Left to their own devices, doctors don’t always do the right thing Obstetricians were outraged when, in 1846, Ignaz Semmelweis reduced mortality from puerperal fever in Viennese women from 16% to 3% by making doctors and medical students disinfect their hands between performing postmortems and delivering babies: they could not accept any criticism of their professional practice. Semmelweis lost his job and died in a lunatic asylum, while his dirty, deluded, and dangerous colleagues abandoned his policies, continued with their distinguished careers, and returned puerperal mortality to its previous appalling level. Of course they did not know then, as we do now, that puerperal fever is caused by group A streptococcus, or that normal human skin is colonised by high concentrations of bacteria that transfer to the hands of staff during routine patient care and then on to other patients.1 2 They would have been shocked to discover that we now have incontrovertible evidence that hand decontamination significantly reduces the transfer of pathogens and the incidence of hospital and healthcare associated infections,2 and that Semmelweis has been vindicated. Between the 1890s and the 1950s, the epidemiology of common bacterial pathogens was elucidated. This led to the universal introduction of standard hygiene measures, such as handwashing, no touch technique, gloving and gowning, instrument sterilisation, environmental …