CNS Exam 4 Flashcards
(47 cards)
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
