The use of PCR-based diagnostics for gastrointestinal pathogens and direct sequence typing of Clostridium difficile to improve routine hospital infection control practice

 A large 1,500 bed hospital will have approximately 25,000 cases with potentially infectious diarrhoea necessitating isolation every year. An infecting organism will be identified in as few as 1 in 10 of these cases. Substantial isolation capacity is therefore required, primarily for diagnostic reasons. However the NHS currently has insufficient single rooms to effectively accommodate all such patients. Single rooms may be ‘blocked’ by patients without infectious diarrhoea as yet confirmed, whilst patients with infectious diarrhoea remain in open bays due to a lack of free side rooms. No single test currently exists to identify the cause of a case of infectious diarrhoea and patient samples often have to undergo multiple tests which can take up to 3 days, impacting further on bed management and patient pathways.

The Oxford Radcliffe Hospitals Trust has received funding to develop rapid molecular tests to identify the aetiology of infectious conditions. Two tests are currently being developed. MassTag multiplex PCR can detect up to 30 pathogens in a single reaction and would allow same day differentiation of non-infectious diarrhoea from infectious diarrhoea caused by the most common pathogens. This would address the current widespread insufficient isolation capacity in the NHS, and allow the instigation of individualised patient treatment and appropriate infection precautions. A rapid informative typing scheme (multi-locus sequence typing - MLST) for detecting Clostridium difficile outbreaks is also under development. Current typing techniques require intensive time-consuming culturing, taking at least 1-2 weeks, and are only offered on a limited scale, providing insufficient information. MLST would allow hospitals to identify outbreaks in real-time and deliver appropriate interventions to prevent further onward transmission. The information provided would also improve national surveillance.

The Health Economics Research Centre is collaborating with Oxford Radcliffe Hospitals Trust to estimate the likely costs and effects of using both MassTag and MLST technologies in this context. A survey will be undertaken across a sample of general medical and surgical specialities in acute NHS trusts across the UK to obtain information on the current procedures for diagnosing gastrointestinal pathogens and managing patients with suspected infectious diarrhoea. This information, along with the cost and effects data, will be combined within an economic evaluation and the net cost to the NHS of adopting these new technologies will be estimated.

Publications

Pankhurst, L, Macfarlane-Smith, L, Buchanan, J, Anson, L, Davies, K, O'Connor, L, Ashwin, H, Pike, G, Dingle, KE, Peto, TE, Wordsworth, S, Walker, AS, Wilcox, MH, and Crook, DW (2014). Can rapid integrated polymerase chain reaction-based diagnostics for gastrointestinal pathogens improve routine hospital infection control practice? A diagnostic study. Health Technol Assess, 18(53):1-167.