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Microbiology > CH 26 - Nervous System Infections > Flashcards

CH 26 - Nervous System Infections Flashcards

1
Q

Blood-brain barrier
(definition)

A

Cells that function together to create protective semipermeable border that separates CNS from bloodstream

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2
Q

Central nervous system (CNS)
(definition)

A

Brain & spinal cord

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3
Q

Cerebrospinal fluid (CSF)
(definition)

A

Fluid produced in brain that flows within & around CNS

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4
Q

Encephalitis
(definition)

A

Inflammation of the brain

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5
Q

Meninges
(definition)

A

Membranes covering brain & spinal cord

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6
Q

Meningitis
(definition)

A

Inflammation of the meninges

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7
Q

Peripheral nervous system (PNS)
(definition)

A

Division of the NS that carries information to & from the CNS

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8
Q

Transmissible Spongiform Encephalopathy (TSE)
(definition)

A

Chronic degenerative brain disease caused by prions

Characterized by spongy appearance of brain tissue

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9
Q

Structures of CNS:

A
  1. Brain
    - Cerebrum = perception & thinking
    - Cerebellum = body movements
    - Brain stem = breathing & HR
  2. Spinal cord (brain stem to lumbar)
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10
Q

Structures of PNS:

A
  1. Sensory nerves
    - Carry signals toward CNS
  2. Motor nerves
    - Carry signals away from CNS
  3. Mixed nerves
    - Carry signals toward & away from CNS
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11
Q

Negative outcomes of central nervous system infections (CNSI):

A
  1. Threaten person’s ability to move, feel, & thick normally
  2. Destroy nerve cells, leading to paralysis
  3. Complete loss of fingers/toes or deformity of face
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12
Q

Portals of infection of CNS:
(how pathogens can access)

A
  1. Breaks in bones/meninges
  2. Medical procedures
  3. Traveling in peripheral neurons to CNS
  4. Infecting/killing cells of the meninges (resulting in meningitis)
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13
Q

Bacterial Nervous System Infections (2 ways):

A
  1. Bacteria infect cells of nervous system
    - Meningitis
    - Leprosy
  2. Bacteria growing elsewhere release toxins that affect neurons
    - Botulism
    - Tetanus
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14
Q

Meningitis:
General Symptoms

A
  • High fever
  • Headache
  • Stiff neck
  • Nausea
  • Vomiting
  • Photophobia
  • Confusion
  • Sleepiness
  • Seizures (late stage)
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15
Q

Meningoencephalitis

A

Inflammation/infection of meninges & brain

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16
Q

Bacteria Meningitis

A

Inflammation of covering of brain & spinal cord

Spread by direct close contact with discharges from nose/throat of infected people (crowded places)

Can result in irreversible neurological damage & death (blindness, deafness, learning deficiencies)

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17
Q

Bacterial Meningitis:
Main Causative Agents

A
  1. Neisseria meningitidis
  2. Streptococcus penumoniae
  3. Haemophilus influenza
  4. Listeria monocytogenes
  5. Streptococcus agalactiae
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18
Q

Bacterial Meningitis:
Main Causes in Newborns

A
  1. Escherichia coli
  2. Streptococcus agalactiae
  3. Listeria monocytogenes
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19
Q

Bacterial Meningitis:
Symptoms over age 2

A
  • High fever
  • Headache
  • Stiff neck
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20
Q

Bacterial Meningitis:
Symptoms in newborns & infants

A

Fever, headache, & neck stiffness may be hard to detect

  • Inactivity
  • Irritability
  • Vomiting
  • Poor feeding
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21
Q

Bacterial Meningitis:
Prevention

A

Vaccines against:
- H. influenza type B
- Most strains of N. meningitidis
- Many types of S. pneumoniae

Rapid diagnosis

Prompt treatment of close personal contacts

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22
Q

Bacterial Meningitis in Newborns:
Streptococcus agalactiae

A

Group B strep
- G+ cocci in chains
- Colonizes vagina (15-40% of pregnant women)
- Leading infectious cause of morbidity & mortality in US newborns

Major cause of “early onset” meningitis in newborns (<72 hrs after birth)

