Asymptomatic carriage of Clostridium difficile in an Irish continuing care institution for the elderly: Prevalence and characteristics

Introduction: Clostridium difficile is an increasing cause of nosocomial diarrhoea and colitis. The aim of this study was to identify the prevalence and characteristics of asymptomatic C. difficile carriage in a continuing care institution for the elderly. Methods: Stool samples were collected from 100 asymptomatic patients, whose median age was 83 years. Samples were tested for C. difficile using traditional culturing methods, 16s rDNA and 16s-23s intergenic spacer (IGS) rDNA sequencing, and analysed for toxin production and toxin genes. Results: The prevalence of C. difficile carriage was 10/100 (10%) following culture and 16s and IGS sequencing. An additional seven isolates, initially identified as C. difficile, were subsequently identified by IGS rDNA sequencing as C. sordellii of the 10% that tested positive for C. difficile, seven tested positive for toxin A and B. A significant number of C. difficile carriers had recent antibiotic exposure compared with non-carriers, P = 0.046. Conclusion: The prevalence of asymptomatic C. difficile carriage in this institution was 10%, 7% of which were toxin positive. This study underscores the importance of increased vigilance for C. difficile using microbial and molecular methodology and identifies patients at increased risk following antibiotic administration.