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Medline ® Abstract for Reference 63

of 'Clostridium difficile in adults: Treatment'

High frequency of rifampin resistance identified in an epidemic Clostridium difficile clone from a large teaching hospital.
Curry SR, Marsh JW, Shutt KA, Muto CA, O'Leary MM, Saul MI, Pasculle AW, Harrison LH
Clin Infect Dis. 2009;48(4):425.
BACKGROUND: Rifampin is used as adjunctive therapy for Clostridium difficile-associated disease, and the drug's derivative, rifaximin, has emerged as an attractive antimicrobial for treatment of C. difficile-associated disease. Rifampin resistance in C. difficile strains has been reported to be uncommon.
METHODS: We examined the prevalence of rifampin resistance among 470 C. difficile isolates (51.1% during 2001-2002 and 48.9% during 2005) from a large teaching hospital. Rifampin sensitivity was performed using E-test. The epidemic BI/NAP1 C. difficile clone was identified by tcdC genotyping and multilocus variable number of tandem repeats analysis. A 200-base pair fragment of the rpoB gene was sequenced for 102 isolates. Data on rifamycin exposures were obtained for all patients.
RESULTS: Rifampin resistance was observed in 173 (36.8%) of 470 recovered isolates and 167 (81.5%) of 205 of epidemic clone isolates (P<.001). Six rpoB genotypes were associated with rifampin resistance. Of 8 patients exposed to rifamycins, 7 hadrifampin-resistant C. difficile, compared with 166 of 462 unexposed patients (relative risk, 2.4; 95% confidence interval, 1.8-3.3).
CONCLUSIONS: Rifampin resistance is common among epidemic clone C. difficile isolates at our institution. Exposure to rifamycins before the development of C. difficile-associated disease was a risk factor for rifampin-resistant C. difficile infection. The use of rifaximin may be limited for treatment of C. difficile-associated disease at our institution.
Department of Medicine, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.