GMOs promote antibiotic resistant bacteria?

[RichardR]

Coming out of the supermarket this weekend I was approached by a woman asking me if I would sign a petition to ban Genetically Modified (GM) farming in Marin county (Northern CA). My robust "certainly not" kind-of surprised her, as did my debunking of a couple of claims she made about the dangers of GMOs.

I took her leaflet anyway, and read its list of six "dangers posed by GM crops". I think I can debunk points 1 to 5, but wasn't sure about point 6:

Genetically engineered crop modification promotes the development of antibiotic resistant bacteria that can cause fatal human infections.

Genetic "engineers" attach genes for the crop characteristics they wish to promote, attached to genes for antibiotic resistance. They then apply antibiotics to the cell culture, destroying all but the altered cells. Unfortunately, the cells created by this process of "unnatural selection" are resistant to antibiotics, and have been shown to transfer that antibiotic resistance to bacteria, some of which can infect people. Bacterial resistance to antibiotics is already the most daunting problem in treating human infections. Genetically engineered crop modifications will make that problem even worse.

Can anyone comment on this process for engineering GM crops? Is it described correctly, above? And what is known about the risks of creating antibiotic resistant bacteria in this way?

Thanks.

[geni]

Plants are resitant to anti-boitics (probably) . It is true that a method of check that your gene has been inserted into the bacteria is by checking anti-biotic resitance but I can't see what this has to do with plants.

[Rolfe]

Originally posted by geni
It is true that a method of check that your gene has been inserted into the bacteria is by checking anti-biotic resitance....I can see why this might be a cause for concern, if the end products being distributed have these genes in them. Is it possible that this might result in the genes becoming more widespread in bacteria?

I don't know the answer to this, but I have a suspicion that there may be a very simple one because it seems intrinsically unlikely that anyone would do anything that daft if it really was the case.

Rolfe.

[geni]

Originally posted by Rolfe
I can see why this might be a cause for concern, if the end products being distributed have these genes in them. Is it possible that this might result in the genes becoming more widespread in bacteria?

I don't know the answer to this, but I have a suspicion that there may be a very simple one because it seems intrinsically unlikely that anyone would do anything that daft if it really was the case.

Rolfe.

But since the whole point of anti-biotics it that they only kill bacteria how could this be used as a alection method in plants? I know it's used with bacteria genitly engered to produce insulin but I've never herd fo this being done with plants.

[Rolfe]

I mean, is there any reason to fear that spreading the genes around the environment might increase the risk of them getting into bacteria? My molecular biology isn't up to answering that one. Can we be sure it's impossible?

I suspect the answer may be yes, but I'd like to hear an explanation.

Rolfe.

[Prester John]

Plants arn't generally affected by antibiotics :). Transfer of the gene from the plant to bacteria is most unlikely. They are most likely to use a common antibiotic resitance gene anyway, that would have very little effect in the extremely unlikely event it got transfered from a plant to a bacteria in the environment anyway.

[RichardR]

(Answering his own question)


The European Food Information Council (http://www.eufic.org/gb/food/pag/food03/food034.htm), "a non-profit organisation which provides science-based information on food and food-related topics to the media, health and nutrition professionals, educators, and opinion leaders", say this:

Concerns have been raised that the use of ARMs could have a negative impact on the use of antibiotics in human medicine. Two genes are widely used in plant biotechnology: kanamycin and ampicillin. These two antibiotics have been specifically chosen because, as a number of recent studies have shown, they have outlived their practical use. Nearly all strains of pathogens they used to kill are now resistant to them.

Googling did return a lot of stuff that said it was dangerous, of course. I'd still be interested in comments from anyone who actually knows about this.

[Rolfe]

kanamycin and ampicillin. These two antibiotics have been specifically chosen because, as a number of recent studies have shown, they have outlived their practical use. Nearly all strains of pathogens they used to kill are now resistant to them.I'd be interested to hear Prester John's take on that. Is ampicillin really so redundant? Is there any cross-resistance with amoxycillin, which is still used quite a bit? (Cripes, ampicillin was the new "greatest thing out" when I first graduated!)

