"We can't say for sure how much of that benefit is down to the yoghurt and how much they are down to a whole range of infection control procedures that the hospital has in place such as the deep cleaning programme, the bare-below-the-elbow programme, and the increased isolation procedures, " Ms Heyes said.

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The director of infection prevention and control at the trust's Royal Liverpool University Hospital, Diane Wake, said she was "continuing to see significant falls in the number of C.diff and MRSA cases".

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In a Gojo-funded study published in 2000 in the journal Infection Control and Hospital Epidemiology, 32 nurses used Purell for two weeks for an average of about twice an hour during their workdays.

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