[ABOUT UNIFICATION OF LABORATORY CRITERIA OF DIFFERENTIATION OF BACTERIAL VAGINOSIS]

The article presents analysis of laboratory criteria and classifcations used to interpret results of laboratory analysis by technique of microscopy on bacterial vaginosis or dysbacteriosis of vagina. Their advantages and restrictions are demonstrated The unified criteria of evaluation are proposed concerning results of microscopy of mucosal discharge of vagina and corresponding classification. Thereafter, three degrees of bacterial vaginosis (dysbacteriosis of vagina) are differentiated: first degree--compensated dysbacteriosis of vagina, second degree--sub compensated dysbacteriosis of vagina and third degree--decompensated dysbacteriosis of vagina. The corresponding laboratory report of physician is formulated. The proposals are presented concerning development of common unified requirements to stages (pre-analytical, analytical, post-analytical) of laboratory diagnostic of bacterial vaginosis (dysbacteriosis of vagina) with purpose of their unambiguous understanding by clinicians and hence their decision making concerning necessity and tactics of management of patient.

More than meets the eye: associations of vaginal bacteria with gram stain morphotypes using molecular phylogenetic analysis

Bacterial vaginosis (BV) is a highly prevalent condition associated with adverse health outcomes. Gram stain analysis of vaginal fluid is the standard for confirming the diagnosis of BV, wherein abundances of key bacterial morphotypes are assessed. These Lactobacillus, Gardnerella, Bacteroides, and Mobiluncus morphotypes were originally linked to particular bacterial species through cultivation studies, but no studies have systematically investigated associations between uncultivated bacteria detected by molecular methods and Gram stain findings. In this study, 16S-rRNA PCR/pyrosequencing was used to examine associations between vaginal bacteria and bacterial morphotypes in 220 women with and without BV. Species-specific quantitative PCR (qPCR) and fluorescence in Situ hybridization (FISH) methods were used to document concentrations of two bacteria with curved rod morphologies: Mobiluncus and the fastidious BV-associated bacterium-1 (BVAB1). Rank abundance of vaginal bacteria in samples with evidence of curved gram-negative rods showed that BVAB1 was dominant (26.1%), while Mobiluncus was rare (0.2% of sequence reads). BVAB1 sequence reads were associated with Mobiluncus morphotypes (p<0.001). Among women with curved rods, mean concentration of BVAB1 DNA was 2 log units greater than Mobiluncus (p<0.001) using species-specific quantitative PCR. FISH analyses revealed that mean number of BVAB1 cells was 2 log units greater than Mobiluncus cells in women with highest Nugent score (p<0.001). Prevotella and Porphyromonas spp. were significantly associated with the “Bacteroides morphotype,” whereas Bacteroides species were rare. Gram-negative rods designated Mobiluncus morphotypes on Gram stain are more likely BVAB1. These findings provide a clearer picture of the bacteria associated with morphotypes on vaginal Gram stain.

Bacteroides dorei sp. nov., isolated from human faeces

Two Gram-negative, anaerobic, non-spore-forming rod-shaped organisms were isolated from human faeces. These isolates were tentatively identified as Bacteroides based on morphological and biochemical criteria and appeared closely related to Bacteroides vulgatus ATCC 8482T. The 16S rRNA gene sequence analysis showed that the isolates were highly related to each other (99.5 %) and confirmed their placement in the genus Bacteroides. 16S rRNA gene sequence similarity values with close phylogenetic neighbours Bacteroides vulgatus ATCC 8482T (96 %) and Bacteroides massiliensis CCUG 48901T (93 %) preliminarily demonstrated that the organisms represented a novel species. The results of phenotypic, chemotaxonomic and 16S rRNA gene sequence analyses, and DNA–DNA homology values provided evidence that these two unknown isolates represent a single species and should be assigned to a novel species of the genus Bacteroides, as Bacteroides dorei sp. nov. The type strain is JCM 13471T (=DSM 17855T).

