WHICH is worse: encouraging antibiotic resistance or releasing genetically
modified bacteria into the environment? This is the dilemma posed by an
alternative to growth-promoting antibiotics patented by the drugs company
Pfizer.
The use of antibiotics on farms has been widely condemned by doctors because
it leads to the development of antibiotic resistance in bacteria. But Pfizer鈥檚
GM alternative could lead to GM bacteria being released into the environment in
the animals鈥� faeces.
Harmless bacteria such as Lactobacillus lactis make an antimicrobial
compound called nisin. Pfizer proposes giving these bacteria extra genes so they
can make normal and artificial variants of nisin. Mark Haxell, Timothy Rolph and
Alison Flanagan of Pfizer say in the patent that such GM bacteria would keep
disease-causing bacteria at bay in the guts of farm animals, be they sheep,
pigs, cows or chickens (WO 99/41978). Protected from debilitating gut
infections, the animals should flourish and put on weight fast, just like
animals given antibiotics.
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Unlike antibiotics, a single dose of the GM bacteria would last a lifetime,
the researchers say. They recommend giving the bacteria to animals as young as
possible. 鈥淭he theory is that you feed a modified GM lactobacillus strain as a
means of delivering the [nisin] to the animals鈥� gut,鈥� says a spokesman for
Pfizer.
He admits, however, that the discharge of the GM bacteria in faeces could be
a problem, and says that because of 鈥渢echnical difficulties鈥�, the idea has been
put on hold for the present.