Study shows antibiotics disrupt gut for months

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Martian
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Study shows antibiotics disrupt gut for months

Post by Martian » Thu 20 Nov 2008 20:34

Source: Canasian press:
This is your stomach on drugs: Study shows antibiotics disrupt gut for months

Provided by: The Canadian Press
Written by: Helen Branswell, THE CANADIAN PRESS
Nov. 19, 2008

TORONTO — This is your gut. This is your gut on drugs.

A new study reveals that a common antibiotic disrupts normal bacterial levels in the digestive tract of healthy adults for longer than previously thought. Six months later, in fact, some beneficial types of bacteria were still wiped out or remained at levels lower than before the drugs were taken.

"You don't want to be giving readers the impression that we shouldn't be using antibiotics (when needed)," says Dr. David Relman, senior author of the study, which was published Tuesday in the journal PLoS Biology.

"But it's the flip side. It's the trade-off part. . . . Because we do overuse antibiotics."

Relman, an infectious diseases specialist at Stanford University and the Veteran Affairs Hospital at Palo Alto, Calif., conducted the study with a team of colleagues. Funding for the work came from the Doris Duke Charitable Foundation and the U.S. National Institutes of Health.

Antibiotics aren't a targeted treatment. The drugs don't zero in on the bacteria you want to kill and leave intact the rest of the body's normal and healthy bacteria. That's why taking antibiotics to cure one problem can give rise to another - for instance yeast infections or C. difficile diarrhea.

But it's not clear just how much damage the drugs wreak on the body's bacterial "flora" - the beneficial bacteria that inhabit places like the gut, helping to keep us healthy and safe from bugs that would make us ill.

To try to quantify the effect, Relman and his colleagues gave three healthy volunteers - two men and a woman - a single course of the antibiotic ciprofloxacin.

While all antibiotics will knock out a range of bacteria, cipro is believed to be among the least disruptive of the drugs.

In fact, thousands of U.S. postal workers were prescribed ciprofloxacin in 2001 after letters containing anthrax were processed through several sorting stations. There were few reports of postal workers suffering side-effects from the drug, Relman said.

In this study, the researchers collected stool samples from their volunteers before they started the five-day course of cipro, during treatment and for months after.

They are actually still studying these individuals plus four others and have samples going out a year after the first dose of the drug. But in this paper they report on results for the first six months only.

They mined the stool samples for traces of bacteria using a technique called polymerase chain reaction or PCR, identifying DNA from between 3,300 and 5,700 different types in the samples collected before treatment. Most of the bacteria - in fact 93 per cent - haven't yet been identified, Relman said.

The diversity in bacterial types was cut by about a third after the volunteers took the antibiotics. Relman said the size of the reduction came as a surprise.

"We find that cipro was more disruptive than we had thought.... About 30 per cent of all of the strains and species that we could see were disrupted. And most of them were ... either knocked out or knocked down."

By four weeks post-treatment, most of the bacterial populations seemed to have recovered, though some were still at depressed levels. And some were not evident at all.

Given that so little is known about most of the bacteria, the researchers can only hazard guesses at whether that effect would have any long-term impact on the health of their volunteers. In the short term, none reported feeling ill.

But these volunteers were healthy. If they were people already fighting some infection or illness, the results might have been different. And even with the healthy people, Relman said it's too soon to say there is no health cost.

"The things that we see getting knocked out or knocked down are typically associated with (good) health," he said.

"We can't say that each and every one of these individual organisms is necessary or important somehow or contributing to health ... But the overall communities are associated with a lot of beneficial features for the host. So the net effect could potentially be harmful."

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LymeEnigma
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Re: Study shows antibiotics disrupt gut for months

Post by LymeEnigma » Thu 20 Nov 2008 22:26

Considering how much of the immune system resides in the gut, I would say these findings are substantial. I have to wonder how many beneficial bacteria, beyond bifidobacteria and lactobacillus (those most readily replaced with probiotics), are disrupted with long-term antibiotic use ... and I wonder what kind of an impact this has on long-term health, as well as recovery....

Martian
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Re: Study shows antibiotics disrupt gut for months

Post by Martian » Thu 20 Nov 2008 22:57

LymeEnigma wrote:I have to wonder how many beneficial bacteria, beyond bifidobacteria and lactobacillus (those most readily replaced with probiotics), are disrupted with long-term antibiotic use ... and I wonder what kind of an impact this has on long-term health, as well as recovery....
Yes, and this is just one example of the negative impacts of antibiotics.

