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That Age-Old Advice to Finish Your Antibiotics Might Do More Harm Than Good

Have we had it all backwards?

MIKE MCRAE
27 JUL 2017
 

Medical experts from the UK have called for physicians and policy makers to stop instructing patients to complete courses of antibiotics, arguing that not only is the advice effectively baseless, but it might actually contribute to the superbug epidemic.

 

Contrary to the conventional wisdom dispensed by GPs for more than half a century, in most cases failing to take an entire course of antibiotics does not increase the risk of most common forms of infectious bacteria developing resistance.

Most of us have gone to the doctor with a killer sore throat or an ear ache that just won't quit and been prescribed an antibiotic with the sage direction to take all of the tablets, even after you start to feel better.

Even the World Health Organisation supports the idea that stopping antibiotics too early could be giving the remaining bacteria a helping hand.

"For example, in materials supporting Antibiotic Awareness Week 2016 WHO advised patients to "always complete the full prescription, even if you feel better, because stopping treatment early promotes the growth of drug-resistant bacteria," Martin Llewelyn from Brighton and Sussex Medical School and his colleagues explain.

The problem is the advice has never been based on research of any kind, instead arising out of an early hypothesis proposed by the Australian pharmacologist Howard Florey, who in the early 1940s carried out clinical trials on the newly discovered bacteria-killer, penicillin.

 

Florey and his team managed to extract only about 4 grams of the compound from the mould Penicillium chrysogenum (P. notatum back then) – enough for about a single day's worth of treatment.

To test its therapeutic effects, they injected the substance into a patient named Albert Alexander, who had developed a nasty Streptococcus pyogenes infection.

Over the next four days the researchers recovered what penicillin they could from Alexander's urine and continued to treat him with slowly-diminishing dosages.

Sadly for the patient, it wasn't enough. His infection initially subsided, only to return and claim his life once the drug finally ran out.

It was something of a Pyrrhic victory for Florey and his colleagues, who lost their patient but established penicillin as a strong contender for a powerful treatment against bacterial infection.

The scientist responsible for identifying penicillin as an antibiotic compound in the first place, Alexander Fleming, had long realised bacteria could become acclimatised to the substance's toxicity.

Fleming advised in his acceptance speech for the 1945 Nobel Prize in Physiology or Medicine, "If you use penicillin, use enough!"

 

According to Llewelyn and his fellow experts, these early messages – of the possibility of leaving behind resistant bacteria, and a patient who died after a too-brief course – have biased medical intuition ever since, encouraging patients to take more antibiotics than is needed to treat most common infections.

On the other hand, there are cases where nuking an infection is important.

Agents that are infection professionals, such as Mycobacterium tuberculosis and Salmonella typhi, or even non-bacterial pathogens such as HIV and the parasites responsible for malaria, can spontaneously mutate into resistant forms.

Once the rest of the infection is cleared, these infectious forms can reappear. Combinations of drugs are important to nail all forms of these deadly microbes, and failure to follow all courses to the end could increase the risk of resistant forms to spread through a population.

Most common infections that give us our sore throats, inflamed cuts, and urinary tract infections aren't so much as professionals as opportunists that commonly live in our bodies and jump the fence when the grass looks a bit greener.

 

Among the countless billions of microorganisms occupying your body right now are a handful that already have some degree of resistance to antibiotics.

Here lies the problem – a course of antibiotics won't kill all of those microbes. And you should be grateful it doesn't! You need those suckers.

For most of those opportunistic infections, it's important to knock out only the trouble-makers. More, in this case, isn't going to be better.

"The longer the antibiotic exposure these opportunist bacteria are subjected to, the greater the pressure to select for antibiotic resistance," the researchers wrote.

The spread of drug-resistant "superbug" pathogens are a huge concern in today's world, where misuse of therapies such as antibiotics has helped make resistant strains more common.

So what's the new message? Even the researchers admit there needs to be more studies on what constitutes a more effective instruction.

"Research is needed to determine the most appropriate simple alternative messages, such as stop when you feel better," they say.

For now, keep in mind that ScienceAlert isn't a medical advice column and that this is just one review. We emphasise the typical disclaimer to talk to your GP and follow their suggestions, maybe after you've asked a few questions first.

This analysis was published in the BMJ.

 

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