960. Nap1 positivity predicts metronidazole failure in a cohort of patients with Non-severe Clostridium difficile-associated diarrhea
Session: Poster Abstract Session: Clostridium difficile Infections: Treatment and Prevention
Friday, October 9, 2015
Room: Poster Hall
  • Nap1 poster for IDSA.pdf (439.7 kB)
  • Background: Currently, treatment of initial, non-severe Clostridium difficile-associated diarrhea (CDAD) is with metronidazole. The emergence of the Nap1 strain of C diff, which is associated with more severe symptoms, higher mortality rates, and increased relapse rate, has brought into question whether treatment of CDAD should consider strain type.


    In this retrospective study involving adults 18 years of age or older, admitted between January 2012 and January 2013, with non-severe CDAD, confirmed and typed with PCR and treated initially with metronidazole, we evaluated for differences in outcomes between patients infected with the Nap1 strain and those with non-Nap1 strain.  We used the Wilcoxon test, the chi square test, and the Fisher exact test to compare the two groups with regards to age, sex, number of days to clinical resolution, frequency of switching to vancomycin, rate of relapse within 3 months, and presence of complications. We finally created a multivariate nominal logistic model to adjust the effect of age, gender, number of days to clinical resolution and Nap1 status on the likelihood to switch treatment to vancomycin. 


    We identified 115 patients who fulfilled the inclusion criteria, 27 of whom were Nap1-positive and 88 were Nap1-negative. The patients diagnosed with the Nap1 strain in our cohort were older compared with the control group (median age 72 and 61 respectively, p = 0.01). The two groups were comparable with regards to gender (p=0.9) and days to cure (p=0.9).  We observed more frequent switching from metronidazole to vancomycin in the Nap1-positive group with 11 of 27 subjects (41%) versus 11 of 77 subjects (13%) in the control group (p=0.002). No significant difference was seen in rates of relapse, 19% in Nap1 positive versus 11% in control, and in rates of complication, 6% in Nap1-positive versus 17% in control.  Further multivariate modeling for prediction of switch of therapy across all groups showed that Nap1-positivity predicts switch of treatment to vancomycin, presumably from metronidazole failure, and that this effect is independent of gender, days to clinical cure, and age (adjusted ORR 7, 95% CI 2.21-24.1).


    Patients with the Nap1 strain of C diff switched more often to vancomycin compared to the non-Nap1 strain in our cohort, and this highlights the consideration of strain type in the treatment of CDAD.

    Lemuel Non, MD1, Anastasios Dimou, MD2, Juliana Da Silva, MD1, Gentry King, MD3, Sherilyn Tuazon, MD3 and Jerry Zuckerman, MD, FSHEA4, (1)Einstein Medical Center, Philadelphia, PA, (2)Department of Medicine, Einstein Medical Center, Philadelphia, PA, (3)Medicine, Einstein Medical Center, Philadelphia, PA, (4)Infectious Diseases, Albert Einstein Medical Center, Philadelphia, PA


    L. Non, None

    A. Dimou, None

    J. Da Silva, None

    G. King, None

    S. Tuazon, None

    J. Zuckerman, None

    Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 7th with the exception of research findings presented at the IDWeek press conferences.