Meningitis Flashcards

1
Q

Meningitis

A

Infection and inflammation of meninges

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2
Q

How does meningitis occur

A

Blood brain barrier usually controls access of potentially toxic metabolites into CSF and tissues.
Failure of this mechanism results in meningitis.

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3
Q

Encephalitis

A

Infection of the brain parenchyma

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4
Q

Meningo encephalitis

A

Inflammation of brain + meninges.

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5
Q

Aseptic meningitis

A

Inflammation of meninges with sterile CSF –caused by viruses

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6
Q

Classification of Meningitis - Duration

A

Acute: Symptoms present in 24 hrs
Sub acute: Symptoms lasting 1-7 days
Chronic: Symptoms lasting over 7 days

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7
Q

Classification of Meningitis - Etiology

A

Bacterial meningitis
Fungal meningitis
Viral (aseptic) meningitis

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8
Q

Acute meningitis - Bacteria

A

Pneumococcus , Meningococcus
Hemophilus influenzae , Group B Streptococcus , Enteric GNB -E.coli
Listeria monocytogenes , Staph. aureus

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9
Q

Acute meningitis - Parasites

A

Naegleria Fowleri
Angiostrongylus , Acanthamoeba spp.
Strongyloides stercoralis , Entamoeba histolytica .

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10
Q

Chronic meningitis - Bacteria

A

Mycobacterium tuberculosis

Cryptococcus neoformans

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11
Q

Chronic meningitis - Fungi

A

Histoplasma , Coccidiodes, Candida, Blastomyces

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12
Q

Chronic meningitis - Others

A

Toxoplasma , Lyme disease , Syphilis , Cysticerosis.

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13
Q

Transmission - Acute meningitis

A

Spread via bloodstream
Spread from Para meningeal structures – e.g. Sinusitis
Direct infection to subarachnoid space via fracture
Direct infection

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14
Q

Pathogenesis - meningitis

A

1) Nasopharyngeal colonization
2) Invasion of epithelium
3) Invasion of blood
4) Further dissemination
5) Cerebrospinal fluid tissues

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15
Q

Symptoms - infant

A
  • Fever
  • Not feeding; possible vomiting
  • Blank stare
  • Lethargic
  • Pale, blotchy
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16
Q

Symptoms - adult

A
  • Stiff neck
  • Headache
  • Fever
  • Vomiting
  • Light sensitivity
  • Drowsiness/confusion
  • Joint pain
    (Small irregular spots on trunk/ Petechiae if meningococcal)
17
Q

Medical emergency

A

Need antibiotic therapy asap; life threatening

18
Q

Specimen

A

Blood, CSF

19
Q

High intercranial pressure

A

Can result from bleeding in the brain, a tumor, stroke, aneurysm, high blood pressure, or brain infection

20
Q

CSF profile

A

Glucose: <40 mg/dL.
Protein: > 150 mg/dL.
WBCs: >500 cells/µL (usually > 1000).
Early: May be < 100.
Cell differential: Predominance of Neutrophils (PMNs)
Culture: Positive

21
Q

Microscope

A

Centrifuge
Examine sediment
Gram stain
India ink – Capsules of cryptococcus neoformans

22
Q

Cultures

A

Blood Agar Plate
Chocolate Agar Plate
Mac Conkey’s agar

23
Q

Latex agglutination

A

Negative reaction:
The suspension remains slightly milky in appearance.

Positive reaction:
agglutination (or visible clumping) and slight clearing of the suspension occurs within 2-10 minutes .

Detects - Meningococci, Pneumococci, H. influenzae

24
Q

H. influenzae

A

Gram –ve short rods (long filamentous form in meningitis-CSF) ,non motile, chocolate agar.

Colonies - smooth moist grey-require factor X & factor V

Staph aureus Factor V Satellitism.

25
Q

Listeria monocytogenes

A

Small pleomorphic, Gram +, coccoid bacilli , motile.

Catalase positive.

Blood agar; produces β haemolysis
Lab identification: Catalase positive. Tumbling motility

26
Q

Escherichia coli

A

Gram: Gram-negative rods/bacilli (pink)
BA (Blood Agar): Large, white, colonies.
MAC (MacConkey): Lactose fermenting, pink colonies ,moist ,smooth
Commercial kits for Enterobacteriacae

27
Q

Strepto. agalactiae

(Gr B Strep.) - lab ID

A

Gram : Gram Positive cocci in pairs and short chains polysaccharide capsule - virulence factor,

BA: Off-White β-haemolytic colonies

CAMP positive reaction – arrowhead shaped area of enhanced haemolysis.

28
Q

Strepto. pneumoniae

A

Gram: Gram Positive cocci in
pairs (diplococci) (purple)
BA: Alpha haemolytic colonies (Green tinged)
Lab. I.D. : Catalase negative. Optochin susceptible, Bile soluble. Quellung reaction.

Most common cause of meningitis

29
Q

Quellung reaction

A

a biochemical reaction in which antibodies bind to the bacterial capsule of Streptococcus pneumoniae etc.

30
Q

Neisseria meningitidis

A

Gram: Gram negative diplococci (pink)
CHOC: Clear, moist colonies. Capnophilic

31
Q

Pseudomonas aeruginosa

A
Gram: Gram negative rods/bacilli (pink)
BA: Colonies may show haemolysis, metallic sheen.
MAC: Non-fermenter, 
		non-pink colonies
Oxidase positive ,-Motility +ve
32
Q

Complications

A

Acute cerebral edema
DIC (disseminated intravascular coagulation of blood)
Brain abscess
Hemorrhagic necrosis of adrenal glands
(Waterhouse Friderichsen Syndrome with meningitis)