Researchers have identified a combination of six probiotic bacteria that may help to eradicate Clostridium difficile, a common noscomial infection causing diarrhoea and in 2011 C. difficile contributed to more than 2,000 deaths in the U.K.

In small amounts Clostridium difficile causes no harm to the human host, as a healthy gut microbiota is able to suppresses the C. diff population and stop it from spreading. However, when the gut microbiota is damaged from broad-spectrum antibiotics, opportunistic pathogens such as C. diff are able to thrive and overrun the gut, causing illness.

Recently, scientists at the Sanger Institute investigated possible methods of treating C. difficile. First of all they infected mice with C. difficile O27, renowned as a particularly virulent and aggressive strain which has also been responsible for epidemics in Europe, North America and Australia. The O27 strain has been dubbed a 'supershedder' because it has been found to release highly resistant spores for extended periods of time, making it difficult to eradicate from an environment.

The infected mice were then treated with a range of antibiotics but this was unsuccessful and resulted in relapse into C. diff infection and high levels of contagiousness.

The research team then attempted to treat the C. difficile infection using faecal transplantation; a process where faeces are taken from a healthy mouse and transplanted into the infected mouse. The theory behind this treatment is that the healthy faeces contains probiotic bacteria which will colonise and support gut immunity in the infected mouse. This method was found to be very effective in suppressing the disease and had no reoccurrence. Lead researcher Dr Trevor Lawley commented on the effectiveness of the faecal transplant:

"This quickly and effectively suppressed the disease and supershedding state with no reoccurrence in the vast majority of cases."

The research team then investigated which probiotic bacteria were responsible for suppressing C. difficile infection and restoring gut microbiota levels. Using genome sequencing they soon isolated a formula of six different bacterial strains which effectively suppressed infection. Senior author from the Sanger Institute wrote:

"Our results open the way to reducing the overuse of antibiotic treatment and harnessing the potential of naturally occurring microbial communities to treat C. difficile infection and transmission, and potentially other diseases associated with microbial imbalances."

This research may provide a basis for further studies and may help develop standardised treatment mixtures for C. difficile in the future. Read about other research undertaken on faecal transplants and C. diff.

Reference: Lawley, T.D et al (2012) Targeted restoration of the intestinal microbiota with a simple, defined bacteriotherapy resolves relapsing Clostridium difficile disease in mice. PLOS Pathogens. Published online ahead of print.


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