Clostridioides difficile: the value of whole genome sequencing to rule out a common source healthcare associated outbreak 

Mrs Helen Newman¹, Dr Joanna Harris¹

¹ISLHD Infection Management And Control Service, Wollongong, Australia

Introduction: Clostridioides difficile (C. difficile) is a Gram positive, anaerobic, spore forming bacterium. Asymptomatic bowel colonisation occurs, but C. difficile infection (CDI) can cause symptoms ranging from mild diarrhoea to pseudomembranous colitis.  CDI is the most common cause of hospital-acquired diarrhoea. Outbreaks can be difficult to manage due to C. difficile spores’ survival for extended periods in the environment. Whole genome sequencing (WGS) can be helpful in outbreak management.

Methods: Five patients, who were co-located in a 30 bed aged care ward developed sudden onset diarrhoea. All 5 patients had been admitted for >48 hours, and all had recently received antibiotics. An outbreak investigation was initiated and control measures implemented. Laboratory testing confirmed C. difficile in stool samples. To determine whether this was a common source nosocomial outbreak of C. difficile the samples were sent for toxigenic C. difficile culture and WGS.

Results: Three isolates were reported as ribotype ce416 belonging to the same sequence type, ST176. Another isolate was reported as ribotype ce417 and the 5th isolate was an unrelated ribotype (RT014).  This sample did not undergo further analysis with WGS. Outbreak control measures were successful and no further patients developed diarrhoea.

WGS revealed the ST 176 sequences were related, but not clonal, dispelling concerns about person-to-person transmission of C. difficile in this cluster of hospital-onset diarrhoea.

Conclusions: The use of WGS provided reassurance to the IPaC team and the hospital executive that there was no ongoing increased C. difficile infection risk to patients admitted to this ward.

Biography: Helen has over 40 years experience in Nursing in a wide variety of clinical settings, the majority of time in Infection Prevention and Control.  She is currently a Clinical Nurse Consultant with the Infection Management and Control Service.