Clinical Microbiology, Cork University Hospital, Wilton, Cork, Ireland; 3 Dept. of Clinical

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1 A prospective, three-centre study to determine the efficacy of the EntericBio realtime C. difficile Assay (EBCD) for the detection of toxigenic C. difficile in stool samples. B. Lucey 1*, L. Blake 2, M. Watson 3, A. McIlhagga 4, N. Quinn 5, G.D. Corcoran 2, N. Ratnaraja 3, J. Swindells 3. 1* Dept. of Biological Sciences, Cork Institute of Technology, Cork, Ireland; 2 Dept. of Clinical Microbiology, Cork University Hospital, Wilton, Cork, Ireland; 3 Dept. of Clinical Microbiology, Sandwell & West Birmingham NHS Hospitals Trust, UK; 4 Dept of Clinical Microbiology, Antrim Area Hospital, Northern Health and Social Care Trust, Northern Ireland, UK; 5 Dept. of Mathematics, Cork Institute of Technology, Cork, Ireland.

2 Different approaches to diagnosis of CDI Results of three individual centres comparative studies considered in tandem Collating the findings as a joint paper Intention to publish Case study

3 Background and complexities of C difficile infection (CDI) diagnosis Causes a spectrum of disease from mild colitis to toxic megacolon Reported that mortality from CDI in EU at 30 days has ranged between 2 and 42% However, 2% asymptomatic rate of toxigenic CD carriage among elderly volunteers without a previous history of CDI or recent treatment with antibiotics, living outside of long-term care facilities Furthermore, approximately 60% to 70% of healthy newborns and infants colonized by CD

4 Laboratory detection of CDI Gold standard traditional method: toxigenic culture and cytotoxin neutralization (CTN) Generally, clinical laboratory methods rely on toxin or toxin gene detection without culture Positive test results combined with clinical suggestion of CDI in diagnosis Toxin detection expensiveness has led to negative screening of samples before progressing to detection of toxin or toxin gene

5 Purpose of these (combined) studies Evaluation/validation in accordance with quality system requirements To add value to our individual findings To make our results publicly available

6 Methods used for detection/investigation of CD in the study C. DIFF CHEK -60 test (Techlab, Blacksburg, VA) Enzyme immunoassay (EIA) used as a screening test to detect glutamate dehydrogenase (GDH), an antigen produced by CD. (60-70 min) The C. difficile Premier TM Toxins A&B assay (Meridian Bioscience, Paris, France) EIA, which detects both toxins A and B, incubated at 37 C (35-40 min) C.diff Quik Chek Complete kit (Techlab). Cassette EIA simultaneously detecting both GDH antigen and toxins A & B of CD in faecal specimens (c. 30 min)

7 Methods used in the study cont d. Xpert C. difficile PCR assay (Cepheid, Sunnyvale, CA) PCR assay, which uses a test cartridge, for the detection of the toxin B gene (tcdb), which is associated with toxigenic CD. Additionally, presumptive identification of 027/NAP1/BI strains of CD is by detection of binary toxin (CDT) gene sequences and the single base pair deletion at nucleotide 117 in the tcdc gene. The tcdc gene encodes for a negative regulator in CD toxin production. (c. 50 min)

8 Methods used in the study cont d. EntericBio realtime C. difficile (EBCD) Assay (Serosep Ltd., Limerick, Ireland). A molecular diagnostic test for the detection of the CD toxin gene directly from stool samples. (c. 60 min) Ribotyping. Method used by one centre for four samples for which the routine CD testing method and the EBCD disagreed. Strains tested to determine whether they matched the hospital s circulating toxigenic CD ribotypes at that time. Sent out for testing.

9 Algorithms used for analysis of EBCD in study Centres 1-3: Clinical Microbiology Laboratories Centre 1: Sandwell and West Birmingham NHS Trust Hospital Centre 2: Antrrim Area Hospital, Northern Health and Social Care Trust Centre 3: Cork University Hospital

10 Results

11 Discussion: EBCD results In <1% of samples an invalid test result was generated using the EBCD assay Findings were similar in each case despite using different algorithms The EBCD assay was adopted in each case after validation

12 Discussion: general points Individual laboratories had opted for different test algorithms for CDI diagnosis A low positivity rate suggests that individual centres need to conduct substantial studies to generate statistically robust results Cost savings elsewhere in the hospital generated through adoption of new diagnostic methods do not routinely translate to provision of larger budgets to laboratories Potential for improvements to healthcare through increased involvement by medical scientists in management of the patient journey?

13 Collaborative multi-centre approach to generating a paper Co-Ordinator/draft writer with communications to all authors, and agreed deadlines Materials and Methods Section Results Section Discussion Section Introduction Section Conclusion Abstract Title decision Reworking Some drafts later.submission of paper for consideration for publication.

14 Publication is not without its challenges

15 Acknowledgements Also on behalf of the collaborative group: To the HSE and NHS for bearing the cost of evaluations/validations To our work colleagues for their support To Serosep for the opportunity to present the work