Bailey 4 Clostridia Flashcards
Are Clostridium gram positive or negative? What shape?
They are gram positive rods
Are Clostridium aerobic or anaerobic and do they produce endospores?
They are strictly anaerobic and do produce endospores. Note that ~30 species are responsible for human infections and many are found in the environment
What about Clostridium causes disease symptoms?
the proteinaceous toxins are responsible for disease symptoms
What genus is responsible for tetanus, botulism, cellulitus, and pseudomembranous colitis?
Clostridium
Are spores metabolically active or inactive?
inactive
Why is C. difficile named the way it is?
it is difficult to culture. It causes pseudomembranous colitis (PMC) and is often contracted when people are on antibiotics for a long period of time and causes SEVERE diarrhea
Where is C. difficile often found?
in hospitals where spores are quite difficult to erradicate
Why does C. difficile prosper when lots of antibiotics are taken?
They are normally out-competed by other bacteria but in their absence, they thrive
Are the toxins of C. difficile invasive?
no
Name the two damaging toxins of C. difficile and what they do
Toxin A) causes lots of fluid loss
Toxin B) a cytotoxin that causes tissue damage
How to toxins A & B of C. difficile function?
they act in the cytoplasm of host cells on GTP-binding proteins and inactivates the GTP proteins, blocking Na+, resulting in fluid loss
Why is the disease caused by C. difficile called pseudomembranous collitis?
because as it kills the epithelial cells of the GI tract, it leaves behind a membrane-like top layer of cell material (fake-membrane)
What is the major pathogen of wound infections (gangrene)?
C. perfringens (20-30% of war wounds), found in most soil, causes local damage as well as systemic effects
Is C. perfringens (wound bacteria) invasive? If so, why?
it is due to the variety of toxins it produces
Why does C. perfringens especially infect large battle wounds rather than small ones?
It needs a special environment to replicate. Remember that is anaerobic, needs a compromised blood supply (burn?), the availability of Ca+ ions and the availability of peptides and AAs
Which C. perfingens toxin is primarily responsible for the tissue damage it causes?
There are many toxins that it produces, but Alpha-toxin is the on that damages cell membranes and causes gas gangrene. It hydrolyzes phosphodylcholine and sphingomyelin that leads to cell death. In this process, muscle tissue is destroyed and gas/discoloration is prevalent
What is a treatment for C. perfringens?
surgical removal of the infected muscle. There are other methods that have been proposed but they are largely ineffective
What can C. perfringens cause besides gangrene?
it can also cause food poisoning which is unrelated to gangrene and is relatively common. It produces an enterotoxin that causes 12-24 hours of diarrhea (short-lived). It goes away within 1-3 days
What is the cause of the botulism disease?
It is caused by the ingestion of the preformed botulism toxin (not the bacteria)
How is C. botulinum primarily spread?
canned foods
Which of the 8 C. botulinum toxins causes disease in humans?
A, B, & E. The botulism neurotoxins are the deadliest substances known to man… one capsule could kill entire human population
Which area of the body is the first to be affected by the botulism toxin?
It starts with the cranial nerves and progresses down where it will cause respiratory failure
What is the effect of infant botulism?
a “floppy” baby due to the intestinal colonization of botulism. Usually has a good outcome
