Emergence and Control of Fluoroquinolone-Resistant, Toxin A–Negative, Toxin B–PositiveClostridium difficile

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Abstract
Background.: Clostridium difficileis a major cause of infectious diarrhea in hospitalized patients. Between August 2003 and January 2004, we experienced an increase in the incidence ofC. difficile–associated disease. We describe the investigation into and management of the outbreak in this article.Methods.: A total of 73 consecutive patients with nosocomialC. difficile–associated diarrhea were identified.C. difficileisolates were characterized using toxin-specific enzyme immunoassays, a tissue-culture fibroblast cytotoxicity assay, polymerase chain reaction (PCR), and antimicrobial susceptibility tests. Rates of recurrence and ofC. difficilecolitis were recorded. Changes in antibiotic use and infection control policies were documented.Results.: The incidence ofC. difficile–associated diarrhea peaked at 21 cases per 1,000 patient admissions. Of theC. difficileisolates recovered, 85 (95%) were identical toxin A–negative and toxin B-positive strains, corresponding to toxinotype VIII and PCR ribotype 017. All clonal isolates were resistant to multiple antibiotics, including ofloxacin, ciprofloxacin, levofloxacin, moxifloxacin, and gatifloxacin (minimum inhibitory concentrations [MICs] of greater than 32μg/mL) and erythromycin, clarithromycin, and clindamycin (MICs of greater than 256μg/mL). RecurrentC. difficile–associated disease occurred in 26 (36%) of the patients. At least 10 (14%) of the patients developedC. difficilecolitis. Additional infection control measures introduced included the use of ward memos, a hand-hygiene awareness campaign, increased environmental cleaning, attention to prescribing practices for antibiotics, increased awareness of diarrheal illness, and early isolation of affected patients. Total use of fluoroquinolones did not change throughout the study period. Despite persistence of this toxin-variant strain, the incidence ofC. difficile–associated disease in our institution decreased to fewer than 5 cases per 1,000 admissions.Conclusions.: We report on the emergence of a fluoroquinolone- and clindamycin-resistant, toxin A–negative, and toxin B–positive strain ofC. difficileassociated with an outbreak ofC. difficile–associated disease in our institution during a 6-month period. We found that careful attention to improvement of infection control interventions was the most important means of controlling this nosocomial pathogen.

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