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Antibiotics and resistance

Antibiotics are medicines that have been developed for the treatment of bacterial infections. There are ten different types of antibiotics. Some examples include the penicillin-like antibiotics (such as amoxicilline) that slow down the bacteria’s ability to form a cell membrane, and the macrolides, which hamper the production of bacterial proteins. Different types of antibiotics are used to fight different types of bacteria.

Antibiotics are a very powerful type of medication. They cure disease, which is contrary to most other types of medication, which often merely suppress symptoms. Antibiotics are crucial in the battle against severe bacterial infections. Many people have been saved by the use of antibiotics.

Sadly, bacteria can evolve to become resistant against antibiotics. This means that they do not react – and are not killed by – antibiotics anymore. For example, they can produce a substance that degrades the antibiotic, or they will develop a means to actively push the antibiotics outside their membrane, rendering the antibiotic useless. Bacteria can also share this resistant trait with each other - not only within one species, but also between species.

More and more species of bacteria are becoming resistant to different types of antibiotics. Also in the student medical practice here in Delft, some patients carry bacteria that are resistant to 60-70% of all available antibiotics. If a strain of bacteria becomes resistant against all types of antibiotics, it is impossible to treat the infection. This means that people who are infected by this ‘super resistant’ strain of bacteria can die because of it - just as they would have before the discovery of antibiotics.

How come antibiotics resistance is increasing?

This is due to natural selection. Since people and animals are using antibiotics, all bacteria that DO respond to the antibiotics are being killed. The only bacteria that survive are the ones that are resistant. These surviving bacteria can then flourish; the antibiotics have destroyed all their competitors. In short, the more antibiotics are used, the more common resistant strains will become.

What can we do to ensure that we can use antibiotics as long as possible?

It is crucial to use antibiotics sparingly. In the Netherlands and the Scandinavian countries, doctors tend to be conservative in their use of antibiotics. As a result, the occurrence of certain resistant strains of bacteria, such as a strain of MRSA (multi-resistant staphylococcus aureus), is only 1-2% here, whereas the average in Europe is 20-25%. In certain Mediterranean countries - such as Portugal – this percentage is above 50% (1).

 E. Coli, one of the most common infectious bacteria in the world, is becoming resistant to an increasingly larger group of antibiotics in all European countries.

Multi-resistant E. Coli – E. Coli that is resistant to three or more groups of antibiotics – occurs at  6.5% in the Netherlands, but has an occurrence of 10-20% in Southern European countries with peaks of 34% and 42% in Cyprus and Bulgaria, respectively (2).

We can therefore conclude that the conservative policy of Dutch doctors has clear benefits. However, the use of antibiotics in animal breeding in the Netherlands is the highest in all of Europe. This is because our livestock is mass-bred with a high density of animals per square meter. The use of antibiotics helps improve yields in breeding in the short term.

This massive use of antibiotics in breeding has of course a downside. It makes animal bacteria increasingly resistant and these can in turn be transferred to humans by handling or eating the meat of these animals.

What can we do to reduce the incidence of disease and reduce resistance?

1. Don’t self-medicate with antibiotics

In many countries antibiotics are freely available, and many students have the habit of taking antibiotics with them ‘just in case’. This results in:

- antibiotics being used for the wrong purpose: The common cold, the flu, a runny nose, an ear ache or a sore throat are often caused by viruses. Viruses are NOT affected by antibiotics!  Most infections go away by themselves, medication is often unnecessary.

- antibiotics being used in the wrong way : The pharmacological properties (such as how fast it breaks down) of the antibiotic determine how many times per day and for how many days it should be taken. The treatment period should ALWAYS be finished. If an antibiotic is used for a period that is too short, bacteria will in fact become resistant even easier. Not using the antibiotic long enough allows only the ‘weaker’  bacteria (i.e. most sensitive to the antibiotics) to die, leaving the stronger ones without competition.

- the wrong type of antibiotic is being used  : Different antibiotics are used for bladder infections than are used for skin infections. Using the wrong type of antibiotic may simply fail to treat the infection. So that will give you no benefits, but will give you the side effects.

2. Discuss with your doctor if antibiotics are necessary

Many doctors – also in the Netherlands – will prescribe antibiotics because they think patients will leave unhappy if they do not. They may prescribe them even when they know that using antibiotics is in fact unnecessary. Let your doctor know that you are open to treatment without antibiotics.

3. Be careful with preparation of meat

Make sure that you thoroughly cook your meat, and that you don't let other food get infected; for instance by using the same cutting board. You could also choose to not eat mass-bred meat in which a lot of antibiotics are used.

What if I still need antibiotics? Is that bad?

Antibiotics are meant to kill bacteria. They do not do this selectively; if you have a bladder infection, antibiotics will not only kill the bacteria in your bladder. They will also kill ‘good’ bacteria in your intestine and on your skin. These ‘good’ bacteria have a function in your body; they protect your skin and mucous membranes. Women are often aware that the use of antibiotics adversely affects their vaginal flora, as it can cause yeast infections.

If you carry a resistant strain of bacteria, using antibiotics may have an adverse affect, as the antibiotics have essentially killed off the competition for the infectious strain. The infectious bacteria may therefore suddenly flourish. It is usually estimated that after taking antibiotics, it takes 6-10 weeks before the normal bacterial flora are once again fully present in and on the body. The use of antibiotics therefore has clear downsides – for the individual, but also for the resistance of bacteria in the world.

However – if antibiotics are used in the right way for the right reasons, their use can be a great benefit. Antibiotics are unique in that they can cure severe infections very effectively. They can therefore save lives. Following the guidelines above will allow us to keep using these medications more effectively for longer.

1. European Centre for Disease Prevention and Control.Annual epidemiological report Reporting on 2011 surveillance data and 2012 epidemic intelligence data. Stockholm, 2013d.

 2. European Antimicrobial Resistance Surveillance Network (EARS-Net), 2014