The instant blood test to tell if you REALLY need antibiotics By Rachel Ellis The test - which involves taking a drop of blood from the finger - measures levels of C-Reactive Protein A simple three-minute blood test could tell GPs whether a patient needs antibiotics. Not only could this help avoid patients suffering nasty side-effects from taking unnecessary drugs, but it could also tackle one of the greatest threats to modern health - antibiotic resistance. The test tells a doctor whether the patient is suffering from a viral or a bacterial infection - that way, they know whether or not to prescribe antibiotics. Antibiotics are only effective against bacteria - they do not kill viruses. Currently, the type of infection can only be confirmed with a blood test which must analysed in a lab, a process that can take two to three days. However, GPs say they often give antibiotics as a fail-safe measure, and that patients pressure them for the pills. According to Public Health England (formerly the Health Protection Agency), if patients ask their GP for an antibiotic, the vast majority will get one. Over-prescribing has consequences for both the patient and the population. As well as causing side-effects, over-use can lead to bacteria becoming resistant, making antibiotics less effective at fighting infections. The Government's chief medical officer has described this as one of the greatest threats to modern health. Over the past five years alone, the number of antibiotic prescriptions has risen by 10 per cent to 41 million prescriptions at a cost of £170 million to the NHS, and a third of all Britons have taken them in the past 12 months. But now a simple fingerstick test could solve this "catastrophic threat." The test - which involves taking a drop of blood from the finger - can tell doctors within three minutes whether an illness is caused by a bacterial infection which requires antibiotics, or a virus, which does not. It measures a substance called C-Reactive Protein (CRP) in the blood. The amount of this protein increases when the body is fighting a bacterial infection, but not when it is fighting a virus, which triggers a different immune response. So a doctor would know that if the CRP level was shown to be low, antibiotics would not be required. Studies show that providing "proof" that they are unnecessary to patients who demand antibiotics can significantly reduce the number of prescriptions. One EU-funded study, presented at the World Association of Family Doctors conference in 2010, looked at how respiratory infections which are generally caused by viruses were treated by 600 GPs in six different countries. It found that antibiotic prescriptions fell by 25 per cent when doctors used the CRP test. British experts say the test could be a useful tool for significantly reducing antibiotic prescriptions. Dr Nick Francis, a senior clinical research fellow at Cardiff University and expert in antibiotic resistance in primary care, says: "Unfortunately, it is very difficult to accurately determine whether an infection is viral or bacterial. Over-prescribing can lead to bacteria becoming resistant, making the antibiotics less effective at fighting infections Markers such as CRP have evolved to help where there is lingering uncertainty after a clinical assessment or where the patient has strong beliefs that antibiotics are needed. However, not everyone needs the test. "Patients who appear very unwell should be treated with antibiotics or admitted to hospital without the test because they could develop complications," explains Dr Francis. But for those patients where there is doubt, or where the GP feels antibiotics are not needed but the patient is putting pressure on to prescribe them, the test can be helpful. The test is currently only available in laboratories in the UK (it can be carried out privately for around £50) because the NHS does not yet fund it in GP practices (the machine to analyse the test would initially cost £1,000 and then £3 per test). Sid Dajani, a community pharmacist in Southampton and spokesman for the Royal Pharmaceutical Society, says it is likely to be some time before the test is routinely available on the NHS. CRP testing would be a natural extension to the clinical services we offer but it will be two or three years before there is enough evidence for it to be made widely available. Other concerns about the test are that the results are not always clear - levels of CRP also increase as a result of inflammation caused by other conditions such as rheumatoid arthritis as well as infections. Dr Francis explains: "The test is only a guide. It does not tell you categorically that this patient has a bacterial infection and this patient does not. It gives you a number that has to be interpreted in light of the other symptoms and the patient's overall risk profile. For example, you are more likely to treat an elderly person with diabetes with antibiotics than a young healthy person, as the elderly person is more likely to develop complications. Experts say the best way to reduce antibiotic prescriptions is to educate doctors and patients about common complaints and when antibiotics are necessary. Mr Dajani warns: "To see this test as the panacea is an extremely dangerous idea. We need to work hard to educate patients about when it is appropriate to take antibiotics and make sure they take them correctly and finish the course. Public Health England adds: "CRP may be useful in a small range of infections provided the test is robustly quality controlled. But nothing can replace taking a detailed patient history and thorough examination.