At 7:15 AM -0700 8/11/01, Terry W. Colvin was kind enough to forward:
]I'd been musing on this very example last night, wondering how to get
]across to ordinary folks how ludicrous it seems to me. But my logic and
]facts might be in error, so I'd like to run my riposte past the biologists
]on the list:
]
]`Superbugs', so-called, are not some new and unheralded kind of omnipotent
]monster bacterium.
Some are worse than their ancestors, because the strategies used to
defeat antibiotics can give them increased resistance against the
human immune system. For example, some bacteria change their
glycoprotein coats, which means that they can reinfect a person who
would normally be immunized from previous exposure. Others produce a
thicker coat, and this makes them invisible to the immune system
because antibodies can't bind. Others pump out toxic chemicals, such
as ions, at a faster rate, which allows them to defeat cytotoxic t
lymphocytes' attempts to destroy them.
Also, these are 'different' in the sense that the bacteria that
infect humans never had these abilities until they were introduced
from livestock. That is: the resistance factors have been transmitted
from the bacteria that infected what we ate. This could only have
happened if our food supply was exposed to antibiotics.
](And of course they can't be any kind of virus, because
]antibiotics shouldn't affect those critters--unless altering the background
]ecological mix does somehow skew the norm of reaction for viri.)
Strictly speaking, yes, but there is an identical product line for
viruses called 'antivirals', and the analogy is identical. There are
antivirals for warts, for cold sores, &c, which are overused, and
these lesions are becoming more frequent again. Unfortunately, one of
the doctors I work for has just published a paper saying there is a
strain of HIV now that is resistant to everything.
]What they are is, by definition, *bacteria resistant to a particular
]antibiotic*, or perhaps a family of similar antibiotics.
Usually a family. Penicillin is part of the 'beta-lactam' family, for example.
]That means that their evolution, at worst, has reverted the balance of play
]to the way it was originally.
And that's the error. Many types of antibiotics emulate something the
immune system already does. Unfortunately, adaptations effective
against the antibiotic are also effective against the immune system.
Secondarily, because of antibiotics in our food supply, the bacteria
that infect humans have all-new powers to which we have had no
ancestral exposure, and against which we have no defense strategies.
]*Except* that, in the meantime, monocultural agribiz has reduced the
]genetic diversity of crops, making widespread variants especially
]vulnerable to the rebound diseases. That's not the fault of antibiotics
]*per se*, though. It might be a very good reason to worry about excessively
]centralized and massively advertised corporate food production.
Yes. Secondarily, though, the human population has rebounded with
large subpopulations which have no resistance to certain bacteria.
Consider: there was a time when most europeans got smallpox and
survived. Today, this inherent resistance is 500 years in the past,
and it would probably kill off 70% of us. Likewise, tuberculosis
isn't necessarily deadlier, but it is probably deadly to a much
larger part of the population. Consider CF or hemophaelia. Until the
last few decades, these people never became parents, but now there
are second generations. Likewise with severe bee allergies. Much more
abundant today because antihistamines and adrenaline needles allow
survival to adulthood.
]My feeling is that one needs to be very careful in describing the real
]problem(s), and allocating blame. As far as I can see, *nobody* has been
]harmed by applying antibiotics to ill humans. I and many others are now
]alive because of them. If we now face, at worst, reversion to a condition
]where resistant bacterial diseases roam the world unchecked, that's very
]sad--not because of the brief, blessed epoch of cheap, effective
]antibiotics, but because it's at an end.
I haven't read the transcrippt, but I think there is a legitemate
complaint to be levelled against those who promote the inappropriate
use of antibiotics. In the US, the direct marketing of medications is
discouraged. This comes from the experience that advertising a drug
increases demand, and advertising its use for everything but the
kitchen sink encourages its inappropriate use. The old antibiotic ads
used to be pretty much "got a cough? demand antibiotics from your
doctor", and doctors capitulated, even though they had read that
overuse will eventually short-circuit effectiveness. So, we had a bit
of a tragedy of the commons here, where sellers and consumers felt
unmotivated to reduce abuse because everybody else would probably
continue overuse anyway.
The other frustrating element is that antibiotics in animal feed were
not used as antibiotics, but as a growth factor. Animals that at the
additives got just as sick, but they grew larger faster, and this was
the appeal. That this has led to resistant strains of bacteria in
humans - even those who did not eat meat - does not seem like a fair
exchange. A good way to extend a patent! I argue it was an
externality.
-Graeme.
-- ------------------------------------------------------------------------------- Graeme Kennedy graeme@seercom.com e 202 - 360 E 2nd St. 604.990.0207 p N. Vancouver, BC V7L 4N6 www.seercom.com/bluto w ------------------------------------------------------------------------------- "A witty saying proves nothing." - Voltaire -------------------------------------------------------------------------------=========================
At 9:59 AM -0700 8/12/01, Graeme Kennedy was kind enough to write:
]]What they are is, by definition, *bacteria resistant to a particular ]]antibiotic*, or perhaps a family of similar antibiotics. ] ]Usually a family. Penicillin is part of the 'beta-lactam' family, for example.
I missed something important here. The worst superbugs are resistant to all known antibiotics. The names can sound too innocent: MRSA stands for 'multiply resistant staph aureus', and VRE stands for 'vancomycin resistant enterococci', but most people don't understand that the reason we say it's resistant to vanco, is because vancomycin is the antibiotic of last resort. You don't try vanco until everything else has failed.
MRSA will kill a person with a weak immune system. ie: the elderly. So, yes, we're at risk of going back to 'the good old days' of 45 year average lifespans.
-Graeme.
-- Terry W. Colvin, Sierra Vista, Arizona (USA) < fortean1@mindspring.com > Alternate: < terry_colvin@hotmail.com > Home Page: < http://www.geocities.com/Area51/Stargate/8958/index.html > Sites: Fortean Times * Northwest Mysteries * Mystic's Cyberpage * TLCB * U.S. Message Text Formatting (USMTF) Program ------------ Member: Thailand-Laos-Cambodia Brotherhood (TLCB) Mailing List TLCB Web Site: < http://www.tlc-brotherhood.org >[Vietnam veterans, Allies, and CIA/NSA are welcome]
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