The Use of a Non-Motile Strain of B. Typhosus in the Agglutination Reaction

are not recovered from the blood, feces, or urine, is difficult by the agglutination test, where the patient's serum is treated with only one standard laboratory strain of B? typhosus ; the reason for this difficulty being that the serological differences between the standard laboratory strain and the irregular strain causing the infection may be so great that at the time when the diagnosis is attempted, the patient's serum may have produced agglutinins for the causative strain but not for the standard strain. Every case of B. typhosus infection should be diagnosed by finding the organisms in the blood or the freces long before the agglutinins are developed; but it is known that one may fail to discover the bacillus either in the blood or the fseces even by repeated cultures under certain conditions, and further the cultural methods may not be applicable. So in some cases the agglutination reaction becomes a necessity for diagnosis. The technique for this agglutination test has been highly improved, especially by Professor Dreyer. Even if Professor Dreyer's technique be employed there is a small percentage of cases where the test may be negative though the cases are typhoid as proved by previous cultural results or by definite clinical signs. It struck me a short time ago that this might be due to the fact that I used only one strain of B. typhosus (in addition to the Paratyphoid strains) in my routine work. This has been borne out by practical experience in observations on several