USE OF PULSED-FIELD GEL-ELECTROPHORESIS FOR INVESTIGATION OF AN OUTBREAK OF CLOSTRIDIUM-DIFFICILE INFECTION AMONG GERIATRIC-PATIENTS

A six-month outbreak of Clostridium difficile infection among elderly residents of a middle-term-care facility was investigated. Pulsed-fiel d gel electrophoresis was used to genotype 22 outbreak strains and 30 epidemiologically unrelated strains. A prospective case-control study was conducted to identify risk factors for epidemic Clostridium diffic ile-associated diarrhea. All epidemiologically unrelated Clostridium d ifficile strains of the same serogroup could be differentiated by thei r DNA patterns with two restriction enzymes (Smal and Kspl). Among clu stered strains, two epidemic serogroups (C and K) were identified. Two different DNA patterns were identified among serogroup C strains and three among serogroup K strains. Multivariate analysis showed that the risk of Clostridium difficile infection increased with antimicrobial chemotherapy (beta-lactam agents and pristinamycin) and the presence o f a feeding tube. This study confirms the high discriminative power of restriction fragment length polymorphism analysis by pulsed-field gel electrophoresis to describe Clostridium difficile epidemiology. The t yping results confirm that infection was principally exogenous in this outbreak. Furthermore, they indicate the need to improve ail measures limiting transmission of infection.