chapter 22: microbial diseases of the nervous system Flashcards

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1
Q

central nervous system

A

brain and spinal cord

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2
Q

peripheral nervous system

A

all nerves that branch off from the brain and spinal cord

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3
Q

meninges

A

trilaminar membrane system that protects brain and spinal cord

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4
Q

subarachnoid space

A

holds CSF

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5
Q

blood brain barrier

A

restrictive capillary system that protects the brain and spinal column from invasion by potentially toxic compounds and microbes

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6
Q

meningitis

A

inflammation of the meninges

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7
Q

encephalitis

A

inflammation of the brain

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8
Q

meningoencephalitis

A

inflammation of the meninges and the brain

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9
Q

bacterial meningitis symptoms

A

fever, headache, stiff neck, often followed by nausea and vomiting; convulsions and coma

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10
Q

viral meningitis

A

most common, aseptic meningitis, mild disease

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11
Q

three species responsible for most cases of bacterial meningitis

A

streptococcus pneumoniae, neisseria meningitidis, haemophilus influenzae type B (nearly eliminated due to HiB childhood vaccine)

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12
Q

all three pathogens responsible for meningitis are

A

encapsulated, to avoid phagocytosis and can grow in the blood stream; and, can invade the meninges reaching the CSF

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13
Q

bacterial meningitis

A

serious life-threatening disease develops rapidly and requires prompt medical intervention

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14
Q

antibiotics for bacterial meningitis

A

antibiotic therapy given by intravenous adminstration

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15
Q

diagnosis for bacterial meningitis

A

spinal tap

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16
Q

H. influenzae

A

small gram negative aerobic rod, misnamed when incorrectly identified as cause for influenza, common member of throat flora; occasionally enters blood stream and bad stuff begins

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17
Q

carbohydrate capsule in H. influenzae

A

aids in avoiding phagocytosis and survival

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18
Q

Antigenic Type B

A

most common in children where risk is high, disease occurs in primarily children under 4, by age 5, children typically immune due to cross immunity to other agents, HiB vaccine given at 6mo has nearly eliminated this childhood disease

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19
Q

streptococcus pneumoniae

A

common inhabitant of nasopharynx, gram + encapsulated diplococci, responsible for about 3000 cases of meningitis annually in the US., most frequent among children 1 month-4 years old, 30% mortality in children, 80% in elderly. starts with case of pneumonia of otitis media and progresses

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20
Q

leading cause of bacterial meningitis

A

streptococcus pneumoniae since HiB is on decline

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21
Q

factors which lead to progression of streptococcal meningitis

A

are part microbial, part host, antibiotic therapy depending upon sensitivity tests

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22
Q

Meningococcal Meningitis

A

caused by Neisseria meningitis, aerobic gram negative cocci, polysaccharide capsule important to virulence, very invasive organism, highly contagious, has 5 main capsule types, vaccine directed against 4/5, 5th on its way

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23
Q

Meningococcal meningitis common to which areas of the body?

A

nose and throat of carriers, without causing disease; 10% of the population constitutes reservoir of infection

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24
Q

meningococcal meningitis typically begins as

A

a throat infection, leading to becteremia and eventually meningitis; can cause death in a few hours after symptoms

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25
Q

meningococcal meningitis is most common in

A

children under the age of 2, sporadic adult cases, usually associated with crowded stressful environments: dorm life, military barracks, etc.

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26
Q

survivors of meningococcal meningitis typically have

A

deafness or brain impairment

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27
Q

Tetanus etiologic agent

A

Clostridium tetani

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28
Q

clostridium tetani

A

gram positive, spore-forming obligate anaerobic rod; common in soil-spores are ubiquitous in soil and animal fecal waste

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29
Q

all symptoms of tetanus are caused by

A

potent neurotoxin: Tetanus Toxin or Tetanospasmin

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30
Q

Tetanus results in

A

aka “lockjaw,” spastic paralysis and death by respiratory failure

31
Q

tetanus usually begins as a result of

A

a puncture wound infection (stepping on a nail, gunshot, knife, any deep puncture, compound fracture)

32
Q

C. tetani spores are taken…

A

deep into tissue; vascular disruption accentuates anaerobic environment which favors germination of spores, growth of bacterium, and production of Tetanus Toxin

33
Q

prevention of tetanus

A

vaccination: composed of Tetanus toxoid (inactive toxin); component of DPT (or DTaP) vaccine (Diphtheria, Pertussis, Tetanus)

34
Q

DPT

A

whole cell Pertussis component, more likely to cause fever and other side effects, although reported serious neurologic side effects of DPT have never been convincingly linked to pertussis whole cell vaccine

