Brucellas

Abstract

A number of strains of Br. abortus, Br. melitensis and Br. suis has been tested concerning the nitrate reduction. According to the author, nitrate is rapidly reduced to nitrite by all of them when tested in the nitrate-broth recommended by the Society of American Bacteriologists. Reduction has been noted after one hour's incubation with some strains, but after five hours' incubation they all showed reduction. The reactions given by the abortus and suis types are much stronger than by the melitensis strains. Further analyses show that the nitrite disappears; this begins after 18 hours' incubation with some strains. However, three strains of Br. abortus, which reduced vigorol1sly nitrate to nitrite, did not exhibit disappearance of nitrite under identical conditions, for the five days during which they were under observation. Because of the complicated technic and the difficulty in interpreting resl1lts when the nitrite reaction given by the microorganism in a medium with nitrate is negative; also, because many of these reactions would be positive if they were verified earlier, the following is suggested by the author. If the microorganism grows well in the above-mentioned nitrate-broth, testing for nítrite would begin some hours after the inoculation. Furthermore several tests would be made, at intervals of some hours.