A warning that the hospital bug Clostridium difficile is threatening lives in Scots communities has been issued by an expert on infectious diseases.

Professor Robert Masterton, director of the Institute of Healthcare Associated Infection at the University of the West of Scotland, urged the NHS not to be complacent about tackling the infection which played a part in 18 deaths during an outbreak at Vale of Leven Hospital in Alexandria, West Dunbartonshire.

Although figures show the spread of C.diff in Scottish hospitals has dropped significantly since 2010, Mr Masterton said the pace of improvement had levelled off and infection rates had recently increased in some health board areas. In Fife three patients died from a new strain earlier this year.

Mr Masterton, a key contributor to a report Think C-differently, published today, called on GPs to be vigilant and identify patients who could be suffering from the infection.

He said: "This report is to try to avoid a sense of complacency, a sense [the superbug] MRSA is done and C.diff is done. Neither of them is done.

"It is about emphasising that about the same number of cases occur in the community as occur in hospital and it is about time we did something about that.

"And about the same number of cases occur in younger people, under the age of 65."

Eighteen people died during the outbreak at the Vale of Leven Hospital in the winter of 2007, and findings from a public inquiry which was set up in 2009 are due to be published within the next five months following repeated delays.

Mr Masterton said: "The Vale of Leven report is not going to make pleasant reading for a large number of people. It is important that it is seen in context. It was several years ago and, yes, there are lessons from it, but let's remember where we have got to."

He praised Nicola Sturgeon, former Scottish Health Secretary, and Alex Neil, who took over the role last year, for their focus on healthcare infection, and said surveillance for the bug and scrutiny of prevention measures such as hand hygiene were much better than they used to be.

However, he stressed GPs should obtain samples from patients with symptoms of C.diff to screen for the infection to crack down on its spread in the community.

Mr Masterton said: "General ­practitioners, especially [when diagnosing] someone who is elderly, especially who has had an antibiotic in the last three months, should be sending in a sample. Frequently, they don't.

"They give the patient something to stop the diarrhoea, but they do not test it."

He suggested GPs were not in the habit of testing because the symptoms were so common.

However, he said doctors should be able to identify patients at greater risk of C.diff, such as people who have recently taken antibiotics, and screen them. This would then allow the infection to be treated appropriately, he said, and for the right infection control measures to be taken in the patient's home or care home.

"C.diff is still fatal," he added. "The death rate remains high at up to 15%."

Mr Masterton, previously lead ­clinician for the west of Scotland cancer network and one of the highest earners in the Scottish NHS before he retired, also warned that the prevalence of C.diff, along with other hospital infections, was higher in Scotland than other parts of the UK and Europe, and "we need to work out why".

In the case of C.diff he said this might be to do with better recording of cases, but this did not necessarily apply to other infections such as MRSA.

A National Audit Office report published in 2009 quoted prevalence rates of hospital infections of 9.5% in Scotland, 8.2% in England and 6.4% in Wales.

The Think C-differently report, which was produced by a panel of C.diff experts, was sponsored by Astellas Pharma Ltd, a company involved in the C.diff drugs market.