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Threads - Some Serious Non-Science, Evolutionary Theory Predicts Nothing?,

On 9/11/2003, Peter Macinnis wrote:

I am looking today at the arguments for the use of antibiotics in animal husbandry, where the aim is to make animals grow a leedle bit faster, by giving them low doses of antibiotics like avoparcin (a compound similar to
vancomycin, the "antibiotic of last resort", to which some pathogens are now resistant).

Note: low doses, hence more conducive to favouring bacteria with some degree of resistance.

To my slightly cynical eye, the arguments of the "Animal Health Institute" (http://www.ahi.org/), an industry lobby group of manufacturers selling antibiotics to farmers, stink. Noty to put too fine a point on it, their methods are reminiscent of the weasel tonues of tobacco pushers and creationists.

Show us proof that there is a real causal link, they say at the AHI. Show us a bacterium actually developing resistance in an animal, they say. In the interim, leave us alone to go on making profits, because the link is
"pretty tenuous", and on and on . . .

A huckster is a huckster, the world over . . . take this abstract for example, touted as peer-reviewed:

"Following the ban of all food animal growth-promoting antibiotics by Sweden in 1986, the European Union banned avoparcin in 1997 and bacitracin, spiramycin, tylosin and virginiamycin in 1999. Three years later, the only attributable effect in humans has been a diminution in acquired resistance in enterococci isolated from human faecal carriers. There has been an increase in human infection from vancomycin-resistant enterococci in
Europe, probably related to the increased in usage of vancomycin for the treatment of methicillin-resistant staphylococci."

(No, once let loose, the level of vancomycin-resistant bacteria HAS to be expected to increase. If you keep cramming avoparcin into farm animals to increase farmers' profits, what bacteria will develop resistance next?)

They continue:

"The ban of growth promoters has, however, revealed that these agents had important prophylactic activity and their withdrawal is now associated with a deterioration in animal health, including increased diarrhoea, weight
loss and mortality due to Escherichia coli and Lawsonia intracellularis in early post-weaning pigs, and clostridial necrotic enteritis in broilers."

(Oh you poor dears, isn't the profit line looking so good? Maybe you should clean up the barn, instead of using antibiotics?)

"A directly attributable effect of these infections is the increase in usage of therapeutic antibiotics in food animals, including that of tetracycline, aminoglycosides, trimethoprim/sulphonamide, macrolides and lincosamides, all of which are of direct importance in human medicine. The theoretical and political benefit of the widespread ban of growth promoters needs to be more carefully weighed against the increasingly apparent
adverse consequences."

(No, these aren't growth promoters at all. They are antibiotics. Get it right, people!)

Gerald Cairnes replied:

That organisation lost all credibility a long time ago, if it ever had any.
Snake Oil salesmen all!
It is the same sort of industrial control reminiscent of the National Registration Authority which manages to price innovators out of the market in favour of the big chemical companies and so on with other such government departments.

On 30/11/2004, Paul Williams posted:

Long time ago now (Friday, February 14, 2003 and thereabouts) we discussed evolutionary theory predictions on Science Matters. Recently, on another list I subscribe to, the predictive value of evolutionary theory was called into question.
For those who missed the link to the wonderful naked mole rat...

[In response to the statement that 'evolutionary theory predicts nothing']:

O.K. - I predict that Staphylococcus aureus will become vancomycin resistant.

The ability to predict a new 'lifeform' is becoming more realisable:
http://www.hhmi.org/news/ferguson2.html

Being mammal biased (as we tend to be), the existence of eusocial mammals is a delightful example of prediction from evolutionary theory:

"The Predictive Power of Evolutionary Biology and the Discovery of Eusociality in the Naked Mole Rat"
http://www.ncseweb.org/newsletter.asp?curiss=4

Peter Macinnis replied:

At 17:01 30/11/03 +1000, Paul wrote:

>O.K. - I predict that Staphylococcus aureus will become vancomycin
>resistant.

A bit late there, I fear.

Better to predict that Gram-positive bacteria will become nisin-resistant -- but it may take a while. There was a 32-year gap between the entry of vancomycin into the marketplace (a term I use advisedly) and the appearance of resistance in 1988. Resistance to erythromycin appeared in 1988 after 36 years of use. Cephalosporins took less than a decade.

