Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Microm 442 > lecture 18 Anaerobes > Flashcards

lecture 18 Anaerobes Flashcards

(48 cards)

Start Studying
1
Q

What are the three classes of disease caused by clostridium?

A
  • gas gang gangrene
  • botulism
  • tetanus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are two enteric diseases caused by clostridium.

A
  • food poisoning

- antibiotic-associated enterocolitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the characteristics of clostridium?

A

-Anaerobic, gram-positive rods, form endospores, natural reservoirs -soil intestinal tracts and skin of humans and animals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the etiology Clostridial wound infections?

A
  • usually mixed clostridial infection in wound following surgery or trauma.
  • By Cl. perfringens, other cl. species
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the etiology of gangrene?

A

Toxins caused by infection of clostridium spread to healthy muscle tissue and produce myonecrosis; by locally invasive organisms, Bacteremia is not common, but systemic toxemia can occur.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the pathogenesis of clostridium wound infections.

A
  • α-toxin, acts on phospholipids and lecithin, causing cell lyses
  • Θ-toxin, pore forming, lyses cell, toxic to heart and alters permeability of capillary
  • No effective host defense in necrotic cells.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How are clostridial wound infections dx clinically?

A
  • Clinical sx:
  • -gas in tissues (crepitus), edema and shock in wound pain.
  • -once a lesion appears, must begin treatment before lab results
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How are clostridial wound infection dx in the lab?

A

-Mixed infection, one must be histotoxic (clostridium)
-Exudate smear - Gram positive rods with cellular infiltrate
-bacterial characteristics - “anaerobic growth”
double xone hemolysis (theta toxin)
check lecithinase activity on egg yolk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How are clostridial wound infection prevented/treated?

A
  • surgical debridement and cleansing -antibiotics -Penicillin
  • hyperberic O2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the source of clostridium in food?

A
  • Meat prroducts
  • spores germinate when food is heated
  • enterotoxin is produces pores in enterocytes.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is Cl. perfingens food poisoning dx clinically?

A
  • onset 7-22 hours post ingestion

- diarrhea, cramps, abd pain, possible fever, nausea vomiting.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is Cl food poisoning dx in the laboratory?

A
  • non-motile (unlike other clostridia)

- spores sometimes seen on smears

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which genus of cl causes food poisoning?

A

Clostridium perfingens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How is Cl food poisoning treated?

A
  • supportive therapy

- mortality near zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What causes botulism?

A

-Clostridium botulinum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where can Cl Botulinum be found?

A

-soil, silt, vegetation, intestinal tracts of humans and animals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is classical botulism?

A

-is an intoxication, not an infection, caused by ingestion of preformed toxin in food contaminated with spores

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What causes wound botulism?

A

usually infection of compound fracture, severe laceration or penetrating wound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What causes infant botulism?

A

caused by germination of spores in intestinal tract of infants; most cases in infants 2 weeks - 6 months; adults not affected by this syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What causes inhalation botulism?

Study These Flashcards
A

bioterrorism threat

21
Q

What types of food are incriminated by Clostridium botulinum?

Study These Flashcards
A
  • improperly canned food
  • fish preserved by salting or smoking
  • prepared meats ingested uncooked
22
Q

What is the action of the botulinum toxin?

Study These Flashcards
A
  • 7 distinct type inducing same disease
  • absorbed in intestine, transported to neuromuscular junction.
  • relatively toxic
  • heat-labile
23
Q

How is clostridium botulinum dx clinically?

Study These Flashcards
A
  • 12-96 hours, maybe 14 days
  • GI sx- vomiting, constipation
  • Nervous system- Flaccid paralysis
  • mortality rate about 20% now declining
24
Q

How is clostridium botulinum dx in a lab?

