CHROMOSOMAL RESTRICTION-ENDONUCLEASE ANALYSIS AND RIBOTYPING OF BACTEROIDES-FRAGILIS

We have analysed the restriction fragment length patterns of chromosom al DNA and of ribosomal RNA (rRNA) genes in order to investigate the c lonal distribution within Bacteroides fragilis isolates. Eighteen bloo d culture isolates from 18 patients and 4 faecal isolates from 4 subje cts were examined. Chromosomal restriction endonuclease analysis (REA) was performed by separating BamHI-generated DNA fragments using polya crylamide gel electrophoresis (PAGE). Ribotyping was accomplished by h ybridizing EcoRI-treated genomic DNA subjected to conventional REA on agarose to a radiolabelled probe obtained from 16 + 23S rRNA of E. col i. All 22 isolates could be differentiated by their REA patterns with a varying percentage of similar fragments. Analysis of the rRNA gene p atterns displayed heterogeneity, and revealed 14 ribotypes among the 1 8 blood culture isolates and 3 among the 4 faecal isolates. The predom inant ribotype among the clinical isolates was also shared by one faec al isolate. The results suggest that no particular clones are predomin antly responsible for systemic infection.