Course:PostgradFamilyPractice/ExamPrep/99 Priority Topics/Meningitis
Meningitis - Key Features
1. In the patient with a non-specific febrile illness, look for meningitis, especially in patients at higher risk (e.g., immuno- compromised individuals, alcoholism, recent neurosurgery, head injury, recent abdominal surgery, neonates, aboriginal groups, students living in residence).
2. When meningitis is suspected ensure a timely lumbar puncture.
3. In the differentiation between viral and bacterial meningitis, adjust the interpretation of the data in light of recent antibiotic use.
4. For suspected bacterial meningitis, initiate urgent empiric IV antibiotic therapy (i.e., even before investigations are complete).
5. Contact public health to ensure appropriate prophylaxis for family, friends and other contacts of each person with meningitis.
Risk factors
- - Extremes of age, specifically neonates & elderly
- - “close contacts” => those living in dormitorities
- - Immunocompromised => alcoholics, HIV, diabetics, hepatic / renal dysfunction
- - Any exposure of meninges to “outside world” => neurosurgery, CSF shunts, basal skull fractures, penetrating head trauma
Pathogenic Causes
- - Aseptic
- o Viral: Enterovirus, HSV, Varicella, HIV
- o Others: syphilis (Treponema pallidum), M. pneumonia, Rocky mountain spotted fever
- - Bacterial
- o Infants: Gp B Strep, E Coli, Listeria
- o Children / Adults: H Influenzae, N meningitidis, S penumoniae
- o Elderly / immunocompromised / alcoholics: Same as above in adults + aerobic Gm neg bacilli
- o Penetrating trauma, post neurosurgery, CSF shunts: S aureus, coagulase neg staph, aerobic Gm neg bacilli (including pseudomonas)
Clinical Findings of bacterial meningitis
- - Fever, neck stiffness, altered mental status & headache (2 of the prev = 95% sensitivity)
- - Photophobia
- - Petechial rash
- - Seizure
- - Focal neurologic signs
- - Papilledema
- - Meningismus (Brudzinski / Kernig)
When to do CT before LP
- - Adult with new onset seizures
- - Focal neurological findings
- - Mod to severe impaired level of consciousness
- - Papilledema
- - Known CNS diseases including CSF shunts, hydrocephalus, trauma, recent neurosurgery, immunocompromised
- - Delay in ability to perform LP
** if need to delay LP for CT, obtain blood cultures and start empiric antibiotics. If suspicious for bacterial meningitis, start dexamethasone 20 mins before antibiotics.
Typical CSF Findings in Meningitis
| Pathogen | WBC (per mcL) | Glucose | Protein (G/L) |
|---|---|---|---|
| Bacterial | >500 (mostly neutrophils) | Low | >100 |
| Partially treated bacterial | >100 | Normal | >70 |
| Aseptic, often viral | 10-1000 (mostly lymphocytes) | Normal | <200 |
Empiric Antibiotic Therapy
- - Neonates: ampicillin + cefotaxime
- - Adults: vancomycin + ceftriaxone
- - Immunocompromised adults (age > 50 yo, altered cellular immunity, alcoholics): ampicillin + vancomycin + ceftriaxone
- - Basilar skull fracture or cochlear implant: vancomycin + ceftriaxone
- - Neurosurgery + CSF shunt + penetrating trauma: vancomycin + cefepime
Prevention
- - H. influenza type B vaccine
- - Conjugate meningococcal vaccine
- - Conjugate pneumococcal vaccine
Prophylaxis
- - Prescribe antibiotics for the following close contacts
- o Anybody in close contact with pt x 8 hrs
- o Contact oral secretions
- o Living in household with 1 or more unvaccinated or incompletely vaccinated children