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PubMed1990

Hemoproteins of Bradyrhizobium japonicum Cultured Cells and Bacteroids.

The hemoprotein content of 17 strains of Bradyrhizobium japonicum bacteroids from field-grown plants and the corresponding strains of cultured cells was determined spectrally. The major terminal oxidases, cytochromes (cyt) aa(3) and o, were present in all strains of cultured cells. cyt aa(3) was present in significant amounts in bacteroids only in strains of DNA homology group II. cyt o appeared to be present in bacteroids of all strains, and the average level was the same as in cultured cells. cyt b and c in the membrane fractions were higher in bacteroids of all strains compared with cultured cells. cyt P-450 was present in both the membrane and soluble fractions of bacteroids of most strains. The total P-450 content varied sixfold among strains. A CO-reactive hemoprotein, P-422, was present in the soluble fraction of all strains of cultured cells. P-422 may be a hemoglobinlike protein, and it was present in significant amounts in bacteroids only in DNA homology group I strains.

Journal Article↗
PubMed1981

A rapid one-step method for the isolation of bacteroids from root nodules of soybean plants, utilizing self-generating Percoll gradients.

Bacteroids were isolated from the nodules of soybean plants by means of self-generating Percoll density gradients. The entire procedure can be performed in less than 1 h using an ordinary refrigerated centrifuge and angle head rotor. All of the markers for cytosol and bacteroid fractions behaved in accord with other reports in the literature. Asparaginase, beta-hydroxybutyrate dehydrogenase, and alanine dehydrogenase were all localized in the bacteroid fraction. Invertase, phosphoenolpyruvate carboxylase, and leghaemoglobin were all found in the cytosol fraction. Very little (less than 7%) cross contamination between the fractions was observed. The isolated bacteroids were viable, and based on electron micrographs, were free from contaminating plant material. Since the entire procedure is performed isosmotically, very little damage to the bacteroids is likely to occur. No organic compounds, except Percoll, were added to the isolating media, thus aiding in the analysis of bacteroid and cytosol metabolites.

Alanine Dehydrogenase↗
PubMed1989

[Utilization of nitrate by bacteroids and cytosol of nodules formed by Rhizobium leguminosarum].

Nitrite production by nodules and roots of pea plants (Pisum sativum L., cultivar Alaska) inoculated with Rhizobium leguminosarum strain 3855 has been studied. Nitrate reductase (NR) activity and nitrite reductase (NiR) activity of the bacteroidal and cytosolic fractions of the nodules were also determined, as well as the nitrite content of the nodules cytosol. Nitrite production by nodules and roots from plants treated with 5 mM KNO3 was higher than that of nodules and roots from plants not treated with nitrate, and regardless of the nitrate treatment, nitrite production increased with the incubation period. The presence of nitrate, propanol or both compounds in the incubation mixtures significantly increased the nitrite production by nodules and roots. Nitrite reductase activity was detected in fresh by isolated bacteroids of R. leguminosarum strain 3855, although the presence of nitrate reductase activity could not be detected both in bacteroids of nodules isolated from plants treated or not with 5 mM KNO3. After isolation, when bacteroids were incubated in a mixture with nitrate, nitrate reductase activity developed after incubation for 12 h. Consequently, there was an increase in nitrite reductase activity, which resulted in the disappearance of the nitrite previously accumulated in the incubation medium. Nitrate utilization by bacteroids was not detected until 5 h from the beginning of the incubation period. Since the presence of chloramphenicol or rifampicin in the incubation medium prevented the development of the nitrate reductase activity, such activity was induced in bacteroids. Nitrite content and nitrate reductase and nitrite reductase activities of the cytosol from nodules of pea plants treated or not with 5 mM KNO3 varied with the buffer used for nodules homogenization. However, no nitrite was found when nodules were homogenized with ethanol, what indicates that nitrite accumulation in the cytosol occurs during the homogenization process of the nodules.

Bacterial Proteins↗
PubMed1992

Encapsulation and pilus formation of Bacteroides spp. in normal flora abscesses and blood.

