fThe rising incidence of Clostridium difficile infections (CDIs) in adults is partly related to the global spread of fluoroquinoloneresistant strains, namely, BI/NAP1/027. Although CDIs are also increasingly diagnosed in children, BI/NAP1/027 is relatively uncommon in children. Little is known about the antibiotic susceptibility of pediatric CDI isolates. C. difficile was cultured from tcdB-positive stools collected from children diagnosed with CDI between December 2012 and December 2013 at an academic children's hospital. CDI isolates were grouped by restriction endonuclease analysis (REA). MICs were measured by agar dilution method for 7 antibiotics. Susceptibility breakpoints were based on guidelines from CLSI and/or the European Committee on Antimicrobial Susceptibility Testing (EUCAST). MICs and REA groupings of C. difficile isolates from 74 adult patients (29 isolates underwent REA) from a temporally and geographically similar adult cohort were compared to those of pediatric isolates. Among 122 pediatric and 74 adult isolates, respectively, the rates of resistance were as follows: metronidazole, 0% and 0%; vancomycin, 0% and 8% (P ؍ 0.003); rifaximin, 1.6% and 6.7% (P ؍ 0.11); clindamycin, 18.9% and 25.3% (P ؍ 0.29); and moxifloxacin, 2.5% and 36% (P ؍ <0.0001). Only 1 of 122 (0.8%) BI/NAP1/027 isolates was identified among the children, compared to 9 of 29 (31%) isolates identified among the adults (P ؍ <0.0001). The 3 moxifloxacin-resistant pediatric isolates were of REA groups BI and CF and a nonspecific group. The 2 rifaximin-resistant pediatric isolates were of REA groups DH and Y. The 21 clindamycin-resistant pediatric isolates were distributed among 9 REA groups (groups A, CF, DH, G, L, M, and Y and 2 unique nonspecific REA groups). These data suggest that a diverse array of relatively antibiotic-susceptible C. difficile strains predominate in a cohort of children with CDI compared to adults. T he increased frequency, morbidity, and mortality of Clostridium difficile infections (CDI) in adults over the past 2 decades are primarily attributable to the emergence and global spread of a fluoroquinolone-resistant strain known as BI/NAP1/027 (1, 2). CDI is now the most frequently encountered health care-associated infection in the United States (3), causing nearly 500,000 infections and 30,000 deaths each year (4). These troubling trends in the clinical and molecular epidemiology of CDI recently prompted the Centers for Disease Control and Prevention (CDC) to classify CDI among the most serious immediate antibiotic-resistant diseases representing "public health threats that require urgent and aggressive action" (5).The molecular epidemiology (6-8) and antibiotic resistance (7-9) patterns of CDI in adults over the past 3 decades have been well described. Although the prevalence of BI/NAP1/027 is declining, recent data from the United States (4) and the United Kingdom (10) indicate that BI/NAP1/027 is still an important cause of CDI in adults. Limited investigation of the molecular epidemiology of...