Posted on 01/20/2006 6:52:28 PM PST by neverdem
Survey of bacteria reveals an array of antibiotic-resistance.
Bacteria that live in soil have been found to harbour an astonishing armoury of natural weapons to fight off antibiotics. The discovery could help researchers anticipate the next wave of drug-resistant 'superbugs'.
Researchers have long known that soil-dwelling bacteria make natural antibiotics, and that they have inbuilt ways to survive their own and other bugs' toxins; in some cases, the genes that help them dodge antibiotics have transferred into infectious bugs that plague humans.
Microbiologists have identified a few of the ways that soil microbes neutralize antibiotics. But Gerard Wright and his team at McMaster University in Ontario, Canada, have shown that soil microbes carry a hidden trove of such arms.
The team collected handfuls of dirt from towns and forests across Canada, and grew the bacteria contained within them. They isolated 480 different strains of the common soil bacteria Streptomyces, which are known to synthesize a large number of antibiotics, and so are expected to have natural defenses against them. They then threw 21 different antibiotics (some natural, some synthetic), at the bugs to see if they could survive.
Hard to beat
The strains were impervious to seven or eight antibiotics on average, the researchers report in Science1, and two hardy ones were resistant to 15 drugs.
Many of the bacterial strains were immune to antibiotics that they have probably never been exposed to before. And the crafty creatures used some previously unknown ways to detoxify some drugs, such as adding a sugar molecule on to the drug telithromycin, which prevents it from crippling a cell.
Being able to disable so many antibiotics so easily may help the underground bacteria survive the cocktail of chemicals released by other microbes, fungi and plants in the underground, Wright suggests.
Out of the dirt
The discovery raises fears that the genes underlying this glut of drug-resistance could jump into bacteria such as Staphylococcus aureus, which causes hospital infections and is already resistant to almost everything on the pharmacy shelf.
"The chances that these genes will end up in a disease-causing organism at some future point is high," says microbiologist Abigail Salyers, who studies microbe gene transfer at the University of Illinois at Urbana-Champaign.
Antibiotic resistance genes have escaped from the dirt before. Researchers think that the genes that allowed superbugs to resist vancomycin, one of the last lines of antibiotic defence prescribed by doctors, originally came from soil-dwelling bugs.
Forewarned is forearmed
On the flip side, the findings could help doctors arm themselves against future superbugs. Drug companies seeking new antibiotics, for example, could test a prototype product on an array of soil bacteria to find organisms that are naturally resistant, and figure out how they manage to disable the drug.
Armed with this knowledge, scientists could tweak the drug to avoid resistance before it even occurs: they might sculpt the antibiotic's chemical shape, for example, or design a second medication that would stop the bacteria from degrading the antibiotic or pumping it out of the cell.
But because the team looked at only a tiny fraction of the soil bacteria, there are probably many more ways of fighting antibiotics that have yet to be discovered, says Jo Handelsman who studies soil microbes at the University of Wisconsin, Madison. "We have an enormous task ahead of us," she says.
References news@nature.com doi:10.1038/news060116-10 D'Costa V., et al. Science, 311. 374 - 377 (2006).
Good post.
What would be really interesting is figuring out why we're still here if all this stuff is as bad as they make it sound. People get into dirt all the time. It would be great if they could figure our why all these bugs that are so bad and resistant haven't killed us all by now, and how the immune system disables them before they infect us. I've studied the immune system only slightly cause of allergies, and it is so complex, that I am in awe of people like my allergist who have PhD's in this area. What I've read only scratched the surface and it was tough.
You're right. The immune system is incredibly complex, and medical research has only scratched the surface so far.
One of the few good things about all the political money poured into AIDS research is that a lot of it goes into researching the immune system. I haven't kept up with this, but I know that several doctors at NYU Medical Center were doing innovative work in this area with AIDS funding. It's not just applicable to AIDS, but to basic medical theory and disease treatment.
There was a very good front page article in the WSJ today about the staph bug. Very bad stuff. This doesn't make me feel any better. There was a distant relative in his 40's who died from a staph infection after breaking his hip in an auto accident. Actually, he overdosed because the pain was unbearable.
This plan sounds like your typical thesis proposal from any slacking undergraduate in bioscience... glad it yielded something interesing, just the same.
I think some of these bugs may not attack us. They may not thrive or spread well in humans. Also, the human skin is a pretty remarkable defense.
