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Quiz 3 Microbiology > Clostridia > Flashcards

Clostridia Flashcards

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1
Q

What are the two pathogenic steps in establishing clostridia botulinum infections?

A

1) Toxins preformed in foods (botulin toxin)

2) Ingestion of microorganisms with adherence, colonization, and toxin formed in the gut (infant boluism)

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2
Q

What is the metabolic status of clostridium?

A

Obligate anaerobe

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3
Q

What is the morphology of clostridium?

A

gram positive rods with spores.

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4
Q

How does clostridium test for oxidase and catalase?

A

Negative for both–because they are OBLIGATE ANAEROBES

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5
Q

Which species of clostridium are noninvasive?

A

clostridium botulinum
clostridium tetani
clostridium difficile

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6
Q

Which species of clostridium are invasive?

A 
Clostridium perfringens
Clostridium septicum (in cancer)
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7
Q

What are the effects of botulism toxin?

A

flaccid paralysis

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8
Q

What are the effects of exotoxins A and B?

A

Diarrhea in pseudomembranous colitis from C. difficile

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9
Q

What are the effects of alpha toxin?

A

lecithinase, which lyses host cell membranes and causes gas gangrene from clostridium perfringens

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10
Q

Describe the morphology of Clostridium tetani

A

Gram + rod with a highly diagnostic “terminal spore”.

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11
Q

How is clostridium tetani contracted?

A

through spores in the soil

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12
Q

How many serological types of clostridium tetani are there?

A

One

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13
Q

How many subunits does the tetanus toxin have? What does it do?

A

2 subunits. Binds to the neurotransmitter synapses, preventing neurotransmitter release of GABA and glycine

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14
Q

What is the incubation period for tetanus?

A

4 days to weeks

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15
Q

What are the symptoms of tetanus? (fevers, senses)

A

No fever, no sensory deficit, violent muscle spasms leading to respiratory failure and arched back

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16
Q

How do you diagnose tetanus?

A

Mostly clinical symptoms and history because the organism is difficult to culture

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17
Q

What are the treatment options for tetanus?

A 
anti-toxin
penicillin
wound debridement
immunization
respiratory support if needed
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18
Q

What is the dosage schedule of tetanus?

A

3 doses in the first six months
booster at 1 year
booster every 10 years

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19
Q

How would you treat a dirty wound with uncertain immunization?

A

anti-tetanus toxin

Complete immunization

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20
Q

What is the morphology of clostridium botulinum?

A

Gram + rod with subterminal oval spores

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21
Q

How would you get rid of botulism toxin?

A

heat labile–cook to inactivate the toxin

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22
Q

What are the three types of botulism?

A

Food botulism
Wound associated botulism- spore germination in wound
Infant botulism - Ingestion and colonization of GI tract

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23
Q

What are the different serotypes of botulism toxin?

A

A, B, and E are the most common

A-G toxins

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24
Q

What is the mechanism of action for botulism toxin?

A

absorption in intestine, carried to peripheral nerve synapses, and blockage of acetylcholine

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25
Q

What are the symptoms of botulism?

A 
flaccid paralysis (symmetrical), no fever, normal mental status
dysphagia
dry throat
diluted pupils
NO SENSORY defect
26
Q

What is the incubation period of botulism toxin?

A

18-36 hours

27
Q

How do you diagnose botulism?

A

Clinical diagnosis
Detection of botulism toxin
Electromyography

28
Q

Is a culture of clostridium botulinum from a patient sample sufficient for a diagnosis?

A

No. Need the presence of toxin.

29
Q

How do you treat Clostridium botulism?

A

Lavage–emptying of stomach
Treatment with antitoxin, must be serotype specific
Supportive care

30
Q

How can you prevent botulism?

A

Cooking food

31
Q

What is a common source of contamination with infant botulism?

A

honey

32
Q

What are the symptoms of infant botulism?

