FIG. 3.

Analysis of AP-PCR profiles of C. difficile strains isolated from the stools of patients with C. difficile infection, the hands of health care workers, and the environments of two medicine hospital wards for elderly patients. The dendrogram includes a small representative type of the predominant hospital genotype (type Ia) and all other genotypes found in the study. Strains isolated from the hands of health care workers are marked with an asterisk. DNA profiles were analyzed by using BioNumerics software (Applied Maths, BioSystematica). Dendrograms were constructed by the unweighted pair group method with arithmetic mean clustering by using the Dice correlation coefficient. The percentage level of similarity chosen for type assignments (roman numerals) is indicated by the thick black line and was based on the guidelines recommended by Tenover et al. (29).