Meningitis
Introduction
Meningitis is inflammation of the meninges as well as the CSF in the subarachnoid space. Meningitis can be bacterial or viral. Bacterial meningitis is a serious cause of morbidity and mortality in all age groups. The likely causative bacteria varies depending on age
Neonates = Group B Strep, E. coli, Listeria, Coag Neg Staph
Children = H. influenza B, N. meningitidis, S. pneumo
Adults = Neisseria meningitis (young), S. pneumo, Listeria (> 50yrs, Alcoholic)
Viral meningitis is usually benign and self-limiting in adults. May need admission for work up and symptomatic management
Clinical Features
Symptoms
Pain
Headache (severe, unrelenting), neck pain, generalised myalgia, Photophobia
GI Symptoms
Nausea, vomiting
Neurological symptoms
New confusion, drowsiness.
Signs
Signs of Sepsis
Fever, Tachycardia, hypotension
Neurological signs
Decreased GCS, Seizures (15-30%), focal neurological signs, papilloedema
Meningism
Neck stiffness in sagittal plane
Kernig’s sign (cannot fully extend knee with hip flexion) + Brudzinski’s sign (flexing the neck causes thighs and knees to flex also)
Rash
Macular or non blanching petechial rash present in only 40%.
Seen in sepsis due to N. meningitidis or S. pneumo. Very sinister sign. Start antibiotics Immediately
Differential Diagnosis
Other Meningitis
Viral (HSV, EBV, Mumps, Coxsackie)
TB
Cryptococcus,
Other Sources of Sepsis
Respiratory
Renal
Intra-abdominal
Skin + Soft Tissue
Infective endocarditis
Other CNS Causes
Encephalitis
Brain abscess
SAH
Drug Overdose
Anticholinergics e.g. antipshychotics, TCAs, atropine
Sympathomimetic Syndrome e.g. cocaine, amphetamines
Seretonin Syndrome e.g. MDMA, SSRIs,
Neuroleptic Malignant Syndrome e.g. older antipsychotics
Clinical Investigations
Bedside
VBG
? high lactate, ? low pH in sepsis. ? Low BM accounting for GCS
Urinalysis
Seeking other causes for sepsis
Urine Toxicology screen
ECG
Laboratory
General Investigations
FBC, U&E, CRP, LFT, CoAg
Assist in building the overall clinical picture e.g. presence of end organ dysfxn
Blood Cultures
Take prior to Empiric antibiotics especially if LP is delayed
Lumbar Puncture – Antibiotics should not be delayed for LP
CT before LP if decreased GCS, focal neurological abnormality, seizure, concern for SOL
If evidence of high ICP on CT there is a risk of brain herniation during LP so it should be delayed
CSF in bacterial meningitis = High opening pressure, High protein, Low glucose, High WCC mostly polymorphs, +ve Gram Stain
CSF or Blood for viral and meningococcus PCR
CSF or urine for rapid antigen tests for Strep, Listeria
MSU - ? other cause of sepsis
Radiology
CT Brain occurs in most cases to out rule increased ICP/other causes of headache e.g. SOL, Haemorrhage etc
CXR – as part of work up
Management and Disposition
Infection Control
Patient should be managed in an isolation room with contact and droplet precautions and staff in full PPE
Initial Resuscitation
Assessment and concurrent management of Airway, Breathing and Circulation
Low GCS -> Pt may need airway management
High Flow O2
Fluid resuscitation as clinically indicated
Specific Treatment
Urgent early broad spectrum antibiotics as per local guidelines is the priority
e.g. Cefotaxime 2g Every 4 hours IV + Vancomycin 25mg/kg BD IV
May be role for steroids (IV Dexamethasone) if meningitis is strongly suspected.
Do NOT give if steroids if meningococcal septicaemia is suspected
If High risk for Listeria e.g. Age > 50yrs, Alcoholic add IV Amoxicillin to the above regimen
Symptomatic Treatment
IV Analgesia and IV Antiemetic as clinically indicated
IV Benzodiazepine if actively seizing
Disposition
All patients with suspected meningitis should be admitted to hospital under the medical team until diagnosis is ruled in or out. They will need an isolation room
Consider chemoprophylaxis for household contacts if ? bacterial meningitis (liaise with Micro/Public Health)
Bacterial meningitis is a notifiable disease to Public Health. They arrange contact tracing
References
1. Singer A, Carmeron P et al. Chapter 9.2 Meningitis from The Adult Textbook of Emergency Medicine 4th Edition
2. Dunn et al. Chapter 44: Headaches. The Emergency Medicine Manual. Vol 1. 5th Edition
3. SJH Prescriber capsule. Antimicrobial prescribing
This blog post was written by Dr. Deirdre Glynn and was last updated in October 2020