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MICRB 106 - FINAL > Rickettsias, Chlamydias, Spirochetes, and Vibrios > Flashcards

Rickettsias, Chlamydias, Spirochetes, and Vibrios Flashcards

1
Q

What is the most common genus of rickettsias associated with human diseases?

A

Rickettsiae

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2
Q

Rickettsias got their name from ______

A

Howard Ricketts

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3
Q

Where do rickettsias live inside their host’s cells?

A

The cytosol

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4
Q

Why are rickettsias obligate intracellular parasites?

A

They cannot use glucose and must find nutrients in the cytosol

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5
Q

What is the fate of a rickettsia outside of its host’s cells?

A

Becomes unstable and dies

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6
Q

Transmission of rickettsias from host to host requires a ______

A

Vector

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7
Q

What is the causative agent of Rocky Mountain spotted fever (RMSF)?

A

R. rickettsii

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8
Q

What kind of arthropod introduces the causative agent of RMSF to human hosts?

A

Hard ticks

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9
Q

Why does it take several hours of feeding by the vector for R. rickettsii bacteria to become infective?

A

They are dormant in the salivary glands of tick vectors

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10
Q

Describe how R. rickettsia enters the cytosol of blood vessel endothelial cells (2)

A
  • Triggers endocytosis
  • Lyses the endosome’s membrane
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11
Q

______ cause leakage of blood into tissues in RMSF

A

Damaged endothelial cells

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12
Q

What are the immediate physiological consequences due to leakage of blood into tissues? (2)

A
  • Hypotension
  • Insufficient nutrients / oxygen
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13
Q

Describe the rash associated with RMSF

A

Spotted non-itchy rash

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14
Q

How is RMSF treated? (2)

A
  • Removal of tick
  • Antibiotics
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15
Q

How is RMSF prevented? (3)

A
  • Tight-fitting clothing
  • Tick repellent
  • Avoiding tick-infected areas
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16
Q

Obligate intracellular chlamydias are restricted to the ______ of host cells

A

Vesicles

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17
Q

What is the morphology of chlamydial elemental bodies (EBs)?

A

Tiny cocci

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18
Q

What is the morphology of chlamydial reticulate bodies (RBs)?

A

Large pleomorphic

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19
Q

Describe chlamydial elemental bodies (EBs) (3)

A
  • Dormant
  • Infective
  • Extracellular
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20
Q

Describe chlamydial reticulate bodies (RBs) (2)

A
  • Non-infective
  • Intracellular
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21
Q

Chlamydial reticulate bodies (RBs) replicate within ______

A

Phagosomes

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22
Q

Why are chlamydias called ‘energy parasites’?

A

They lack enzymes needed to synthesize ATP

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23
Q

Describe EBs / RBs in the life cycle of chlamydias (3)

A
  • EBs trigger endocytosis
  • EBs convert into RBs
  • EBs are released via exocytosis
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24
Q

Inclusion bodies occur in the life cycle of chlamydias when the infected vesicle becomes filled with ______

