CNS Exam 4 Flashcards
For a pt < 1 month of age, what are the likely pathogens for community acquired CNS infection?
- Group B Streptococcus
- Escherichia coli
- Klebsiella pneumoniae
- Listeria monocytogenes
- Gram-negative bacilli
For a pt 1 month of age and less than 18 y/o, what are the likely pathogens for community acquired CNS infection?
- Streptococcus pneumoniae
- Neisseria meningitidis
- Haemophilus influenzae
For a pt between 18 and 50 y/o, what are the likely pathogens for community acquired CNS infection?
- Streptococcus pneumoniae
- Neisseria meningitidis
- Gram-negative bacilli (in immunocompromised individuals)
For a pt > 50 y/o, what are the likely pathogens for community acquired CNS infection?
- Streptococcus pneumoniae
- Listeria monocytogenes
- Gram-negative bacilli
community acquired CNS infection: Listeria
common in the very old and very young
What are the common pathogens for healthcare associated CNS infections?
- Staphylococcus aureus
- Staphylococcus epidermidis
- Gram-negative bacilli (including Pseudomonas aeruginosa)
What are worldwide causes of CNS infections?
- Measles and mumps—viral or aseptic meningitis
- Japanese B encephalitis virus
- Enterovirus, arboviruses, and varicella zoster
- Herpes simplex virus (HSV)
Normal CSF values
- Opening Pressure: 60-200 mm H2O
- WBC count (cells/mm3): Up to 5
- Dominant Cell Type: Lymphocytes
- Protein: 20-60 mg/dL
- Glucose: Two-thirds of serum levels
Bacterial Meningitis CSF values
- Opening Pressure: Increased (>250 mm H2O)
- WBC count (cells/mm3): 1,000-5,000
- Dominant Cell Type: Neutrophils
- Protein: Usually increased (100-500 mg/dL)
- Glucose: Low (< 40 mg/dL or 40% of concurrent serum) bacteria organisms are eating up the glucose
Viral Meningitis/ Encephalitis CSF values
- Opening Pressure: Rarely increased
- WBC count (cells/mm3): 100-500
- Dominant Cell Type: Lymphocytes
- Protein: Normal / slightly increased
- Glucose: Rarely low
What are the factors that affect antibiotic penetration?
- Inflammation
- Molecular Weight
- Lipid solubility
- Protein binding
- Ionization
- Dosing
Factors that affect antibiotic penetration: Inflammation
increased inflammation = increased penetration; inflammation decreases the activity of efflux pumps in the choroid plexus
Factors that affect antibiotic penetration: Molecular Weight
low molecular weight will penetrate better
Factors that affect antibiotic penetration: Lipid solubility
high lipid solubility will penetrate better
Factors that affect antibiotic penetration: Protein binding
low protein binding will penetrate better
Factors that affect antibiotic penetration: Ionization
only non-ionized drugs will penetrate
Factors that affect antibiotic penetration: Dosing
often times dosing is higher
For a neonate (less than 28 days), what is appropriate empiric therapy?
Ampicillin plus cefotaxime or gentamicin
For a pt >1 month- 50 years, what is appropriate empiric therapy?
Vancomycin plus cefotaxime or ceftriaxone
For a pt >50 years, what is appropriate empiric therapy?
Vancomycin plus cefotaxime or ceftriaxone plus ampicillin
For a pt that has penetrating head trauma, post-neurosurgery, or CSF shunt in place, what is appropriate empiric therapy?
Vancomycin plus cefepime or meropenem
Duration of therapy for antibiotics for CNS infections
- At least 48-72 hours or until diagnosis can be ruled out
- Continue therapy based on clinical signs, cultures, susceptibility results
What is the most common cause in children > 2 months?
S. pneumoniae
What is the most common cause of neonatal meningitis?
- Group B Streptococcus
- also common in neonatal sepsis, pneumonia, and meningitis
What is appropriate empiric therapy for neonatal meningitis? (same as definitive treatment)
- Ampicillin or Penicillin
- Alternative: cefotaxime
What is the leading cause of children and adults? (occurs in spring or winter)
N. meningitidis
Who should have prophylaxis for meningococcus?
