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SP14 Microbiology > Final; Clostridia > Flashcards

Flashcards in Final; Clostridia Deck (48):
1

What oxygen level does clostridium tolerate

strictly anaerobic

2

clostridium are gram-positive rods that produce what

endospores

3

How many clostridium species are responsible for human infections and are in the environment

~30 cause infection in humans
>50 are found in the environment

4

What does clostridium produce that is responsible for disease symptoms

proteinaceous toxins

5

This clostridium species causes pseudomembraneous colitis (PMC)

C. difficile

6

This clostridium species causes cellulitis, gas gangrene, and food posioning

C. perfringens

7

This clostridium species causes botulism

C. botulinum

8

This clostridium species causes tetanus

C. tetani

9

This is a metabolically inactive state in which organisms can remain viable for hundreds of years; making them resistant to adverse conditions

endospore

10

What can cause endospore formation

unfavorable environment, of which when the environment becomes favorable then growth resumes

11

This is a yellow plaque containing fibrin and cellular debris in ulcers of colonic mucosa and is the leading cause of nonsocomial dirrhea

psuedomembraneuous colitis

12

True or False
C. difficile is harbored in a dormant state in the large intestine of small percentage of healthy humans in low numbers

True

13

How is C. difficile transmitted

transmitted as the endospore via hands of health care personnel

14

What is the disease state of C difficile associated with

antimicrobial drugs; spores are resistant to antibiotics of which will only kill the normal flora

15

The spore produce what which results in diarrhea

produces a toxin; invasion of the bowel wall does not occur

16

What is toxin A of C. difficile

enterotoxin; fluid production and damage to the mucosa

17

What is toxin B of C. difficile

cytotoxin; round of tissue-culture cells

18

How to toxin A and B of C. difficile act

act in the cytoplasm of the host cell to glycosylate GTP-binding proteins
the cell then loses cytoskeletal structures and dies

19

This is found in the soil (except Sahara desert) and intestinal tract of animals and is a major pathogen of wound infections (especially war wounds)

C. perfringens

20

What type of damage does C. perfringens inflict

local damage and systemic effects
invasive properties due to a variety of toxins produced

21

Severe trauma introduces C. perfringens spores from that environment that germinate under what conditions

anaerobic
compromised blood supply
calcium ions
availability of peptides and amino acids

22

Toxins produced by C. perfringens typically cause what

cellulitis that can lead to gas gangrene, associated with systemic signs of shock

23

How many different toxins does C. perfringens produce and what is the main one

12
Alpha-toxin (lecithinase) damages cell membranes and causes gas gangrene

24

How does alpha toxin of C. perfringens cause gangrene

it hydrolyzes phosphatidylcholine and sphingomyelin that leads to cell death
muscle tone is destroyed
shock and renal failure usually result (100% fatal is left untreated)

25

What is the treatment and prevention for C. perfringens

surgical removal of infected tissue
antibiotics to control
antitoxin from horses (little effect)
high oxygen concentrations
prompt care in imperative

26

This is the third most common type of food poisoning in the US

C. perfringens

27

What causes the C. perfringens food poisoning

sporulatng C. perfringens produce enterotoxin in intestines of people who have consumed contaminated food
causes diarrhea but disappears in 1-3 days

28

This is found in soil and marine sediments and is the causative agent of botulism

C. botulinum

29

What is special about the C. botulinum spores

They are heat-resistant which often survive food processing and germinate in an anaerobic condition

30

How does C. botulinum cause botulism

the intoxication of ingestion of pre-formed toxin (do not need to organism to be present)

31

True or False
botulism is not a bioweapon or bioterrorism threat

False; it is a threat

32

What are the C. botulinum toxins

produces 8 neurotoxins (BoNT) serotypes A-g
and are among the most poisonous substances known* with one 1 component of the toxin

33

What is the lethal dose of the C. botulinum toxins in humans

< 1µg

34

What is the mechanism of the C. botulinum toxins

it prevents the release of acetylcholine neurotransmitter and cleaves the proteins involved in docking of neurotransmitters (zinc metalloprotease)

35

What are the symptoms of C. botulinum toxin

flaccid paralysis within 12-36 hours
cranial nerves affected first
paralysis descends, respiratory failure

36

This is the ingestion of preformed toxin in food that have not been canned or preserved properly

food-borne botulism

37

This is the systemic spread of toxin produced by organisms inhabiting wounds

wound botulism (rare)

38

This is the intestinal colonization of organisms in infants younger than 1 year, "floppy state" has a favorable outcome

infant botulism

39

What is the current mortality rate, with good supportive care for botulism

25%

40

What is the treatment for botulism

trivalent antitoxin from a horse
however some muscles may be permanently damaged

41

This is ubiquitous in the GI tract of humans and animals, also in the soil (spore resistant to the environment), and infection is usually associated with traumatic wounds

C. tetani

42

What is the major toxin of C. tetani

tetanospasmin

43

Tetanospasmin is responsible for what

all symptoms of tetanus
similar structure to the botulism toxin

44

How does tetanospasmin cause tetanus

attaches to peripheral nerve near wound and is transmitted to cranial nerve nuclei
it inhibits neurotransmitter release (GABA) and inhibitory input
results in reflex spasms and spastic paralysis

45

This is the tetanic spasm of masseter muscle that prevents the opening of the mouth

trismus; lockjaw
seen in 80% of cases

46

What are the symptoms of tetanus

paralysis descends to the neck and back muscles and produces rigidity of abdomen and stiffness of extremities
tonic seizures
respiratory failure due to paralysis of chest muscles

47

What is used to treat/prevent tetanus

DPT (diptheria pertussis and tetanus) vaccine
human globulin as passive immunity to tetanus-prone wounds
surgical debridement of the wound to prevent bacterial growth

48

What is the mortality rate of tetanus

11%
antitoxin should be administered immediately along with penicillin to prevent further paralysis