The idea that we have a moral duty to complete any course of antibiotics that the doctor prescribes is intuitively comforting. Following the course to the end appears as an act of solidarity against the genuinely terrible threat of widespread antibiotic resistance, something that could make medicine as we know it impossibly dangerous. Following the doctor’s orders allows us to be mildly uncomfortable in pursuit of collective good. So it is rather shocking when the British Medical Journal reports that the instruction is mistaken and indeed counterproductive. We should not only take antibiotics less often; we should take them for much less time.
Nonetheless, the argument of the BMJ paper is very strong. It starts from history. At the beginning of the antibiotic era, the danger to patients came from insufficient dosage, not from too much. The very first patient ever treated with penicillin died after supplies ran out, even when they were recycled from what he had already consumed. Sir Alexander Fleming himself believed that antibiotic resistance would be stimulated by inadequate courses of antibiotics. In any case, there are compelling legal and social reasons why doctors are more worried about being accused of doing too little than too much.
It took decades for the dangers of antibiotic resistance to appear and to be recognised as the very serious threat they are. By that time the habits of antibiotic prescription were well established, even if they had seldom been clinically tested. Besides, there is a very large general problem of patients failing to take the pills they have been prescribed. From that perspective, urging patients to finish their course of antibiotics is no more than consistency, and telling them that they may stop as soon as they feel well again is undermining the principle on which long-acting drugs like statins are prescribed, since they have to be taken regularly even though they make no immediately noticeable difference to wellbeing.
So, while the medical profession is determined to cut down on needless prescription, there has been little enthusiasm for, and some active resistance to, cutting down on the needless consumption of antibiotics once prescribed. The problem that arises lies in the nature of bacteria and the enthusiastic way in which they can swap genes without sex and even between species. The great mass of bacteria that coat our skins and live inside us are not the targets of any normal course of antibiotics, but they are affected anyway. Those colonies will be selected for antibiotic resistance, and once that is established, they can exchange the genes involved with other, more malignant species. This seems to have been the mechanism by which the MRSA bug arose.
The great, global danger of antibiotic resistance comes of course from their indiscriminate use in agriculture, especially in developing countries. The next global pandemic will probably arise from the pig farms of China. But the example of MRSA shows how much suffering even a much smaller infection can cause. Within hospitals today it is becoming common to test and monitor the effects of antibiotics and to withdraw them as soon as they have done their work. That is much harder to do in the world outside. Clinical trials to establish the optimum length of treatment for different infections with different antibiotics would be prohibitively expensive.
It is easy to understand why some experts are reluctant to undermine the authority of the medical profession by countermanding one of the few pieces of medical advice that everyone knows and thinks that they understand. But the known dangers of encouraging antibiotic resistance must outweigh this. The reason we obey doctors’ orders is that they have access to more and better information than we do. When their knowledge of the facts changes, they should change their conclusions. In the long run this is much better for their authority than pretending to infallibility would be.