Exam 2 - Bacteria Flashcards
Clostridium: G(?)
G(+)
Chlamydiae G(?)
G(-)
Rickettsiae G(?)
G(-)
Ehrlichiae G(?)
G(-)
Clostridium: Spores?
Yes
Chlamydiae: Spores?
No
Rickettsiae: Spores?
No
Ehrlichiae: Spores?
No
Clostridium: Ob. Int’cell Parasite? Energy Parasite?
No ; No
Chlamydiae: Ob. Int’cell Parasite? Energy Parasite?
Yes ; Yes
Rickettsiae: Ob. Int’cell Parasite? Energy Parasite?
Yes ; No
Mycoplasma: Ob. Int’cell Parasite? Energy Parasite?
No (but needs sterols) ; No
Clostridium (in general) cause disease by ______. (invasive? toxin producing?)
Producing toxins
Clostridium are ______ (structurally)
Rods
Process of spore formation:
- Part of bacterium buds off
- That part gets engulfed by mother bacterium
- Engulfed particle develops a thick peptidoglycan layer and thick protein coat
- mother cell eventually dies and lyses, releasing the spore
Clostridium difficile normally found in the ______ (site)
Intestines
Clostridium difficile causes __________?
Pseudomembranous colitis (PMC)
Pseudomembranous colitis is characterized by what appearance? Of what is that appearance consisting?
Yellow plaques containing fibrin and cellular debris
Clostridium does not invade the intestinal cells, but produces toxins. In this way, it is similar to what 2 bacteria already covered?
E. coli and V. cholerae
What causes diarrhea and Pseudomembranous colitis (PMC), respectively?
Toxin A –> enterotoxin leads to diarrhea
Toxin B –> cytotoxin leads to damage of epithelial cells of colon.
What is Toxin A (produced by Clostridium difficile)
Enterotoxin that cause fluid production and damage to the mucosa of intestines. It cause epithelial cells too absorb Na+ and causes fluid loss from intestines
What is Toxin B (produced by Clostridium difficile)
Cytotoxin causes some damage to the clonic epithelial cells and the dead cells begin to accumulate on the surface/lumen on the intestines. This generates the cellular debris part of the pseudomembrane. The other component of the pseudomembrane is fibrin.
Both toxin A and toxin B (produced by Clostridium difficile) act in the _________ (location) by _______ (mechanism)
They act in the cytoplasm. They glycosylate GTP-binding proteins (Ex: Rho, Rac)
How is diagnosis of Clostridium difficile is achieved?
Perform ELISA for toxin A. This is necessary because you can’t just look for the bacteria since they are endogenous of the gut, but they SHOULD be only spores and should not be producing the toxins.
Clostridium perfringens is usually found ____ (nature) and in the ______ (part of body and creature)
Clostridium perfringens is normally found in soil and digestive tract of animals
Is Clostridium perfringens invasive? Toxin producing?
Yes ; Yes (most of the disease is caused by toxins)
Explain how Clostridium perfringens is good at infecting war wounds.
Spores are in the soil and then when a soldier gets wounded and gets the wound ‘dirty’ the spores can germinate. The Clostridium perfringens is aided by the anaerobic environment created by blood loss and also by the tissue damage making Ca++ and Peptides and amino acids available.
Initially what happens with a Clostridium perfringens infection? Then what happens?
Initially it grows and causes a cellulitis and then progresses to gas gangrene (necrotizing process with gas production in muscle) and is associated with systemic signs of shock
Clostridium perfringens can produce 12 toxins. What is alpha-toxin? What does it do? What results locally and systemically?
Alpha-toxin is a Lecithinase (attacks lecithin, or basically phosphotidyl choline, which is embedded in cell membranes) and leads to disrupting cell membranes.
Locally it causes cellulitis and if progresses deeper to destroy muscle it causes myonecrosis. This causes a blue-green look and the toxin attacks dead cells and produces gas bubbles characteristic of Gas Gangrene.
Systemically it causes renal failure and has a 100% fatality of untreated.
Clostridium perfringens is treated by ________.
Surgical removal of infected tissue and immediately return blood supply if possible. Once bacteria have germinated, must amputate.
A.B.’s and antitoxins have been tried to control infection but still need to amputate.
Some cases of pressurized O2 helps.
In addition to Gas Gangrene, Clostridium perfringens also produces what?
Food poisoning but through different strains than those that cause gas gangrene. Usually in ppl who have eaten contaminated food. Within 12-24 hours water loss, 1-3 days duration. Usually not treated
Where are Clostridium botulinum spores found? Why are they significant?
Clostridium botulinum has spores found in soils and seawater. They commonly survive the canning process and then sporulate in the anaerobic environment of a sealed can.
Colstirdium botulinum produces 8 neurotoxins, but A, B, and E are the most common. Describe the neurotoxin structure?
They are a stable 900kDa protein complex with a 150kDa toxic component and a 750kDa non-toxic component. The non-toxic component helps the toxin bind to the target cell. The toxic component prevents release of ACh.
How does the Clostridium botulinum toxin affect a cell?
The Clostridium botulinum neurotoxin binds to ACh containing neurons that release their neurotransmitter via exocytosis. The toxin prevents the vesicles from docking at the membrane so they cannot release the ACh. This causes flaccid paralysis (usually affecting CN’s and working its way down to where it reaches the respiratory tract and causes death (12-36 hrs).
What does the Clostridium botulinum toxin cause in a person? (what do you see?)
Flaccid paralysis.
What are the 3 types of toxins produced by Clostridium botulinum (Mechanism of entry/effect)?
Food-borne botulism - ingestion of toxin that has been produced in food by bacteria already present and growing
Wound botulism (rare in the USA) - systemic spread of toxin produced by organisms inhabiting wounds. Contracted by trauma, surgery, subcutaneous heroin injection and sinusitis from intranasal cocaine abuse.
Infant botulism: intestinal colonization of organisms in infants younger than 1 year old. Slow onset with favorable outcome but causes a hypotonic floppy state related to flaccid paralysis. (this is why to not give honey to infants).