Superbug possibly the same as US killer strain

Jun 8 2005

Microbiologists at the Health Protection Agency suspect that the superbug which has already caused 12 deaths at Stoke Mandeville Hospital, in Buckinghamshire, may be the same strain that has spread in many American hospitals since 2001, and killed more than 100 patients in Quebec, Canada, last year.

Scientists are currently testing samples of a Clostridium difficile bacterium from Stoke Mandeville to establish if it is the same hypertoxin-producing strain that has been isolated in North America.

Clostridium difficile, known as C. diff, is one of the most common infections and causes diarrhoea, it can be life-threatening to elderly patients and those whose immune systems are in some way compromised. Once it has become established in the bowel it produces a toxin there and it is suspected that the strain causing illness at Stoke Mandeville may produce more toxin, or more potent toxin, than other strains.

The strain which was identified in Quebec carried 20 times as much toxin as previous C. diff strains, and has also been found across the United States. People infected with this more toxic strain suffer much more serious symptoms and in addition to diarrhoea, they have high fevers and high white blood cell counts. It has been found that they do not respond as quickly to treatment and in some cases may need surgery for removal of the colon which was previously rarely needed.

A spokeswoman for the agency said that tests are underway to determine if the Stoke Mandeville strain was the same. If so, there are dangers outside hospitals as well as inside them. In the US and Canada, some patients have caught C. diff without setting foot in a hospital, suggesting that it may have reached the community.

Cases of hospital-based C. diff infection in Britain have soared in recent years, but part of this is the result of increased reporting. From 2004, reporting of cases by hospitals has been mandatory, so the rise from 1,217 reports in 1990 to 43,682 in 2004 probably exaggerates the growth in the number of cases. The trend nevertheless, does appear to be sharply upwards, with cases doubling since 2000.

The figures show that in total 934 people died after contracting the C. diff bug in 2003, similar to the number of people who died from the MRSA superbug in the same year.

The agency says that supertoxin strains of C. diff have emerged in the past, only to disappear again. C. diff is able to colonise the gut because the use of antibiotics that kill off protective bacteria in the gut, enables C. diff to multiply. Other antibiotics, such as vancomycin and metronidazole, are then used to treat it.

More than 300 patients at Stoke Mandeville Hospital have been infected with a virulent strain of C. diff since the end of 2003. Twelve patients, whose average age was 85, died from the infection.

But according to the hospital in the 18-month period from late 2003, around 225,000 members of the public were seen at Stoke Mandeville Hospital.

It was in this same period 300 cases of C. diff were reported and of these, 12 instances have been identified in which C. diff was a probable or actual cause of death.

A Health Department spokesman says that in order to establish the scale of the problem, C. diff associated diarrhoea, was added to the mandatory surveillance system for healthcare associated infection last year, and the first results will be published later this year.