Meningococcal Disease
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Direct answer
Meningococcal disease is an invasive infection caused by Neisseria meningitidis, a gram-negative encapsulated diplococcus, and it presents as meningitis, meningococcaemia or both. Its hallmark is a non-blanching petechial or purpuric rash, and close contacts in households, hostels and similar settings need chemoprophylaxis because secondary cases can occur among them.
What you must remember
- Organism: Neisseria meningitidis is a gram-negative encapsulated diplococcus, and serogroups A, B, C, W and Y cause most disease.
- Meningococcaemia: A non-blanching petechial or purpuric rash is the hallmark, and purpura fulminans is its severe form.
- Waterhouse-Friderichsen syndrome: Bilateral adrenal haemorrhage causes shock and acute adrenal insufficiency in fulminant septicaemia.
- Chemoprophylaxis: Close contacts receive rifampicin, ciprofloxacin or a single dose of ceftriaxone, chosen by age and pregnancy status.
- Vaccines: MenACWY covers serogroups A, C, W and Y, while MenB is needed for serogroup B.
- Complement deficiency: Defects in terminal complement components C5 to C9 predispose to recurrent meningococcal infection.
- Empirical treatment: A third-generation cephalosporin such as ceftriaxone is the usual empirical choice.
- Travel link: Pilgrims travelling for Hajj require meningococcal vaccination, which is a common examination link to Indian practice.
Managing suspected meningococcal disease
A 19-year-old college student presents with fever, vomiting and a non-blanching purpuric rash on the legs. The key decision is to treat as meningococcal sepsis before any laboratory result is available.
- Recognise the rash: A non-blanching petechial or purpuric rash suggests meningococcaemia, and the glass tumbler test confirms that the lesions do not fade under pressure.
- Start antibiotics: Give an empirical third-generation cephalosporin such as ceftriaxone immediately, without waiting for lumbar puncture or culture results.
- Consider steroids: Give dexamethasone with the first antibiotic dose in suspected bacterial meningitis according to current guidance, since its benefit is best established in pneumococcal disease.
- Support circulation: Give fluid resuscitation and vasoactive support as needed, because septic shock and adrenal haemorrhage can coexist.
- Confirm the diagnosis: Take blood cultures and CSF for Gram stain, culture and PCR, and send any isolate for serogroup typing.
- Protect contacts: Start chemoprophylaxis for close contacts as early as possible after the index case is identified.
Where the exam tries to catch you
Most traps involve the order of treatment, the choice of contact prophylaxis and the recognition of severe forms.
- Trap: Delaying antibiotics for lumbar puncture. Correct: Antibiotics start immediately, because a delay for lumbar puncture can cost a life in fulminant disease.
- Trap: Using ciprofloxacin prophylaxis in a pregnant contact. Correct: Fluoroquinolones are avoided in pregnancy, and rifampicin is also not recommended, so a single dose of ceftriaxone is preferred.
- Trap: Treating adrenal crisis in meningococcal shock as septic shock alone. Correct: Waterhouse-Friderichsen syndrome needs corticosteroid cover alongside fluids and vasoactive support.
- Trap: Ignoring a petechial rash because the patient looks only mildly unwell. Correct: A non-blanching rash is an emergency sign, and it can precede rapid deterioration.
Frequently asked questions
Which antibiotic is used for chemoprophylaxis of meningococcal contacts?
Rifampicin is the classic chemoprophylaxis for close contacts of meningococcal disease, with ciprofloxacin and a single dose of ceftriaxone used in selected groups. The choice depends on the contact's age, pregnancy status and any drug allergy.
What is Waterhouse-Friderichsen syndrome?
Waterhouse-Friderichsen syndrome is acute bilateral adrenal haemorrhage in fulminant meningococcal septicaemia, causing shock and adrenal insufficiency. It is a medical emergency that needs prompt fluid resuscitation and corticosteroid support.
Which serogroups does the MenACWY vaccine cover?
The MenACWY vaccine covers serogroups A, C, W and Y of Neisseria meningitidis, but it does not cover serogroup B. Serogroup B needs its own vaccine, because its capsule is poorly immunogenic with conventional polysaccharide-based vaccines.
Why does purpura fulminans occur in meningococcaemia?
Purpura fulminans results from widespread microvascular thrombosis and consumption of clotting factors during meningococcal sepsis. It causes skin necrosis, and early antibiotics with supportive care are vital to prevent further damage.
Which complement deficiency predisposes to recurrent meningococcal infection?
Deficiency of the terminal complement components C5 to C9 predisposes to recurrent meningococcal infection, because the membrane attack complex cannot kill the bacterium effectively. Such patients are usually considered for vaccination and prophylaxis.