Meningitis Flashcards
1
Q
CSF Profile in Bacterial Meningitis
A
- Protein: ⇡⇡
- Glucose: ⇣⇣
- Cell infiltration: PMNs
- Pressure: ⇡
2
Q
CSF Profile in Viral Meningitis
A
- Protein: ⇡ or normal
- Glucose: normal
- Cell infiltration: lymphocytes
- Pressure: normal
3
Q
CSF Profile in Fungal Meningitis
A
- Protein: ⇡
- Glucose: ⇣
- Cell infiltration: lymphocytes
- Pressure: ⇡
4
Q
DDx for Neonatal Meningitis
A
S. galactiae
L. monocytogenes
E. coli
5
Q
Streptococcus agalactiae
A
-
Gram ⊕ coccus, catalase ⊖, beta-hemolytic, bacitracin-resistant
- Immunogenic capsular polysaccharide
- CP: neonatal meningitis (MCC), neonatal PNA, neonatal sepsis
-
Pathobiology: bacteria carried in maternal genital tract → colonizes neonate, esp. following obstetric complications, causing:
- meningitis: seizures, irritability develop weeks after birth → survivors may have neurological impairment
- PNA: respiratory distress, lethargy, hypoTN develop w/in a day after birth
- Dx: Gram stain of CSF, urine, blood
-
Tx: penicillin G
- Prophylaxis: ampicillin for pregnant women that test positive for S. agalactiae
6
Q
Listeria monocytogenes
A
-
Gram ⊕ rod, non-spore-forming, motile, catalase ⊕
- Many flagella → “tumbling” motility
- Only Gram ⊕ w/ LPS
- Can survive both intra- and extracellularly
- Can grow at refrigerated temperatures
- CP: listeriosis (meningitis and sepsis in neonates and immunocompromised)
-
Pathobiology: Heat resistant & survives in poorly pasteurized milk → consumption by host → penetration of GI mucosa → invasion of phagocytes → intraceullar growth in macrophages (or neutrophils) → spreads through blood w/ a tropism for neural tissue → meningitis
- In fetus, neonates: organism normally colonizes vaginal tract → transmission across placenta or during birth → spread through blood → disseminated abscesses, meningitis
- Dx: Gram ⊕ rod w/ tumbling motility
- Tx: ampicillin +/- gentamicin or TMP-SMX
7
Q
Escherichia coli
A
- Gram ⊖ rod
-
Lactose fermenter
- Grows green** on **EMB, light purple on MacConkey
- Fast-fermenter
- Indole ⊕
- K, O, & H antigens
-
CP:
- neonatal meningitis, neonatal PNA
- Enteritis
- complications: HUS
- UTI
- Septic shock
8
Q
DDx for Meningitis in Patients age 6mos-6yrs
A
S. pneumoniae
N. meningitidis
H. influenzae type B (HIB)
9
Q
Streptococcus pneumoniae
A
-
Gram⊕coccus, catalase⊖, alpha-hemolytic, bile-esculin⊖, optochin-S, ⊕Quellung rxn
- Capsule is antiphagocytic and makes up antigens for the Pneumovax vaccine
-
CP:
- Local: lobar PNA, otitis media
- Systemic: meningitis
-
Pathobiology: spread by respiratory droplets → colonization of nasopharynx epithelium → evasion of host defenses by capsule and IgA proteases, then:
- May travel to anatomically connected structures and stimulate inflammation → otitis media, sinusitis
- May travel to alveoli and stimulate inflammation → dissemination through lobe via pores of Kohn → lobar PNA
- If host lack anti-capsular IgG → invasive strains that enter lung lymphatics → enter bloodstream → seed target organs and stimulate inflammation → meningitis
- Dx: see characteristics above
- Tx: penicillin or cephalosporins; vancomycin for meningitis
10
Q
*Neisseria meningitidis *
A
-
Gram⊖, diplococcus, maltose & glucose oxidizer
- Capsule = antiphagocytic
- LPS endotoxin
- IgA protease - cleave IgA in half
- Can extract iron from human transferrin via a non-energy requiring mechanism
- Pili - allow attachment to human nasopharyngeal cells & undergo antigenic variation to avoid immune system attack
- CP: meningococcemia w/ petechial rash (fulminant = Waterhouse-Friderichsen syndrome); meningitis
-
Pathobiology: Carried by humans → colonizes nasopharynx epithelium → evasion of IgA antibodies w/ IgA protease → crossing of mucosa via phagocytic vacuoles of non-ciliated cells → entrance in bloodstream and proliferation → release of **LPS **endotoxin → vascular necrosis & hemorrhaage in skin (petechial rash)
- In fulminant cases: vascular necrosis & hemorrhage in adrenal glands → adrenal insufficiency (W-F syndrome) along with shock & DIC → multiorgan failure → possible death
- Organisms in bloodstream may have tropism for meninges → stimulation of inflammation → meningitis
- Dx: gram⊖ rods within PMNs, selectively grows on Thayer-Martin media
-
Tx:
- pencillin G, ceftriaxone
- rifampin for close contacts as prophylaxis
- vaccines w/ capsule polysaccharides
11
Q
*Haemophilus influenzae *type B (HIB)
A
-
Gram⊖ coccobacillus, pleomorphic, X&V factors required
- Type B polysaccharide capsule (=antigen in vaccine, conjugated to Diptheria toxoid)
-
CP:
- Local: epiglottis; otitis media, PNA
- Systemic: meningitis, septic arthritis, cellulitis
-
Pathobiology: only human carriers → inhaled in aerosol → evades IgA antibodies w/ IgA protease → colonization of upper respiratory tract → inflammation → epiglottitis, otitis media
- avoids phagocytosis w/ capsule → invasion of submucosa, spread to bloodstream →may seed CNS, large joints, or soft tissue → meningitis, septic arthritis, cellulitis
-
Dx: requires both hemin (X-factor) and NAD (V factor) to grow on chocolate agar
- Immunofluorescence
- ⊕Quellung rxn
-
Tx: ceftriaxone
- rifampin prophylaxis for close contacts
12
Q
DDx for Meningitis in Patients age 6-60yrs
A
N. meningitidis
Poliovirus
S. pneumoniae
13
Q
DDx for Aseptic Meningitis
A
Coxsackie virus
Echovirus
Mumps virus
Poliovirus
14
Q
DDx for Fungal Meningitis
A
Cryptococcus neoformans
15
Q
Cryptococcus neoformans
A
- Fungal opportunistic infection
- CP: cryptococcal meningitis, cryptococcosis (PNA)
- Resevoir: soil, pigeon droppings (birds)
-
Pathobiology:
- Yeast inhaled → local infection in lung → asymptomatic or PNA
- Inhalation → yeast may spread via blood, especially to CNS → meningitis → abscess formation → pressure and displacement of brain tissue → brain damage
-
Diagnosis:
- Culture on Sabouraud agar
- CSF India Ink and mucicarmine staining: yeast with narrow-based budding and a **large polysaccharide capsule **(can see halo)
- CSF or serum cryptococcal antigen
- Brain CT: Well-circumscribed ringlike lesions
-
Treatment:
- Meningitis: amphotercin B and flucytosine
- Prophylaxis in AIDS pts: fluconazole