A

RBs

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25
What is the host range for Chlamydia trachomatis?
Humans
26
How does Chlamydia trachomatis enter the human body?
Abrasions / lacerations
27
What are the 2 major body systems by which Chlamydia trachomatis enters a human body?
- Conjunctiva - Mucous membranes
28
What is the causative agent of lymphogranuloma venereum?
C. trachomatis
29
Why is the initial lesion of lymphogranuloma venereum often overlooked?
It is painless and heals rapidly
30
The second stage of lymphogranuloma venereum is characterized by development of ______
Buboes
31
How do urethritis / proctitis develop from LGV strains of C. trachomatis?
Lymphatic spread
32
What is proctitis?
Inflammation of the rectum
33
What is the causative agent of trachoma?
C. trachomatis
34
What is trachoma?
Non-traumatic blindness
35
Describe the pathology that causes blindness from trachoma (3)
- Multiplies in the conjunctiva - Eyelids turn inward - Cornea fills with blood
36
What does the term spirochete mean in Greek?
Coiled hairs
37
What is the morphology of a spirochete?
Helical axial filaments
38
Where are axial filaments and endoflagella located?
Between the cytoplasmic membrane and outer membrane
39
Describe the mechanism by which spirochetes move through their environment (2)
- Axial filament rotates - Spirochetes corkscrew through the environment
40
What is the causative agent of syphilis?
T. pallidum
41
What qualities make T. pallidum an obligate intracellular parasite? (2)
- Fastidiousness - Environmental sensitivity
42
What is the host range for T. pallidum?
Humans
43
How is T. pallidum transmitted?
Sexual contact
44
Chancre formation and millions of spirochetes refers to ______ syphilis
Primary
45
Spreading through the bloodstream and a widespread rash refers to ______ syphilis
Secondary
46
Disappearance of rash refers to ______ syphilis
Latent
47
Gumma formation refers to ______ syphilis
Tertiary
48
Tertiary syphilis is NOT associated with effects of ______
Treponema
49
Latent syphilis can last ______ years
30 or more
50
What is a chancre?
Small, painless red lesion
51
Why are chancres considered to be extremely contagious?
They are filled with spirochetes
52
What tissues or organs are affected by tertiary syphilis?
ANY
53
What are gummas?
Rubbery, painful, swollen lesions
54
What is the causative agent of Lyme disease?
B. burgdoferi
55
From what incident did Lyme disease get its name?
The extremely high incidence of childhood rheumatoid arthritis in Lyme, Connecticut
56
What kind of arthropod introduces the causative agent of Lyme disease to human hosts?
Hard ticks
57
Erythma migrans refers to phase ______ of Lyme disease
1
58
Neurological symptoms and cardiac dysfunction refers to phase ______ of Lyme disease
2
59
Severe arthritis refers to phase ______ of Lyme disease
3
60
What is erythma migrans?
A bull's eye rash
61
Why should people living in areas where Lyme disease is prevalent take precautions particularly during spring and early summer?
Nymphs are feeding during this time
62
What kinds of repellents should be used to avoid contracting Lyme disease?
DEET repellents
63
What is the morphology for the genus Vibrio?
Curved bacilli
64
Where do Vibrio bacteria naturally live?
Marine environments
65
What is the causative agent of cholera?
V. cholerae
66
What is the specific reservoir for V. cholerae?
Freshwater
67
______ played an important role in understanding the spread of cholera
John Snow
68
How do humans become infected with V. cholerae?
Ingestion of contaminated food / water
69
Describe the effects of serious cases of cholera in the body (2)
- Fluid and electrolyte loss - Watery, colorless, odorless stool
70
How is ‘rice-water stool’ associated with the above pathology?
Stool flecked with mucus
71
What is cholera toxin?
Exotoxin / virulence factor of V. cholerae
72
What is the specific role of the cholera toxin B subunits?
Bind receptors of intestinal epithelial cells
73
What is the function of the A1 cholera toxin subunit after entering the cell’s cytosol?
Activates adenylate cyclase (AC)
74
What is the function of activated adenylate cyclase regarding cholera?
Converts ATP into cAMP
75
What specific effect does cAMP have upon intestinal epithelial cells?
Secretion of electrolytes
76
What specific effect does electrolyte secretion have upon the intestinal lumen?
Water follows the movement of electrolytes into the intestinal lumen
77
What causes dehydration, kidney failure, coma, or death associated with cholera?
Severe fluid and electrolyte loss
78
What is the treatment for cholera?
Fluid and electrolyte replacement
79
What is the morphology for H. pylori?
Helical and motile
80
What organ in the body does H. pylori colonize?
The stomach
81
What is the causative agent of microbial gastritis and most peptic ulcers?
H. pylori
82
How does urease serve as a virulence factor for H. pylori? (3)
- Degrades urea - Produces alkaline ammonia - Neutralizes stomach acid
83
How does the formation of a peptic ulcer begin?
H. pylori borrows through the protective mucus of the stomach
84
What is the effect of colonization / multiplication of H. pylori on the lining of the stomach?
Acids digest the stomach lining
85
How does H. pylori gain access to underlying muscle tissue and blood vessels?
The epithelial layer becomes ulcerated

MICRB 106 - FINAL (4 decks)

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