A

Constipation
Flaccidity
Cranial nerve deficit

33
Q

What is the morphology of Clostridium difficile?

A

Gram + rod

34
Q

What does exotoxin A bind to?

A

Enterotoxin that binds to the gut receptor

35
Q

What does exotoxin B bind to?

A

ADP-ribosylates Rho, damaging the colonic mucosa and formation of pseudomembrane

36
Q

What are the clinical symptoms of C difficile?

A

diarrhea with pseudomembrane visualized on colonoscopy

Diarrhea can be bloody sometimes

37
Q

How do you diagnose C difficile?

A

History of antibiotic use (ampicillin, cephalosporin, clindamycin)
Eotoxin B detected in stool samples
Sigmoidoscopy to visualize stool samples

38
Q

How can you treat C. difficile?

A

Stop the offending antibiotics

Treat with metronidazole, vancomycin, or fidaxomicin

39
Q

What are the causes of clostridium perfringens?

A

Surgical disease

Food poisoning-self limiting

40
Q

What are the symptoms of clostridium perfringens?

A

gas gangrene and tissue necrosis

41
Q

Where can clostridium perfringens be found?

A

soil, but also human GI tract+vagina

42
Q

What are the other species of clostridium that can also cause gas gangrene?

A

C septicum, C bifermentans and C ramosum, all anaerobes

43
Q

What is the morphology of clostridium perfringens?

A

A gram + rod

44
Q

What toxins does clostridium perfringens secrete?

A

lecithinase (alpha toxin)
collagenase
hyaluronidase (breaks down host matrix)

45
Q

What are the growth byproducts of C perfringens?

A

h2 and co2 gases

46
Q

What is unique about the growth of clostridium perfringens?

A

Rapid growth

47
Q

Are a lot of spores needed for clostridium perfringens food poisoning?

A

Yes, 10^8

48
Q

How does clostridium perfringens cause food poisoning?

A

After spores are ingested, the enterotoxin associated with the spore coat is released into the intestine

49
Q

What are the symptoms of clostridium perfringens gas gangrene?

A

Depends on where the bug is located. If gas gangerene is in skin=cellulitis.
Necrotizing cellulitis, necrotizing fasciitis, myositis, myonecrosis

50
Q

What are the symptoms of clostridium perfringens food poisoning?

A

Abdominal cramps and watery diarrhea, usually resolved by 24 hours. It is the 2nd or 3rd most common cause of food poisoning

51
Q

How would you diagnose clostridium perfringens?

A

Crepitus, discoloration, and edema of the skin, which should be painful.
Gram stain of fluid
Culture of wound
X-ray for gas in tissues

If food poisoning, detect through ELISA enterotoxin in feces/food

52
Q

How would you treat gas gangerene by C. Perfringens?

A

Surgical-wound debridement
Penicillin to kill remaining bacteria
Hyperbaric oxygen if available. Fatal if untreated

53
Q

Why wouldn’t you want to culture a clostridium tetanus wound?

A

Because the culture would only be positive 39% of the time.

54
Q

Which serotypes are most common in food botuulism?

A

A,B, and E. ABE likes to eat a lot which gives him food botulism. This is important because antitoxins are serotype specific

55
Q

Which serotypes are common in infant botulism?

A

F, A, B.

56
Q

Why wouldn’t you want to culture a clostridium tetanus wound?

A

Because the culture would only be positive 39% of the time.

57
Q

Which serotypes are most common in food botuulism?

A

A,B, and E. ABE likes to eat a lot which gives him food botulism. This is important because antitoxins are serotype specific

58
Q

Which serotypes are common in infant botulism?

A

F, A, B.

59
Q

Which antibiotics are notorious for causing C. Diff infections?

A

Cephalosporins, fluoroquinolones, and Clindamycin

60
Q

Which species of clostridium are non-motile?

A

Clostridium perfringens

Quiz 3 Microbiology (4 decks)

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