Can you get sick from your own dung?

[aychamo]

Aychamo: a question:

Why are bacteria labelled as gram- and gram+? Is there a fundamental property that it is relevant to group them like this?

Well, with bacteria, for the most part, if you just looked at them without doing anything to them, under the microscope most of them bascailly look the same (either as spheres or rods.) Gram staining is just a technique to help classify bacteria.

The http://en.wikipedia.org/wiki/Gram_stain" helps microbioligsts distinguish between different bacterial species. Gram positive bacteria have a thick wall of peptidoglycan, which retains the violet color stain in the gram stain procedure (read the link above), and gram negatives don't have the thick outer wall of petidoglycan, so they don't retain the violet stain, and they instead pickup the counter stain, which is red.

So yes, it's the composition of their outer membrane (the amount of peptidoglycan) that allows them to be classified as gram positive or gram negatives.

I'm sure you've heard of "Strep throat" or a "Staph infection". Those are both (medically important) gram positives (and there are many others, like Clostridium botulinum (which causes botulism, the food poisoning, etc). And there are a ton of medically important gram negatives (ie, E. Coli, Haemophilus influenza [what you have the Hib vaccine for], Psuedomonas, N. ghonorrhea, etc.)

Gram negatives are especially dangerous because they have what's called an "endotoxin." It doesn't actually hurt you until the bacteria is dead. When a gram negative dies, it releases, from its LPS layer (lipopolysaccharide), a Lipid A component (which is the endotoxin) that wreaks havoc on your body. That's what I was talking about earlier when I said if you have a patient with gram negative bacteremia (baceria in the blood) and you kill all the bacteria, they will release the lipid A, and the patient can die in 5 hours! I'm not sure what you do in terms of treating the patient in that case.

I'm only a 3rd sem medical student, so I'm sure some of the microbiologists on the board will murder my explanations and explain things better :)

Aychamo

 

[aychamo]

I don't believe you can build an immunity to things you're not exposed to. If you live in a sterile environment, you'd be more likely to get sick when you venture into the real world. Someone correct me if I am wrong here, this is purely my opinion.

I got over my allergy to cats by being around them all the time. They no longer make me sneeze or cause huge swollen welts. And I used to be deathly allergic to them. Dust and pollen, however, still make me sneeze and will swell my eyes. So, maybe that kills my thoughts about the cat exposure.

Never mind.

Yes, you need to be exposed to something (ie, an antigen) to be able to build an immunity (antibody) to it.

 

[aychamo]

I think Helicobacter pylori are implicated in stomach ulcers.
http://digestive.niddk.nih.gov/ddiseases/pubs/hpylori/

There may be a correlation between H. pylori and cancer in the sense that condition of stomach tissue with which one is more susceptible to H. pylori infection also renders it susceptible to cancer. However, that certainly does not mean that H. pylori 'causes' cancer. On the other hand, lesions may be more susceptible to cancer and therefore there could be an indirect cause. But the title "evidence from a prospective investigation" suggests a study in progress to which Evo alluded.

You're right. In med school they teach us that H. pylori is essentially the cause of like 90% of GI ulcers. People used to think that it was stress, but it was demonstrated that H. pylori was the culprit. Stress can precipitate the problem though, of course.

And yes, chronic inflammation due to a chronic infection can help form a cancer. If you are exposed to some carcinogen, and then have chronic inflammation, you can get cancer. It's freaking crazy how they go hand in hand.

I'm sure when the guy above said "bacteria cause cancer" he must have meant viruses, like Human Papilloma Virus, etc..

 

[Mk]

I like this aychamo guy, what have you studied? Microbiology?

 

[iansmith]

So yes, it's the composition of their outer membrane (the amount of peptidoglycan) that allows them to be classified as gram positive or gram negatives.

It's the presence or absence of a outer membrane that determines if it's a Gram negative or Gram positive. Gram positive do not have an outer membrane and Gram negative do.

Also, the stain is no good for certain type of bacteria with atypical cell membrane and cell wall and will be false positive for some eukaryotes such as yeast.

 

[pitchharmonics]

Helicobacter pylori has been found in feces, and the world health organization is calling it a class 1 carcinogen, which means cancer causing agent.

 

[Schrodinger's Dog]

I don't believe you can build an immunity to things you're not exposed to. If you live in a sterile environment, you'd be more likely to get sick when you venture into the real world. Someone correct me if I am wrong here, this is purely my opinion.

I got over my allergy to cats by being around them all the time. They no longer make me sneeze or cause huge swollen welts. And I used to be deathly allergic to them. Dust and pollen, however, still make me sneeze and will swell my eyes. So, maybe that kills my thoughts about the cat exposure.

Never mind.

Yeah by controversial I meant it was little more than a tentative theory that that was the cause of increased asthma, as few serious studies have yet to be undertaken, I think the idea behind it is sound though, but then I'm not an immunologist and I formed that impression from reading magazines not scientific journals, I think it's healthy to be conservative with your opinions when your not well educated in a subject, egg on your face is not pleasant