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Clinical Microbiology > (exam 2) ch 22 microbial diseases of the nervous system > Flashcards

(exam 2) ch 22 microbial diseases of the nervous system Flashcards

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1
Q

what are the two main divisions of the nervous system?

A

1) central nervous system (CNS)

2) peripheral nervous system (PNS)

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2
Q

what is the central nervous system (CNS) ?

A

consists of the Brian and spinal cord; it is the control center of the body

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3
Q

what is the peripheral nervous system (PNS) ?

A

consists of nerves that branch from the CNS; nerves from the branch of from CNS and serves as communication lines

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4
Q

what are the meninges?

A

continuous membranes that protect the brain and spinal cord

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5
Q

what are the three layers of the meninges and where are they positioned?

A

1) outer— dura mater
2) middle — arachnoid mater
3) inner— pia mater

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6
Q

_________ mater is the layer of the meninges is the outer potion.

A

dura mater

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7
Q

_________ mater is the layer of the meninges that is in the middle.

A

arachnoid mater

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8
Q

_________ mater is the layer of the meninges that is in the inner portion.

A

pia mater

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9
Q

what is cerebrospinal fluid (CSF)?

A

fluid in the subarachnoid space (between arachnoid and Pia mater) that acts as a ‘cushion’

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10
Q

what is the blood brain barrier?

A

layer of endothelial cells that prevent solutes in circulating blood from non-selectively crossing into CNS (effective at keeping pathogens out)

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11
Q

what are two of the most common routs of Central Nervous System (CNS) invasion?

A

via the bloodstream and lymphatic system

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12
Q

what can alter the permeability of the blood brain barrier?

A

inflammation

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13
Q

what three things does the central nervous system have low levels of?

A

low levels of

1) complement
2) circulating antibodies
3) phagocytic cells

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14
Q

what is meningitis?

A

inflammation of the brain meninges

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15
Q

what is encephalitis?

A

inflammation of the brain

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16
Q

what is meningoencephalitis?

A

inflammation of both the brain meninges and the brain

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17
Q

(as an overview) what is meningitis caused by?

A

can be caused by a variety of pathogens (bacteria, viruses, fungi, or protozoa); viral meningitis is more common but usually mild

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18
Q

what are the symptoms of meningitis?

A

Triad of fever, headache, and a stiff neck; followed by nausea and vomiting. Symptoms may progress to convulsions and coma (neurological specific)

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19
Q

Haemophilus influenzae type b, neisseria meningitides, and streptococcus pneumoniae are all three species of what?

A

three species of bacterial meningitis

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20
Q

what do these three species, Haemophilus influenzae type b, neisseria meningitides, and streptococcus pneumoniae have in common?

A

they all have a capsule

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21
Q

how does death usually occur from bacterial meningitis?

A

death from shock and inflammation (due to endotoxin (gram - ) and cell wall release (gram +); survival often results in neurological damage

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22
Q

what is the structure of Haemophilus influenzae type b (Hib) Meningitis?

A

gram negative, aerobic bacteria; (opportunistic) in normal throat bacteria and can enter the blood stream. Its pathogenicity is due to capsule antigen type b

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23
Q

what is another name for Haemophilus influenzae type b?

A

Hib meningitis

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24
Q

what group is Hib meningitis most common?

A

occurs mostly in children 6 months to 4 years

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25
Q

is there prevention for Hib meningitis?

A

yes, prevented by the Hib vaccine

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26
Q

what is the structure of neisseria meningitides Meningitis?

A

aerobic, gram negative diplococcus with a capsule; there are six serotypes associated with the disease. Microbiota of nose and throat in about 40% of people

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27
Q

what is another name for neisseria meningitides meningitis?

A

Meningococcal Meningitis

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28
Q

what are symptoms for neisseria meningitides meningitis? aka meningococcal meningitis

A

begins as a throat infection, RASH, and bacteremia; symptoms are mostly from endotoxin; death can occur within hours after fever onset - very rapid

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29
Q

where is neisseria meningitides meningitis (aka meningococcal meningitis) most common and what age group?

