People with depression have a higher risk of catching one of the most common and potentially dangerous hospital-acquired infections in the world, a new study suggests.

Clostridium difficile, known as C.diff, is the most rapidly increasing hospital-acquired illness in the Western world. It usually occurs following antibiotic therapy in hospitals, although it can also occur in the community.

Infections arise as a direct result of disturbing gut bacteria following antibiotic treatment. The bug causes diarrhoea, abdominal pain, inflammation of the colon, fever, vomiting and dehydration. It can be particularly dangerous for vulnerable groups, such as elderly hospital patients.

A number of medications are thought to increase the risk of catching the bug, including anti-depressants. Since depression is so common, US scientists decided to look into this further.

They looked at people with and without depression who had been infected with C.diff in hospital and found that overall, those with depression were 36% more likely to catch the bug than those without depression.

These findings applied for a number of depressive disorders.

Age and marital status also appeared to affect risk, with older widows more likely to catch the bug than their married peers.

The scientists then investigated whether certain antidepressants affected the risk of acquiring the bug in hospital. They tested 12 drugs and two - mirtazapine and fluoxetine - appeared to increase the risk. In both cases, the risk was doubled.

The scientists said that it was unclear whether the increased risk was caused by the depression itself or the antidepressants.

"Depression is common worldwide. We have long known that depression is associated with changes in the gastrointestinal system. The interaction between the brain and the gut, called the ‘brain-gut axis' is fascinating and deserves more study.

"Our finding of a link between depression and C.diff should help us better identify those at risk of infection and perhaps encourage exploration of the underlying brain-gut mechanisms involved," the team said.

Details of these findings are published in the journal, BMC Medicine.

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