Bacterial Meningitis Flashcards
What age has the highest pediatric risk factor for bacterial meningitis?
Highest in age < 2 years (esp age < 3 months)
B/c less developed immune system
What are pediatric risk factors?
- Incomplete immunization (add Hib, pneumococcal)
- Immunocompromised
- Cranial structural defects
- Medical devices like CSF shunts, cochlear implants
What are some immunocompromised risk factors?
- Hypogammaglobulinaemia
- Complement deficiency
- Common variable immunodeficiency
- Sickle cell disease
- Asplenia
- Immunosuppressive meds
- HIV
- Cancer
What are some perinatal risk factors?
- Premature
- Low birth weight
- Premature rupture of membranes
- Mother has group B strep colonization
- Chorioamnionitis
What is the source of entry?
- Nasopharyngeal colonization followed by inflammation (i.e., URT) which allows access to bloodstream, results in bacteremia and hematogenous spread to the CNS
- Direct inoculation (CSF catheter, trauma)
- Para meningeal focus (middle ear infection, paranasal sinus infection)
How does the pathogen evade the immune system?
- Bacteria secretes enzymes that degrade protective immunoglobulins in nasal secretions that otherwise inhibit colonization
- Bacteria with polysaccharide capsules resist neutrophil phagocytosis
What are some diagnostic markers in the CSF?
- WBC: 1000-5000
- Differential: > or equal to 80
- Protein: 100-500 mg/dl
- Glucose: < 40 mg/dl
Viral meningoencephalitis
Treatable “common” viral meningitis limited to Herpes Simplex Virus (HSV)
What are some clinical suspicion of viral meningoencephalitis?
- Focal neurologic deficits
- Seizures
- Depressed mental status
How do you treat viral meningoencephalitis?
IV acyclovir added until HSV is eliminated
* PCR available in 24-48 hours
What pathogens are associated with bacterial meningitis?
- S. pneumoniae
- N. meningitidis
- H. influenzae
- group B Streptococcus (Streptococcus agalactiae)
What is the best empiric antimicrobial regimen?
Ceftriaxone and vancomycin
Vancomycin + third gen cephs (cefotaxime or ceftriaxone)
What are some empiric antibiotic consideration?
- SOA
- PK
- PD: Bactericidal effect desired in CF
- Allergies
- Timing: Should NOT be delayed, even if LP is not done
- W/ or w/o inflammation
S. Pneunoniae
- Gram neg and diplococcus
- # 1 US cause after intro of Hib vaccine
- Neurologic complications are common in survivors, esp infants and children
- Impact of PCN resistance due to altered PBP
Haemophilus influenza
- Gram-negative rods
- WAS the most common cause of meningitis in children 6 months - 3 years
- Spread via infected sinuses or bacteremia from a local focus (AOM)
- 30-40% of isolates are ampicillin-resistant beta-lactamases (therefore 3rd and 4th gen cephs provide options due to stability