Application of a direct fluorescence-based live/dead staining combined with fluorescence in situ hybridization for assessment of survival rate of Bacteroides spp. in drinking water

To evaluate the viability and survival ability of fecal Bacteroides spp. in environmental waters, a fluorescence-based live/dead staining method using ViaGram Red+ Bacterial gram stain and viability kit was combined with fluorescent in situ hybridization (FISH) with 16S rRNA-targeted oligonucleotide probe (referred as LDS-FISH). The proposed LDS-FISH was a direct and reliable method to detect fecal Bacteroides cells and their viability at single-cell level in complex microbial communities. The pure culture of Bacteroides fragilis and whole human feces were dispersed in aerobic drinking water and incubated at different water temperatures (4 degrees C, 13 degrees C, 18 degrees C, and 24 degrees C), and then the viability of B. fragilis and fecal Bacteroides spp. were determined by applying the LDS-FISH. The results revealed that temperature and the presence of oxygen have significant effects on the survival ability. Increasing the temperature resulted in a rapid decrease in the viability of both pure cultured B. fragilis cells and fecal Bacteroides spp. The live pure cultured B. fragilis cells could be found at the level of detection in drinking water for 48 h of incubation at 24 degrees C, whereas live fecal Bacteroides spp. could be detected for only 4 h of incubation at 24 degrees C. The proposed LDS-FISH method should provide useful quantitative information on the presence and viability of Bacteroides spp., a potential alternative fecal indicator, in environmental waters.

Alkaliflexus imshenetskii gen. nov. sp. nov., a new alkaliphilic gliding carbohydrate-fermenting bacterium with propionate formation from a soda lake

Anaerobic saccharolytic bacteria thriving at high pH values were studied in a cellulose-degrading enrichment culture originating from the alkaline lake, Verkhneye Beloye (Central Asia). In situ hybridization of the enrichment culture with 16S rRNA-targeted probes revealed that abundant, long, thin, rod-shaped cells were related to Cytophaga. Bacteria of this type were isolated with cellobiose and five isolates were characterized. Isolates were thin, flexible, gliding rods. They formed a spherical cyst-like structure at one cell end during the late growth phase. The pH range for growth was 7.5-10.2, with an optimum around pH 8.5. Cultures produced a pinkish pigment tentatively identified as a carotenoid. Isolates did not degrade cellulose, indicating that they utilized soluble products formed by so far uncultured hydrolytic cellulose degraders. Besides cellobiose, the isolates utilized other carbohydrates, including xylose, maltose, xylan, starch, and pectin. The main organic fermentation products were propionate, acetate, and succinate. Oxygen, which was not used as electron acceptor, impaired growth. A representative isolate, strain Z-7010, with Marinilabilia salmonicolor as the closest relative, is described as a new genus and species, Alkaliflexus imshenetskii. This is the first cultivated alkaliphilic anaerobic member of the Cytophaga/ Flavobacterium/ Bacteroides phylum.

Belliella baltica gen. nov., sp. nov., a novel marine bacterium of the Cytophaga–Flavobacterium–Bacteroides group isolated from surface water of the central Baltic Sea

Two bacterial isolates from the Baltic Sea, BA1 and BA134T, were characterized for their physiological and biochemical features, fatty acid profiles and phylogenetic position based on 16S rRNA gene sequences. The strains were isolated from surface water of the central Baltic Sea during the decay of a plankton bloom. Phylogenetic analysis of their 16S rRNA gene sequences revealed a clear affiliation to the family ‘Flexibacteriaceae’ and showed highest sequence similarity (91 %) to Cyclobacterium marinum. The G+C content of the DNA was 35·4 mol%. The strains were pink-coloured due to carotinoids, Gram-negative, rod-shaped and catalase- and oxidase-positive. Growth was observed at 0–6 % salinity, with good growth at 0–3 %. Temperature for growth was 4–37 °C, with an optimum around 25 °C. The fatty acid profiles were dominated by branched-chain fatty acids (70 %), with a high abundance of iso-C15 : 0 (29–33 %), iso-C17 : 1 ω9c (7–10 %) and C17 : 1 ω6c (5–10 %). According to their morphology, physiology, fatty acid composition, 16S rRNA gene sequences and DNA–DNA similarity, on one hand, the described bacteria are considered to be members of the same novel species; on the other hand, they are suggested as a novel genus of the family ‘Flexibacteriaceae’. To honour the late aquatic microbiologist Russell T. Bell, the name Belliella baltica gen. nov, sp. nov. is suggested for the Baltic Sea isolates, for which the type strain is BA134T (=DSM 15883T=LMG 21964T=CIP 108006T).

