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Microbiology > CH 26 - Nervous System Infections > Flashcards

CH 26 - Nervous System Infections Flashcards

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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
Meningococcal Meningitis: Virulence Factors (N. meningitidis)
1. Fimbriae 2. Capsule 3. Lipooligosaccharide (LOS)
26
Meningococcal Meningitis: Pathogenesis
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
27
Meningococcal Meningitis: Symptoms
- Cold - Headache - Fever - Nausea - Vomiting - Shock - Petechiae
28
Meningococcal Meningitis: Epidemiology
Spreads rapidly in crowded populations
29
Meningococcal Meningitis: Prevention
Vaccine - Purified capsular polysaccharides of N. meningitidis serogroup A, C, Y, & W135
30
Meningococcal Meningitis: Treatment
Antibiotics - Ceftriaxone & penicillin (in high doses) Rifampin can be given as prophylactic treatment to people intimately exposed to cases
31
Listeriosis: Causative Agent
Listeria monocytogenes - G+ rod - Motile - Non-spore forming - Facultative anaerobe Grows in macrophages & at 4C (low temps)
32
Listeriosis: Pathogenesis
Worldwide distribution in animals, plants, & soil Intracellular growth
33
Listeriosis: Transferred to humans by...
1. Contact with animal feces 2. Unpasteurized milk & cheese 3. Contaminated vegetables
34
Listeriosis: Infections occur primarily in 2 clinical settings...
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
35
Listeriosis: Prevention
- Cook meat thoroughly - Wash raw vegetables - Avoid soft cheeses (when pregnant)
36
Listeriosis: Treatment
Ampicillin (effective antibiotic)
37
Hansen's Disease (Leprosy): Causative Agent
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
Hansen's Disease (Leprosy): Symptoms
- Increased/decreased sensation in certain areas of skin - Numbness - Muscle wasting - Ulceration - Loss of fingers/toes
39
Tuberculoid leprosy
Cellular immunity suppresses proliferation of M. leprae
40
Lepromatous leprosy
Cellular immunity is suppressed Unrestricted growth of M. leprae in skin macrophages & peripheral nerves
41
Hansen's Disease (Leprosy): Epidemiology
Transmission via human-to-human contact - Mainly nasal secretions Natural infections occur in wild 9-banded armadillos & mangabey monkeys
42
Hansen's Disease (Leprosy): Treatment
Effective antibiotics: - Dapsone - Rifampin - Clofazimine NO vaccine
43
Botulism: Causative agent
Clostridium botulinum - G+ rod - Spore-forming - Anaerobe Endospores survive boiling for hours (autoclaving kills) Intoxication NOT CNS infection
44
3 forms of botulism:
1. Food-borne 2. Intestinal 3. Wound
45
Botulism: Pathogenesis
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
Botulism: Symptoms
Paralysis (flaccid) = principal symptom - Dizziness - Dry mouth - Blurred/double vision - Abdominal pain - Diarrhea
47
Botulism: Epidemiology
C. botulinum normally found in soil Food-borne botulism occurs when C. botulinum germinates & grows in food (anaerobic conditions)
48
Botulism: Prevention
Heat food to 100C for 15 min - BoTox = heat labile Clean infected wounds of dirt/dead tissue
49
Botulism: Treatment
IV administration of antitoxin
50
Viral Meningitis: Causative Agent
1. Enteroviruses - Member of picornaviruses - Small - Non-enveloped - + stranded RNA 2. Mumps virus - Enveloped; - stranded RNA More common than bacterial - Usually mild disease
51
Enteroviruses that cause viral meningitis:
1. Coxsackieviruses - Throat/chest pain 2. Echoviruses - Rash
52
Viral Meningitis: Symptoms
Similar to bacterial meningitis - Headache - Pain - Sensitivity of eyes to light - Nausea/vomiting
53
Viral Meningitis: Pathogenesis
Begins with infection of throat & intestinal epithelium Progresses to lymphoid tissue in blood stream - Viremia results in meningeal infection
54
Viral Meningitis: Epidemiology
Enteroviruses - Relatively stable in environment - Survive chlorinated water - Transmission via fecal-oral route Mumps virus - Transmitted via respiratory droplets (common in fall/winter)
