Comparison of strains of gram-negative, anaerobic, agar-corroding rods isolated from soft tissue infections in cats and dogs with type strains of Bacteroides gracilis, Wolinella recta, Wolinella succinogenes, and Campylobacter concisus.

A total of 64 strains of gram-negative, asaccharolytic, anaerobic, agar-corroding, rod-shaped bacteria from soft-tissue infections of cats and dogs were compared with other agar-corroding, anaerobic organisms isolated from human periodontal pockets (Wolinella recta ATCC 33238T), bovine rumens (Wolinella succinogenes ATCC 29543T), and gingival crevices of humans (Bacteroides gracilis ATCC 33236T and Bacteroides ureolyticus NCTC 10941T). Campylobacter concisus ATCC 33237T (from human gingival crevices) which did not corrode agar but which biochemically resembled organisms in this group was also included in this study. Although the type strains of W. recta, W. succinogenes, and B. gracilis resembled the animal strains phenotypically and in DNA base ratios, none had bacterial protein patterns (as indicated by isoelectric focusing) identical with the animal strains studied. The animal strains could be divided into motile and nonmotile groups. The motile animal strains were similar biochemically but could be divided into three groups by isoelectric focusing of bacterial proteins. Some had cell wall ultrastructural features identical with W. recta; others had the smooth walls of conventional gram-negative organisms. One group of nonmotile animal strains closely resembled B. gracilis phenotypically, and they had the cell wall ultrastructure of conventional gram-negative bacteria as described previously (4). The other nonmotile group had cell wall ultrastructure like that of W. recta.