Full text of the study (and source of summary): http://biology.plosjournals.org/perlser ... io.0060280
The Pervasive Effects of an Antibiotic on the Human Gut Microbiota, as Revealed by Deep 16S rRNA Sequencing

Les Dethlefsen1,2, Sue Huse3, Mitchell L. Sogin3, David A. Relman1,2,4*

1 Department of Microbiology and Immunology, Stanford University, Stanford, California, United States of America, 2 Department of Medicine, Stanford University, Stanford, California, United States of America, 3 Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, Massachusetts, United States of America, 4 Veterans Affairs Palo Alto Health Care System, Palo Alto, California, United States of America


Author Summary

The intestinal microbiota is essential to human health, with effects on nutrition, metabolism, pathogen resistance, and other processes. Antibiotics may disrupt these interactions and cause acute disease, as well as contribute to chronic health problems, although technical challenges have hampered research on this front. Several recent studies have characterized uncultured and complex microbial communities by applying a new, massively parallel technology to obtain hundreds of thousands of sequences of a specific variable region within the small subunit rRNA gene. These shorter sequences provide an indication of diversity. We used this technique to track changes in the intestinal microbiota of three healthy humans before and after treatment with the antibiotic ciprofloxacin, with high sensitivity and resolution, and without sacrificing breadth of coverage. Consistent with previous results, we found that the microbiota of these individuals was similar at the genus level, but interindividual differences were evident at finer scales. Ciprofloxacin reduced the diversity of the intestinal microbiota, with significant effects on about one-third of the bacterial taxa. Despite this pervasive disturbance, the membership of the communities had largely returned to the pretreatment state within 4 weeks.
Also see this related article: Gut Reaction: Pyrosequencing Provides the Poop on Distal Gut Bacteria

seanna
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Re: Study shows antibiotics disrupt gut for months

Post by seanna » Mon 1 Dec 2008 18:36

Very Interesting, thx for posting this. Does anyone know of any studies relating to the use IV antibiotics? Since Iv's go right into your blood stream rather than through your gut, do they still affect the flora in your gut I wonder?

cave76
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Re: Study shows antibiotics disrupt gut for months

Post by cave76 » Tue 2 Dec 2008 0:27

A Study of One (me) but I'm sure there are others.

Long term antibiotics helped me, but then I had/have Lyme disease.

Any 'disruption' of my intestinal flora (and I was never aware of any) was minor compared to how I feel off antibiotics.

But, that's just a Study of One. :)

Thank god for long term antibiotics. Just my opinion.

:woohoo:

cave76
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Re: Study shows antibiotics disrupt gut for months

Post by cave76 » Tue 2 Dec 2008 0:56

Seanna,

I forgot to address your questions.

Does anyone know of any studies relating to the use IV antibiotics?

If you mean studies relating to IV abx and gut flora, I don't know of any. Maybe others can post a study on that?
Remember, each study is just a 'study' in and of itself. The study posted I'm sure presented the facts as stated and there's no argument there.

It's how it's interpreted that counts. And that can be many different ways.

Some might interpret it as never go on long term antibiotics.

I interpret it as----- yes, long term antibiotics do disrupt the intestinal flora----- but since I had a potentially life threatening illness and was so sick I could barely get out of bed and had to resort to being pushed in a wheelchair to do shopping ----- I opted for antibiotics and take a lot of probiotics and prebiotics to try and keep my intestinal flora as balanced as possible.

Figured, I'd worry about healthy poop later. :)

And I'm now a LOT better off. And to hell with my poop. :D

Since Iv's go right into your blood stream rather than through your gut, do they still affect the flora in your gut I wonder?


I'll let others find those studies. Gotta go take my antibiotics.

Curiouser
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Re: Study shows antibiotics disrupt gut for months

Post by Curiouser » Tue 2 Dec 2008 14:17

Nice to know my instincts are still working from time to time. Figured just because I stopped taking the antibiotics, my gut wasn't going to magically get back in the groove, so to speak.

Since I've been off antibiotics (more than a month now), I've continued to take the probiotics and nystatin. Will drop the nystatin soon, but will continue on with the probiotics.

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