Validity of wet-mount bacterial morphotype identification of vaginal fluid by phase-contrast microscopy for diagnosis of bacterial vaginosis in family practice

The aim of this study was to determine the accuracy of a wet-mount bacterial morphology scoring (BMS) system and Nugent's Gram stain analysis for the diagnosis of bacterial vaginosis, using Amsel's criteria as the gold standard. The three diagnostic criteria were assessed independently The BMS diagnosis was based on a scoring system which weighed the number of small bacterial morphotypes regarded as typical of bacterial vaginosis against lactobacillary morphotypes in phase-contrast microscopy of wet-mount preparations. Three groups of non-pregnant women attending either because of vaginal discharge, other genitourinary symptoms, or for a routine check-up, and a group of pregnant women attending for antenatal care were studied. The diagnostic accuracy was measured by sensitivity, specificity, positive and negative predictive values, and likelihood ratio. The accuracy of the BMS diagnosis was substantially high in all of the examined groups (LR 15.4-20.3). The accuracy of the Gram stain diagnosis was lower (LR 7.6-10.9). In the total material, the accuracy of the BMS diagnosis was higher than that of the Nugent's Gram staining. Intra- and inter-observer reproducibility of all three criteria applied was high. We propose greater routine use of the new BMS diagnosis for point-of-care testing in family practice as well as in research and in microbiology laboratories.

Fermentation of maize bran, oat bran, and wheat bran by Bacteroides ovatus V975

Bacteroides ovatus is a Gram-negative obligate anaerobe that was isolated from the human colon and is capable of utilizing xylan. The objective of this study was to evaluate the ability of B. ovatus V975 to digest maize bran, oat bran, and wheat bran as well as the isolated cell walls from each bran source. Strain V975 was incubated in basal medium that contained either 0.1 or 0.3 g of each bran or each bran cell wall for 0, 24, 48, and 72 h. Acetate and succinate were the main products detected from each fermentation; however, less of each end product was produced from the isolated cell walls than from each bran. More of the oat bran was digested (in vitro dry matter disappearance = 74.8%) during the 72 h incubation than any other bran source. While each bran contained arabinose and xylose, more glucose, galactose, and mannose were utilized by strain V975 during the 72-h incubation than either pentose sugar. Compared with each bran, the bran cell walls had lower concentrations of most sugars, and more glucose than any other sugar was utilized by strain V975. These results suggest that strain V975 preferentially utilizes glucose, galactose, and mannose in each bran, while glucose is the main sugar fermented in bran cell walls.

Comparative distribution and taxonomic value of cellular fatty acids in thirty-three genera of anaerobic gram-negative bacilli

Cellular fatty acid profiles were determined for species in 33 genera of anaerobic gram-negative bacilli and were confirmed to be a useful taxonomic tool. Most of the genera could be differentiated by visual inspection of their profiles. The three genus pairs that were most difficult to distinguish visually (Bacteroides and Prevotella, Pectinatus and Megamonas, and Serpulina and Bilophila) and the species of these genera were differentiated by the MIDI (Microbial ID, Inc.) identification system. Similarities in cellular fatty acid profiles may be correlated with similarities in other phenotypic characteristics, but more often there is no other obvious phenotypic relationship. Although medium components may not change the constituents detected or the ratios among the constituents detected for some species, identical medium changes may result in vast differences in the profiles obtained with other species. Thus, if a worker wishes to compare profiles of various taxa, it is essential that the same cultural and analytical conditions be used.

