.^1,9
If transfer is significantly delayed, or meningococcal disease is strongly suspected, give one dose of ceftriaxone 2 g or benzylpenicillin 1.2 g intramuscularly or intravenously.^1,10,11,5
In hospital, take blood cultures then give intravenous ceftriaxone 2 g every 12 hours within 1 hour of arrival. Cefotaxime is the alternative if ceftriaxone is contraindicated.^1,10,12
Severe antibiotic allergy: get infection-specialist advice and consider chloramphenicol; add co-trimoxazole as well when Listeria risk factors are present.¹
Add intravenous amoxicillin 2 g every 4 hours if Listeria is plausible: age 60 or over, pregnancy, immunosuppression, diabetes or alcohol dependence.^1,6,8
Give intravenous dexamethasone 10 mg every 6 hours with or before the first antibiotic dose. Never delay antibiotics for it; if over 12 hours late, ask an infection specialist.^1,7

Get the cerebrospinal fluid without stopping the clock

Perform lumbar puncture before antibiotics only if safe and it will not delay them past 1 hour. Otherwise treat first and puncture as soon as it is safe.^1,4
Stabilise an unprotected airway, respiratory compromise, shock, uncontrolled seizures or bleeding risk first. Do not puncture with spreading purpura or infection at the puncture site.¹
CT first only for space-occupying-lesion risk, new focal signs including seizures or posturing, abnormal pupils, or GCS 9 or less. Take bloods and treat before imaging.^1,4
Send cell count and differential, protein, glucose with a paired blood glucose, Gram stain, culture and PCR. Also send a throat swab marked for meningococcal culture.¹

Read the cerebrospinal fluid

Normal adult fluid: under 5 white cells per microlitre, protein below 0.4 g/L, glucose 2.6 to 4.5 mmol/L, fluid to plasma glucose ratio above 0.66.⁸
Bacterial: turbid, typically over 100 white cells per microlitre, neutrophil predominant, raised protein, glucose ratio very low. A ratio below 0.36 is about 93% sensitive and specific.⁸
Viral: clear, 5 to 1000 white cells per microlitre, lymphocyte predominant, mildly raised protein, near-normal glucose. Tuberculous: lymphocytes, markedly raised protein, very low glucose.⁸
Add intravenous aciclovir 10 mg/kg every 8 hours for at least 14 days only if herpes simplex encephalitis is strongly suspected, not routinely.^1,13

Treat shock and organ dysfunction

Score with the National Early Warning Score 2 (NEWS2), the standard NHS bedside score; 7 or above is high risk of severe illness or death from sepsis.⁹
Give a 250 mL crystalloid bolus over 10 to 15 minutes, repeat in 250 mL steps up to 1000 mL, reassessing each time, then get senior review if not improving.⁹
Do not restrict maintenance fluid and do not use glycerol. Involve critical care for shock, falling GCS, seizures or airway compromise; osmotic agents only for suspected herniation.¹
Continue dexamethasone only for pneumococcus or Haemophilus influenzae type b. Do not give corticosteroids routinely in meningococcal disease.¹

Public health, hearing and recurrence

Notify the health protection team the same day. Adult close contacts get ciprofloxacin 500 mg orally as one dose, ideally within 24 hours of diagnosing the index case.^5,15,16
Rifampicin 600 mg twice daily for 2 days is the alternative if ciprofloxacin is unsuitable or the strain is likely ciprofloxacin resistant.^5,17
Close contact means household-type contact in the 7 days before onset. Classmates, colleagues, friends and fellow passengers do not qualify.^5,15
Before discharge, plan for hearing, neurological, cognitive, psychosocial, skin, orthopaedic and renal needs, test adults for HIV, and give written return advice if sent home undiagnosed.^1,4

Exam traps

No rash does not exclude meningococcal disease, and the tumbler test turns positive late. Look at the conjunctivae on brown, black or tanned skin.
A normal CT does not make lumbar puncture safe: NICE says do not puncture until the raised-pressure features themselves have resolved.
Dexamethasone works only if given with or before the first antibiotic dose. Do not hold antibiotics to find it, and do not give it routinely in meningococcal disease.
A normal CRP, procalcitonin or white cell count does not rule out bacterial meningitis.
Ceftriaxone monotherapy does not cover Listeria, so it is inadequate over 60, in pregnancy and in immunosuppression.
Prophylaxis is for household-type contacts in the 7 days before onset, not classmates, colleagues or fellow passengers.
Partially treated bacterial meningitis can give lymphocyte-predominant fluid that looks viral; so can Listeria.
Early symptoms can pass for flu, a stomach bug or a hangover, which is how young adults get sent home.

Illustrations

Non-blanching rashClinical photograph of a purpuric, non-blanching rash; in meningococcal septicaemia this does not blanch under a glass tumbler.Gley A.I. and Shkurba A.V., Wikimedia Commons · Public domain

Lumbar puncture techniqueDiagram of lumbar puncture needle placement into the subarachnoid space for cerebrospinal fluid sampling.PassFinals · original

CSF findings comparedTable diagram comparing cerebrospinal fluid appearance, cell count, protein and glucose in bacterial versus viral meningitis.PassFinals · original

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.