Tuesday, June 4, 2013

In which something something broken computer

Jessie has deadlined (Army for broken in a manner which makes it non mission capable) her computer.

Now that explanations are complete, this post is about my favorite gram positive anaerobic bacteria.

Clostridium spp.

Clostridium is a genus of about 100 specific species.
General characteristics of the genus include:

- Gram positive: meaning the cell wall surrounds a single phospholipid bilayer. This is important for culture staining and antibody/antigen interactions.

- Anaerobic: meaning the cells are unable to neutralize reactive oxygen species like O2-, H2O2, or -OH. This means that the cells thrive in low oxygen environments. Think environments created in home canning or found in honey or your intestine.

- Spore forming: meaning that the cells will form a dormant, durable spore when environmental conditions are  poor for survival. Spores can survive a long time. Supposedly the oldest known viable recovered spore was 25 million years old in a bee trapped in amber(wikipedia). I'm not sure I believe that yet, but they can last a long time.

- The various species of the genus compete poorly with many of the other bacteria you have probably heard of. Many of these other bacteria are actually normal flora (sort of good for you bacteria) of humans. E. coli and various Staphys and Streps tend to hang out with us.
This is good because...

- Neurotoxins

The neurotoxins are why this bacteria is so awesome.

Clostridium (C) botulinum produces the single most deadly toxin that is known to humanity. The toxin acts by preventing neurons from transmitting an action potential (go command) to muscles. This results in a flaccid paralysis and eventual asphyxiation. 1 microgram/kg is potentially fatal.
Most people recognize the toxin's medicinized name; Botox.

C. tetani produces a slightly less deadly toxin. This toxin acts by preventing the inhibition of muscle activity. This results in tetany (constant muscle contraction) and eventual asphyxiation.

C. difficile can colonize your digestive tract if you have been on antibiotics for a long period of time. Basically, an antibiotic might create a situation where difficile can out-compete your normal digestive flora. When this happens, difficile produces a toxin (not a neurotoxin I think) that causes pseudomembraneous colitis. An easier way to say that is your bowel gets inflamed and you have very foul smelling diarrhea. A severe infection could cause the patient to begin to pass bloody, foul smelling, diarrhea.

Now before anyone reads the above paragraph and starts jumping to assumptions like a kangaroo on atropine + epinephrine understand that if you need an antibiotic you should take an antibiotic.
Many antibiotics tend to work well on specific types of bacteria but not others.

Any time you've gotten sick and the doctor took a specimen for culture but didn't give you an antibiotic immediately was because they were running the cultures through SURVIVOR: Laboratory Version where the losers die out from antibiotics and the winners are incinerated. As such, if you take an antibiotic for your ear infection and difficile takes over, you shouldn't think of it in terms of the difficile is now a super bug and you're doomed. I mean, you might be, but you probably just need a different antibiotic with a different target profile. Think of it this way, you don't use a APFSDS round on a dismount squad, you use a canister round (use google).

Finally, C. perfringens produces a toxin which can cause food poisoning and gas gangrene. If you don't like looking at open wounds and dead tissue you should probably just imagine gas gangrene and avoid google images.

There are many more species but these are ones important from a primary care perspective.

The good news is that most people don't encounter these bacteria because they can't really compete against more common aerobic bacteria (aerobic doesn't refer to a need for O2 in this usage). That being said, don't feed infants honey or home canned food before the age of one. Commercially canned baby food is prepared in a way to destroy any present spores.

Also; dangit Jes I'm a physician assistant student not an english major.


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Mary said...

I lol'd. At the PA Army Jeremy post, not the broken compooter, of course.

Anonymous said...

Interesting. And the test about all of this is on what day?
HELP please.

Anonymous said...

Hahaha! Loved Jer's blog post. Very different style. Now I know why I'm not supposed to feed my daughter honey for the first year.

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