MEDICINE
Bacteria win
JOHN ROWAN WILSON
The chemists are in full retreat these days. One by one their panaceas are being re- jected. First it was cyclamates, then DDT; now it is antibiotics that are under a cloud. The report of the Swann Committee on an- tibiotics in animal husbandry will almost certainly lead to legislation designed to con- trol and regulate their use.
It is all part of a new attitude of scepticism and disenchantment regarding antibiotics generally. It is not surprising that the world was knocked a little off balance by them in the beginnihg. Antibiotics were so different from any anti-infective agent that had preceded them—so much more rapidly effec- tive, so much less toxic—that they appeared to show a difference in kind rather than merely in degree. Penicillin was miraculous enough, but when within a few years substances appeared of even wider range, which could be taken by mouth and were apparently non-toxic, almost anything seemed possible.
In th9se early days I was attached to the research staff of a company which had discovered one of the most successful of these antibiotics. The atmosphere of elation, almost of omnipotence, is hard to describe. We were flown over to the parent laboratories in the us where it had been found that this incredible substance not only cured most common infections, but also had some mysterious quality that increased the growth of animals. It came almost as a disappointment to learn at a later date that the antibiotic did not, as we first thought, have a specific nutritive value, but simply acted by suppressing chronic infections of the animals' intestinal canal.
The antibiotic was rather like the Worn- porn in the well-known song by Michael Flanders—you could use it for almost anything. It was developed in the form of a spray for preserving the carcases of battery hens from corruption; it could be in- corporated in ice for packing around fish. In our innocence we visualised it as becoming an integral part of modern life, like nylon or refrigeration or the diesel engine.
What has emerged gradually over the last fifteen years is that such hopes can never be entertained of any chemical that acts within a biological situation. It is a characteristic of living organisms to adapt themselves in order to survive. At one time there were great hopes of eradiCating certain diseases coni- pktely, of driving hostile bacteria or insects off the planet. Candidates for this kind of total war were the plasmodium which causes malaria, the tubercle bacillus, and the spirochaete of syphilis. But such high hopes have had to be modified. As Dr Candau. the Director General of the World Health Organisation, said .ruefully two years ago: 'we underestimated the intelligence of the mosquito and of the plasmodium.'
Bacteria have developed resistance to an- tibiotics in the same way as the mosquito has developed resistance to DDT, by selectise breeding. The chemical kills those organisms that are susceptible and leaves a few behind which are accidentally immune. These reproduce and soon produce a population which cannot be harmed by the antibiotic. But within the last few years another way of acquiring resistance has come to light, bt which resistance to an antibiotic can he passed from one bacteria to another with which it lives in contact. This raises the possibility that resistance may spread through bacteria like a kind of infection.
The obvious conclusion is that we should keep back antibiotics for circumstances where they are really necessary and not use them indiscriminately. This was graphical') demonstrated during a recent prolonged epidemic of paratyphoid fever in calves. An attempt to control this by giving massi‘e doses of antibiotics was not only futile, but led to the development of bacteria which were not responsive to conventional an• tibiotics. Infection with these bacteria in due course caused a considerable number of resistance cases of paratyphoid in humans. It is not easy for any government to formulate precise regulations for such complex situation. It would be far too 1 radical a step to prohibit the use of an' tibioticS in animals altogether—this woukl not only be a serious blow to farmers. and difficult to enforce, but the danger is not great enough to justify it. It would be ideal if we could have two different groups of an• tibiotics, one for hUmans and one fee animals, but this is unfortunately not eacs" ble at the present time. However, it certainlf seems reasonable, as the committee sugge, to control the use of antibiotics as a rout addition to feeds, and to restrict their ministration to qualified veterinary surgeons.
What is also clear now is that our rela- tionship with bacteria will never be the dominant one that was considered possible at one time. Man has been deluded by his success in exterminating the larger mammajs into an exaggerated sense of his own biological mastery. But insects and micro- organisms are a vastly different proposition from wolves and gorillas. They are won- derfully fitted for survival and for adaptation to different environments. We cannot dispose of them at will, and it is even questionable whether it would always be to our advantage to do so. We must reconcile ourselves to sharing the world with them. Indeed, when it comes to ultimate survival, they probably have a better chance than we have.
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