Meningitis Flashcards
Bacterial causes of pyogenic meningitis:
Group B streptococcus
H. flu, type B
Strep pneumoniae
Neisseria meningiditis
Fungal causes of pyogenic meningitis:
Histoplasma capsulatum
Coccidiodomyces immitus
Cryptococcus neoformans
Amoebic causes of pyogenic meningitis:
Naegleria
Infectious causes of aseptic meningitis:
Enteroviruses, arboviruses, mumps virus, HSV, VSV, adenovirus, EBV, parvovirus, cryptococcus, tuberculosis, syphilis, Lyme disease
Non-infectious causes of aseptic meningitis:
IVIg, bactrim, carcinomatous meningitis, leukemia, lymphoma, Kawasaki disease.
Bacterial meningitis in the immunocompromised:
Listeria monocytogenes
Cryptococcus neoformans
Bacterial meningitis in those younger than 2 months:
Group B streptococcus
E. coli
Listeria monocytogenes
Pathophysiology of meningitis:
1) Carriage, transmission, or colonization by encapsulated pathogenic bacteria.
2) Bacteremia (children don’t produce anti-capsular antibodies well)
3) Penetration of BBB
4) Diminished cerebral blood flow (vasculitis, cerebral edema)
Major viral causes of aseptic meningitis:
Group B coxsackievirus, echoviruses. Aseptic meningitis occurs in the seasonal pattern observed with enterovirus infections (marked SUMMER-FALL predominance).
Pathophysiology of enterovirus aseptic meningitis:
- Transmission (direct and indirect fecal-oral transmission)
- Minor viremia
- Systemic lymphoid involvement
- Major viremia
- Involvement of CNS, myocardium, etc.
Signs/symptoms of meningitis in neonates:
Irritability, lethargy, poor feeding, vomiting, seizures, temperature instability, tense fontanelles, cranial nerve palsy, FEVER AND NUCHAL RIGIDITY MAY BE ABSENT
Signs/symptoms of meningitis in children/adults:
Headache, vomiting, lethargy, mental confusion, stiff neck, fever, nuchal rigidity, Kernig’s sign, Brudzinski’s sign
CSF analysis in meningitis:
Opening pressure
WBC count/differential
Glucose/protein
Gram stain/culture
CSF results in bacterial meningitis:
CSF white cell count >200.
CSF WBC differential, usually >90% polys
CSF glucose decreased (<40)
CSF protein elevated
CSF results in viral meningitis:
CSF white cell count usually 10-500 cells
CSF WBC differential initially predominance of polys, but drops to <50% polys within 24 hours
CSF glucose normal to slightly low
CSF protein normal to slightly increased
Diagnosis of viral meningitis:
PCR to detect enterovirus RNA Cell culture (only in 30-40% of cases). Likelihood of a positive viral culture correlates directly with CSF WBC count.
Sequellae of meningitis:
Usually none
Deafness (10%)
Bilateral/profound deafness (5%)
Mental retardation (4%)
Acute complications of meningitis:
Seizures, SIADH, hydrocephalus, subdural effusion, hearing loss, hemiparesis, stroke.
Meningitis prognosis:
For bacterial meningitis: Mortality is lower for children (<5%) than for adults (20-30%).
For viral meningitis: Most infants and children recover completely within 3-7 days of onset. Adults may experience more severe and more prolonged symptoms.
Chronic viral meningitis in immunocompromised patients:
Patients with agammaglobulinemia and CVID are susceptible to persistent or recurrent meningoencephalitis with enteroviruses. CNS manifestations include: weakness, lethargy, headache, cognitive and intellectual decline, hearing loss, ataxia, seizures, and sensory abnormalities.
Treatment of bacterial meningitis:
Vancomycin and ceftriaxone until susceptibility is known with adjunctive steroid therapy.
Treatment of viral meningitis:
Antibiotics until CSF and blood cultures are reported negative at 48-72 hours.
Enterovirus PCR assay may assist in immediate management decisions.
PLECONARIL reduces the duration of headache and other symptoms by 50%.
Post-exposure prophylaxis:
Four doses of rifampin over 2 days, or a single dose of ciprofloxacin.
Immunization:
Routine immunization of all infants and children with HiB, and 13-valent pneumococcal conjugate (PCV13).
Selective immunization for individuals at risk for meningococcal disease and pneumococcal disease is recommended with quadrivalent meningococcal conjugate (MCV4) and 23-valent pneumococcal polysaccharide (PPV23).