Culture + women treated with antibiotics prior/during labor

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23
Q

Bacterial Meningitis in Newborns:
E. coli

A

G- rods
- From mother’s GI tract

2nd most common cause of “early onset” meningitis
- Most caused by E. coli K1 strains (produce polysialic acid K1 capsule)

Invasion across BBB requires several genes for:
1. Binding
2. Invasion
3. Intracellular survival

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24
Q

Meningococcal Meningitis:
Causative Agent

A

Neisseria meningitidis
- G- diplococcus
- Nonmotile
- Most common cause of bacterial meningitis

13 antigenic groups
- Most serious infections due to strains: A, B, C, Y, & W135

Can progress to death within a few hours

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25
Q

Meningococcal Meningitis:
Virulence Factors (N. meningitidis)

A
  1. Fimbriae
  2. Capsule
  3. Lipooligosaccharide (LOS)
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26
Q

Meningococcal Meningitis:
Pathogenesis

A
  1. Inhale airborne droplets from respiratory tract of another person
    - Humans = ONLY source of infection
  2. Attaches to mucous membrane by pili
  3. Invades bloodstream
    - Blood carries to meninges & CSF

Much damage results from vesicles
- Used to shed extrusion of outer membrane

Lipid A of LOS released into body
- Fever, vasodilation, inflammation, & widespread clotting

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27
Q

Meningococcal Meningitis:
Symptoms

A
  • Cold
  • Headache
  • Fever
  • Nausea
  • Vomiting
  • Shock
  • Petechiae
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28
Q

Meningococcal Meningitis:
Epidemiology

A

Spreads rapidly in crowded populations

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29
Q

Meningococcal Meningitis:
Prevention

A

Vaccine
- Purified capsular polysaccharides of N. meningitidis serogroup A, C, Y, & W135

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30
Q

Meningococcal Meningitis:
Treatment

A

Antibiotics
- Ceftriaxone & penicillin (in high doses)

Rifampin can be given as prophylactic treatment to people intimately exposed to cases

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31
Q

Listeriosis:
Causative Agent

A

Listeria monocytogenes
- G+ rod
- Motile
- Non-spore forming
- Facultative anaerobe

Grows in macrophages & at 4C (low temps)

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32
Q

Listeriosis:
Pathogenesis

A

Worldwide distribution in animals, plants, & soil

Intracellular growth

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33
Q

Listeriosis:
Transferred to humans by…

A
  1. Contact with animal feces
  2. Unpasteurized milk & cheese
  3. Contaminated vegetables
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34
Q

Listeriosis:
Infections occur primarily in 2 clinical settings…

A
  1. Fetus or newborn
    - Transmission across placenta or during delivery
    - Infected mother may be asymptomatic or have flu-like illness
  2. Immune suppressed pts
    - Can lead to sepsis or meningitis
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35
Q

Listeriosis:
Prevention

A
  • Cook meat thoroughly
  • Wash raw vegetables
  • Avoid soft cheeses (when pregnant)
36
Q

Listeriosis:
Treatment

A

Ampicillin (effective antibiotic)

37
Q

Hansen’s Disease (Leprosy):
Causative Agent

A

M. leprae
- Rod
- Aerobic
- Acid-fast (mycolic acid in cell wall)

Grows very slowly (generation time = 12 days)

Preferentially infects cells in peripheral nerves
- Granulomatous disease of PNS

38
Q

Hansen’s Disease (Leprosy):
Symptoms

A
  • Increased/decreased sensation in certain areas of skin
  • Numbness
  • Muscle wasting
  • Ulceration
  • Loss of fingers/toes
39
Q

Tuberculoid leprosy

A

Cellular immunity suppresses proliferation of M. leprae

40
Q

Lepromatous leprosy

A

Cellular immunity is suppressed

Unrestricted growth of M. leprae in skin macrophages & peripheral nerves

41
Q

Hansen’s Disease (Leprosy):
Epidemiology

A

Transmission via human-to-human contact
- Mainly nasal secretions

Natural infections occur in wild 9-banded armadillos & mangabey monkeys

42
Q

Hansen’s Disease (Leprosy):
Treatment

A

Effective antibiotics:
- Dapsone
- Rifampin
- Clofazimine

NO vaccine

43
Q

Botulism:
Causative agent

A

Clostridium botulinum
- G+ rod
- Spore-forming
- Anaerobe

Endospores survive boiling for hours (autoclaving kills)