My daughter mentioned over lunch that she made up two litres of a fairly noxious ant-fouling compound, and that the flask has algae growing in it. Herbicides typically take about a decade to be blunted -- Picloram and
Trifluralin took from 1963 to 1988 to be resisted. All in all, 1988 was a vintage years for resistant organisms. (Triallate and Diclofop failed in 1987 . . .)

We are contemplating a deal with the anti-fouling people: they provide lots of money, we don't release the algae :-)

For reasons that the perceptive may deduce, I am getting rather deeply involved in this issue at the moment. Most bacteria will be susceptible, some may be tolerant, and in time, many will be resistant. Tolerant forms are insidious -- they stop growing while the antibiotic is around, and at the end of the course, like a horror movie monster, they jump up again.

The so-called "Animal Health Institute", a US consortium of pharmaceutical thugs (lobby group, whatever), argues that they should be allowed to keep selling avoparcin, a close relative of vancomycin, to make cattle, chooks and pigs grow better. "Most of the growth promoters we use are not used as antibiotics in humans", they say.

Pigs' buttocks, I say. I spent much of the weekend reading selected papers from the past five years in "Nature" and "Science" and getting a hit list of further reading, and I am filled with righteous wrath.

Especially when Donald Kennedy, editor of "Science" reminds us that he (and others) were arguing to keep antibiotics away from herds and flocks as far back as 1977.

Rubbish, say the AHI, Campylobacter in chooks protects the people eating contaminated chook from being infected . . . and no mention of Guillain-Barré syndrome as a potential end-result if the suckers DO get infected because they did not read the right flaky "tobacco research" on best practice in splatting antibiotics around, squandering our children's health for a fast buck.

Not long after this list started, I was accused of doctor-bashing when I mentioned GPs who slather antibiotics around. Several years ago, a third of US pediatricians admitted to giving antibiotics for viral infections, just to shut the parents up. A third of them admitted it. How many of then others were too ashamed to be honest?

Soap box is free . . .

On 26/2/2004, Daya Papalkar posted:

I had a look through the archives and saw some previous comments about VRSA.so I had to add my bit.

1) Of patients with VRSA, I have only read the report in NEJM about VRSA & I was not surprised to see that it was isolated in a dialysis patient (chronic renal failure, diabetic, vascular access, prevalence of MRSA in dialysis units etc). Anecdotally, I have heard that some units do not screen for VRE (vancomycin resistant Enterococcus) anymore because it is much more common than they would like...

2) I agree that it is a travesty that antibiotics are used in feed stock. Basically, my view is that the companies that use this practice are deciding that the health of the population is less important than their profit. I would be very surprised if the economic cost of infections (in humans) due to multiply-resistant organisms created through this practice was not higher
than the profit to be gained by the practice. Or at least the potential for this is massive, and the risks far outweighs the benefit of the practice. It is crazy that it is allowed to go on (especially when compared to the restrictions placed on "dealings" with GMOs), which leads to the next point.

3) I went to a safety course on Gene Technology recently which was primarily about the Office of the Gene Technology Regulator (OGTR) and the new legislation. I found it *so ironic* that so much red tape has been created to manage GMOs and yet it would not be hard to create a VRSA in the lab (if one were an evil scientist) without the use of technology that would define it as a GMO. That is, by using chemical selection (and therefore not a GMO "dealing"), exactly as feeding antibiotics to animals creates antibiotic-resistant organisms.

4) There is not much incentive for drug companies to produce antibiotics that are effective against multiply-resistant bacteria (unless the antibiotic can be promoted as providing broad-spectrum cover), because the use of these agents is (necessarily) restricted to (rare) infections with these bacteria. Hence, how will they recoup their research costs when the drug they create is encouraged (appropriately) to be used as scarcely as possible?

5) With regard to over-prescription of antibiotics, I agree that it is a serious problem. However, some patients have to take on some responsibility for this happening. In spite of attempts to educate, some patients will just go and doctor-shop until they get the prescription that they "need". This is just one issue in a multifactorial problem; I think it is an oversimplification to blame doctors entirely without looking at the other issues at hand.

In summary, much has been made of the dangers of GMOs now & in the past, but the people who are jumping up and down about GMOs should be just as concerned (or even more concerned) about the effect of non-gene technology practices that are likely to create difficult-to-treat pathogenic organisms.

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Vancomycin-Resistant Staph

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