QuestionSBA
QuestionChoice
Streptococcus pneumonia and Neisseria meningitidis are the two most common causes of meningitis in children and adults. They are both bacterial infections, so will typically show on CSF a cloudy appearance; elevated protein; low glucose; white cell count above 200 cells/mL mostly made up of neutrophils; and an elevated opening pressure. They will lead to a negative India ink stain
32857
e
Streptococcus Pneumonia
QuestionChoice
CSF examination in Mycobacterium Tuberculosis will most likely have a cloudy appearance; elevated protein; low glucose; white cell count of roughly 20 cells/ mL; and an elevated opening pressure. However, it will lead to a negative India ink stain
32855
c
Mycobacterium Tuberculosis
QuestionChoice
Viral meningitis tends to be milder clinically. On CSF examination, a viral infection typically produces CSF with a clear appearance; normal or mildly elevated protein; normal glucose; a raised white cell count up to 200 cells/mL with predominantly lymphocytes; and a slightly elevated opening pressure. Viral meningitis will lead to a negative India ink stain
32854
b
Herpes simplex virus
QuestionChoice
Neisseria meningitidis and streptococcus pneumonia are the two most common causes of meningitis in children and adults. They are both bacterial infections, so will typically show a cloudy CSF appearance, with elevated protein, low glucose, a white cell count above 200 cells/mL mostly made up of neutrophils, and an elevated opening pressure. They will lead to a negative India ink stain
32856
d
Neisseria Meningitidis
QuestionChoice
This is a typical fungal meningitis. Fungal meningitis is most common in immunosuppressed patients, particularly patients who are HIV positive. India ink staining is used to detect cryptococcal fungi, which are most associated with HIV patients
32853
a
Cryptococcus
Concept
Chapter
# Summary
 
Meningitis refers to inflammation of the meninges which line the brain and spinal cord. The most common cause is infection, with bacterial meningitis being an important emergency presentation that may be life-threatening. The commonest causative bacteria are Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenza type b. Key investigations include a throat swab for meningococcal culture, blood testing including PCR for meningococcal and pneumococcal bacteria and a lumbar puncture. Management is with IV antibiotics, with ceftriaxone the recommended first line option until the cause is identified. 
 
# Definition
 
Meningitis occurs when there is inflammation of the pia mater and arachnoid mater, the two innermost linings of the brain and spinal cord. This can occur for a variety of causes, including malignancy, autoimmune disorders and medications as well as infection. This chapter will focus on bacterial meningitis as the key emergency presentation, however other infections can cause meningitis including viral and fungal causes. 
 
# Epidemiology
 
Risk factors for bacterial meningitis include:

- Young age (especially under 2 year olds)
- Older age (over 65 year olds)
- Winter season
- Immunocompromise e.g. HIV, chemotherapy
- Incomplete immunisations against meningococcal, haemophilus influenza b and pneumococcal bacteria
- Comorbidities e.g. splenic dysfunction, renal disease, sickle cell disease
- Overcrowding or close living with other e.g. dormitories
- Cochlear implants
- Local infection e.g. otitis media, sinusitis
 
# Aetiology

The commonest causative bacteria are:

- Streptococcus pneumoniae (pneumococcus) - the commonest cause in adults
- Neisseria meningitidis (meningococcus)
- Haemophilus influenza type b (Hib)

Other causes include Listeria monocytogenes, Escherichia coli and Streptococcus agalactiae.

# Signs and Symptoms

- Headache
- Photophobia
- Neck stiffness
- Fever
- Confusion or altered level of consciousness
- Seizures
- Nausea and vomiting
- Kernig's sign (unable to fully extend the knee when the hip is flexed to 90 degrees due to pain)
- Brudzinski's sign (when the neck is actively flexed, the knees and hips spontaneously flex)

Signs of systemic infection or sepsis may be present e.g. tachypnoea, tachycardia and hypotension. 

Presence of a non-blanching rash is suggestive of meningococcal disease.