Coaggregation of Prevotella intermedia with oral Actinomyces species

Five strains of Prevotella intermedia were examined for their ability to coaggregate with various gram-positive and gram-negative species of oral bacteria. Two of the P. intermedia strains coaggregated with selected Actinomyces species, P. intermedia 27 with Actinomyces viscosus T14V and Actinomyces naeslundii ATCC 12104, PK606, PK984, and PK947, and P. intermedia 113 with Actinomyces odontolyticus WVU 1546 and Actinomyces israelii WVU 838. Exposure of both Prevotella strains but not the Actinomyces strains to heat, trypsin, or proteinase K abolished most coaggregations. All pairs were disaggregated by the addition of sodium dodecyl sulfate, but only those coaggregations involving P. intermedia 113 were reversed by the addition of 2.0 M urea. P. intermedia 27 was sensitive to periodate oxidation, whereas the partner strains were stable to this treatment. Most coaggregations occurred in the presence of saliva; however, reactions involving P. intermedia 27 were not as strong as those of buffer-suspended cells. Treatment of both P. intermedia 113 coaggregations pairs with proteinase K and the results obtained from suspensions of these pairs in saliva suggest that different surface molecules of this P. intermedia strain may mediate each of these coaggregations. These data suggest that all of these coaggregations involve either a protein or glycoprotein on the Prevotella strain, which may interact with carbohydrates or carbohydrate-containing molecules on the surface of the Actinomyces strain.

Migration of bacteria along synthetic polymeric fibers

E. coli, S. epidermidis, and B. distasonis were observed to migrate readily along polymer fibers impressed upon the surface of nutrient agar. E. coli was also observed to migrate readily along polymer fibers embedded in brain-heart infusion agar. Within periods of about 24 h, migration distances of about several centimeters were observed. No migration was observed in control experiments conducted on or in the same media, but without fibers. Migration speed was greatest for E. coli and slowest for B. distasonis. Cell population density was found to decrease rapidly with distance from a source culture. Swimming motility or natural convection in liquid between fiber and gel appears to be improbable based on the expected dimensions of capillary-condensed liquid between fiber and gel.

Phagocytosis and virulence of different strains of Porphyromonas gingivalis

In this study 17 strains of Porphyromonas gingivalis, both reference and clinical isolates, were investigated for their in vitro interaction with human polymorphonuclear leukocytes, hydrophobicity, density, and virulence in a mouse model. The results of the phagocytosis, hydrophobicity, and density experiments showed that P. gingivalis strains could be divided into two distinct groups. One group of strains were readily attached and phagocytosed when exposed to the leukocytes. These bacteria were hydrophobic and had a higher buoyant density than the other group, which were poorly phagocytosed, had a low buoyant density, and were hydrophilic. This latter group also exhibited an extracellular meshwork resembling a glycocalyx when examined by electron microscopy. There were also significant differences between strains in the mouse pathogenicity model. Two strains caused an invasive, spreading infection compared with the other 15 strains which produced small, localized abscesses. There was no clear correlation between the results of the phagocytosis assay and the virulence of the bacteria when injected subcutaneously in mice. Resistance to phagocytosis may be important for survival of these bacteria, but it does not in itself imply the ability to cause damage to the host.

Bacteroides gingivalis vesicles bind to and aggregate Actinomyces viscosus

Isolated Bacteroides gingivalis 2561 vesicles aggregated suspensions of Actinomyces viscosus and Actinomyces naeslundii of all taxonomy clusters. Vesicles bound near A. viscosus cell walls and among its surface fibrils. Tritiated vesicles bound slightly better to saliva-coated hydroxyapatite (SHA) than to SHA coated with A. viscosus; saturation was approached at the concentrations that were tested. Pretreatment of A. viscosus-coated SHA with vesicles impaired the subsequent adherence of B. gingivalis whole cells.

Collagenolytic activity of the extracellular vesicles of Bacteroides gingivalis W50 and an avirulent variant W50/BE1

The activities of the extracellular vesicle fractions of these two organisms were compared. Lytic activity against a native type I placental collagen substrate at 30 degrees C was assessed following sodium dodecyl sulphate-polyacrylamide gel electrophoresis and densitometry. A rapid rate of collagen depolymerization was achieved by the extracellular vesicle fraction of W50, yielding approx. 90% substrate degradation compared to 5% for W50/BE1 extracellular vesicles over 6 h incubation. The polypeptide digestion patterns produced by incubation with extracellular vesicle fractions of both organisms were identical, and similar to those yielded by incubation of substrate with whole W50 cells.