A

typically occurs in children under 2 yrs; highest incidence in “meningitis belt” which is in sub-saharan Africa

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30
Q

is there prevention for neisseria meningitides meningitis (aka meningococcal meningitis) ?

A

vaccination protects against 5/6 serogroups

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31
Q

what is the structure of streptococcus pneumoniae?

A

gram positive, encapsulated diplococcus; 70% of people are healthy nasopharyngeal carriers

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32
Q

is there another name for streptococcus pneumoniae?

A

pneumococcal meningitis

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33
Q

which of the three types of bacterial meningitis is the leading cause?

A

streptococcus pneumoniae (aka pneumococcal meningitis)

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34
Q

what two other things can streptococcus pneumoniae (aka pneumococcal meningitis) cause?

A

pneumonia and otitis media

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35
Q

what group is streptococcus pneumoniae (aka pneumococcal meningitis) most common in?

A

most common in children 1 month to 4 yrs

36
Q

is there prevention for streptococcus pneumoniae (aka pneumococcal meningitis)?

A

yes, prevented by conjugated vaccine

37
Q

how would you diagnose the most common types of bacterial meningitis?

A

sample of cerebral spinal fluid via a spinal tab or lumbar puncture; samples are used for gram staining, culturing, and latex agglutination tests

38
Q

why do tests used to diagnose some of the most common types of bacterial meningitis require prompt and careful handling?

A

because pathogens in CSF do not survive storage or changes in temperature

39
Q

what does the beginning standard treatment for the most common types of bacterial meningitis look like?

A

chemotherapy (antibiotics) are initiated before diagnosis; due to rapid disease progression and threat of mortality; use of broad spectrum antibiotics- more specific treatment after identification

40
Q

what is the cause of listeriosis?

A

caused by Listeria monocytogenes

41
Q

what is the structure of listeriosis?

A

gram positive rod; excepted in animal feces; wide distribution in soil and water; it is a psychrophile (food borne illness)

42
Q

what are three notable virulence factors of listeriosis?

A

1) not destroyed by phagocytes
2) reproduces within them
3) moves directly between them

43
Q

what are two forms of listeriosis?

A

1) adult infection

2) infection of fetus and newborn

44
Q

what is adult infection of listeriosis?

A

mild or symptomless infection; can invade the bloodstream causing sepsis; meningitis is more common in the immunocompromised

45
Q

what is infection with listeriosis of a fetus or newborn?

A

infects pregnant women, crossing the placenta and leading to stillbirth; diseases manifests weeks after birth usually meningitis (infant mortality rate ~60%)

46
Q

why is listeriosis listed under a type of meningitis?

A

because if a fetus or newborn is infected it can result in meningitis after birth

47
Q

what type of disease to the nervous system is tetanus?

A

bacterial disease

48
Q

what is tetanus caused by?

A

clostridium tetani

49
Q

what is the structure of tetanus?

A

gram positive, endospore-forming, obligate anaerobe; grows deep within wounds with anaerobic conditions

50
Q

what is the disease state of tetanus?

A

infection causes no inflammation; bacteria do not leave infection site; tetanospasmin neurotoxin (bad toxin) released from bacterial cells and enters the CNS via blood or peripheral nerves

51
Q

what are the effects of the tetanospasmin neurotoxin of tetanus?

A

blocks relaxation pathway in muscles causing muscle spasms - jaw muscles are usually affected early resulting in lock jaw (indicative of tetanus)

52
Q

how does death typically occur from tetanus?

A

death occurs from spasms of respiratory muscles

53
Q

is there prevention for tetanus?

A

yes, prevented by vaccination with tetanus toxoid (DTaP); stimulates antibodies that neutralize the toxin; booster is required every 10 yrs (40% of US adults are not protected)

54
Q

what are alternative treatments for tetanus?

A

treatment with tetanus immune globulin (TIG) antibody again toxin; or infected tissue removed via debridement

55
Q

what type of disease to the nervous system is botulism?

A

bacterial disease

56
Q

what is the structure of botulism?