35
Q

DTaP

A

newer acellular version of Pertussis component

36
Q

TDaP

A

newer acellular booster following DTaP

37
Q

Tetanus vaccine

A

96% of children have good immunity but only 30% of adults over 70, booster is required every 10 years or so, tetanus rare today b/c of immunization

38
Q

Tetanus Immune Globulin (TIG)

A

can be administered to non-immune individual following severe wound, prepared from serum of immune humans

39
Q

Botulism

A

potentially deadly form of food poisoning

40
Q

botulism caused by

A

ingesting botulism neurotoxin

41
Q

botulism toxin

A

a product of Clostridium botulinum, an obligate anaerobic, gram positive, spore forming rod-shaped bacterium; also produced in neutral canned foods

42
Q

C. botulinum spores are found in

A

soil and water sediments, improperly canned foods are most common source of illness

43
Q

blood sausage

A

eastern Europe, pig intestine filled with blood, ground meats, tied off, boiled, smoked, stored at room temp

44
Q

Type A neurotoxin

A

deadly; causes flaccid paralysis; death by respiratory failure; symptoms include slurred speech, blurred vision, paralysis

45
Q

polio is the best known cause of

A

paralysis

46
Q

paralytic form of polio only affects __% of all those infected

A

1

47
Q

polio first appeared

A

in US in 1984 with an outbreak in Vermont, summer breakouts for following decades

48
Q

most affected by polio

A

adolescents and young adults

49
Q

death from polio because

A

respiratory failure

50
Q

transmission of polio

A

ingestion of contaminated water

51
Q

polio: invasion of

A

tonsils and small intestine leads to involvement of lymphatic system and blood stream

52
Q

Viremia

A

leads to invasion of capillary walls and CNS involvement

53
Q

polio: virus infects

A

the motor nerve cells of the CNS, cells dies and paralysis results

54
Q

salk vaccine

A

developed in 1954, inactivated polio vaccine (IPV) required series of injections…90% effective

55
Q

salbin vaccine

A

introduced in 1963, three living attenuated virus strains, administered orally, single dose vaccine

56
Q

oral vaccine for polio

A

OPV

57
Q

rabies virus

A

Lyssavirus of the Phabdoviridae family, neurotropic virus (targets the nervous system); single stranded RNA virus with no proofreading capability, thus, mutant strains develop quickly

58
Q

humans typically infected with rabies (worldwide) by

A

the bite of an infected (rabid) animal-especially dogs

59
Q

in the US the most common cases of rabies if from a

A

variant virus carried by the silver haired rat (dogs in US have high immunization rate)

60
Q

rabies virus can ____ in epidermal cells…

A

replicate, can also multiply in muscle and CT, virus then enters peripheral nervous system and travel along peripheral nerves at a rate of 15-100 mm per day

61
Q

once the rabies virus enters the CNS

A

causes encephalitis, virus inaccessible to immune system and CNS begins to be destroyed (when reaches brain-encephalitis is COD)

62
Q

slow migration of rabies virus allows

A

post exposure immunization; post exposure prophylaxis (PEP)-series of anti-rabies vaccine and immune globulin injections

63
Q

with CNS involvement of rabies patients

A

express agitation mixed with intervals of calm

64
Q

rabies symptoms

A

muscle spasms in mouth and pharynx, especially when swallowing liquid (sets off spasms hence historic common name of hydrophobia)

65
Q

final stages of rabies results in

A

extensive damage to nerve cells of the brain and spinal cord

66
Q

prevention of rabies

A

vaccine; vets and animal control individuals also immunized

67
Q

Prions

A

infectious misfolded glycolipoprotein associated with mammalian brain; spontaneous or infectious introduction results in misfolding cascade, producing insoluble protein fibrils in the brain resulting in death

68
Q

transmissible spongiform encephalopathies (TSEs)

A

srapie (sheep), Creutzfeld-Jacob Disease (CJD, human), Kuru (human), Bovine Spongiform Encephalopathy (bovine), Chronic Wasting Disease (deer, antelope)

69
Q

transmission of prion diseases

A

consumption of infected brain tissue

70
Q

Endogenous Prion Protein (PrP) has an

A

alpha helical structure, found in neurons; if the alpha helix converts to a beta-sheet structure, protein aggregates and catalyzes the convertion of other normal PrP (PrP^c) to pathogenic form (PrP^sc)

71
Q

PrP^sc

A

induces aggregate formation and subsequent neuronal toxicity

72
Q

Creutzfeld-Jacob Disease

A

often in families suggesting a genetic predisposition, transmission from comeal transplants observed, thus “infectious” transmission is certain

73
Q

symptoms of Creutzfeld-Jacob Disease

A

memory problems, behavioral changes, personality changes, failing vision, and problems with thinking and judgement. Later, involuntary jerking, blindness, loss of speech and death

74
Q

Kuru

A

appeared in tribes native to New Guinea, transmission associated with practice of cannibalism