6/24- Infections of the Nervous System I Flashcards
What kind of inflammatory reaction is seen in infections: bacterial?
Polymorphonuclear cells
What kind of inflammatory reaction is seen in infections: mycobacterial?
Granulomatous
What kind of inflammatory reaction is seen in infections: fungal?
Granulomatous
What kind of inflammatory reaction is seen in infections: viral?
Lymphocytic
What kind of inflammatory reaction is seen in infections: protozoal?
Lymphocytic
What kind of inflammatory reaction is seen in infections: metazoal?
Eosinophils
What kind of inflammatory reaction is seen in infections: Prion?
No inflammation
What is this?
Empyema- surface collection of pus
What is this?
Meningitis- subarachnoid pus
What is this?
Abcesses- parenchymal collection of pus
What is this?
Granuloma
What is this? Cause/characteristics?
Convexity meningitis
- More likely to be bacterial (polymorphonuclear)
What is this?
Basilar meningitis
- Morel likely to be fungal or TB (granulomatous)
What infections commonly cause convexity meningitis?
Bacterial
What infections commonly cause basilar meningitis?
Fungal and TB
What are the main causes of bacterial meningitis in neonates?
- Group B strep
- E. coli
- Listeria
What are the main causes of bacterial meningitis in childhood?
- Meningococcus
- Pneumococcus
What are the main causes of bacterial meningitis in adolescence?
Meningococcus
What are the main causes of bacterial meningitis in adults?
Pneumococcus
What etiology of bacterial meningits has been dramatically lessened due to vaccines?
H. influenza
Which agent may be used in bioterrorism in regards to meningitis? Characteristics? Diagonsis?
Inhalational anthrax with systemic dissemination may produce severe hemorrhagic meningitis
- Dx: Gram(+) bacilli in CSF
How is bacterial meningitis diagnosed?
Lumbar puncture
- Polys
- Low glucose (consumed by PMNs)
- High protein
What is this?
Bacterial Meningitis
- Left layers are dura
- Box is around subarachnoid space
- See mostly polys
- PMN inflammation -> bacterial meningitis
Where do brain abscesses occur?
In the brain parenchyma
Often occurs as direct extension from a sinusitis or mastoiditis
- Frontal, temporal, or cerebellar as direct extension
Brain abscesses may mimic what?
Brain tumor
What are the most common causes of brain abscesses?
Suppurative bronchopulmonary infections with hematogenous spread (#1 cause)
- Deep, particularly in MCA distribution
- Multiple at gray-white junction when hematogenous
Often occurs from sinusitis or mastoiditis with direct extension
- Frontal, temporal, or cerebellar
Penetrating or surgical wounds
What is a common characteristic of bacteria that typically cause abscesses?
Micro/anaerobes
- Hard to grow/culture
T/F: May have multiple brain abscesses
True; multiple in 15-20%
What is seen on imaging for brain abscess?
- Smooth ring enhancing mass
- Purulent material within (smoother ring points to abscess rather than neoplasm, but there may be exceptions)
What is this?
Brain abscess with smooth ring enhancing mass
What are the zones of a classic brain abscess (4)?
1. Central necrosis with acute inflammatory cells
2. Granulation tissue (contrast-enhancing on imaging; neovascularization?)
3. Fibrous “capsule” (proliferating fibroblasts with abundant collagen deposition)
4. Reactive astrogliosis and edema
Label the picture
What are common characteristics of mycobacterial infection meningitis?
Tuberculous meningitis
- Basilar
- Thick exudate
- Involvement of CNs (and CSF foramina)
- Chronic
- Tends to be slower-paced than bacteria
What does the CSF look like in mycobacterial-caused meningitis (tuberculous meningitis)?
- Lymphocytes
- Increased protein
- Decreased glucose
- Increased pressure
- Send for culture
What is this?
Cortical TB granuloma
What is this? When would it typically be seen?
Granulomatous inflammation
- Multinucleate giant cells (can be seen in any granulomatous inflmn, not just TB)
- Lymphocytes
- Plasma cells
This suggests mycobacteria (TB) or fungal infections
What kind of necrosis is associated with TB?
Caseous necrosis
What is this?
TB seen on acid fast stain (bacilli)
What are the two types of fungi (and common fungi within them) causing meningitis?
Yeast
- Cryptococcus
- Coccidioiomycosis
- Histoplasmosis
- Blastomycosis (uncommon)
Hyphae
(tend to involve BV walls -> infarction -> tissue substrate for growth of fungi)
- Aspergillosis
- Mucormycosis
What is the most common cause of fungal meningitis?
In AIDS population?
Cryptococcus
- Even moreso in AIDS pts
- Seeing cryptococcal meningitis is an indicator for AIDS
Source and characteristics of Cryptococcus?
- Found in pigeon droppings (C. neoformans)
- “Soap bubble” cysts in parenchyma (intra-axial microabscesses; glistening)
- “Tear drop” (narrow-based) budding yeast seen with india ink and mucicarmine
- Encapsulated (polysaccharide)-thick, slimy; cloaks from immune response
What is this?
Multiple cryptococcal microabscesses
- Clear like “soap bubbles”
- Shiny b/c encapuslated
What is this?
Narrow-budding yeast of cryptococcus
What is this?
Thick capsule of cryptococcus
What are common characteristics of Histoplasmosis? Location, diseases caused, histology…
- Common pulmonary infection in Ohio, Mississippi, and Missouri Valleys
- OBLIGATE intracellular (intracytoplasmic) yeasts; very small (2-5 um) in cytoplasm of macrophages
- Calcified granulomas- usually benign and self-limited
- Disseminated disease does occur in infants and immunosuppressed
What is this?
Multiple granulomata seen in Histoplasmosis
- Thought before that these were brain mets
What is this?
Touch prep of masses from last scan
- Can see macrophages with tiny little dots in cytoplasm; Histoplasmosis
What is this?
Tiny yeast forms inside of macrophages seen in Histoplasmosis
Characteristics of Aspergillosis? Commonly infects who? Histology?
- Common, lethal infection in immunosuppressed
- Hemorrhagic due to angioinvasive nature
- Septate, true branching at 45’ uniform diameter
- Sets up in lung and can spread hematogenously to the brain
- Tends to occur in SW (CA, AZ, W TX); aerosolized by earthquakes
Characteristics of Rhinocerebral mucormycosis?
- Poorly controlled diabetics or immunocompromised
- Moor likely to have fever and elevation in peripheral white count
- Tends to progress a little more slowly than straight up stroke
- Angioinasive large non-septate hyphae
- Non-uniform and branching; 90’
What is this?
Aspergillosis cerebritis
- Can’t be sealed off by brain
- Hemorrhagic, dusty, and discolored
What is this?
Aspergillosis cerebritis (GMS stain)
- Septate, true branching at 45’ uniform diameter
What is this?
(LEFT) Sphenoid bone in mucomycosis
- Can see hypothalamus at the top of the pic
- Cavernous sinus (normal) and open carotid artery on right
- Clogged carotid a. on left due to mucor
(RIGHT) Inside of sphenoid sinus
- Black discoloration is infarcted mucosa due to mucor growing in BVs supplying this area
What is this?
Mucor
What is this?
Mucormycosis
- Can see hyphal forms in lumen of vessel and invading wall
- Can impede flow and cause infarct
Characteristics of Candidiasis: form, affected populations, symptoms, histology?
- Hyphae and yeast forms
- Commonly in immunocompromised hosts; the very ill
- Ubiquitous in environment
- # 1 fungal infxn of CNS found at autopsy
- Microabscesses
- PAS/GMS positive
