Karl Hoenke questions whether we should adhere to the medical orthodoxy of completing a course of antibiotics, suggesting that this might encourage the emergence of resistant bacteria rather than discourage it (13 June, p 25). His quandary is easily answered.
While antibiotics inhibit or kill susceptible bugs, they are not the only defence mechanism at work. The body's own cellular and humoral mechanisms are usually still operating at some level. The crucial points is whether the bacterial load is too great for them to cope with.
Killing or inhibiting as many bugs as possible makes it more certain that the body's systems can take care of the rest, including any fully drug-resistant organisms. Stopping early, before the body itself can mount an effective defence, allows those bugs that are only inhibited to multiply, reduces the likelihood of full recovery and promotes the spread of drug-resistant versions.