I don't remember ever using kanamycin for anything much.

Rolfe.

[Prester John]

I've never seen Kanamycin used, however ampicillin is still used, quite reguarly as a first line antibiotic for treatment of Urinary Tract Infections (UTIs). Ampicillin and Amoxycillin are very close relatives, antibiotic resistance to one implies antibiotic resistance to the other. Resistance to ampicillin is pretty common, in maybe as much as 40-50% of cases of UTI's, i'd seen the resistance levels go up in the 10 yrs i worked in clinical bacteriology.

Ampicillin is a penicillin-like antibiotic used to treat certain infections caused by bacteria such as pneumonia; bronchitis; and ear, lung, skin, and urinary tract infections. Antibiotics will not work for colds, flu, or other viral infections.

http://www.nlm.nih.gov/medlineplus/druginfo/medmaster/a685002.html


I'd say the ampicillin (resistance)gene is so common anyway and easily acquired by bacteria that its not going to make any difference.

[Rolfe]

Originally posted by Prester John
I've never seen Kanamycin used, however ampicillin is still used, quite reguarly as a first line antibiotic for treatment of Urinary Tract Infections (UTIs). Ampicillin and Amoxycillin are very close relatives, antibiotic resistance to one implies antibiotic resistance to the other.That's what I thought too.Originally posted by Prester John
I'd say the ampicillin (resistance)gene is so common anyway and easily acquired by bacteria that its not going to make any difference. Well, maybe that's their point. Presumably somebody decided it was no big deal.

Rolfe.

[RichardR]

Thanks for the replies – this board is an education, as usual.

I emailed the author of the article and asked him for the studies that show that kanamycin and ampicillin have outlived their practical use. I'll post the result.

[Shane Costello]

Long story short: Research has been carried out into the possibility of gene transfer from GMOs to bacteria. This hasn't been observed "in the wild" and experimental models suggest that the chances of it happening are very remote. In any event it seems that anti-biotic resistance is very established in the human gastrointestinal tract. Remember this is an age where people demand antibiotics for viral infections.

[Shane Costello]

An assessment of the risks associated with the use of antibiotic resistance genes in genetically modified plants: report of the Working Party of the British Society for Antimicrobial Chemotherapy.

J Antimicrob Chemother. 2004 Mar;53(3):418-31. Epub 2004 Jan 28.

[I]Development of genetically modified (GM) plants is contentious, in part because bacterial antibiotic resistance (AR) genes are used in their construction and often become part of the plant genome. This arouses concern that cultivation of GM plants might provide a reservoir of AR genes that could power the evolution of new drug-resistant bacteria. We have considered bacterial DNA transfer systems (conjugation, transduction and transformation) and mechanisms of recombination (homologous recombination, transposition, site-specific recombination and DNA repair) that together might productively transfer AR genes from GM plants to bacterial cells, but are unable to identify a credible scenario whereby new drug-resistant bacteria would be created. However, we cannot entirely rule out the possibility of rare transfer events that involve novel mechanisms. Hence, we also considered if occasional transfers of AR genes (bla(TEM), aph(3'), aadA) from GM plants into bacteria would pose a threat to public health. These AR genes are common in many bacteria and each is found on mobile genetic elements that have moved extensively between DNA molecules and bacterial cells. This gene mobility has already severely compromised clinical use of antibiotics to which resistance is conferred. Accordingly, the argument that occasional transfer of these particular resistance genes from GM plants to bacteria would pose an unacceptable risk to human or animal health has little substance. We conclude that the risk of transfer of AR genes from GM plants to bacteria is remote, and that the hazard arising from any such gene transfer is, at worst, slight.

That's the latest review I can find.

[Shane Costello]

Some research here (http://www.foodstandards.gov.uk/science/research/researchinfo/foodcomponentsresearch/novelfoodsresearch/g01programme/G01genetransfer/)

A broader review of the GM debate (http://intl.plantphysiol.org/cgi/content/full/126/1/8#SEC5)

[Eos of the Eons]

Geez, when you eat food you don't get their genes transfered to yours. I would like to see what mechanism they think a bacterium has that could extract dna from a plant and incorporate it into theirs.