# Differential Diagnosis

CSF interpretation can be used to differentiate bacterial from other causes of meningitis, for example viral, fungal or tuberculous: 

|         | **Bacterial meningitis**           | **Viral meningitis**                   | **Fungal meningitis**                    | **Tuberculous meningitis**               |
|-----------------------|-----------------------------------------|----------------------------------------|------------------------------------------|------------------------------------------|
| **Opening pressure**  | Elevated                                | Normal or mildly elevated              | Elevated                                 | Elevated                                 |
| **Appearance**        | Turbid                        | Clear                                  | Fibrin web                 | Cloudy                 |
| **White cells**         | Elevated neutrophils | Elevated lymphocytes| Elevated lymphocytes | Elevated lymphocytes|
| **Protein**           | Elevated                | Normal or mildly elevated | Elevated                  | Elevated                |
| **Glucose**           | Decreased                | Normal                 | Decreased                   | Decreased                  |
| **Additional tests**  | Gram stain and culture                                          |     PCR for viral DNA/RNA                                   | Fungal staining, antigen tests or culture         | Acid-fast bacilli staining, TB PCR   |

**Other differential diagnoses include:**

- **Drug-induced meningitis** with causes including NSAIDs, co-trimoxazole and amoxicillin)
- **Encephalitis** which shares features of fevers, headache and altered mental status however other neurological findings are present (e.g. dysphasia, motor abnormalities)
- **Subarachnoid haemorrhage** which also causes meningism and altered mental status, however headache is usually "thunderclap" in nature followed by progressive worsening of other symptoms

# Investigations 
 
**Bedside tests:**

- **Lumbar puncture** is the key diagnostic test that should ideally be done before starting antibiotics (or as soon as possible after) - cerebrospinal fluid (CSF) should be sent for:
    - Cell count
    - Total protein
    - Glucose
    - Microscopy, culture and sensitivities
    - Bacterial PCR
- **Throat swab** for meningococcal culture to identify meningococcal meningitis
- **Capillary blood glucose** immediately before lumbar puncture to compare with CSF glucose levels

**Blood tests:**

- **Blood cultures** to identify a causative bacteria
- **FBC** and **CRP** for inflammatory markers which should be raised
- **HIV test** for all adults with bacterial meningitis
- **Meningococcal and pneumococcal PCR** to identify the cause of meningitis
- **U&Es**, **LFTs** and **coagulation screen** as a baseline, may be deranged due to infection

**Imaging:**

- **CT head** should be done prior to lumbar puncture in patients who have any of:
    - Risk factors for a space-occupying lesion
    - New focal neurological signs
    - Abnormal pupillary reactions
    - GCS < 10 or rapid decline in consciousness
 
# Management

- If there is a strong suspicion of bacterial meningitis, treatment may be started outside of hospital with IM or IV ceftriaxone or benzylpenicillin
- Otherwise, antibiotics should be started within an hour of arrival in A&E
- Ideally, a lumbar puncture and blood tests would be done prior to antibiotic administration however these should not delay treatment
- IV ceftriaxone is first-line; amoxicillin should be given too in patients with risk factors for Listeria meningitis (e.g. neonates, elderly or immunocompromised patients)
- Chloramphenicol is second line in patients with severe penicillin allergy
- IV dexamethasone should be given to all over the age of 3 months with strongly suspected or confirmed bacterial meningitis - this is particularly important in pneumococcal meningitis to reduce neurological complications
- Bacterial meningitis is a notifiable disease; ensure the local health protection unit is informed and antibiotic prophylaxis or vaccination may be required for close contacts
 
# Complications

- Hearing loss
- Seizures
- Cerebral infarction leading to focal neurological deficits including motor deficits and visual impairment
- Cognitive impairment
- Obstructive hydrocephalus
- Death (bacterial meningitis has a mortality rate of 25% in adults) 

# NICE Guidelines

[NICE - Meningitis (bacterial) and meningococcal disease](https://www.nice.org.uk/guidance/ng240/)

[NICE CKS - Meningitis](https://cks.nice.org.uk/topics/meningitis-bacterial-meningitis-meningococcal-disease)

# References
 
[UK joint specialist societies guideline on the diagnosis and management of acute meningitis](https://www.journalofinfection.com/article/S0163-4453(16)00024-4/fulltext)

[Public Health England - Guidance for public health management of meningococcal disease](https://assets.publishing.service.gov.uk/media/5d6fa400e5274a0989ca9aed/PHE_meningo_disease_guideline.pdf)
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6227
Meningitis
Topic
39
Emergency Medicine
6571
Cryptococcal meningitis commonly occurs in immunocompromised individuals, particularly those with HIV, presenting with elevated protein and low glucose in CSF.
A 35-year-old male is brought to A&E by his girlfriend. He has been complaining of a progressive, severe headache for the last two hours. He has become increasingly violent in the waiting area. He has a past medical history of HIV and intravenous drug use (IVDU). On examination, he has neck stiffness and reduced visual acuity. A lumbar puncture is done urgently due to suspected meningitis.

Cerebrospinal fluid (CSF) results:

- Appearance - Cloudy
- Protein - Elevated
- Glucose - Low
- White Cell Count - 25 cells/mL
- Opening pressure - Very high
- India ink stain - Positive

What is the likely cause of these symptoms?
a