The Bacteroides glycocalyx as visualized by differential interference contrast microscopy

The glycocalyx of eight strains representing six species of Bacteroides was examined by differential interference contrast microscopy. Wet mounts in India ink were prepared from bacteria cultured in broth and on an agar medium; the wet mounts were observed by phase-contrast microscopy and differential interference contrast microscopy. With differential interference contrast microscopy, all bacteria demonstrated a glycocalyx, which included capsules surrounding single cells and microcolonies, strands of glycocalyx connecting cells and microcolonies, detached slime, and solid masses of glycocalyx in which innumerable bacteria were enmeshed. Bacteria showed comparable amounts of glycocalyx by visual observation with differential interference contrast microscopy whether grown on plates or in broth. Serial transfers of cultures did not diminish the amount of glycocalyx. Differential interference contrast microscopy proved to be a superior method to phase contrast for examining wet preparations of Bacteroides.

Intergeneric rosettes: sequestered surface recognition among human periodontal bacteria

The human oral bacteria, Streptococcus sanguis and Bacteroides loescheii, when mixed in equal numbers in vitro, formed large settling coaggregates. As the relative number of each cell type was changed, coaggregates became smaller until at cell-type ratios of 10 to 1, rosettes formed. Rosettes consisting of a streptococcal cell in the center surrounded by bacteroides cells exhibited surface recognition properties of only the bacteroides, which coaggregated with many other cell types such as Actinomyces naeslundii, and formed large settling multigeneric aggregates. The ecological significance of these results derives from the following: (i) the direct demonstration that intergeneric coaggregates can protect the central cell from or prevent its access to other cells in the environment, and (ii) the potential for these effects to occur during bacterial succession of various cell types observed in progressively more severe stages of human periodontal disease.

Isolation of capsulate anaerobic bacteria from orofacial abscesses

The presence of capsulate Bacteroides spp. and anaerobic gram-positive cocci was investigated in pus specimens from 182 children with chronic orofacial infections or abscesses and in pharyngeal swabs from 26 children without inflammation. Of 216 Bacteroides spp. and anaerobic cocci isolated from clinical infections, 170 (79%) were capsulate, compared with 34 (35%) of 96 isolates from normal pharyngeal flora (p less than 0.001). The commonest organisms found to be capsulate more often from infected patients than from controls belonged to the B. melaninogenicus group. The possible evolution of encapsulation in these organisms and their importance in mixed orofacial infections are discussed.

Selective medium for the isolation of Bacteroides gingivalis

Bacteroides gingivalis has been implicated in various forms of periodontal disease and may be responsible for other diseases in humans. The role of B. gingivalis in disease has been difficult to assess, because it is inhibited by most selective media commonly used by clinical laboratories to aid in isolating gram-negative, nonsporeforming anaerobes. We have developed a new medium, Bacteroides gingivalis agar, which contains bacitracin, colistin, and nalidixic acid as selective agents. This medium allowed B. gingivalis to be isolated from oral specimens with little difficulty and also allowed B. gingivalis to be isolated from phenotypically similar Bacteroides species, such as B. asaccharolyticus and B. endodontalis, with which it can easily be confused.

Further characterization of Bacteroides endodontalis, an asaccharolytic black-pigmented Bacteroides species from the oral S cavity

In this study, the isolation, characterization, and identification of Bacteroides endodontalis is described. It was found that this asaccharolytic black-pigmented Bacteroides species is associated with infected dental root canals and oral submucous abscesses. B. endodontalis could be differentiated from B. gingivalis by a negative direct hemagglutination test and the absence of trypsin and N-acetyl-beta-glucosamidase. B. endodontalis could be differentiated from B. asaccharolyticus by the absence of alpha-fucosidase, its inability to grow in an atmosphere of 95% N2-5% H2, and a growth requirement for menadione. Immune serum raised against B. endodontalis strain HG 370T agglutinated only B. endodontalis cells. Precautions for the isolation of B. endodontalis are discussed.

Comparative growth of Bacteroides species in various anaerobic culture media

The growth of five species of Bacteroides in four anaerobic culture media was continuously monitored turbidimetrically. Interspecies differences were observed in the growth of Bacteroides spp. in the various media, but growth in Brain Heart Infusion broth supplemented with yeast extract, haemin and menadione, was consistently better than in Wilkins-Chalgren, Thioglycollate or Schaedler broths. Microscopy of cultures grown overnight in Brain Heart Infusion broth showed that the bacteria exhibited normal morphology but most species grown in the other media displayed filamentation or chain formation. Four of the five species grown in Schaedler broth also exhibited spheroplast formation. This morphological change occurred in the stationary phase of growth, was reduced by inclusion of NaCl in the medium and was abolished in Schaedler broth prepared at double the recommended strength.

