CNS Infections part 1 Flashcards
What is the most common route for CNS infections to arise?
Hematogenous (via blood)
– usually arterial
What are the 4 ways that a CNS infection can reach the CNS?
- Hematogenous
- Direct Implantation
- Local extension
- Peripheral Nervous System
What are the only 2 organisms that reach the CNS via infecting the peripheral nervous system and moving to the CNS?
Rabies
Herpes Zoster
What is the importance of the CSF being completely exchanged in the brain every 3-4 hours with CNS infections?
Completely bathes the brain in the bacteria!
Which organism uses direct seeing from a subepidural or submeningeal granuloma to infect the CNS?
Tuberculus Meningitis
Describe how Rabies infects the CNS
Virus binds the Ach receptors at the NMJ and ascends motor neurons to the CNS
Describe how Herpes Zoster infects the CNS
Infects sensory ganglia and replicates in schwann cells and ascends to CNS via sensory nerves
Capillaries in the BBB are impermeable to what types of things?
Antibiotics
Complement
Immunoglobulins
How do molecules cross the BBB capillaries?
Active transport
Lipid soluble
Which populations are at the highest risk for Meningitis?
< 5
> 60
Diabetics
Immunosuppressed
A lumbar puncture is performed to diagnose Meningitis. What organism is commonly Gram (-) Diplococci in the CSF?
N. Meningitidis
A lumbar puncture is performed to diagnose Meningitis. What organism is commonly Gram (+) Diplococci in the CSF?
S. Pneumoniae
A lumbar puncture is performed to diagnose Meningitis. What organism is commonly Gram (-) pleomorphic in the CSF?
H. Influenzae
A lumbar puncture is performed to diagnose Meningitis. What organisms are commonly Gram (+) Cocci?
S. Aureus
Streptococci
A lumbar puncture is performed to diagnose Meningitis. What organism is commonly Gram (-) Bacilli in the CSF?
E. Coli
What are some symptoms of Meningitis?
Meningeal irritation - fever, headache, N/V, confusion, stiff neck
What is the CNS response to pyogenic (bacterial) meningitis?
Cerebral Edema (loss of BBB)
Cerebral edema is the CNS response to pyogenic meningitis. What accelerates it and what slows/resolves it?
Accelerated by = Bacteria
Slowed/Resolved by = Corticosteroids
CSF appearance for Bacterial vs Viral Meningitis?
Bacterial - cloudy/turbid
Viral - clear
CSF lab value of Neutrophils/Lymphs/Monos for Bacterial vs. Viral Meningitis?
Bacterial - NEUTROPHILS
Viral - Lymphs/Monos