119 Kinetics of Stool Polymerase Chain Reaction in Clostridioides difficile Infection and Its Utility in Predicting Recurrence

Abstract

INTRODUCTION: Testing strategies for Clostridioides difficile infection (CDI) remain a clinical conundrum with stool polymerase chain reaction (PCR) being highly sensitive; this high sensitivity may mean that PCR would remain positive for several weeks after CDI resolution. We studied the kinetics of PCR testing positivity in CDI, and whether a positive test during or after treatment predicts recurrence. METHODS: Adults with watery diarrhea and positive C. difficile PCR from 10/2009 to 5/2017 were included. Treatment was given per standard of care. Five serial stool samples collected within 60 days after treatment initiation and additionally clinically indicated samples were included. Recurrent CDI was defined as typical CDI symptoms after interim symptom resolution with positive stool PCR within 56 days of treatment. A positive stool test in the absence of symptoms was considered colonization and treatment was not offered. Descriptive statistics and Fisher's test were used, as appropriate. Kaplan-Meier survival curves for time to first negative PCR from treatment initiation, and log-rank test to compare treatments [metronidazole (MET) vs vancomycin (VAN)] were used. P < 0.05 was considered statistically significant. RESULTS: Fifty patients, median age 51 (range 20–86) years, 66% female, were included. Initial treatment was MET in 50% (25), VAN in 44% (22), both MET and VAN in 4% (2) and fidaxomicin in 2% (1). Median treatment duration was 14 (range 8–60) days. Overall, 82% (41) patients submitted ≥3 samples at variable times. Median time to first negative PCR was 9 days (95% CI, 7–14 days) after treatment initiation (Figure 1). This was similar in MET and VAN treated patients (P = 0.5; Figure 2). CDI recurred in 28% (14) of patients. Overall, 13 patients (33%) had ≥1 positive PCR(s) during and 45% (19) had ≥1 positive PCR(s) after treatment. Patients with positive vs negative PCR(s) during treatment trended towards a higher risk of recurrence [OR 3.9 (95% CI, 0.9–16.1), P = 0.054]. Patients with positive PCR(s) after treatment completion also had a non-significant trend towards a higher risk of recurrence [OR 2.8 (95% CI, 0.7–11.5), P = 0.15]. CONCLUSION: Median time to first negative PCR in CDI was 9 days from treatment initiation. Positive PCR during or after treatment did not predict recurrence, though the positive odds ratio indicates the need for a larger study. Patients with CDI should not routinely undergo repeat testing to predict recurrence.