Meningitis Flashcards
What are the types of pathogens that can cause meningitis? What are the most common?
Virus, mycobacteria, bacteria, parasites, fungal
Most commonly bacterial or viral (viral > bacterial)
Viral is mild and self-limiting
Bacterial (gram-negative) has 60% chance of complication
In the U.S. for bacterial the BIG ones are:
- Streptococcus pneumoniae (MOST common cause, reason for PCV 13 vaccine)
- Neisseria meningitidis (esp. teens)
- Listeria monocytogenes (found in nasty foods, more often in weaker indiv. i.e. pregnant, newborn, elderly, immune-compromised)
- Decreased H. influenzae incidence since Hib vaccine
How does meningitis infect the nervous system? (steps)
Colonizes mucosa (fibriae by H. influenzae and N. meningitidis… polysaccharide by S. pneumoniae)
Survives intravascularly
Invades meninges
Then invades subarachnoid space
Finally disrupts the blood brain barrier (BBB)
How does meningitis presentation very by age?
Adults: HA, nuchal rigidity, fever, vomiting photophobia, altered mental status, obtundation, seizures
Children: lethargic, confused, somnolent
Infants: irritable, altered sleep, high-pitch cry, vomiting and decreased oral intake
What two signs/maneuvers support meningitis diagnosis?
Stretch the meninges to cause pain
Brudzinski’s (neck flex)
Kernig’s (knee flex)
LP draw of CSF used to diagnose meningitis.
How might CSF findings distinguish between bacterial, viral and fungal meningitis before the culture comes back?
Bacterial have neutrophilic differential, compared to lymphocytic for fungal and viral
Bacterial has more protein and WBC count, but compared to fungal and viral
Glucose in Bacterial is 1/2 of serum, compared to 30-70 for both fungal and viral
Fungal and viral hard to distinguish (very similar WBC count, differential, protein and glucose)
What is the general treatment plan for meningitis?
Empiric treatment especially if patient symptomatic, need to destroy the pathogen and stabilize patient:
Bacterial-empiric antibiotics Anti-inflammatory agent (usually corticosteroid) Fluids Electrolytes Antipyretics (usually NSAIDs) Analgesia
What is the time frame for starting empiric therapy for meningitis?
Start within 30 minutes of presentation (even before LP results)
Continue for 48-72 hours or if rule-out meningitis
Once LP and culture returns to confirm pathogen, alter therapy to be more specific for that organism
*A CSF gram stain that is negative does NOT mean stop empiric therapy
What is empiric antibiotic therapy based on age groups?
Younger than 1 month (higher risk of Listeria monocytogenes) = Ampicillin and Cefotaxime OR Gentamicin
1 month-50 years = Cefotaxime OR Ceftriaxone and Vancomycin (plus Dexamethasone)
Older than 50 years or alcoholic (higher risk of Listeria monocytogenes) = Ampicillin and Cefotaxime OR Ceftriaxone and Vancomycin (plus Dexamethasone)
*Rule: always give Cefotaxime OR Ceftriaxone, Vancomycin if older than 1 month, and ADD Ampicillin if suspect Listeria
What is the empiric therapy after the CSF gram stain comes back as positive (shows growth)?
Therapy will be adjusted accordingly depending on the type of pathogen found:
Gram positive diplococci (Strep): Cefotaxime OR Ceftriaxone and Vancomycin plus Dexamethasone
Gram negative diplococci (Neisseria): Cefotaxime OR Ceftriaxone
Gram positive bacilli or coccobacilli (think Listeria): Ampicilin and Gentamycin
Gram negative bacilli (H.influenzae): Ceftazidime OR Cefepime (with or without Gentamycin)
What is the logic behind giving Dexamethasone with i.e. Vancomycin?
Anti-inflammatory effect
Dexamethasone inhibits production of proinflammatory cytokines (TNF, IL-1)… improves CSF parameters for bacterial meningitis, reduced mortality in S. pneumoniae meningitis, unfavorable outcome reduced
Need to give it BEFORE antibiotics, best benefit in patients with GCS score 8-11
ADR: increased GI bleed, decreased antibiotic penetration (BUT doesn’t seem to affect Vancomycin penetration), increased hearing loss in kids
*AVOID giving in meningitis patients that also have septic shock (could worsen outcome)
How is response to treatment for meningitis assessed?
Evaluate signs and symptoms
Check vital signs and cerebral dysfunction every 4 hours (for 72 hours)
If PCR diagnostics not working, re-culture CSF (identification and susceptibility testing usually takes 72 hours)
Based on results, adjust therapy
In whom/when does Neisseria Meningitidis (Meningococcus) occur? What is the drug of choice?
Neisseria = gram negative diplococci
Occurs mostly during winter and spring, and in kids and young adults
Symptoms: immunologic reaction (fever, arthritis, pericarditis), behavioral change (seizure, coma), up to 50% will have DIC and purpuric lesions
Treatment: NSAIDs for immunologic reaction
Empiric treatment for suspected gram-negative diplococci like Neisseria was Ceftotaxime OR Ceftriaxone, so could technically continue this, or use Chloramphenicol… but the DOC is HIGH DOSE IV PCN G (should switch when susceptibility confirmed)
When is meningitis prophylaxis indicated?
For RECENT close contacts (household, day care, close crowded population, direct exposures to oral secretions from patient)
Give ASAP (best within 24 hours) *Giving 14 days after contact probably not useful
Fully vaccinated people older than 2 years old may NOT benefit from prophylaxis
*But since Neisseria does not have a vaccine, must get prophylaxis if exposed to that type
What are the available prophylaxis regimens for post-contact with infected meningitis patient?
Rifampin (dose varies based on age, for children it is weight-based)
Alternative: Ceftriaxone IM (i.e. for pregnancy)
What is the most common cause of adult meningitis? How is it treated? Prevented?
Streptococcus pneumoniae (Pneumococcus, gram positive cocci in pairs)
Also seen commonly in children
Higher fatality in elderly
*Survivors commonly have neurologic sequelae
Predisposition for this infection with pneumonia, endocarditis, splenectomy, head trauma, alcoholism, sickle cell disease, bone marrow transplant… higher risk in people with cochlear implant
Treatment: IV 3rd Generation Cephalosporin for 10-14 days (i.e. Cefotaxime OR Ceftriaxone)… if it is found to be PCN susceptible can switch to PCN (but tends to be more resistance to PCN nowadays anway)
*If resistance to beta-lactams, switch to Vancomycin
Prevention with Vaccination (Prevnar): indicated for ages over 65, immunocompromised and asplenic patients…
Can also be helpful in those predisposed i.e. for sickle cell disease, vaccination and prophylactic PCN decreases incidence of pneumococcal disease
