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.
J. Da Silva, None
G. King, None
S. Tuazon, None
J. Zuckerman, None
See more of: Poster Abstract Session