A bacteriological and serological study of organism B5W (Bacterium antiratum).

Over a period of several years there has been isolated in the laboratories of the Receiving Hospital, Detroit, an unusual gram-negative organism, characterized by mucoid growth and relatively simple biochemical activity, which fits into no known bacteriological classification. A large percentage of these cultures were isolated from urine specimens, although an occasional strain was found in sputum, material from lung abscesses, and even in blood. The frequent occurrence of this organism in pathologic processes indicated that it was of possible pathogenic significance. In January, 1947, a representative culture was sent to Dr. C. A. Stuart, who reported that the organism was similar to fortysome cultures studied by him which were designated B5W for want of a specific appellation. Since that time the reports of Schaub and Hauber (1948) and of Stuart, Formal, and McGann (1949) have described in detail the morphological and biochemical characteristics of the organism known to these authors as Bacterium anitratum or B5W, respectively. The 15 cultures examined by Schaub and Hauber were definitely a biochemical entity, whereas those described by Stuart and his colleagues varied in lactose and rhamnose fermentation and in motility. Of 81 cultures examined by the latter authors, 26 were motile. It was evidently on the basis of variation in motility that Stuart et al. used the term "group" for the B5W organisms rather than a more limiting designation. According to Schaub and Hauber (1948), their 15 cultures were characterized by mucoid growth when first isolated, and the individual organisms were possessed of a small capsule that could be demonstrated in India ink preparations and by the quellung reaction in the presence of specific serum. An "S" variant devoid of capsules was noted by these workers as well as an "R" form and a small colony variant. In the encapsulated state B. anitratum was found to be serologically homogeneous. Stuart, Formal, and McGann (1949), however, found that their nonmotile cultures were antigenically heterogeneous, with no serologic agreement existing between cultures fermenting or failing to ferment rhamnose or between cultures positive and negative in lactose. In the present study 109 nonmotile cultures of organism B5W have been examined for growth characteristics and biochemical activity, and a limited