Observations on the problem of Brucella blood cultures

Of the various laboratory data that are sought to support a tentative clinical diagnosis of chronic brucellosis, none is given more emphasis than a positive culture. Cultures, particularly from blood, are frequently negative, however, even when taken daily for a week or more. These failures have been variously ascribed to nutritional inadequacies of the culture media employed and to the absence of brucellae in the blood stream. Some credence, indeed, may be given to the latter proposal in view of the positive cultures obtained from biopsy speci-mens by various investigators (Spink, 1948; McVay, Guthrie, Michelson, and Sprunt, 1948, 1950; Weed and Dahlin, 1950). A third possibility, and one that does not appear to have been adequately explored, may be expressed as follows: Brucellae may well be present in a 5- to 10-ml blood specimen (and probably intracellular), but their growth, when commonly employed cultural procedures are followed, will be suppressed by concomitant antibody, even though the latter may not be manifest in the agglutinin titer. Accordingly then, a "washed" specimen should be used and should realize not only removal of inhibitory anti