It reminds me of the space program in the 60's. All this research went into putting a man on the moon and we have benefitted so greatly from the technology that was developed then; things that might not have been pursued if the astronauts lives hadn't depended on it.
A few weeks ago, a guy in our town injured his foot by stepping on something in his yard. He was dead 3 days later from a staph infection. Of course it might have ended differently had he gone to the hospital when he first noticed trouble instead of waiting 24 hours until his leg had swollen up to twice its normal size.
This book I have (written by an immunologist) discusses how the environment created by some bacteria, such as the Acidophilus type, is hostile to the bad bacteria, which is why antobiotic use often results in repeated infections. As the good bacteria are killed off too, the chemical environment changes to be friendlier to the harmful stuff. Then it gets a foothold. That's why there is the recommendation to load up on active culture yogurt after a course of antibiotics.
I have seen a case of exactly what you describe. Devastating. Except the case I saw there were no outward manifestations like a swollen leg. Just a history of a scrape while climbing some rocks and a couple of days later a young, healthy man was dead. I think the case I saw was strep, not staph, but it was a devstating outcome.
Strep and staph are both just as nasty, especially when they get into the blood stream or become the infamous "flesh eating" bacteria.
Oh yes, this was definitely in the blood, and the toxins from the infection basically made his heart fail which was the immediate cause of death. There may not have been any antibiotic resistance in the case I saw - by the time this guy reached the hospital and the diagnosis was made (it wasn't obvious) it was too late. Devastating.
interesting. May I ask the name of the book? And is it readable for a layman?
I find this field fascinating, but have no particular background in biology or immunology. But I have read all the Stephen Jay Gould books that talk a lot about the ongoing battle between organisms.
I got a staph infection many years ago while working in the dirt and cold (chapped & cracked hands).
My thumb started to ache and I figured I must have jammed it somehow. After several days of dealing with it we had some down time so I stopped in at the local small-town Idaho hospital. It was a Saturday and to bring the doctor in would be an extra $50 for an "emergency" call.
I felt kinda' dumb having him come in for a sprained thumb, but the swelling and redness was increasing and figured I'd be out working the entire next week so I might as well get it looked at.
He took one look at it and said "that's quite the staph infection!" They got me on an I.V. drip antibiotic and kept it going for the next 4 - 5 days while I layed in my hospital bed!
He said if I hadn't come in that day I could have lost my arm or worse. Not so sure about that, as I had had it for a few days anyway - but I suppose.
The title, the article premise...I don't understand the "revelation" here.
Bugs found in dirt...all our planet's infectious agents that exist are here on the planet! No surprise there. That they're in "the dirt" is just nothing extraordinary. They're also in water, some even are in the atmosphere.
Meaning, the planet is home (already) to us and everything else that lives upon and in it. Were these researchers expecting to find sterile environments in "the dirt" or, what?
"Understanding Allergy, Sensitivity & Immunity" by Janice Vickerstaff, PhD, and Leonard Bielory, MD.
ISBN 0-8135-1521-1
I found it some years ago advertised on the back of a Science News magazine and ordered it. I don't know if it's still in print. It gives a basic overview of the immune system and how it works and it appears that the author tried to make it as simple to explain as possible, but I had to read it more than once to get the hang of it. It's hard to keep track of all the killer cell, mast cells, B cells, T cells, leuko_____ (whatevers) etc.
I would say it is written for the layman and in that respect it is readable by laymen; it is not written in medicalese for other doctors. That being said, there's only so much you can do to simplify the subject so it can be tough going in other respects. Also, this book is copyrighted from 1990 and some of the information is a little dated.
Years ago, before I knew him, a buddy of mine had cut his foot in some kinda accident. For the next few days, he started getting a fever and feeling like crap.
He ended up almost dead in a hospital bed, and they still weren't sure what it was.
A visiting doctor from Korea looks in the door at him and starts screaming, mostly in Korean, "this man has tetanus!!!".
So now he can step on all the nails he wants to, he has lifelong immunity to tetanus. I learned the story because we were trout fishing, and he got a hook stuck in him, he just yanked it out and didn't sweat it at all.
Google "endotoxins" and "exotoxins". Some pretty interesting sites came up. A lot of what causes death in some of these infections is from these substances or the bodies immune response to them. Some kinds of immune response cause the body to "leak" fluid into tissue, which is what causes swelling and imflammation. The body then can go into shock and death can follow. It appears that a of of what you're looking for can be found on the internet.
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