The subgingival bacterial flora from 2 gingival sites was cultured and characterized monthly in twenty periodontitis-free women during pregnancy and again post-partum. Monthly plaque samples were also cultured in eleven age and disease matched non-pregnant women. Plaque was processed anaerobically on selective and nonselective media and the predominant colony types were characterized. A portion of each plaque sample was tested for bacterial uptake of Ci4-estradiol and C^-progesterone. Plasma levels of estrogens and progesterone were measured four times in each subject. The number of gingival bleeding sites, the Gingival Index and the Plaque Index were determined at each sampling period. In the second trimester there was a significant increase in gingivitis, the ratio of anaerobic to aerobic bacteria, and the proportional levels of Bacteroides melaninogenicus ss. intermedius. In the third trimester both gingivitis and the levels of B. melaninogenicus ss. mtermedius decreased. Plaque uptake of Ci4-steroids increased significantly during pregnancy and paralleled the plaque levels of B. melaninogenicus ss. intermedius. In the second trimester, recovery of B. melaninogenicus ss. intermedius was strongly correlated with plasma levels of estrogens and progesterone. No changes were observed in clinical parameters or the subgingival flora of non-pregnant subjects. Pregnancy and specifically steroid hormones appear capable of influencing the normal bacterial flora and inducing alterations in the subgingival ecology.

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The subgingival microbial flora during pregnancy.

The asaccharolytic, pigmented Bacteroides, Bacteroides asaccharolyticus, Bacteroides gingivalis, and Bacteroides endodontalis, form a group of relatively homogeneous species which differ markedly in biochemical and chemical properties from the type species of Bacteroides, Bacteroides fragilis (Castellani and Chalmers), such that they should not be retained within this genus. Therefore, we propose that Bacteroides asaccharolyticus (Holdeman and Moore) Finegold and Barnes, Bacteroides gingivalis Coykendall, Kaczmarek and Slots, and Bacteroides endodontalis van Steenbergen, van Winkelhoff, Mayrand, Grenier and de Graaff be reclassified in a new genus, Porphyromonas, as Porphyromonas asaccharolytica comb. nov., Porphyromonas gingivalis comb. nov., and Porphyromonas endodontalis comb. nov., respectively.

Proposal for Reclassification of Bacteroides asaccharolyticus, Bacteroides gingivalis, and Bacteroides endodontalis in a New Genus, Porphyromonas

The fatty acid and isoprenoid quinone composition of 37 Bacteroides strains was examined. In a single strain of Bacteroides melaninogenicus subsp. levii neither menaquinones nor ubiquinones was detected. Menaquinones were the only isoprenoid quinones found in the remaining 36 Bacteroides strains examined. Unsaturated menaquinones with six isoprene units were the main components isolated from B. ochraceus. The menaquinone components of B. asaccharolyticus strains enable them to be divided into two subgroups containing menaquinones with nine and ten isoprene units respectively. Bacteroides vulgatus strains contained menaquinones with ten isoprene units as the major component, whereas B. fragilis, B. thetaiotaomicron and B. melaninogenicus subsp. melaninogenicus were characterized by comparable amounts of menaquinones with 10 and 11 isoprene units. Unsaturated menaquinones with 11 isoprene units were found in B. melaninogenicus subsp. intermedius and with 11 and 12 isoprene units in rumen strains of B. ruminicola subsp. brevis and B. ruminicola subsp. ruminicola. By contrast, oral strains of B. ruminicola subsp. brevis were characterized by major amounts of menaquinones with 12 and 13 isoprene units. Strains at present designated B. oralis, however, were heterogeneous with respect to menaquinone composition.



The non-hydroxylated fatty acids of all the Bacteroides strains examined consisted predominantly of straight-chain, anteiso- and iso-methyl branched-chain acids. Monounsaturated fatty acids were found in only small amounts. The major fatty acid in B. ochraceus and B. asaccharolyticus strains was 13-methyltetradecanoic acid (iso C15) whereas 12-methyl-tetradecanoic acid (anteiso C15) predominated in B. melaninogenicus subsp. melaninogenicus. B. melaninogenicus subsp. intermedius. B. melaninogenicus subsp. levii, B. oralis and oral isolates of B. ruminicola subsp, brevis. The rumen strains of B. ruminicola subsp. brevis and B. ruminicola subsp. ruminicola were characterized by major amounts of anteiso C15 and pentadecanoic (C15:0) fatty acids.



The accumulated lipid data correlate well with the major trends in Bacteroides taxonomy and appear to be of value in the classification of this group.

Fatty acid and isoprenoid quinone composition in the classification of Bacteroides melaninogenicus and related taxa.

Gram-negative anaerobic bacilli of the Bacteroides group were isolated on an enriched selective medium from specimens of faeces from 20 normal healthy adults and identified by conventional bacteriological methods. A heavy growth of Bacteroides spp. was obtained from all specimens and 10 representative colonies from each subject were identified. Most isolates (84%) belonged to the B. fragilis group. The commonest species identified in this group were B vulgatus and B. thetaiotaomicron (22% each), B. distasonis (18%) and the B. eggerthii/variabilis complex (14%), and only 9% were B. fragilis. B. vulgatus was isolated from 80% of subjects, B. thetaiotaomicron and B. distasonis from 70% each and the B. eggerthii/variabilis complex from 65%, but B. fragilis was detected in only 45% of specimens. Asaccharolytic species were isolated in smaller numbers from 14 (70%) subjects, but only five strains of the B. melaninogenicus/oralis group were isolated and fusobacteria were not detected.

The isolation and identification of bacteroides spp. from the normal human faecal flora

Bacteroides fragilis resistant to metronidazole after long-term therapy.

One hundred and sixty-five reference strains and laboratory isolates of Gram negative, non-sporing, anaerobic bacilli were subjected to a series of simple laboratory tests that were initially selected for their discriminatory value. Conventional biochemical tests, tests of resistance to antibiotics, and tolerance to dyes and bile salts were included. These tests allowed a clear separation of strains into three main groups: Bacteroides fragilis, B. melaninogenicus and Fusobacterium spp. Certain tests were found useful for identifying recognized subspecies of B. fragilis and B. melaninogenicus. A scheme for the identification of unknown laboratory isolates of Gram negative anaerobic bacilli is presented.

The characterization of clinically important gram negative anaerobic bacilli by conventional bacteriological tests.

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The characterization of clinically important gram negative anaerobic bacilli by conventional bacteriological tests.