The presence of encapsulated and piliated Bacteroides spp. (mostly Bacteroides fragilis and melaninogenicus groups was investigated in isolates from blood, abscesses and normal flora. Of the strains of Bacteroides spp. isolated 45 of 54 (83%) recovered from blood and 31 of 40 (78%) found in abscesses were encapsulated. In contrast, only seven of 71 (10%) similar strains isolated from the faeces or pharynx of healthy persons were encapsulated (P < 0.001). Pili were observed in three of 54 (6%) of strains isolated from blood, 30 of 40 (75%) of those recovered from abscesses (P < 0.001), and 49 of 71 (69%) of those found in normal flora (P < 0.001). The predominance of encapsulated forms in all strains of B. fragilis and B. melaninogenicus in blood as well as in abscesses suggests an increased virulence of these compared with non-encapsulated isolates. In contrast, the presence of pili in Bacteroides spp. recovered mostly from abscesses and normal flora suggests that this structure may play a role in the ability of these organisms to adhere to mucous membranes and may interfere with their ability to spread systemically. These findings illustrate the morphological differences that may be observed in Bacteroides spp. from various anatomical sites.

Abscess↗
PubMed1979

Rapid diagnosis of Bacteroides infections by indirect immunofluorescence assay of clinical specimens.

43 specimens from a variety of sites were directly examined by indirect immunofluorescence assay (I.F.A.) with specific antisera against the capsular polysaccharide of Bacteroides fragilis and pooled antisera against a number of serotypes of Bacteroides sp. (all of the former B. fragilis subspecies). The findings were compared with those of routine anaerobic bacteriology and gas liquid chromatography for short chain fatty acids. Examination by I.F.A. was a sensitive (100%) and specific (90.3%) means of identifying B. fragilis. Use of the pooled serum was sensitive (100%) but less specific (64.3%) than the capsular antiserum (90.3%) although it had the advantage of detecting Bacteroides species other than B. fragilis. The capsular serum I.F.A. gave 9.7% false positives and no false negatives. The predictive value of a positive identification of B. fragilis in a clinical specimen using this anticapsular serum I.F.A. test was 80%; with the pooled Bacteroides group-serum it was 60%. The predictive value of a negative test was 100% for both sera, indicating that a negative I.F.A. test is a reliable index of the absence of Bacteroides from the culture I.F.A. of clinical material provides a rapid (less than 2 h) specific and sensitive means for the diagnosis of B. fragilis infections and would be of use in a clinical laboratory.

Abdomen↗
PubMed2000

Antimicrobial resistance and clinical outcome of Bacteroides bacteremia: findings of a multicenter prospective observational trial.

There is debate regarding the correlation between in vitro susceptibility testing and clinical response to therapy for Bacteroides bacteremia. We conducted a prospective multicenter observational study of 128 patients with bacteroides bacteremia. Outcome was correlated with results of in vitro susceptibility testing of Bacteroides isolates recovered from blood and/or nonblood sites, determined with use of 3 end points: mortality at 30 days, clinical response (cure vs. failure), and microbiological response (eradication vs. persistence). The mortality rate among patients who received inactive therapy (45%) was higher than among patients who received active therapy (16%; P=.04). Clinical failure (82%) and microbiological persistence (42%) were higher for patients who received inactive therapy than for patients who received active therapy (22% and 12%, respectively; P=.0002 and.06, respectively). In vitro activity of agents directed at Bacteroides species reliably predicts outcome: the specificity was 97%, and positive predictive value was 82%. Antimicrobial susceptibility testing may be indicated for patients whose blood specimens yield Bacteroides species.

Adolescent↗
PubMed1984

Synergistic effect of bacteroides, Clostridium, Fusobacterium, anaerobic cocci, and aerobic bacteria on mortality and induction of subcutaneous abscesses in mice.

The potential for synergy between aerobic, facultative, and anaerobic bacteria was studied by subcutaneous inoculation of mixtures of these organisms into mice and observation of subsequent mortality and abscess formation. The anaerobic bacteria tested included 12 strains of gram-positive cocci and two strains each of Bacteroides species, Clostridium species, and Fusobacterium species. The facultative and aerobic bacteria included one strain each of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. Mortality increased significantly when each aerobic organism was inoculated along with either of the Bacteroides species. A similar increase occurred when the anaerobic gram-positive cocci were inoculated along with P. aeruginosa (four of six combinations) or S. aureus (four of six). The rate of abscess induction increased significantly when 10 of the 12 strains of anaerobic gram-positive cocci were injected along with B. fragilis and when nine of these strains were inoculated along with Bacteroides asaccharolyticus . The results demonstrate synergistic potential between Bacteroides species and all aerobic bacteria tested, between Bacteroides species and most anaerobic gram-positive cocci, and between most anaerobic gram-positive cocci and P. aeruginosa or S. aureus.