- young children
- household
- daycare
- military contacts
Adult prophylaxis for meningococcus
- Rifampin 600 mg q12h x 4 doses
- Alternative: IM Ceftriaxone 250 mg x 1 OR Ciprofloxacin 500 mg po x 1 OR Meningococcal vaccine
Children > 1 month prophylaxis for meningococcus
- Rifampin 10 mg/kg q12h x 4 doses
- Alternative: Ceftriaxone 125 mg x 1 for children < 12 OR Ciprofloxacin 500 mg po x 1 for children > 12 OR Meningococcal vaccine (ages 10-25)
Children < 1 month prophylaxis for meningococcus
Rifampin 5 mg/kg q12h x 4 doses
Who should receive the Meningococcal vaccine?
- all pts age 10-25 that have some risk factors
- all pts who has had their spleen removed or spleen dysfunction
- Meningococcal polysaccharide vaccine (MPSV4): adults 56 and older
- Meningococcal conjugate vaccine quadrivalent (MCV4): age less than 55
Prophylaxis of close contacts
- If fully vaccinated then no need to use prophylaxis
- Children: rifampin 20 mg/kg/day x 4 days
- Adults: rifampin 600 mg/day x 4 days
- Unvaccinated 12-48 mo: 1 dose
- Unvaccinated 2-11 mo: 3 doses
Listeria monocytogenes
- 8% of all cases of meningitis
- Neonates, alcoholics, immuno-compromised, elderly
- Peaks in summer and early fall
What are predisposing factors for Gram-Negative Meningitis?
- Congenital defects involving the CNS
- Cranial trauma
- Neurosurgery
- Diabetes
- Malignancy
- UTI in neonates
Causes of Herpes Simplex
- HSV-1 associated with adults
- HSV-2 with newborns
Therapy for HSV viral encephalitis
- Limited in most cases to supportive care with fluids, seizure control, antipyretics, and analgesics
- Adults: Acyclovir 10 mg/kg IV q8h for 2-3 weeks
- Neonates: Acyclovir 20 mg/kg IV q8h for 2-3 weeks
- Resistance reported especially in immuno-compromised patients
- Alternative is foscarnet; watch for renal toxicity; make sure pt is adequately hydrated
Empiric treatment for Streptococcus pneumoniae (Pneumococcus or Diplococcus)
- Vancomycin plus ceftriaxone
- Vancomycin plus cefotaxime
- Alternatives: meropenem or moxifloxacin
Who should receive Pneumovax 23®?
- Persons older than 65
- Persons 2-64 who have chronic illness, who live in high-risk environments (residents of long-term care facilities), who lack a functioning spleen
- Immunocompromised persons older than 2 (including HIV)
- Questionable recommendation for college students living in dormitories
Who should receive Prevnar 13®?
- Children 2 months and older and adults over the age of 65
- Children with cochlear implant
Empiric treatment for N. meningitidis
- Ceftriaxone or cefotaxime
- Alternatives: Penicillin G, Ampicillin, Fluoroquinolone, Aztreonam
Empiric treatment for Haemophilus influenzae
- Ceftriaxone or Cefotaxime
- Alternatives: Cefepime, Meropenem, Fluoroquinolone
Empiric treatment for Listeria monocytogenes
- Ampicillin or penicillin G
- Alternatives: trimethoprim-sulfamethoxazole or meropenem
Gram-Negative Meningitis
- Enteric gram-negatives are the fourth leading cause of meningitis
- includes Klebsiella, E. coli, Serratia marcescens, Pseudomonas, Salmonella
Adult dosing for ampicillin
- Total daily dose (dosing interval in hours): 12g (4)
- 2g q4h
Adult dosing for ceftriaxone
- Total daily dose (dosing interval in hours): 4g (12-24)
- 4g q24h OR 2g q12h
Adult dosing for meropenem
- Total daily dose (dosing interval in hours): 6g (8)
- 2g q8h
Adult dosing for vancomycin
- Total daily dose (dosing interval in hours): 30-45mg/kg (8-12)