Adherent interactions which may affect microbial ecology in the mouth

Bacteria attach to teeth and oral mucosal surfaces in a surprisingly selective manner, and attachment appears to be the first step in the colonization process. Attachment is thought to involve lectin-like and/or hydrophobic ligands, called adhesins, often present in bacterial surface appendages which interact with receptors on oral tissues. A variety of factors can influence bacterial attachment, and therefore have the potential to affect host-parasite interactions in the mouth. Factors discussed include salivary components, dietary lectins, and sublethal concentrations of antibiotics.

Colonization of the subgingival area by Bacteroides gingivalis

The initial event in colonization of the subgingival area by B. gingivalis is its attachment to host cells and Gram-positive bacteria in pre-formed plaque. The level of B. gingivalis is partly governed by products of other plaque bacteria, especially by sanguicin. Once B. gingivalis resides in its nidus and starts to proliferate, expulsion of pre-existing residents may occur, especially of attached Gram-positive bacteria, through the inhibitory action of the B. gingivalis product, hematin. The bacteriocin produced by black-pigmented Bacteroides also seems to play an important role in their establishment. Melaninogenicus possessed strong inhibitory activity against Actinomyces species. This was not completely confirmed with fresh isolates of B. gingivalis from advanced periodontitis patients. Various factors other than inhibitory substances produced by B. gingivalis and related bacteria can also affect the colonization of this species. Since the crevice area is influenced by gingival fluid, the nature of specific antibody and the other affecting components should be considered collectively with the interaction between new predominant colonizers and other pre-existing residents.

The effect of supragingival plaque removal on anaerobic bacteria deep periodontal pockets

A study was made to determine if the numbers of subgingival anaerobes in deep periodontal pockets can be controlled by removal of only supragingival plaque. The study was based on the premises that the subgingival flora is dependent on the supragingival plaque for its source of organisms as well as for its perpetuation. Daily professional removal of only supragingival plaque produced a statistically significant reduction per sample in subgingival facultative and obligatory anaerobes.

[Proportion and frequency of 3 kinds of anaerobic bacteria in relation to the gingival index]

The proportion and frequency of three groups of particular bacteria (Bacteroides, Fusobacterium and spirochetes) were studied in relation to the gingival index on the sites from which they were sampled. Seventy eight samples collected from 40 individuals were studied together with measurements of the gingival index and the pocket or sulcus depth. The samples were dispersed by ultrasonic treatment, diluted and cultured on a non-selective medium. The identification of the species was done by biochemical tests and by analysis of the metabolic products with gas chromatography. As a whole, our results support the hypothesis of an important change in the microbial flora from a clinical healthy status (with predominant Gram positive facultative anaerobic bacteria) to disease (with predominant Gram negative strict anaerobic bacteria). Furthermore the results suggest that Bacteroides gingvalis as well as Fusobacterium nucleatum and spirochetes through their high frequency and important proportion at the affected sites played an etiological role in the pathogenesis of gingivitis and periodontis Man.

Characterization of rat cecum cellulolytic bacteria

Cellulose-degrading bacteria previously isolated from the ceca of rats have been characterized and identified. The most commonly isolated type was rods identified as Bacteroides succinogenes. These bacteria fermented only cellulose (e.g., pebble-milled Whatman no. 1 filter paper), cellobiose, and in 43 of 47 strains, glucose, with succinic and acetic acids as the major products. The only organic growth factors found to be required by selected strains were p-aminobenzoic acid, cyanocobalamine, thiamine, and a straight-chain and a branched-chain volatile fatty acid. These vitamin requirements differ from those of rumen strains of B. succinogenes, indicating the rat strains may form a distinct subgroup within the species. The mole percent guanine plus cytosine was 45%, a value lower than those (48 to 51%) found for three rumen strains of B. succinogenes included in this study. Cellulolytic cocci were isolated less frequently than the rods and were identified as Rumminococcus flavefaciens. Most strains fermented only cellulose and cellobiose, and their major fermentation products were also succinic and acetic acids. Their required growth factors were not identified but were supplied by rumen fluid.

