New research into superbug Clostridium difficile

Jun 1 2008

New research into the toxins, virulence, spread and prevention of the superbug Clostridium difficile is reported in the June special issue of the Journal of Medical Microbiology. These findings will play a crucial role in providing us with ammunition in the fight against a sometimes deadly pathogen.

Clostridium difficile is found in the environment but is most common in hospitals. It can cause a serious hospital-acquired infection when antibiotics are used as they upset the balance of the normal gut flora, allowing C. difficile to grow and produce toxins. It is carried in the guts of 3% of healthy humans but carriage rates in hospital patients tend to be much higher and elderly people in hospitals, being treated with antibiotics are most at risk of developing infection. The bacteria produce spores when they encounter unfavourable conditions. Transmission of infection is through the ingestion of these spores which can survive on surfaces and floors for years and are resistant to many disinfectants and antiseptics, including alcohol hand gel.

Symptoms include diarrhoea, nausea, abdominal pain, loss of appetite, fever, bowel inflammation and possible perforation, which can be fatal. Only two antibiotics are regularly used to treat C. difficile infection: metronidazole and vancomycin, but relapse is a common problem following treatment. In 2004, a hypervirulent strain (C. difficile 027/NAP1/BI) was reported, which appears to make toxins more rapidly and at higher levels than other strains, as well as being resistant to many antibiotics, including fluoroquinolones.

Several studies in the Journal of Medical Microbiology look at the spread of C. difficile in different countries, including Austria and Korea. Research shows that the use of antibiotic increased the risk of outbreaks of the hypervirulent strain of C. difficile in the Netherlands. The issue also contains evidence to suggest that C. difficile could be spread between animals and humans - researchers have isolated the bacterium from food animals in Slovenia.

Scientists investigated the effects of antibiotics, antigens and other agents on the virulence and pathogenicity of C. difficile. Toxins were also studied; research reveals some important information about the synthesis, processing and effects of different toxins. A new gene sequence has been discovered in the hypervirulent C. difficile 027 strain, which could be related to its increased virulence by affecting toxin binding.

The potential for a 'designer' probiotic for C. difficile is discussed. Professor Ian Poxton, former Editor-in-Chief of the Journal of Medical Microbiology said "this is an important approach that is hopefully much better than previously reported studies using commercially available yoghurt-like drinks, and certainly more palatable than 'faecal transplants'."