SELECTIVE ENUMERATION OF BACTEROIDES-VULGATUS AND B-DISTASONIS ORGANISMS IN THE PREDOMINANT HUMAN FECAL FLORA BY USING MONOCLONAL-ANTIBODIES

The genus Bacteroides represents about one-third of the isolates from human fecal samples. The proportions of the different species are diff icult to estimate because there is no method for rapid identification of mixtures of anaerobes. Monoclonal antibodies against Bacteroides vu lgatus and B. distasonis were prepared. They did not react with the ot her Bacteroides species of the B. fragilis group. These reagents allow ed direct enumeration of B. vulgatus and B. distasonis organisms in hu man fecal samples. Anaerobic bacteria resistant to 1-h contact with ai r were enumerated in fecal human samples, a filter was layered on the colonies, and then B. vulgatus colonies were identified by an immunoas say performed with the prepared monoclonal antibodies. Healthy human a dult volunteers were tested. Most of them harbored B. vulgatus at high levels, while the B. distasonis levels were always lower. Kinetic stu dies suggested that time variations for each volunteer were small. The simplified quantification of Bacteroides strains at the species level described here will prove useful in complementing our knowledge of th e factors which may influence the predominant human fecal flora.