MCB Exam 3-B

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MCB Exam 3-B
2011-03-29 10:39:47
Microbial Diseases Nervous System Microbiology UF Asghari

Microbial Diseases of Nervous System Microbiology
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  1. Pathogens can enter CNS by:
    (4 routes)
    • 1. Breaks in bones & meninges
    • 2. Medical procedures (ie epidural)
    • 3. Traveling in peripheral neurons to CNS
    • 4. Infecting & killing cells of meninges resulting in meningitis
  2. Bacterial Meningitis:

    Signs & symptoms w/3 types
    Diagnoses, Trtmt
    • Rapid development of S&S so antibiotics must be fast! Animal foods can be contaminated
    • Three Types:
    • 1. Inflamed cranial meninges: severe headache, vomiting, pain
    • 2.Inflamed spinal meninges: stiff neck, altered muscle control (b/c nerves in neck travel down arms)
    • 3. Brain infection, encephalitis: behavioral chgs, coma, death
    • Diagnose w/spinal tap
    • Vaccines
  3. 4 species produce bacterial meningitis
    Streptococcus pneumoniae: only encapsulated strains harmful; #1 cause in adults

    Neisseria meningitidis: Fimbria, capsule, LPS

    Haemophilus influenzae

    Listeria monocytogenes
  4. Leprosy
    (Mycobacterium leprae)
    Describe organism, how get it, how diagnose
    Two Forms:
    • G+ bacillus w/mycolic acid in cell wall
    • Person-person or broken skin
    • Diagnoses confirmed by presence of acid-fast rods (thick waxy coat)
    • Two Forms
    • 1. Tuberculoid- nonprogressive
    • 2. Lepromatous- progressive tissue destruction, starting in cold parts of body, both immune system & bacteria destroy cells
  5. Botulism
    Clostridium botulinum
    Describe org, S&S
    3 Forms
    3 Trtmts
    • G+ obligate anaerobe, so can go deep into body, causing gangrene
    • Intoxication from endospores
    • Diarrhea main symptom

    • 3 Forms
    • -Food-borne: paralysis of voluntary muscles
    • -Wound botulism: " "
    • -Infant botulism: grows in intestine b/c stomach acid insufficient to destroy

    • 3 Trtms:
    • -Wash intestinal tract
    • -Administer botulism immune globulin
    • -Antibiotics
  6. Examples viral diseases of nervous system (4)
    • Meningitis
    • Polio
    • Rabies
    • Encephalitis
  7. Viral Meningitis
    What org causes, how get it, what it does in body
    • Most common meningitis & milder than bacterial, fungal
    • Mostly caused by Enterovirus fam of viruses,
    • From infected food, respiratory droplets, feces
    • Goes on to attack intestinal tract but no GI illness; no trtmt, goes away on its own
  8. Polio

    How get it
    4 Conditions caused by it
    • Drinking contaminated water; today only in Africa, Asia
    • Four Conditions
    • Asymptomatic infection: most common
    • Minor
    • Nonparalytic: muscle spasms & back pain
    • Paralytic
  9. Rabies

    S&S, Incubation, Trtmt
    • S&S: pain or itching at infection site; if neurological symptoms begin, it is terminal
    • Incubation: 1-2 mo
    • Trmt: Postexposure prophylaxis (vaccine given b/4 virus reaches CNS); human rabies immune globulin; rabies vaccine
  10. Arboviral Encephalitis

    S&S, Trtmt
    • arthropod-borne viruses (usually mosquitoes)
    • S&S: mild, coldlike symptoms; but can pass blood-brain barrier causing encephalitis similar to meningitis
    • Trtmt: supportive (none)
  11. Cryptococcal meningitis caused by _______ _______
    Cryptococcus neoformans

    (encapsulated yeast)
  12. Cryptococcal Meningitis

    How get it:
    Spores enter via resp tract or dried yeast cells

    • Susceptibility: Immunocompromised ppl (common in HIV ppl) & those exposed to bird droppings w/fungus
    • S&S: prolonged cough, similar to bacterial meningitis
    • Trmt: Amphotericin B (attacks fungal cell wall component, ergosterol, which humans don't have)
  13. Prion
    Infectious proteins that can cause disease by chg normal alpha sheets into beta sheets
  14. Prion Disease

    What is does in body
    How infected (3)
    Ex: (3)
    Accumulation of beta-sheet protein, causing neurological disease

    • Triggered by:
    • Transplants
    • Contamination via surgery
    • Injection of growth hormones from infected pituitary glands

    • Ex:
    • Scrapie- sheep
    • Mad cow disease
    • Creutzfeldt-Jakob disease- humans