The very real problem of resistance to antibiotics

IimgID17378541_jpg-pwrt3n 1929 Alexander Fleming discovered the antibiotic power of penicillin, changing our medicine and life expectancy by rendering often fatal bacterial infections into treatable (even trivial!) conditions. However, nowadays infectious diseases are on the rise: it is estimated that 70000 deaths have been caused by antibiotic-resistant infections this year, and it could hit 10 million in 2050- overtaking cancer’s fatal toll. The latest bad news in this domain were published yesterday by BBC, reporting that “Bacteria that resist ‘last antibiotic’ found in the UK“.  This antibiotic, Colistin, was one of the few still considered to be globally effective. That is, until the recent discovery of resistant strains in China- and now in the UK.

But, what are these resistant bacterial strains? why are our antibiotic therapies failing?

The antibiotics we use in the clinic nowadays are synthesized in the lab but they still resemble the natural antibiotics produced by fungi as an evolutionary mechanism to protect themselves against bacterial infections. Like us (and like fungi!), bacteria are made up of cells. However, bacterial cells are substantially different: they are simpler, they lack some elements like mitochondria (the engine of the cells, which we discussed in this blog) and they are protected by a thick external wall, whose composition is different than any of the membranes in mammal cells (and in fungal cells!).

Antibiotics exploit these differences between bacterial cells and more advanced organisms. For example penicillin prevents bacteria from building their wall, so they cannot divide and they die. Eventually, however, bacteria acquire resistance to penicillin by getting a mutation in their DNA which results in an enzyme which breaks the penicillin and deactivates it. Of note, similar resistance mechanisms have been as well observed against all the other types of antibiotic.

Acquisition of resistances happen by natural selection. If a colony of bacteria are exposed to penicillin, and one of them (by chance) gets the mutation that causes resistance to the antibiotic, it will quickly take over the colony, passing the resistance gene to its daughter cells. Hence, in spite of the fact that resistances happen naturally, it is easy to realise that irresponsible human use of antibiotics causes unnecessary or insufficient exposure to antibiotics and greatly accelerates the generation of resistant strains.

However, this is only part of the problem. Another major issue is the indiscriminate use of antibiotics in farm animals: in the United States 70% of the antibiotic usage is on animals, leaving only 30% for human treatment. That is in spite of the solid association between the use of antibiotics in farming and the appearance of resistances in human. According to this report, 72% of the studies conducted so far found a robust link (only 5% of studies found no link and 23% were inconclusive).

Farm animals also need to be protected from infections, and antibiotic use is necessary to some extent; in very populated farms, infectious diseases spread very quickly and can have disastrous consequences.

Unfortunately however, due to lax regulation, antibiotic use in farms is out of control.

First of all, antibiotics are used to prevent infections, rather than just being used to treat an actual infection. This causes an exponential increase in the use of and exposure to antibiotics. As a result of this, all farming products and byproducts – not only the meat, but also the soil and water – end up containing small amounts of antibiotics, which we are exposed to.

On top of that, it is common practice to use antibiotics to speed up the pace at which the animals put weight. This practice was banned in the EU in 2006, but it is still frequent in other places like the United States. And what is worse, some of the latest generation antibiotics are used in farming – antibiotics which are still highly effective in human, increasing the exposure and accelerating the generation of resistances. This is the case of the abovementioned colistin. For the time being the resistance has been observed in farm animals, but it is a matter of time until it is transferred to human.

It is clear that this is an urgent problem that needs to be tackled if we want to count on reliable antibiotics in the near future. Some countries like Denmark and the Netherlands have already implemented some measures to minimise and control the usage of antibiotics on farming animals, and have been able to do so with little economic impact. Let’s follow the example and fight for incorporating similar measures in our political agenda.

 

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