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THE DANGER OF ANTIBIOTIC RESISTANT BACTERIA

© Juan C. Mendible

Part I

Up until 1944 any bacterial infection had the potential of being mortal. The discovery in 1944 of the antibiotic penicillin, a substance extracted from the mould Penicillum by Alexander Fleming, had such success that it is considered to be one of the most defining moments in the history of medicine.

Its success, and that of other antibiotics, was so spectacular that some doctors said that soon infectious diseases would disappear and would be a thing of the past. However, almost 60 years later we are under attack by new microbes and some of the old ones have become resistant to the antibiotics that used to kill them. What happened?

It is known that doctors are always looking for magic bullets able to eliminate any kind of disease; and at the first success some of them start to use such drugs indiscriminately, without totally understanding the science behind them. Of course, they did not know in 1944 that antibiotics , if not used properly could make the bacteria resistant, rendering the drugs totally useless.

To try to understand this problem, let's remember that antibiotics work by interfering with some cell proteins that are vital to the survival of the bacteria. Now, under ideal conditions, bacteria divide at a very fast pace, once every half an hour; thus, they are prone to make mistakes in the duplication of their DNA, that is, to mutate. Even though some of those mutations could be damaging to the bacteria, others are not and their only effect is to produce a protein that is slightly different from the normal one, or a wild type.

It is important to emphasize that the reaction between the antibiotic and its target is specific -- that is, there is some kind of shape complementarity between both molecules and if this complementarity is not perfect to begin with or it changes because the target molecule has been mutated the action of the antibiotic is not very effective or it no longer recognizes the target and becomes useless.

Bacterial antibiotics do not work against viruses; and in some cases, the first symptoms of a viral infection are very similar to those of a bacterial one. Doctors can tell them apart using an antibiogram, which tells not only if the infection is caused by bacteria but also which antibiotic to use. Also a white blood cell test distinguishes between the types of infections.

A lot of times for different reasons such distinctions are not made, however, and the patient is given a medicine that is not useful.

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