523. Use of Whole-Genome Sequencing to Guide a C. difficile Diagnostic Stewardship Program
Session: Poster Abstract Session: Healthcare Epidemiology: Updates in C. difficile
Thursday, October 4, 2018
Room: S Poster Hall
  • IDSA 5.0.pdf (1.0 MB)
  • Background: Hospital-onset C. difficile infection (HO-CDI) has been problematic at our hospital, with rates almost 50% greater than predicted.  C. difficile whole-genome sequencing (WGS) data was used to define the transmission pattern, followed by a diagnostic stewardship intervention.

    Methods:   Isolates from CDI cases were sequenced for strain relatedness and epidemiologically analyzed using a single nucleotide polymorphism (SNP)-based approach. In June 2017, a diagnostic stewardship intervention began which included provider education and a weekday review of CDI orders placed after hospital day 3 for the following indications: >3 stools/24 hours, the absence of laxative administration, the presence of fever/leukocytosis or a history of inflammatory bowel disease. In Nov 2017, an EMR-based testing algorithm was introduced to supplement the review process. Orders not meeting testing criteria were discussed with the ordering provider, with a suggestion to cancel orders without appropriate indications.

    Results: WGS assigned 36 isolates to 19 different multi-locus sequence types (ST), including 5 assigned to ST-1, a sequence that encompasses the ribotype 027 clade (Figure 1).  SNP-based analysis indicated closely related, but non-identical strains, inconsistent with nosocomial transmission.  646 CDI orders were reviewed, of which 421 (65%) met criteria and 64 (15%) were positive.  225 (35%) of orders were recommended for cancellation.   The HO-CDI rate decreased from 11.67/10k in the 5-month baseline period to 7.13/10k in the 9-month intervention period (p=0.0008) (Figure 2).

    Conclusion:   WGS revealed that nosocomial transmission of C. difficile was an unlikely cause for our elevated CO-CDI rate.  A diagnostic stewardship intervention which focused on identifying community-acquired infection and avoiding over-testing was associated with a sustained decrease in the HO-CDI rate which has persisted for 9 months.

    Figure 1

    Figure 2

    Kunal Jakharia, MBBS1, Ghassan Ilaiwy, MD1, Siobhan Moose, RN2, Masahi Waga, -3, Joel McAlduff, MD4, Lynne Karanfil, RN, MA, CIC, FAPIC5, Patrick Mcgann, PhD6 and Glenn Wortmann, MD7, (1)Department of Internal Medicine, Medstar Washington Hospital Center, Washington, DC, (2)Infection Control, Medstar Washington Hospital Center, Washington, DC, (3)Pathology and Laboratory Medicine, Medstar Washington Hospital Center, Washington, DC, (4)Information Services, Medsar Health, Columbia, MD, (5)Infection Prevention, MedStar Institute for Quality and Safety, Columbia, MD, (6)Multi-Drug Resistant Organism Repository and Surveillance Network (MRSN), Walter Reed Army Institute of Research, Silver Spring, MD, (7)Infection Prevention and Infectious Diseases, MedStar Washington Hospital Center, Washington, DC


    K. Jakharia, None

    G. Ilaiwy, None

    S. Moose, None

    M. Waga, None

    J. McAlduff, None

    L. Karanfil, None

    P. Mcgann, None

    G. Wortmann, None

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