If they are so worried about the bacteria, then what about humans consuming it? Are they worried we can inherit genes from our food too?

This is a hoot, and rather typical of the imaginations of the people agains GM foods. Let's fear something new because it has to bad...they are playing with genes...oh no!!! The hysteria!

At one time people thought that driving cars was an unknown danger. Who knew what going those speeds every day would do to the body?

It is ignorance, plain and simple.

[RichardR]

Originally posted by Eos of the Eons
Are they worried we can inherit genes from our food too? To be fair, I don't think that's what they were saying in the leaflet they gave me.

Although I agree some people do seem to believe that.

[RichardR]

Originally posted by Shane Costello
Some research here (http://www.foodstandards.gov.uk/science/research/researchinfo/foodcomponentsresearch/novelfoodsresearch/g01programme/G01genetransfer/)

A broader review of the GM debate (http://intl.plantphysiol.org/cgi/content/full/126/1/8#SEC5) Thanks Shane. Interesting reading material.

[RichardR]

Btw, my discussion with the anti-GMO woman last Saturday prompted me to educate myself on the "issues" listed in the leaflet she gave me. I searched the forum and re-read a few of the old threads on GMOs. I found I was able to refute all the points made after reading the threads and their referenced articles, and by doing a few more searches. Input from Shane C, headscratcher4 and Eos were all useful. Glad the threads hadn't been pruned.

The leaflet the anti-GMO woman gave me appeared to be just dogma. One example – Bt corn is killing Monarch butterflies. (Something I didn't have an answer for off the bat – I do now though.) ALL of the stuff on their leaflet related to flawed or superceded studies, or just false information. Either they really don't know or they just don't care and are lying. My money is on the latter.

Anyway, the anti-GMO woman had one useful influence on me – she forced me to educate myself on the subject, and now I feel I can rebut the whole thing. That probably wasn't the result they had in mind when they wrote the leaflet.

[Shane Costello]

Originally posted by Eos of the Eons:
If they are so worried about the bacteria, then what about humans consuming it? Are they worried we can inherit genes from our food too?

I'll try and track down a link, but a high percentage of people believe that "conventional" food doesn't contain any DNA at all.

It is ignorance, plain and simple.

And how. I've come across this personally, although not in connection with GM food. Right now in Ireland there's a debate on the virtues of incineration as a means of waste disposal. Anti-incineration campaigners claim we'll be filling the air with all sorts of pollutants, dioxins in particular. The pro-incineration lobby claim that modern incinerators run at such high temperatures that dioxons are eliminated, and cite the example of eco-friendly countries like Germany and Scandinavia, where incinerators are often placed slap bang in the middle of town centers.

By and large people are inclined to give the anti's the benefit of the doubt. What's annoying is the gap between what people say and believe, and their actual behaviour. One woman I know is vehemently opposed to incineration because of the possible impact on air quality. The same woman smoke 40 cigarettes a day, and strong ones at that. I know of another man who finds the idea of dioxins polluting the atmosphere very worrying. He regularly burns plastic in his back yard, and quite a bit of it too.

[Eos of the Eons]

Originally posted by Shane Costello


I'll try and track down a link, but a high percentage of people believe that "conventional" food doesn't contain any DNA at all.


I have a link to a funny site that people can mistake as real
http://home.iprimus.com.au/ttguy/

And thank you for the rest of your post. I had my laugh for the day, and a shake of the head!
Anyway, the anti-GMO woman had one useful influence on me – she forced me to educate myself on the subject, and now I feel I can rebut the whole thing. That probably wasn't the result they had in mind when they wrote the leaflet.

I LOVE that kind of irony :)

[Eos of the Eons]

From my link :D

http://home.iprimus.com.au/ttguy/hit_tracking.jpg

[Capsid]

Kanamycin resistance genes are advised by the FDA because kanamycin (added to the bacterial cultures to select for the expression plasmid) is not extensively used in the treatment of clinical infections due to its low activity spectrum. Further ampicillin is not advised due to problems of sensitivity in the general population. The concern is more with the antibiotics themselves than the resistance.