From 1974 to 1998, 22 isolates of an unusual bacterium, designated as CDC group nonoxidizer 1 (NO-1), were sent to the Centers for Disease Control and Prevention for identification. The organism's phenotypic characteristics were similar to asaccharolytic strains of Acinetobacter, but differed in their cellular morphology and cellular fatty acid profile. We report here on NO-1's clinical and epidemiologic significance. In all cases, isolates were recovered from an animal bite wound; 17 (77%) were isolated from a dog bite wound, 4 (18%) from a cat bite wound, and one (5%) from an unspecified animal bite. Clinical data were retrieved and reviewed for 12 (55%) of the 22 bite victims. None of the patients had pre-existing conditions associated with immunosuppression. Seven (58%) patients were hospitalized for a median stay of 5 days (range, 2 to 11 days). The median time between bite to the worsening of symptoms was 17.5 hours (range, 3 to 78 hours). All patients recovered following antibiotic treatment.