Intoxication NOT CNS infection

44
Q

3 forms of botulism:

A
  1. Food-borne
  2. Intestinal
  3. Wound
45
Q

Botulism:
Pathogenesis

A

Produce endospores that are highly resistant

Spores germinate, grow, & release exotoxin (BoTox) into food

BoTox = neurotoxin
- 1 of most powerful toxins known
- Cleaves SNARE protein involved in ACh release at NMJ
- No ACh release = flaccid paralysis

46
Q

Botulism:
Symptoms

A

Paralysis (flaccid) = principal symptom

  • Dizziness
  • Dry mouth
  • Blurred/double vision
  • Abdominal pain
  • Diarrhea
47
Q

Botulism:
Epidemiology

A

C. botulinum normally found in soil

Food-borne botulism occurs when C. botulinum germinates & grows in food (anaerobic conditions)

48
Q

Botulism:
Prevention

A

Heat food to 100C for 15 min
- BoTox = heat labile

Clean infected wounds of dirt/dead tissue

49
Q

Botulism:
Treatment

A

IV administration of antitoxin

50
Q

Viral Meningitis:
Causative Agent

A
  1. Enteroviruses
    - Member of picornaviruses
    - Small
    - Non-enveloped
    - + stranded RNA
  2. Mumps virus
    - Enveloped; - stranded RNA

More common than bacterial
- Usually mild disease

51
Q

Enteroviruses that cause viral meningitis:

A
  1. Coxsackieviruses
    - Throat/chest pain
  2. Echoviruses
    - Rash
52
Q

Viral Meningitis:
Symptoms

A

Similar to bacterial meningitis

  • Headache
  • Pain
  • Sensitivity of eyes to light
  • Nausea/vomiting
53
Q

Viral Meningitis:
Pathogenesis

A

Begins with infection of throat & intestinal epithelium

Progresses to lymphoid tissue in blood stream
- Viremia results in meningeal infection

54
Q

Viral Meningitis:
Epidemiology

A

Enteroviruses
- Relatively stable in environment
- Survive chlorinated water
- Transmission via fecal-oral route

Mumps virus
- Transmitted via respiratory droplets (common in fall/winter)

55
Q

Viral Meningitis:
Prevention/Treatment

A

Hand washing & avoidance of crowded swimming pools

NO vaccine against coxsackievirus or echovirus

Vaccine against mumps virus

56
Q

Sporadic Viral Encephalitis:
Causative Agents

A
  1. Herpes simplex virus
  2. Mumps
  3. Measles
  4. Infectious mononucleosis
57
Q

Endemic Viral Encephalitis:
Causative Agents

A
  1. Arboviruses
    - Arthropod born viruses
  2. Togavirus
    - Eastern & western equine viruses
  3. Flavivirus
    - St. Louis encephalitis
    - Yellow fever
    - Dengue virus
  4. Bunyavirus
    - California equine virus
  5. Reovirus
    - Colorado tick fever virus
58
Q

Viral Encephalitis:
Symptoms

A
  • Fever
  • Headache
  • Vomiting

1 or more CNS abnormalities:
- Disorientation
- Localized paralysis
- Deafness
- Seizures
- Coma

59
Q

Viral Encephalitis:
Pathogenesis

A

Viruses multiply at site of bite & in lymph nodes

Enter bloodstream, cross BBB, & infect nerve cells

60
Q

Viral Encephalitis:
Prevention

A

Animals often used to ID emergence of disease

Avoid outdoor activities at night when mosquito populations highest

61
Q

Poliomyelitis:
Causative Agent

A

Polio virus
- Picornavirus
- Non-enveloped
- ssRNA

3 antigenic types (protection requires Abs to all 3)

62
Q

Poliomyelitis:
Symptoms

A
  • Headache
  • Fever
  • Stiff neck
  • Nausea
  • Pain
  • Paralysis
  • Muscle-shrinking
  • Abnormal bone development
63
Q

