Final; Clostridia Flashcards
What oxygen level does clostridium tolerate
strictly anaerobic
clostridium are gram-positive rods that produce what
endospores
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
What does clostridium produce that is responsible for disease symptoms
proteinaceous toxins
This clostridium species causes pseudomembraneous colitis (PMC)
C. difficile
This clostridium species causes cellulitis, gas gangrene, and food posioning
C. perfringens
This clostridium species causes botulism
C. botulinum
This clostridium species causes tetanus
C. tetani
This is a metabolically inactive state in which organisms can remain viable for hundreds of years; making them resistant to adverse conditions
endospore
What can cause endospore formation
unfavorable environment, of which when the environment becomes favorable then growth resumes
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
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
How is C. difficile transmitted
transmitted as the endospore via hands of health care personnel
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
The spore produce what which results in diarrhea
produces a toxin; invasion of the bowel wall does not occur
What is toxin A of C. difficile
enterotoxin; fluid production and damage to the mucosa
What is toxin B of C. difficile
cytotoxin; round of tissue-culture cells
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
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
What type of damage does C. perfringens inflict
local damage and systemic effects
invasive properties due to a variety of toxins produced
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
Toxins produced by C. perfringens typically cause what
cellulitis that can lead to gas gangrene, associated with systemic signs of shock
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
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)
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
This is the third most common type of food poisoning in the US
C. perfringens
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
This is found in soil and marine sediments and is the causative agent of botulism
C. botulinum
What is special about the C. botulinum spores
They are heat-resistant which often survive food processing and germinate in an anaerobic condition
How does C. botulinum cause botulism
the intoxication of ingestion of pre-formed toxin (do not need to organism to be present)
True or False
botulism is not a bioweapon or bioterrorism threat
False; it is a threat
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
What is the lethal dose of the C. botulinum toxins in humans
< 1µg
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)
What are the symptoms of C. botulinum toxin
flaccid paralysis within 12-36 hours
cranial nerves affected first
paralysis descends, respiratory failure
This is the ingestion of preformed toxin in food that have not been canned or preserved properly
food-borne botulism
This is the systemic spread of toxin produced by organisms inhabiting wounds
wound botulism (rare)
This is the intestinal colonization of organisms in infants younger than 1 year, “floppy state” has a favorable outcome
infant botulism
What is the current mortality rate, with good supportive care for botulism
25%
What is the treatment for botulism
trivalent antitoxin from a horse
however some muscles may be permanently damaged
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
What is the major toxin of C. tetani
tetanospasmin
Tetanospasmin is responsible for what
all symptoms of tetanus
similar structure to the botulism toxin
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
This is the tetanic spasm of masseter muscle that prevents the opening of the mouth
trismus; lockjaw
seen in 80% of cases
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
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
What is the mortality rate of tetanus
11%
antitoxin should be administered immediately along with penicillin to prevent further paralysis
