1980. Efficacy of an Oral Vancomycin Loading Dose (LD) in the Treatment of Confirmed Clostridium Difficile Infection (CDI)

BACKGROUND: Over the past decade the incidence and severity of CDI has increased significantly. The 2018 IDSA Guidelines now recommends oral vancomycin 125 mg every 6 hours as the first-line therapy for initial occurrence of CDI. However, the optimal dosage of vancomycin is not well established. Pharmacokinetic data demonstrate that patients who receive 125 mg every 6 hours may have low fecal levels of vancomycin during the first 24 hours of therapy. Given that the fecal levels are relatively proportional to the dosage administered, a vancomycin LD may improve clinical outcomes. This study compared two vancomycin oral dosing regimens in patients with CDI. METHODS: A retrospective study evaluating pre and post-implementation of a 48-hour LD of vancomycin 500 mg every 6 hours was conducted. The control group included patients from January 2013 to January 2016. The intervention group included patients from February 2016 to December 2017, after the implementation of an LD as part of the order in the electronic medical record. Included subjects had confirmed CDI defined as diarrhea plus a positive C. difficle antigen and a positive rapid toxin by ELISA or positive cytotoxin. Subjects were exclude if they were <18 years of age, history of CDI in the past 90 days, received metronidazole within 24 hours of vancomycin initiation, or were treated for CDI in the past 28 days. The primary outcome was time to resolution of diarrhea defined as the interval, in days, from the start of treatment until the last unformed bowel movement. Secondary outcomes included clinical cure, defined as resolution of diarrhea and symptoms with no need for further treatment and recurrence of CDI. RESULTS: Three hundred ten patients were enrolled in the study with 155 patients in each arm. Time to resolution of symptoms was faster in the LD group compared with the control group (4 vs. 4.5 days; P = 0.05). There was no significant difference between the LD and control groups with respect to clinical cure (90% vs. 85%; P = 0.17); but patients <65 years had a higher clinical cure rate using the LD (95% vs. 84%; P = 0.03). CONCLUSION: An oral vancomycin LD for CDI therapy was associated with a decrease in time to resolution of symptoms. Patients aged <65 years had improved clinical cure with the LD. Additional prospective studies are needed to clarify the optimal oral vancomycin dosing strategy. DISCLOSURES: All authors: No reported disclosures.