The Molecular Epidemiology of Clostridium difficile: Description of Clostridium difficile Associated Diarrhea (CDAD) Following a Formulary Change From Levofloxacin to Gatifloxacin

Abstract

Background: The processes’ underlying a recent rise in the rate of Clostridium difficile associated diarrhea (CDAD) at the Southern Arizona Veterans Administration Health Care System (SAVAHS) is unclear. Past changes to formulary in workhorse oral flouroquinolone from levofloxacin to gatifloxacin are under scrutiny. An infection-control component was also possible. Methods: 142 patients suspected of having CDAD had stool specimens submitted for toxin assay from late July to late Oct of 2004. A retrospective chart review was performed using the Veterans Administration Computerized Patient Record System (CPRS) to examine total antibiotic use in the three months prior to having specimens submitted for laboratory toxin analysis. A subset-analysis was performed on 100 specimens submitted for toxin analysis. Parallel culture was performed and 9 isolates of C. difficile were obtained for molecular analysis and fingerprinting. Results: Of the 142 patients sampled, 20 tested positive for C. difficile toxin with the remaining 122 patients testing negative. Antibiotic usage was categorized by total antibiotic use and gatifloxacin use. 98 patients received at least 1 antibiotic within the preceding 3 months with 44 patients receiving no antibiotic therapy of any kind. Of the 98 patients that received antibiotic therapy, 44 received gatifloxacin, however, all of these patients also received at least one other antibiotic. Of the nine isolates fingerprinted, two distinct genetic clusters were identified.