55
Viral Meningitis: Prevention/Treatment
Hand washing & avoidance of crowded swimming pools NO vaccine against coxsackievirus or echovirus Vaccine against mumps virus
56
Sporadic Viral Encephalitis: Causative Agents
1. Herpes simplex virus 2. Mumps 3. Measles 4. Infectious mononucleosis
57
Endemic Viral Encephalitis: Causative Agents
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
Viral Encephalitis: Symptoms
- Fever - Headache - Vomiting 1 or more CNS abnormalities: - Disorientation - Localized paralysis - Deafness - Seizures - Coma
59
Viral Encephalitis: Pathogenesis
Viruses multiply at site of bite & in lymph nodes Enter bloodstream, cross BBB, & infect nerve cells
60
Viral Encephalitis: Prevention
Animals often used to ID emergence of disease Avoid outdoor activities at night when mosquito populations highest
61
Poliomyelitis: Causative Agent
Polio virus - Picornavirus - Non-enveloped - ssRNA 3 antigenic types (protection requires Abs to all 3)
62
Poliomyelitis: Symptoms
- Headache - Fever - Stiff neck - Nausea - Pain - Paralysis - Muscle-shrinking - Abnormal bone development
63
Poliomyelitis: Pathogenesis
Transmission fecal-oral route Spreads through bloodstream to CNS Replicates in motor nerves of brain & spinal cord
64
Poliomyelitis: Prevention
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
Rabies: Causative Agent
Rabies virus - Rhabdovirus family - Enveloped - ssRNA
66
Rabies: Symptoms
- Fever - Headache - Nausea - Vomiting - Sore throat - Spasms of muscle of mouth/throat (later) - Coma (later)
67
Rabies: Pathogenesis
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
Rabies: Epidemiology
Bite of rabid animal (bats, racoons, et.c)
69
Rabies: Prevention & Treatment
Avoid suspect animals Immunize pets Immediately wash wound & apply antiseptic
70
Cryptococcal Meningoencephalitis: Causative Agent
Cryptococcus neoformans Infection of meninges & brain by yeast
71
Cryptococcal Meningoencephalitis: Symptoms
- Dizziness - Headache - Vomiting - Seizure - Paralysis - Coma
72
Cryptococcal Meningoencephalitis: Pathogenesis
Infection starts in lung - C. neoformans multiply Enter bloodstream & carried to various parts of body - Can invade meninges & brain
73
Cryptococcal Meningoencephalitis: Epidemiology
C. neoformans located in soil & vegetation - Especially soil with pigeon droppings Infection contracted by inhaling contaminated dust
74
Cryptococcal Meningoencephalitis: Prevention
NO vaccine or preventative measures available
75
Cryptococcal Meningoencephalitis: Treatment
Amphotericin B = effective antibiotic
76
African Trypanosomiasis: Causative Agent
Trypanosoma brucei (protozoa) Infection of blood & CNS
77
African Trypanosomiasis: Symptoms
- Fever - Headache - Uncontrollable sleepiness - Poor concentration - Coma
77
African Trypanosomiasis: Pathogenesis
Bite of infected tsetse fly - T. brucei in fly's saliva enters bite wound Trypanosomas multiply & enter lymphatic & blood circulation - Can infect CNS
78
African Trypanosomiasis: Epidemiology
10,000-20,000 cases/year Determined by distribution of tsetse fly
79
African Trypanosomiasis: Prevention
Protective clothing Insecticides
80
African Trypanosomiasis: Treatment
- Melarsoprol - Eflornithine - Suramine
81
Transmissible Spongiform Encephalopathy (TSE): Causative Agent
Prions (PrP) - Proteinaceous infectious particles Brain disease
82
Transmissible Spongiform Encephalopathy (TSE): Symptoms
- Muscle jerks - Lack of coordination - Memory loss - Loss of muscle function
83
Transmissible Spongiform Encephalopathy (TSE): Pathogenesis
Infection starts in spleen & other lymphoid tissues Prions transported to CNS by B cells
84
Transmissible Spongiform Encephalopathy (TSE): Epidemiology
Transmission of cattle prions to humans - Eat contaminated beef - Mad cow disease (cows) Rare in humans - Creutzfeldt-Jakob disease
85
Transmissible Spongiform Encephalopathy (TSE): Prevention
Use of sterile surgical instruments

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