No high risk antibiotics?

We select the letters for these pages from the rapid responses posted on bmj.com favouring those received within five days of publication of the article to which they refer.Letters are thus an early selection of rapid responses on a particular topic.Readers should consult the website for the full list of responses and any authors' replies, which usually arrive after our selection. O damika/mediscan Probiotics and diarrhoea Data are not widely applicableWe caution against extrapolating the results of Hickson et al, which support the benefit of probiotics in antibiotic associated diarrhoea.1 We are particularly concerned about their conclusion that a probiotic yoghurt drink, given during and after antibiotic treatment, "has the potential to decrease morbidity, healthcare costs, and mortality if used routinely in patients aged over 50." 1 The magnitude of the protective effects of the probiotic yoghurt against antibiotic associated diarrhoea and Clostridium difficile infection were stark.However, important issues about the study design and conclusions were not considered or given sufficient weighting in the discussion.In particular, the highly selective inclusion and exclusion criteria are crucial in result interpretation.It took over two years to recruit 135 patients out of 1760 screened individuals, and only 113 of these were followed up for evidence of diarrhoea.Put simply, how can data pertaining to less than 7% of a potential target population be extrapolated to routine use?