A

gram positive, endosperm forming, obligate anaerobe

57
Q

what typically causes botulism?

A

caused from ingesting toxin through contaminated food

58
Q

what is the toxin of botulism specific for?

A

specific for the synaptic end of the nerve and blocks release of the neurotransmitter acetylcholine, causing flaccid paralysis

59
Q

lock jaw and muscle spasms are indicative of ________ whereas the ‘opposite’ flaccid paralysis (limb muscles) is indicative of _______.

A

tetanus; botulism

60
Q

what are the symptoms of botulism?

A

difficulty swallowing, general weakness, blurred or double vision

61
Q

how does death usually occur from botulism?

A

death usually from respiratory or cardiac failure

62
Q

what are the three botulinal types??

A

1) Type A toxin
2) Type B Toxin
3) Type E toxin

63
Q

which of the three botulinal types is the most virulent?

A

type A toxin; 60-70% fatality

64
Q

what is type A toxin of botulism?

A

most virulent because it is made in proteolytic strains with heat resistant spores; Western US

65
Q

what is type B toxin of botulism?

A

fatality 25% most common in Europe and eastern US

66
Q

what is type E toxin of botulism?

A

spree are less heat resistant than other strains; produced by organisms in marine and lake sediments (Pacific Northwest, Alaska, and Great Lakes)

67
Q

which of the three botulinal types is responsible for 50% of cases; which two is responsible for the other 50%?

A

type A is responsible for 50% of cases;

type B and type E are responsible for the other 50% of cases

68
Q

why is botulism in adults not serious?

A

because in adults, Clostridium is outcompeted by normal intestinal microbes

69
Q

why is botulism more serious in infants?

A

C. botulinum grows in infants due to lack of intestinal microbiota

70
Q

what is wound botulism?

A

growth of C.botulism in wounds

71
Q

how is botulism diagnosed?

A

diagnosed by inoculating mice with patient samples

72
Q

what is the treatment for botulism?

A

supportive care (long recovery process); recovery requires regeneration of nerve endings (slow process); extended respiratory assistance and application of antitoxins (against toxins)

73
Q

what is a therapeutic approach to botulism?

A

Botox; treatment of migraine, painful muscle contractions (Parkinson’s disease), involuntary eyelid twitching and there are purely cosmetic applications

74
Q

how can botulism be prevented?

A

prevented with proper canning and the use of nitrates in food

75
Q

what type of disease to the nervous system is leprosy?

A

bacterial disease

76
Q

what causes leprosy?

A

Mycobacterium leprae

77
Q

what is another name for leprosy?

A

Hansen’s disease

78
Q

what is the structure of leprosy ( Hansen’s disease)?

A

acid-fast rod (waxy coating); grows best at 30 degrees celsius (prefers cooler areas of the body such as peripheral nerves and skin cells); able to survive macrophage ingestion and eventually invades nerve cells

79
Q

what is the generation time for leprosy?

A

long generation time ~12 days

80
Q

what is unique about leprosy?

A

has never bene grown on an artificially media; only on some animals

81
Q

what are the two primary forms of leprosy?

A

1) Tuberculoid (neural) form

2) Lepromatous (progressive) form

82
Q

what is Tuberculoid (neural) form of leprosy?

A

reflects effective patient immune response (can fight it off); loss of sensation in skin areas

83
Q

what is Lepromatous (progressive) form?

A

less effective immune response (disease progresses past the tuberculoid stage); disfiguring nodules over the body; mucous membranes are affected

84
Q

what is the cause of death usually from leprosy?

A

not from leprosy itself but from disease complications from having leprosy

85
Q

how is leprosy transmitted?

A

transmission requires prolonged contact with an infected person or the inhalation of secretions (often years between infection and appearance of symptoms

86
Q

how do we diagnose leprosy?

A

diagnosed with a skin biopsy, skin smear or blood test

87
Q

what is the typical treatment for leprosy?

A

long term antibiotic treatment ranging from 6-24 months

Clinical Microbiology (17 decks)

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