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
N. meningitidis
- Gram-negative diplococcus
- Leading cause of bacterial meningitis in children and young adults
- Direct person-to-person spread in close contacts from asypmtomatic carrier, Winter-sparing predominance, Purpuric or petechial lesion
What is the dosing for ceftriaxone?
80-100 mg/kg/day divided every 12 to 24 hours
* MAX dose: 4,000 mg/day
* Loading dose (ex: 1200 mg IV) and maintenance
What is the dosing of Vancomycin?
15 mg/kg/dose every 6 hours
What is the AUC: MIC target level for S. aureus induced bacterial meningitis?
400, potentially up to 600
Trough based monitoring
- 15-20 mg/L
- Infants, children, and adolescents: 7 to 10 mg/L have been associated with AUCs>400
What is the monitoring plan for efficacy?
- Vital signs: continuous in ICU, every 4 hours on units
- Neurological exam: every 4-6 hours
- WBC & differential: daily
- Check results of CSF and blood culture daily, expect gram stain w/in 24hrs; preliminary culture results in 24-48 hours; sensitivity data in 24-48 hours
What are some toxicity adverse effects of Ceftriaxone?
- Hypersensitivity-rash, fever, SOB
- N/V, diarrhea
- Phlebitis: swelling and pain at infusion site
- White plaques in mouth: oral flush (also vaginal in females, skin esp. diaper areas)
What are some toxicity adverse effects of Vancomyin?
- Flushing, itching, blood pressure, hives (Vancomyin infusion reaction)
- Daily BUN and SCr for nephtrotoxicity, I/O’s with IV fluids
- Vancomycin trough as surrogate for efficacy
* After 3-4 doses (approx. steady-state)-target 15-20 mg/L
* Repeat 2x/week, sooner if dose change OR renal function change
Corticosteroid
- Timing prior to or at the same as the administration of antibiotics (Ideally, within 4 hours of presumptive diagnosis)
- No significant decrease in mortality but significant decrease in the rate of hearing loss