Abscess↗
PubMed1995

Bacteroides infections in children.

From 1974 to 1990, 336 Bacteroides isolates were obtained from 312 specimens from 274 patients. They comprised 180 (54%) B. fragilis isolates, 55 (16%) B. theta-iotaomicron, 36 (11%) B. vulgatus, 34 (10%) B. distasonis, 21 (6%) B. ovatus and 10 (3%) B. uniformis. Infections in 253 (92%) patients were polymicrobial, but in 21 (8%) children, a Bacteroides sp. was isolated in pure culture. Most Bacteroides isolates were from peritoneal fluid (114), abscesses (110), wound infections (20), blood cultures (10) and from patients with pneumonia (14) or chronic otitis media (8). Predisposing conditions were present in 145 (53%) children; these were previous surgery (46), trauma (28), malignancy (21), prematurity (19), immunodeficiency (18), steroid therapy (12) foreign body (10), diabetes (9) and sickle cell disease (7). The micro-organisms isolated most commonly mixed with Bacteroides spp. were anaerobic cocci (221), Escherichia coli (122), Fusobacterium spp. (38) and Clostridium spp. (30). All patients received antimicrobial therapy in conjunction with surgical drainage or correction of pathology in 197 (72%) cases. All but 12 (5%) patients recovered. These data illustrate the importance of Bacteroides spp. in infections in children.

Abscess↗
PubMed1987

Evaluation of a fluorescent antibody technique for the rapid enumeration of Bacteroides fragilis group of organisms in water.

The Bacteroides fragilis group has been evaluated as a prospective rapid indicator of faecal contamination of water. Fluorescent antibody (FA) stained B. fragilis group bacteria were enumerated microscopically and compared with faecal coliform or Escherichia coli counts as indicators of faecal contamination. Environmental samples included surface waters (raw drinking water and known contaminated water). Laboratory disinfection experiments with ozone, chlorine and u.v. radiation were also performed. Bacteroides FA counts specifically detected recent human faecal contamination in field samples in 2-3 h. Samples with a high content of particulates or debris limited the sensitivity to about 10 FA counts/ml. Viable counts showed that the sensitivity to all three disinfection agents was essentially the same for Bacteroides and E. coli. Fluorescent antibody counts of Bacteroides, conversely, were not altered by any of the agents. Therefore, the Bacteroides FA method is not recommended for routine monitoring but may be useful for cases where extensive human faecal contamination is suspected (e.g. pipeline rupture or pollution of recreational water) and where rapid remedial action must be taken to protect the public health.

Bacteroides↗
PubMed1992

Survey of Bacteroides fragilis group susceptibility patterns in Canada.

The in vitro activities of penicillin, clindamycin, chloramphenicol, metronidazole, piperacillin, piperacillin-tazobactam, ticarcillin, ticarcillin-clavulanate, ampicillin-sulbactam, cefoxitin, ceftizoxime, cefotetan, moxalactam, and imipenem against 348 Bacteroides fragilis group isolates collected from six Canadian cities during 1990 were determined by the National Committee for Clinical Laboratory Standards (NCCLS) agar dilution technique. All isolates were susceptible to chloramphenicol, metronidazole, piperacillin-tazobactam, and imipenem. For the other antibiotics tested, the following resistance rates were observed: penicillin, 97%; clindamycin, 9%; piperacillin, 19%; ticarcillin, 31%; ticarcillin-clavulanate, 0.28%; ampicillin-sulbactam, 0.85%; cefoxitin, 26%; ceftizoxime, 15%; cefotetan, 53%; and moxalactam, 17%. Susceptibility profiles to beta-lactam antibiotics varied among the different species tested: B. fragilis and Bacteroides vulgatus demonstrated lower resistance rates than Bacteroides distasonis and indole-positive Bacteroides thetaiotaomicron and Bacteroides ovatus. Ceftizoxime results should be interpreted cautiously, because the MICs obtained with the recommended NCCLS control strain were lower than expected.

Anti-Bacterial Agents↗
PubMed1980

Opsonization of four Bacteroides species: role of the classical complement pathway and immunoglobulin.

