The oral antibacterial Rifamycin (marketed as Aemcolo) has been approved to treat travellers' diarrhoea driven by non-invasive strains of E. coli. The drug, an RNA-polymerase inhibitor, is indicated for adults whose condition is not complicated by blood in the stool or fever.
In a study of 250 adults, Rifamycin significantly reduced travellers' diarrhoea symptoms compared with placebo. Drug safety was tested in two clinical trials of some 620 patients. Constipation and headache were the most common side effects.
The tablets are absorbed directly into the colon and should not affect beneficial bacteria in the upper gastro-intestinal tract, according to the manufacturer.