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Antibiotic treatment – How long is short enough?

In this video Dr Dag Berild challenges the concept that taking whole antibiotic courses prevents bacteria from becoming resistant.
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How long is short enough? I will try to answer that. But first, I have to kill a myth. We have learned that we have to take the whole antibiotic course. If not, the bacteria will become resistant. That is evidence free area. And I will tell you why. All humans have two kilo bacteria in their body. And normally, we live in harmoniously symbiosis with our bacteria. We cannot live without them. They digest the food, they make vitamins and fatty acids, and so on. We call our bacterial flora our microbiome. But, in a population of let’s say, 100 millions of bacteria, there be a slight minority of bacteria that are resistant. They are born resistant.
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When you give antibiotic, like this hammer illustrate. Then you kill the antibiotic susceptible bacteria. And the resistant bacteria, they will survive. And bacteria have a very short generation time. Maybe 10 or 15 minutes. And within a week, the originals– or the original susceptible bacteria will be replaced by resistant bacteria. If you then continue to treat with a broader spectrum antibiotic, or for a longer duration, you will kill the original resistant bacteria. But there will still be some bacteria that are even more resistant. So, within a week or two, the original antibiotic susceptible bacteria will be replaced by resistant bacteria that you have selected from your own normal bacterial flora.
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Another fact is that the disease causing bacteria are killed very rapidly by antibiotics. And they seldom develop resistance during short therapy. And it’s obvious that the longer treatment facilitates selection of resistant bacteria from the normal bacterial flora. The resistant bacteria are mostly from your own flora. And they can be trasmited to other patients or health personnel. The optimal duration of therapy must be long enough to kill the bacteria. And short enough not to disturb the normal flora.
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In the last 15 years, there has been conducted a lot of randomised controlled studies that have documented that shorter treatment is not inferior to longer treatment. And the first study was performed by Dutch researchers. They documented that three days treatment of mild pneumonia was not inferior to eight days of treatment. Since That, there has been a considerable numbers of studies. And they are summarised in the Cochrane Library. Documented that short therapy in pneumonia is not inferior to longer treatment. Most importantly, French researchers has demonstrated that shorter treatment of ventilator associated pneumonia is not inferior to longer treatment. In some countries, this is implemented.
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And in this figure, you can see that there are an increasing number of Swedish doctors that treat pneumonia less than seven days. Swedish researchers also documented that seven days of treatment of serious pyelonephritis is not inferior to 14 days of treatment. And the patient that they treated were very seriously ill. More than 20% of the patients had growth of bacteria in their blood. They had sepsis. From the United States there was a beautiful randomised controlled study that showed that abdominal infections, mostly peritonitis, four days treatment were not inferior to eight days treatment. Provided that the patient responded. This is from hospitals. But most of the antibiotic treatment are used for general practise.
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Swedish researchers also documented a five day treatment of streptococcal tonsillitis was not inferior to 10 days. And, take it in consideration, that streptococcal tonsillitis is one of the most common indications for antibiotics. This is a very important study. It’s also well performed. So to conclude, in randomised controlled studies, short treatment is not inferior to longer treatment. And to fulfill the course should be replaced by shorter is better.

You have probably learned at some time in your life that completing whole antibiotic courses prevents bacteria from becoming resistant.

While this is true for infections with microbes such as Mycobacterium tuberculosis, for a majority of other infectious agents, such practice is debatable. Prolonging antibiotic exposure may actually increase the selection pressure for antibiotic resistance. In this video Dr Dag Berild discusses numerous randomized control studies indicating that, for a range of common infections, short treatments have not been inferior to long treatments.

You will find the pdf for the cited articles in the downloads section below.

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Exploring the Landscape of Antibiotic Resistance in Microbiomes

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