Colon

62 - The NAP1 Strain of Clostridium difficile Is Strongly Associated With Fecal Microbiota Transplant Failure: A Large Retrospective Study

Wednesday, October 10
9:40 AM - 9:50 AM
Location: Terrace Ballroom 4 (level 400)

Category: Colon
Matthew T. Bender, MD1, Thomas Hunold, BSPH1, R. Ann Hays, MD2
1University of Virginia, Charlottesville, VA; 2University of Virignia, Charlottesville, VA

Introduction: Multiply recurrent Clostridium difficile infection (mrCDI) incidence increased from 2001-2012 along with an increasing prevalence of the NAP1 strain of C. difficile. NAP1 genotype positivity is reported to be associated with failure of standard of care (SOC) antibiotic therapy. Fecal microbiota transplant (FMT) is more effective for treatment of mrCDI than SOC antibiotics, however FMT for mrCDI still has a 10-20% failure rate; the source of which is not fully understood. Even though NAP1 positivity is an established risk factor for antibiotic treatment failure, NAP1 genotype testing is not widely performed. Data on the effect of NAP1 positive strains in patients with mrCDI undergoing FMT is lacking. Our institution sees referrals from hospitals which test for NAP1. We hypothesized that NAP1 strain positivity would be associated with FMT failure in patients being treated for mrCDI.

Methods: Retrospective cohort study at an academic tertiary medical center of all patients with mrCDI who underwent outpatient FMT for the first time between 2014 and 2018. Pre-FMT variables included: NAP1 genotype, demographics, comorbidities, and pre-FMT antibiotic therapy. NAP1 genotype result was determined based on the most proximal positive C. difficile result that then prompted FMT therapy. Primary endpoint was failure of FMT, defined as recurrent diarrhea with positive lab confirmation of C. difficle within 12 weeks after FMT. Data analyzed using SPSS software, utilizing chi squared and Student’s t-tests.

Results: There were 144 patients who underwent an initial FMT for mrCDI, with an overall failure rate of 11.8% (17/144). Of those 144 patients, 76 (52%) had NAP1 genotype testing, and 34.2% of those tested (26/76) were NAP1 positive. The FMT failure rate in all patients tested for NAP1 was 15.7% (12/76). The FMT failure rate in NAP1 positive patients was 38.4% (10/26) versus 4.0% (2/50) in NAP1 negative patients, and was significantly different [X2 (1, N=76)=15.27; p<0.0001]. The relative risk (RR) of FMT failure in NAP1 positive patients was 9.62 (95% CI: 2.27 - 40.68). Among just those patients who were NAP1 positive, there was no risk factor associated with failed FMT.

Discussion: This is the first study to show the NAP1 strain of mrCDI to be strongly associated with FMT failure. C. difficile strain type may play a role in an evolving understanding of why FMT fails, and could provide predictive clinical information for patients and providers. A well designed prospective study is indicated.

Table 1. – Comorbidities and risk factors among patients tested for NAP1, based on successful or failed FMT procedures. The NAP1 positive genotype was significantly more likely in failed FMT procedures than in successful FMTs
Table 2. – 2x2 contingency table breaking down the distribution of the 76 patients who had NAP1 testing performed on their C. difficile sample.

Disclosures:
Matthew Bender indicated no relevant financial relationships.
Thomas Hunold indicated no relevant financial relationships.
R. Ann Hays indicated no relevant financial relationships.

Matthew T. Bender

University of Virginia
Charlottesville, Virginia

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