By Rowland Benjamin

Worldwide overuse of antibiotics is decreasing their effectiveness, because of bacteria’s natural process of mutation. The more that bacteria come into contact with an antibiotic, the more they are encouraged to mutate to avoid being killed by it. The new mutated bacteria are then able to resist the effectiveness of the antibiotic.

Bacteria are an example of evolution through natural selection, except that their evolution happens much more rapidly than that of animals or humans. This is not particularly surprising, considering that the life cycle of most bacteria is only 2 to 3 weeks compared with decades for animal and human life cycles. When bacteria are first exposed to an antibiotic, those most susceptible die rapidly, but the surviving bacteria will pass on their ability to resist the antibiotic to successive generations. Bacteria have now had approximately 60 years to adapt to antibiotics, and hence it is no surprise that they are becoming resistant. Even one course of antibiotics may have adverse effects upon communities. Research in Australia has revealed that children who have had a recent course of antibiotics are twice as susceptible as others to possess low levels of antibiotic-resistant bacteria in their bodies. At low levels, the bacteria are harmless, but if they flare into an infection, they may be unresponsive to antibiotics, and the child could become very ill.

Misuse of antibiotics may also encourage bacteria to become antibiotic resistant. Many people do not take the full course, and some may even stop taking them after only a day or two. This is due to the fact that symptoms are relieved very quickly, and patients may believe that they have already recovered, and do not need to take the rest of the treatment. However, a patient who feels better but has not completed the course is likely to still be harbouring a population of mutant bacteria. In time, these will multiply until they cause a repeatedoutbreak of the infection. The patient may then pass on these resistant bacteria to others, and if those other people also misuse antibiotics, further mutations will occur. Eventually this may lead to the creation of a ‘super bug’ that is immune to all classes of antibiotics. Clearly, it is much better to not use antibiotics at all, rather than to misuse them.

 Return to Antibiotics Introduction