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There’s a test that shows doctors if antibiotics will work or not – so why isn’t it being used?

It is estimated that antibiotics add an average of 20 years to all of our lives. However, their overuse, misuse and inappropriate use has encouraged microbes to evolve resistance, resulting in the emergence of untreatable “superbugs” that threaten the basis of modern medicine.

Drug-resistant infections are already responsible for more than half a million deaths worldwide each year, estimated to rise to over 10m by 2050. Antimicrobial resistance must be managed with the utmost urgency and careful stewardship of antibiotics can help conserve antibiotics for future generations.

One of the big problems is that antibiotics are routinely prescribed for infections where they simply won’t work. If you have a virus such as cold or flu, you feel bad and would like the doctor to give you antibiotics because many of us believe they can fix everything. Your doctor wants to help too and has a busy workload so they prescribe them. But this exacerbates the problem because it builds resistance in a population. It has been suggested that 10% of the 34m antibiotics prescribed in the UK every year are given to people who don’t need them. In the US, this may be as high as 30%.

Respiratory tract infections (RTIs), such as cold and flu and pneumonia, affect the throat, chest (airways and lungs) and sinuses. While they are most often caused by viruses (where antibiotics do not help), they can also be caused by bacteria (where antibiotics help). Given that RTIs are one of the main reasons why people visit their GP or pharmacist, developing a good way of telling between the two is crucial to cutting inappropriate prescriptions.

The £10m Longitude Prize, introduced in 2014, aims to reward the development of new diagnostic tests that can help to guide the effective use of antibiotics and avoid their inappropriate use. Rapid, affordable, easy-to-use tests that indicate the presence of a bacterial infection used at a GP clinic, for example, would allow more targeted use of antibiotics, and an overall reduction in misdiagnosis and prescription. But there is some reason to think that not enough is being done to make use of these tests.

Take the diagnosis of pneumonia. There is convincing evidence that measurement of a C-reactive protein (CRP) in the blood, which increases in the body when there is inflammation caused by infection, can help GPs determine whether or not a person with symptoms of a chest infection has pneumonia and should be treated with antibiotics.

In 2014, NICE, the UK health watchdog, recommended that GPs should consider carrying out a CRP blood test on patients with symptoms of lower respiratory tract infection. It said that if, after a clinical assessment, a diagnosis of pneumonia cannot be made and it’s unclear whether antibiotics should be prescribed, the test should be carried out.

A simple pinprick to do the CRP test. Shutterstock

Fast and preventative

This point-of-care method offers GPs a simple test that can be performed within five minutes and can help to distinguish whether patients with respiratory tract infection need antibiotics or not. But although point-of-care CRP testing has been widely adopted in many Scandinavian countries and the Netherlands, there remain barriers to its adoption elsewhere.

In the UK, the primary issue appears to be a lack of funding and reimbursement for doing the test. Fundamentally, GPs need financial incentives to adopt the technology. Point-of-care tests for accurate measurement of CRP levels are available from a number of manufacturers. The instruments needed to measure and record the test results are not overly expensive, costing around £1,500 while test strips cost £3-£4 per sample. However, compare this to antibiotics – a course of amoxicillin costs just £1.50 and a course of erythromycin just £3.

There are other possible reasons for reluctance (that can be solved) – including quality control and training and effects on flow and workload in the GP clinic – but perhaps herein lies the main problem: the test costs more than the course of antibiotics it is designed to protect.

And any new diagnostic test developed beyond the CRP method as a result of the Longitude Prize challenge is likely to cost considerably more than the existing CRP tests. Meanwhile, the rise of antibiotic resistance and erosion of antibiotic efficacy continues at an alarming pace. But there is a difference between short-term thinking here, which may be catastrophic and end up costing more in the long run, or longer-term preventative thinking.

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