Poliomyelitis:
Pathogenesis

A

Transmission fecal-oral route

Spreads through bloodstream to CNS

Replicates in motor nerves of brain & spinal cord

64
Q

Poliomyelitis:
Prevention

A

Global vaccination campaign has ALMOST eliminated
- Wild virus only found in Afghanistan & Pakistan

Salk vaccine
- Inactivated vaccine (formalin-killed)

Sabin vaccine
- Attenuated vaccine
- Given orally
- Induces secretory IgA (interrupts fecal-oral transmission)

65
Q

Rabies:
Causative Agent

A

Rabies virus
- Rhabdovirus family
- Enveloped
- ssRNA

66
Q

Rabies:
Symptoms

A
  • Fever
  • Headache
  • Nausea
  • Vomiting
  • Sore throat
  • Spasms of muscle of mouth/throat (later)
  • Coma (later)
67
Q

Rabies:
Pathogenesis

A

Transmission via saliva of rabid animal

Virus enters axon & carried along length of nerve
- Reaches brain & multiplies in brain tissue
- Symptoms of encephalitis

Negri bodies
- Characteristic inclusion bodies

68
Q

Rabies:
Epidemiology

A

Bite of rabid animal (bats, racoons, et.c)

69
Q

Rabies:
Prevention & Treatment

A

Avoid suspect animals

Immunize pets

Immediately wash wound & apply antiseptic

70
Q

Cryptococcal Meningoencephalitis:
Causative Agent

A

Cryptococcus neoformans

Infection of meninges & brain by yeast

71
Q

Cryptococcal Meningoencephalitis:
Symptoms

A
  • Dizziness
  • Headache
  • Vomiting
  • Seizure
  • Paralysis
  • Coma
72
Q

Cryptococcal Meningoencephalitis:
Pathogenesis

A

Infection starts in lung
- C. neoformans multiply

Enter bloodstream & carried to various parts of body
- Can invade meninges & brain

73
Q

Cryptococcal Meningoencephalitis:
Epidemiology

A

C. neoformans located in soil & vegetation
- Especially soil with pigeon droppings

Infection contracted by inhaling contaminated dust

74
Q

Cryptococcal Meningoencephalitis:
Prevention

A

NO vaccine or preventative measures available

75
Q

Cryptococcal Meningoencephalitis:
Treatment

A

Amphotericin B = effective antibiotic

76
Q

African Trypanosomiasis:
Causative Agent

A

Trypanosoma brucei (protozoa)

Infection of blood & CNS

77
Q

African Trypanosomiasis:
Symptoms

A
  • Fever
  • Headache
  • Uncontrollable sleepiness
  • Poor concentration
  • Coma
77
Q

African Trypanosomiasis:
Pathogenesis

A

Bite of infected tsetse fly
- T. brucei in fly’s saliva enters bite wound

Trypanosomas multiply & enter lymphatic & blood circulation
- Can infect CNS

78
Q

African Trypanosomiasis:
Epidemiology

A

10,000-20,000 cases/year

Determined by distribution of tsetse fly

79
Q

African Trypanosomiasis:
Prevention

A

Protective clothing

Insecticides

80
Q

African Trypanosomiasis:
Treatment

A
  • Melarsoprol
  • Eflornithine
  • Suramine
81
Q

Transmissible Spongiform Encephalopathy (TSE):
Causative Agent

A

Prions (PrP)
- Proteinaceous infectious particles

Brain disease

82
Q

Transmissible Spongiform Encephalopathy (TSE):
Symptoms

A
  • Muscle jerks
  • Lack of coordination
  • Memory loss
  • Loss of muscle function
83
Q

Transmissible Spongiform Encephalopathy (TSE):
Pathogenesis

A

Infection starts in spleen & other lymphoid tissues

Prions transported to CNS by B cells

84
Q

Transmissible Spongiform Encephalopathy (TSE):
Epidemiology

A

Transmission of cattle prions to humans
- Eat contaminated beef
- Mad cow disease (cows)

Rare in humans
- Creutzfeldt-Jakob disease

85
Q

Transmissible Spongiform Encephalopathy (TSE):
Prevention

A

Use of sterile surgical instruments

Microbiology (15 decks)

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