Hospitals may be adopting the wrong strategy for tackling a notorious healthcare associated infection, a study suggests.

Research showed that contact between patients only accounted for a minority of C difficile infections.

The new findings from a team based at John Radcliffe Hospital in Oxford contradict previous thinking.

Until now it has been assumed that disease spreads through personal contact with infected patients showing symptoms.

Scientists collected stool samples from almost 15,000 hospital patients and found evidence of C difficile in 4.4 per cent.

Further tests identified 69 strains of the bacterium, but only 23 per cent of these could be linked to known symptomatic patients.

The authors, led by Professor Tim Peto, wrote in the online journal Public Library of Science Medicine: “In this endemic setting with well-implemented infection control measures, up to three quarters of new C difficile infections are not easily explained by conventional assumptions of ward-based transmission from symptomatic patients and so may not be targeted by current interventions.

“A better understanding of other routes of transmission and reservoirs is needed to determine what other types of control interventions are required to reduce the spread of C difficile.”

Even the cases linked to ward contact represented a “major hospital-acquired infection problem” said the scientists.

But the roughly 75 per cent of unexplained transmissions “raised concern about other acquisition routes” not captured by the study.

Other ways C difficile might be able to spread included transmission by non-symptomatic carriers, including patients’ relatives and staff, or through food or animals.

C difficile rarely causes any problems in healthy people, but may trigger diarrhoea and fever in hospital patients taking antibiotics.

Older people are most likely to be affected. Patients usually recover with treatment but in rare cases infection can be fatal.

In 2007-08, a total of 55,498 cases were reported in England.

Between 2008-09 there were 36,095 reported cases, a decrease of 35 per cent.