PROPIONATE NEGATIVE SACCHAROLYTIC BACTEROIDES STRAINS (B ORALIS) - OCCURRENCE, IDENTIFICATION, ANTIMICROBIAL SUSCEPTIBILITY AND SEROLOGICAL BEHAVIOR

  • 1 January 1977
    • journal article
    • research article
    • Vol. 237  (4) , 536-547
Abstract
Propionate negative non-pigmented Bacteroides strains (23) were isolated from mixed [human] infections (peritonitis, endometritis, abscess of the abdominal wall, etc.) and vaginal secretions of healthy parturients in the course of 3 yr. The cultures were indole negative, produced acetic, isobutyric and isovaleric acids and had a final pH of 5.0-5.5 in glucose broth; they were assigned to B. oralis as described by Loesche and coworkers in 1964. Pathogenic significance of this organism may be assumed in those cases of mixed infection where the microbial association consisted solely of gram-positive species with low virulence (lactobacilli, Staphylococcus epidermidis, Peptococcaceae). Antibiotic susceptibility of 12 B. oralis strains was studied by tube dilution tests. Resistance to cephalosporins was detected in 8 strains, about half of them resistant to ampicillin and penicillin G. Like other Bacteroides spp., the B. oralis strains showed resistance to aminoglycosides and sensitivity to clindamycin, chloramphenicol and erythromycin. The serological behavior of 9 B. oralis strains was studied in cross-agglutination and gel-diffusion experiments. Cross-reactivity was particularly pronounced in immunodiffusion tests with autoclaved extracts. According to the results obtained, the strains belonged to a homogeneous group with 1-2 identical antigens. These B. oralis antigens were shared by B. melaninogenicus intermedius 2965. There were, however, no cross-reactions between the aforementioned strains and B. melaninogenicus melaninogenicus 8117/1. The taxonomic implications of a close relationship between B. oralis and B. melaninogenicus intermedius are discussed.

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