What is Clostridium difficile and why is it so dangerous?
The large intestine of the average person contains as many as 1,500 types of bacteria, one of which is C. diff. It is of the family Clostridium, which includes the bacterium that cause tetanus, botulism and gas gangrene.

It is found naturally in the gut of up to 3 per cent of healthy adults and 66 per cent of children, where it rarely causes problems. People who carry C. diff without problems are said to have been “colonised” by the bacteria, but it can cause infections and illness when it is allowed to grow unchecked. More than 50,000 patients aged 65 and over developed a C. diff infection at NHS hospitals in England last year.

How does it make you sick?
Infection can cause no symptoms at all, or mild or severe diarrhoea, or, in some cases, severe inflammation of the bowel (colitis) which can be life-threatening. Typically this occurs when the normal, healthy intestinal bacteria have been killed off by antibiotics. When not held in check by the normal bacteria, C. diff multiplies in the intestine and produces two toxins (known as A and B) that damage the cells lining the intestine. The result is diarrhoea, and about one in ten cases of infection proves fatal.

Who gets C. diff infection?
Patients being treated with broad spectrum antibiotics (those that affect a wide range of bacteria, including those in the intestine) are at greatest risk of infection. Most of these will be elderly patients with serious underlying illnesses, whose immune systems may already be weakened with age.

Others with conditions or treatments affecting their immune systems or those who have had repeated gut surgery are also at increased risk.

Most infections occur in hospitals, community hospitals or nursing homes but infections can also result from patients taking antibiotics at home.

Is this a recent problem? Why is it causing so many deaths now?
Although C. diff was first described in the 1930s, it was not identified as the cause of diarrhoea and colitis linked to antibiotic therapy until the late 1970s.

As the use of antibiotics has increased, so has the infection rate, but some of this can be accounted for by better reporting.

Since 1990, testing laboratories have reported the number of confirmed cases to the Health Protection Agency.

Reports increased from less than 1,000 a year in the early 1990s to 55,000 in 2006, dipping only slightly last year.

Since 2005, doctors have also been asked to record C. diff infection on death certificates, even if it was not the main cause of death.

Is it a drug-resistant “superbug”?
No. At present it can be treated relatively easily. But patients with diarrhoea can unintentionally spread the infection to others. The spores by which C. diff spreads are also very resilient, capable of surviving for long periods on surfaces, lavatory areas and medical equipment.

There is also evidence that some strains of C. diff have started to acquire resistance to several antibiotics in common use to treat infections.

This suggests that the bacterium is quickly evolving and could reach superbug status in the not-too-distant future.

What is type 027 and why is it causing concern?
More than a hundred types of C. diff have been identified. Type 027 was initially rare in Britain; the first case was identified in 1999 and the second in 2002. But it has proved to be a much more virulent strain than other types, responsible for outbreaks at Stoke Mandeville and the Royal Devon and Exeter Hospitals and Maidstone and Tunbridge Wells NHS Trust in recent years.

It produces much more of the toxins than most other types, because a mutation has knocked out the gene that normally restricts toxin production.

It also seems to be very capable of spreading between patients. This results in a greater proportion of severe disease and appears to have a higher mortality – in Maidstone, 1,100 patients became infected, with C. diff directly killing 90 patients and being regarded as a contributing factor in a further 246 deaths.

The same type has been responsible for severe disease in hospitals in Quebec, Canada, and the northeast of America since 2000.

Can we kill it with a “deep clean” of hospitals?
After the high-profile outbreaks, Gordon Brown ordered all 1,500 hospitals in England to be intensively scrubbed down and disinfected earlier this year.

But experts remain unconvinced about how effective it will be at reducing infections, pointing out that the effects of the deep clean would last only a few weeks.

Other recommended procedures include prudent prescribing of antibiotics, isolation of infected patients, use of chlorinated disinfectant and handwashing – using alcohol gel alone does not kill the C. diff spores.

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