(British Medical Journal) -- Probiotics (microbes that protect their host and can prevent disease) can prevent diarrhoea associated with the use of antibiotics, finds a study in this week's BMJ.

Researchers at the Hammersmith Hospital in London reviewed nine trials carried out to study the benefits of probiotics in the prevention of antibiotic associated diarrhoea. In all nine trials, the probiotics were given in combination with antibiotics and the control groups received placebo and antibiotics.

They found that probiotics are useful in preventing antibiotic associated diarrhoea. In particular, the yeast S boulardii and three strains of Lactobacillus have the potential to be used in this situation.

Commercially available strains are being marketed in capsules and yoghurt based drinks, but these were not tested in the above trials and their potential benefit needs further investigation, say the authors.

A large trial looking at the efficacy of probiotics in preventing antibiotic associated diarrhoea, particularly in elderly patients, with an emphasis on the optimal dose and cost benefits is needed, they conclude.