Study These Flashcards
A
  • isolation for organism form contaminated food or stool samples (oval, subterminal spores)
  • Demonstration of toxin in food or patient serum or feces.
25
How is clostridium Botulinum treated?
-eliminate unabsorbed toxin; stomach lavage and enemas -eliminate source of toxin -neutralize unbound toxin -supportive care (especially respiratory support)
26
How is clostridium botulinum treated/prevented?
- antitoxin therapy (passive immunization) - antibiotics of questionable value, except in cases of wound botulism - Boil raw or fermented native dishes and home canned foods 10 minutes before eating - Follow recommended home-canning procedures
27
What is the etiological agent of tetnus?
-Cl. tetani toxin, several antigen serotypes, but one toxin
28
What is the pathogenesis of Cl. Tetani?
- spastic paralysis following penetrating wound - spores contaminate wounds - germination, outgrowth and toxin production - toxin enters motor neurons, transported to CNS by retrograde axonal transmission (travels along nerve fibers) - highest mortality in elderly: >50% over 60 years
29
What is the action of the tetanus toxin?
- protein toxin is sole virulence factor - Spastic paralysis: blocks inhibitory neurotransmitters - very toxic like botulism
30
How is clostridium tetani dx clinically?
-initial sx- cramping and twitching of muscles around wound, then head and neck (lock jaw)
31
How is Cl Tetani dx in a lab?
- isolation of organism from wound - spores - demonstration of toxin neutralization with antitoxin
32
How is clostridium treated/prevented?
- maintenance of airway - Benzodiazepines - -(GABA* agonists) tetanus immunoglobulin - antibiotics to clear infectious focus
33
Does tetanus and botulinum toxins have the same enzymatic effect?
-They have the same effects, but in different neurons. Tetanus attacks interneuron while botulism attacks the neuromuscular junction. They both cleave the protein VAMP.
34
What causes abx-associated (pseudomembranous) colitis?
Clostridium difficile
35
What is the etiology of abx-associated colitis?
- follows antibiotic therapy; normal microbiota altered, spores germinate, overgrow, produce toxins and cause colitis; normal microbiota serve a protective role - organism - normal microbiota, slender, gram positive rod with large, oval subterminal spores
36
What is the pathogenesis of Clostridium difficile?
- resistant to may abx - two principal toxins cause disease by disrupting cytoskeletal elements of epithelial cells/submucosal tissue, A (enterotoxin) and B (cytotoxin) .
37
How does C. Difficile toxins work?
- large toxin - 3 functional domains (receptor, membrane translocation, glucosyltransferase activity) - once in cytoplasm, inactivate rho proteins by transferring glucose onto them.
38
What are some sx of C. Diff?
-abdominal pain; watery diarrhea, and mucus or blood may be seen -Mortality rate; 27-44% in untreated pts
39
How is C. Diff Dx?
- demonstration of pseudomembrane (sigmoidoscopy) | - fecal filtrates can be assayed for toxin
40
How is C. Diff treated?
-in most identified cases, symptoms resolve after antibiotic therapy is discontinued -Cl. difficile are usually susceptible to vancomycin and metronidazole -relapse may occur following therapy Fecal Transplants
41
What made a C diff strain more virulent?
- More severe disease, increased complications, high mortality rate, increased risk of relapse - Has mutation in regulatory gene – makes 16 to 24X as much toxin A&B
42
What are the characteristics of Bacteroides fragilis?
- Gram-negative rods; non-spore forming - found primarily in the intestine; relatively O2 tolerant - most frequently isolated anaerobe from diseased tissues; usually involved in diseases of the lower 1⁄2 of body - bile resistant
43
What diseases are caused by Bacteroides Fragilis?
- intra abd abscess - Skin and soft tissue infections - secretory diarrhea in children
44
What are sx of intra abdominal abscesses?
- localized infections following compromise of the integrity of the intestine - low grade fever abdominal pain - can lead to bacteremia with high morality rate
45
What are some sx of skin and soft tissue infections?
- cellulitis, fasciitis associated with surgical wound infections - infections of diabetic and decubitus ulcers
46
What is the pathogenesis of bacteroides fragilis?
- capsular polysaccharides, forms abscess - mixed infections - penicillin resistant
47
How is bacteroides fragilis dx?
- abscesses, Radiologic CT and or aspiration | - gram stain culture
48
How is bacteroides fragilis treated?
- abx, use a couple in case is polymicrobial | - drainage of abcess

Microm 442 (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions