Not Taking a Full Course of Antibiotics

The Academic edition of the BMJ comes out once a month; readers may have noticed that one or more BMJ articles feature in alternate News Blogs. The most recent issue of the BMJ had less papers that caught my eye than most. There was lots of worthy stuff. For example, age-specific dementia incidence is declining slightly,[1] antidepressants may very slightly increase the risk of autism if taken during pregnancy,[2] specialist palliative care has rather small effects on quality of life,[3] exercise and diet reduce the risk of high blood pressure in women who had high blood pressure in pregnancy.[4] There was also an excellent article on the precision of cluster randomised trials by CLAHRC WM collaborator Karla Hemming.[5] But the article that really caught my eye was a commentary on the importance of completing a full course of antibiotics as prescribed.[6]

Of course, we always love articles that confirm our prior beliefs. I have always thought that insisting that people take a ‘full course’ of antibiotics to reduce resistance is illogical. Prolonging exposure of the bacterial population to the antibiotic is likely to increase the chance for selection to take place. And that is exactly what this study confirms. Apparently the idea that it was important to take the full course of treatment was based on Albert Alexander’s Staphylococcal sepsis, which re-established itself when Howard Florey’s penicillin ran out.[7] However, the wisdom of continuing antibiotics until the infection is quelled somehow became translated into instructions to finish the course even if infection is no longer a threat. Remember, genetic mutations arise spontaneously and are only selected for when the antibiotic is present in the environment. It follows that the shortest course of antibiotics compatible with effective treatment should be used. And, of course, resistance does not just appear among the organisms causing the infection, but among all the organisms carried in the patient’s body, some of which may go on to infect another person. The argument against continuing to take antibiotics once the threat has passed is therefore unequivocal. It may be necessary to continue antibiotic treatment to prevent a relapse, as was the case for the hapless Alexander, and middle ear infections have a tendency to relapse, but we should not insist on taking a full course simply to prevent antibiotic resistance; the opposite is the case.

— Richard Lilford, CLAHRC WM Director

References:

1. Ahmadi-Abhari S, Guzman-Castillo M, Bandosz P, et al. Temporal trend in dementia incidence since 2002 and projections for prevalence in England and Wales to 2040: modelling study. BMJ. 2017; 358: j2856.
2. Rai D, Lee BK, Dalman C, et al. Antidepressants during pregnancy and autism in offspring: population based cohort study. BMJ. 2017; 358: j2811.
3. Gaerner J, Siemens W, Meerpohl JJ, et al. Effect of specialist palliative care services on quality of life in adults with advanced incurable illness in hospital, hospice, or community settings: systematic review and meta-analysis. BMJ. 2017; 357: j2925.
4. The International Weight Management in Pregnancy Collaborative Group. Effect of diet and physical activity based interventions in pregnancy on gestational weight gain and pregnancy outcomes: meta-analysis of individual participant data from randomised trials. BMJ. 2017; 358: j3119.
5. Hemming K, Eldridge S, Forbes G, Weijer C, Taljaard M. How to design efficient cluster randomised trials. BMJ. 2017; 358: j3064.
6. Llewelyn M, Fitzpatrick JM, Darwin E, et al. The antibiotic course has had its day. BMJ. 2017; 358: j3418.
7. Abraham EP, Chain E, Fletcher CM, et al. Further observations on penicillin. Lancet. 1941; 358: 177-89.