C'est difficile

Researchers develop cocktail of bacteria that eradicates Clostridium difficile infection in mice

C'est difficile

cdiffcycle.jpgDOI: 10.1371/journal.ppat.1002995
Proposed model for establishment of C. difficile-mediated dysbiosis and successful bacteriotherapy.

In a new study out today, researchers used mice to identify a combination six naturally occurring bacteria that eradicate a highly contagious form of Clostridium difficile, an infectious bacterium associated with many hospital deaths. Three of the six bacteria have not been described before. This work may have significant implications for future control and treatment approaches.

The researchers found that this strain of C. difficile, known as O27, establishes a persistent, prolonged contagious period, known as supershedding that is very difficult to treat with antibiotics. These contagious ‘supershedders' release highly resistant spores for a prolonged period that are very difficult to eradicate from the environment. Similar scenarios are likely in hospitals.

C. difficile can cause bloating, diarrhoea, abdominal pain and is a contributing factor to over 2,000 deaths in the UK in 2011. It lives naturally in the body of some people where other bacteria in the gut suppress its numbers and prevent it from spreading. If a person has been treated with a broad-spectrum antibiotic such as clindamycin, our bodies' natural bacteria can be destroyed and the gut can become overrun by C. difficile. The aggressive strain of C. diff analysed in this study has been responsible for epidemics in Europe, North America and Australia.

"We treated mice infected with this persistent form of C. diff with a range of antibiotics but they consistently relapsed to a high level of shedding or contagiousness. We then attempted treating the mice using faecal transplantation, homogenized faeces from a healthy mouse. This quickly and effectively supressed the disease and supershedding state with no reoccurrence in the vast majority of cases."

"This epidemic caused by C. diff is refractory to antibiotic treatment but can be supressed by faecal transplantation, resolving symptoms of disease and contagiousness."

Dr Trevor Lawley, first author from the Wellcome Trust Sanger Institute

The team wanted to take this research one step further and isolate the precise bacteria that supressed C. diff and restored microbial balance of the gut. They cultured a large number of bacteria naturally found in the gut of mice, all from one of four main groups of bacteria found in mammals. They tested many combinations of these bacteria, until they isolated a cocktail of six that worked best to suppress the infection.

"The mixture of six bacterial species effectively and reproducibly suppressed the C. difficile supershedder state in mice, restoring the healthy bacterial diversity of the gut."

Professor Harry Flint, senior author from the University of Aberdeen

The team then sequenced the genomes of the six bacteria and compared their genetic family tree to more precisely define them. Based on this analysis, the team found that the mixture of six bacteria contained three that have been previously described and three novel species. This mix is genetically diverse and comes from all four main groups of bacteria found in mammals.

These results illustrate the effectiveness of displacing C. diff and the supershedder microbiota with a defined mix of bacteria, naturally found in the gut.

"Our results open the way to reduce the over-use of antibiotic treatment and harness the potential of naturally occurring microbial communities to treat C. difficile infection and transmission, and potentially other diseases associated with microbial imbalances. Faecal transplantation is viewed as an alternative treatment but it is not widely used because of the risk of introducing harmful pathogens as well as general patient aversion. This model encapsulates some of the features of faecal therapy and acts as a basis to develop standardized treatment mixture."

Professor Gordon Dougan, senior author from the Wellcome Trust Sanger Institute

Notes to Editors
Publications
  • Targeted restoration of the intestinal microbiota with a simple, defined bacteriotherapy resolves relapsing Clostridium difficile disease in mice.

    Lawley TD, Clare S, Walker AW, Stares MD, Connor TR et al.

    PLoS pathogens 2012;8;10;e1002995

Funding

This project was funded by the Wellcome Trust and the Medical Research Council.

Participating Centres
  • Bacterial Pathogenesis Laboratory, Microbial Pathogenesis Laboratory, Pathogen Genomics and Mouse Genomics, Wellcome Trust Sanger Institute, Hinxton, UK
  • Microbial Ecology Group, Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen AB21 9SB, UK
  • Departments of Infectious and Tropical Diseases and Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
Selected Websites
Contact the Press Office

Emily Mobley, Media Manager

Tel +44 (0)1223 496 851

Dr Samantha Wynne, Media Officer

Tel +44 (0)1223 492 368

Dr Matthew Midgley, Media Officer

Tel +44 (0)1223 494 856

Wellcome Sanger Institute,
Hinxton,
Cambridgeshire,
CB10 1SA,
UK

Mobile +44 (0) 7748 379849

Recent News

Uncovering the pathway to colon cancer
Scientists identify patterns of genetic changes in healthy colon tissue, giving insight into the very earliest stages of cancer
Accumulation of DNA mutations found in healthy liver leads to disease
Largest study of its kind seeks to better understand how liver disease and hepatocellular carcinoma develop
Resurrection of over 50,000-year-old gene reveals how malaria parasite jumped from gorillas to humans
Discovery of molecular pathway is valuable example of how a pathogen can switch from one host species to another