Effect of long generation times on growth of Bacteroides thetaiotaomicron in carbohydrate-induced continuous culture

We investigated the ability of Bacteroides thetaiotaomicron, an obligate anaerobe from human colonic microflora, to grow in a carbohydrate-limited continuous culture at generation times ranging from 3.5 to 28 h per division. Four carbohydrates were tested: glucose, N-acetylglucosamine, glucuronic acid, and glucosamine. At a generation time of 3.5 h per division, the growth yields for bacteria growing on glucose, N-acetylglucosamine, and glucuronic acid were 76, 68, and 50 g of cells (dry weight) per mol of substrate, respectively. Growth yields at 28 h per division were 61, 52, and 37 g/mol of substrate, respectively. When glucosamine was the carbohydrate source, a stable population of bacteria was attainable only at generation times longer than 12 h per division. Growth yields at 15 and 32 h per division were 11 and 33 g/mol of substrate, respectively. There was no significant variation with increasing generation times in the specific activities of selected glycolytic enzymes, of disaccharidases such as alpha- and beta-glucosidases and alpha- and beta-galactosidases, or of the polysaccharidase chondroitin sulfate lyase. By contrast, the pattern of fermentation products varied with both the generation time and the carbon source. At a generation time of 3.5 h per division, the main products from the fermentation of glucose were acetate and succinate, with a trace of propionate. At 28 h per division, propionate concentrations were higher and succinate concentrations were lower than at 3.5 h per division. The products from the fermentation of glucosamine were the same as those from glucose fermentation. However, when N-acetylglucosamine was fermented, the concentration of acetate was much higher at all generation times than when glucose was the carbon source. When glucuronic acid was the carbon source, acetate was the main fermentation product, and only traces of propionate and succinate were detected. Another characteristic that varied with the growth rate was the ability of B. thetaiotaomicron to produce the inducible enzyme alpha-glucosidase when exposed to maltose. The ability of the organism to produce this enzyme declined with increasing generation times.

Characteristics of Bacteroides asaccharolyticus from dental plaques of beagle dogs

Gram-negative, non-saccharolytic, brown- or black-pigment-forming, nonmotile anaerboic coccobacilli, capable of decomposing hydrogen peroxide and identified as Bacteroides asaccharolyticus (B. melaninogenicus subsp. asaccharolyticus), were isolated from the supra- and subgingival plaques of beagle dogs with gingivitis or periodontitis. The organisms remained viable for many hours in an aerobic atmosphere as evidenced by their ability to grow subsequently in an anaerobic environment. They also grew well on agar media that were not reduced before use. Although blood was required for pigmentation of colonies, organisms grew on media that lacked hemin, menadione, blood, or reducing compounds. Increased oxygen tolerance, catalase activity, and different nutritional requirements differentiate these organisms from strains of B. asaccharolyticus isolated from humans.

The isolation and identification of Bacteroides ssp. from the normal human vaginal flora

The occurrence of gram-negative anaerobic bacilli in the normal vaginal flora was studied in 20 normal healthy women attending a family-planning clinic. A swab was taken from the cervix and posterior fornix and Bacteroides spp. were isolated on a selective medium from 13 (65%) subjects. A heavy growth of Bacteroides was obtained from 11 specimens but only a few colonies were isolated from two specimens. Where possible, 10 representative colonies from each subject were studied and 113 isolates were identified by conventional bacteriological tests. Most isolates (78%) belonged to the B. melaninogenicus/oralis group. The commonest species identified in this group were the B. bivius/disiens complex (42%), B. melaninogenicus ss. intermedius (22%) and ss. melaninogenicus (16%). Asaccharolytic strains were isolated in smaller numbers from 54% of subjects, but only five strains of the B. fragilis group were isolated from two subjects; fusobacteria were not detected.

