Fiona Wise, the chief executive of Ealing Hospital in west London, sighs as she describes a letter that she received from a local resident last week: "He wrote to me saying he was coming in for an operation and wanted me to guarantee that he wouldn't get MRSA."

It was the latest expression of public anguish about the MRSA "superbug" - and other so-called hospital-acquired infections generating concern in healthcare systems around the world - that she and her colleagues constantly encounter.