(A) Moxifloxacin# CLOSTRIDIUM DIFFICILE INFECTION (CDI) is a unique colonic disease that is acquired almost exclusively in association with antimicrobial use and the consequent disruption of the normal colonic flora.> Most commonly diagnosed diarrheal illness acquired in the hospital, CDI results from the ingestion of spores of C. difficile that vegetate, multiply, and secrete toxins, causing diarrhea and pseudomembranous colitis (PMC).> Pseudomembranes of PMC are confined to the colonic mucosa and initially appear as 1- to 2-mm whitish-yellow plaques.> Intervening mucosa appears unremarkable, but, as the disease progresses, the pseudomembranes coalesce to form larger plaques and become confluent.> Clindamycin, ampicillin, and cephalosporins were the first antibiotics associated with CDI.> Second and third generation cephalosporins, particularly cefotaxime, ceftriaxone, cefuroxime, and ceftazidime, are agents frequently responsible for this condition, and the fluoroquinolones (ciprofloxacin, levofloxacin, and moxifloxacin) are the most recent drug class to be implicated in hospital outbreaks.