New treatment for hospital-acquired superbug C. difficile - June 2010
Scientists at University College Cork, Teagasc and the University of Alberta have identified a new antibiotic, thuricin CD, that is effective against the hospital-acquired superbug Clostridium difficile. The research, funded by Science Foundation Ireland, is published in the Proceedings of the National Academy of Sciences of the USA.
C. difficile is the most rapidly increasing hospital-acquired illness in the Western world and is a major cause of death, particularly in the elderly. It is estimated that the annual cost of treating the diarrhea (CDAD) associated with C. difficile amounts to €3 billion, in the EU alone.
C. difficile infections arise as a direct result of disturbing gut bacteria following antibiotic treatment. Current antibiotics of choice for the treatment of the diarrhea (CDAD) associated with C. difficile are the broad spectrum antibiotics vancomycin or metronidazole, but treatment failures and recurrence of infection are common. The emergence of strains with increased resistance to these antibiotics has also been reported.
The new antimicrobial peptide which is licensed to Alimentary Health Ltd could reduce the risk of disease recurrence compared with that of broad-spectrum antibiotic treatment because it spares the normal gut flora that helps limit C. difficile growth.
Given the importance of normal gut flora in controlling C. difficile growth, Professor Hill a professor of microbial food safety in the Alimentary Pharmabiotic Centre at University College Cork. and colleagues, Professor Paul Ross and Mary Rea at the Teagasc Moorpark Food Research Centre analysed the very bacterial populations that keep C. difficile at bay during normal conditions, with the goal of finding a compound that could specifically eliminate this organism. The potent new antimicrobial peptide was discovered by screening over thirty thousand bacteria isolated from the human gut.
The first study described how thuricin was identified, purified and characterised. Thuricin CD consists of two distinct peptides that act together to kill a wide range of clinical C. difficile. This specificity of thuricin towards Clostridium difficile is a key advantage it has over other antibiotic treatments.
The second study shows that thuricin compares very favourably with standard antibiotics in terms of controlling C. difficile in a model of the human colon. It has the significant advantage that it does not have an impact on other bacteria in the gut (very little 'collateral' damage). The complete study, published as two papers in the Proceedings of the National Academy of Sciences of the USA, involved the combined efforts of a team of scientists and students from Ireland and Canada.