A serogrouping scheme for the study of the epidemiology of Bacteroides fragilis

Publisher Website
Google Scholar
Abstract
To study the hosptial epidemiology of Bacteroides fragilis, 343 isolates from infected hospitalized patients (112), infected out-patients (102), and from the faeces of uninfected hospitalised patients (147) and normal subjects in the community (82), were examined by an immunofluoresence technique. In tests with antisera against strains of 20 distinct serotypes of the fragilis group of Bacteroides, 271 (79%) strains were typable. Similarity between strains was estimated by the Jaccard similarity measure and strains were then serogrouped by cluster analysis; 88.1% of hospital strains were typable but only 71.2% of community strains (P<0.001). Three serogroups were prevalant among both faecal and infection isolates of hospital strains (p<0.01). However, no particular serogroup was prevalent among community strains and no diffence was found in the distribution of serogroups between strains from faeces and those from infected lesions. One serogroup showed a significant increase (p < 0.05) within the period of study. These findings suggest that strains of B. fragilis infecting hospitalised patients may be acquired in hospital and that they may spread to other patients.