The isolation and identification of Bacteroides spp. from the normal human gingival flora

Gram-negative anaerobic bacilli were isolated on an enriched selective medium from specimens of subgingival plaque from 20 normal, healthy adults without periodontal disease. a heavy growth of Bacteroides and Fusobacterium spp. was obtained from all specimens and 10 representative colonies from each subject were selected for identification by conventional bacteriological methods. Results were obtained in these tests with 188 isolates; some strains of the B. melaninogenicus/oralis group would not grow in pure culture on solid media and showed satellitism in mixed culture, and some strains of fusobacteria did not survive repeated subculture. Most isolates (68%) belonged to the B. melaninogenicus/oralis group. The commonest species identified in this group were B. oralis (41%), B. melaninogenicus ss. melaninogenicus (26%) and ss. intermedius (17%). B. oralis was isolated from all subjects and at least one strain of B. melaninogenicus was isolated from 18 out of 20 subjects. Only eight strains of the B. fragilis group were detected and they probably represented transient carriage. Fusobacterium spp. and L. buccalis were isolated from 15 out of 20 subjects and accounted for 21% of the isolates studied, but most could not be identified specifically by the set of tests used. Asaccharolytic species of Bacteroides were isolated in small numbers from seven subjects.

Deep fasciitis of the biceps region

An infection of the biceps fascia, later myositis, and spreading to the pectoralis is described in six patients. The majority were synergistic infections with an anaerobic Peptococcus, Eikenella, or Bacteroides and an aerobic Streptococcus. Five of the patients were drug abusers. Excision of the biceps and portions of the pectoralis major was necessary in four patients.

Colonial variation, capsule formation, and bacteriophage resistance in Bacteroides thetaiotaomicron

A Bacteroides thetaiotaomicron strain segregated two unstable colonial variants at high frequency. There is a correlation between colony morphology, encapsulation, Giemsa staining, and bacteriophage resistance.

Purification and immunochemical characterization of the outer membrane complex of Bacteroides melaninogenicus subspecies asaccharolyticus

Morphologic study of Bacteroides melaninogenicus subspecies asaccharolyticus by electron microscopy disclosed the presence of a capsule and a cell wall structure otherwise typical of a gram-negative organism. An outer membrane complex was isolated with use of gentle methods. Relative purity of the preparation was confirmed by electron microscopy and by the formation of a single band in a sucrose density gradient. Gel chromatography was used for separation of the major components of the membrane. Antigenicity of the first component, a protein-polysaccharide complex, which cross-reacted with antiserum to another strain of the same subspecies. This component probably represents the capsular antigen and may prove to be the basis for serogrouping. The second membrane fraction differed chemically from the first fraction and represents the lipopolysaccharide component of the outer membrane. Notably, this component lacks 2-keto-3-deoxyoctonate, one of the backbone sugars of aerobic, gram-negative lipopolysaccharides.

Cell envelope morphology of rumen bacteria

The cell walls of three species of rumen bacteria (Bacteroides ruminicola, Bacteroides succinogenes, and Megasphaera elsdenii) were studied by a variety of morphological methods. Although all the cells studied were gram-negative and had typical cytoplasmic membranes and outer membranes, great variation was observed in the thickness of their peptidoglycan layers. Megasphaera elsdenii evidenced a phenomenally thick peptidoglycan layer whose participation in septum formation was very clearly seen. All species studied have cell wall "coats" external to the outer membrane. The coat of Bacteroides ruminicola is composed of large (approximately 20 nm) globules that resemble the protein coats of other organisms, whereas the coat of Bacteroides succinogenes is a thin and irregular carbohydrate coat structure. Megasphaera elsdenii displays a very thick fibrillar carbohydrate coat that varies in thickness with the age of the cells. Because of the universality of extracellular coats among rumen bacteria we conclude that the production of these structures is a protective adaptation to life in this particular, highly competitive, environment.

Spheroplast formation by an anaerobic gram-negative bacterium Bacteroides ruminicola

The spontaneous formation of spheroplasts was observed in stationary phase cultures and in aging cultures of Bacteroides ruminicola when grown in synthetic or a rumen fluid medium. Unlike most other gram-negative bacteria, spheroplasts of this organism also were formed when log-phase cells were treated with lysozyme in the presence of 0.01 M Mg2+ in 0.01 M Tris, pH 8.4.