Presented by Mark Reacher network analysis by Iain Roddick

1. Space-Time Relations of Clostridium difficile cases within a health economy: A Social Network Analysis Presented by Mark Reacher network analysis by Iain Roddick Wendy Rice, Rowan Slowther, Judy Ames, GiriShankar

2. Clostridium difficile natural history • A common antibiotic associated infectious diarrhoea • Transmission by ingestion of toxin producing spores in faeces of an infected case. • Spores may remain “dormant” in large gut as part of microbiota until ….. • Antibiotic treatment perturbs large gut microflora, spores no longer held in check and proliferate causing Clostridium difficile Associated Disease Space-Time Relations of Clostridium difficile cases within a health economy: A Social Network Analysis

3. Clostridium difficile Associated Disease (CTAD) • Comprises a wide range of illness from self limiting diarrhoea to severe protracted diarrhoea, fluid loss , toxic shock, toxic megacolon (requiring life saving colectomy) and acute death. Presentation title - edit in Header and Footer

4. Clostridium difficile control • Universal infection control essential including hand hygiene in care staff : cleaning lavatories and all sanitation surfaces wards and fomites - oxidising disinfectants as well as physical cleaning with detergent required to destroy spores Presentation title - edit in Header and Footer

5. BBC Friday, 5 November, 2004 Hospital superbug must be halved. Bloodstream infections with the hospital superbug MRSA must be halved in three years, the government has said. Health Secretary John Reid tasked NHS hospitals with achieving a year on year reduction up to and beyond March 2008. Presentation title - edit in Header and Footer

6. Development of Health care associated infections Mandatory surveillance • 2004 April CDI > 65 years; MRSA bacteraemia • 2005 April Enhanced MRSA bacteraemia • 2007 April CDI > 2 years • 2011 January MSSA and E.coli bacteraemia added Presentation title - edit in Header and Footer

7. Attributing site of acquisition of infection • Cases of Clostridium difficile infection occurring within 72 hours of admission have been regarded as acquiring infection prior to admission to that hospital – at another hospital or in the community • Hospitals have only been held accountable for infections occurring greater than 72 hours following admission Presentation title - edit in Header and Footer

8. Clostridium difficile reports mandatory surveillance 2007 to 2013 in England Presentation title - edit in Header and Footer

9. Examination of space time relations of Community attributed Clostridium difficile cases • A substantial proportion of Clostridium difficile cases arising in the North Norfolk health economy were attributed to acquisition in the community • Community health services in Norfolk recorded the dates of arrival and discharge in care settings and to home for all new cases of Clostridium difficile infection diagnosed by GP testing in the community over a two year period Presentation title - edit in Header and Footer

10. The Norfolk Community attributed Clostridium difficile cases • 199county residents who had samples submitted by a GP and tested positive for C.difficile between 2010-2012 • 78had been admitted at least once to Hospital A • 40 had been admitted at least once to Hospital B • No cases had been admitted to both hospitals • 26cases had been to Care Homes with at least one other resident case Space-Time Relations of Clostridium difficile cases within a health economy: A Social Network Analysis

11. Social Network Analysis (SNA) • The methods have their roots in the work of 18th Century mathematicians on Graph Theory • Focuses on relationships between individuals rather than their attributes • Applied in a wide variety of scientific research – • e.g. genetics, linguistics, electrical engineering, sociology • Advances in computing power and availability of software have made it easier to apply SNA to a wide range of problems outside of formal research Space-Time Relations of Clostridium difficile cases within a health economy: A Social Network Analysis

12. Data & Software • Very simple dataset – Just 5 data fields, captured in Excel: • Procedures written in SQL Server to • a) detect space-time coincidences between people in the cohort • b) Measure time spent at risk of infection Space-Time Relations of Clostridium difficile cases within a health economy: A Social Network Analysis

13. Hospital A CARE HOME Co-locationof peopleC.diffiicilestatus not considered85 of 199people did spend some time together…in 2 hospitals, and in 5 care homes Hospital B CARE HOME CH B CH +B A CARE HOMES: Space-Time Relations of Clostridium difficile cases within a health economy: A Social Network Analysis

14. Hospital A – Taking C.difficile status into consideration – Who was at risk? Arrow direction represents possible transmission Arrow size is indicative of Number of Days at Risk Hospital A – Who spent time with who? Positive specimens not taken into account Joining lines represent co-location for 1 or more days CARE HOME Space-Time Relations of Clostridium difficile cases within a health economy: A Social Network Analysis

15. Conclusions • Most community diagnosed Clostridium difficile infections had space time overlaps with earlier onset cases at their local hospital • The “72 hour rule” of attributing cases to community acquisition denies the centrality of hospital transmission • Higher levels of infection control are still urgently needed in hospitals to contain the continuing risk of Clostridium difficile Space-Time Relations of Clostridium difficile cases within a health economy: A Social Network Analysis

16. Acknowledgements Alongside my co-authors I’d like to acknowledge the contributions of The Norfolk Health System HCAI Group, and Mr. Steven Martin of Cambridge Institute of Public Health Space-Time Relations of Clostridium difficile cases within a health economy: A Social Network Analysis