Previous investigators have suggested that opsonization of two Bacteroides species is mediated exclusively by the alternative complement pathway and requires immunoglobulins. In this study, the nature of the opsonic factors in nonimmune human serum for four species of Bacteroides was investigated by measuring uptake of [(3)H]thymidine-labeled bacteria by human polymorphonuclear leukocytes. Normal human serum, C2-deficient serum, immunoglobulin-deficient serum, and serum chelated with ethylene glycol-bis(beta-aminoethyl ether)-N,N-tetraacetic acid (EGTA), MgEGTA, and ethylenediaminetetraacetic acid (EDTA) were used as opsonic sources. Heat inactivation of each of these sera significantly reduced its opsonic activity for all four Bacteroides species, suggesting that serum complement was essential for effective opsonization. All strains were opsonized in the absence of the classical complement pathway; however, kinetics studies revealed that opsonization proceeded at a significantly faster rate when the classical complement pathway was intact. Although two strains were opsonized in immunoglobulin-deficient sera, opsonization was less efficient and appeared to occur via the alternative complement pathway. Unexpectedly, all strains were well opsonized by the classical complement pathway in 10% serum which had been effectively chelated with EGTA or EDTA. The explanation for this finding is unknown; however, it is possible that cell wall cations of Bacteroides species may participate in the activation of complement in chelated serum, resulting in effective opsonization. It was also found that Bacteroides, when incubated with an Escherichia coli strain in normal serum, could compete for opsonins and thereby reduce phagocytosis of E. coli. It is possible that competition for opsonins among bacterial species contributes to the synergistic role these organisms share in mixed floral infections.

Bacteroides↗
PubMed2005

"Bacteroides goldsteinii sp. nov." isolated from clinical specimens of human intestinal origin.

Phenotypic and phylogenetic studies were performed on an unknown gram-negative, strictly anaerobic, rod-shaped bacterium isolated from human clinical specimens. This organism was indole negative, resistant to 20% bile, produced acetic and a lesser amount of succinic acids as the major end products of glucose metabolism, and possessed a G+C content of approximately 43 mol%. Comparative 16S rRNA gene sequencing demonstrated that the unidentified bacterium was a member of the Cytophaga-Flavobacter-Bacteroides phylum of gram-negative bacteria and formed a close association (with an average sequence similarity of 93.6%) with the second subcluster of the Porphyromonas cluster in the Bacteroides subgroup. Phylogenetically and phenotypically it resembled Bacteroides merdae; however, a 16S rRNA gene sequence divergence of approximately 5.5% between the unknown bacterium and B. merdae, as well as distinguishable biochemical characteristics, demonstrate that the unknown bacterium is genotypically and phenotypically distinct and represents a previously unknown subline within the Porphyromonas phylogenetic cluster. Furthermore, a DNA-DNA reassociation value of 17.8% between isolates WAL 12034(T) (the type strain of this novel taxon) and ATCC 43184(T) (B. merdae type strain) also documented the separateness of the unknown species and B. merdae. Based on the phenotypic and phylogenetic findings, a new species, "Bacteroides goldsteinii sp. nov," is proposed. The G+C content of the DNA is 43 mol% for Bacteroides. The type strain of "B. goldsteinii" is WAL 12034(T) (= CCUG 48944(T) = ATCC BAA-1180(T)).

Bacterial Typing Techniques↗
PubMed2023

Bacteroides ovatus alleviates dysbiotic microbiota-induced intestinal graft-versus-host disease.

Acute gastrointestinal intestinal GVHD (aGI-GVHD) is a serious complication of allogeneic hematopoietic stem cell transplantation, and the intestinal microbiota is known to impact on its severity. However, an association between treatment response of aGI-GVHD and the intestinal microbiota has not been well-studied. In a cohort of patients with aGI-GVHD (n=37), we found that non-response to standard therapy with corticosteroids was associated with prior treatment with carbapenem antibiotics and loss of Bacteroides ovatus from the microbiome. In a mouse model of carbapenem-aggravated GVHD, introducing Bacteroides ovatus reduced severity of GVHD and improved survival. Bacteroides ovatus reduced degradation of colonic mucus by another intestinal commensal, Bacteroides thetaiotaomicron, via its ability to metabolize dietary polysaccharides into monosaccharides, which then inhibit mucus degradation by Bacteroides thetaiotaomicron and reduce GVHD-related mortality.

Bacteroides ovatus↗
PubMed1975

[Bacteroides and appendicitis (author's transl)].

Bacteroides fragilis is frequently recovered from cases of appendicitis with perforation and from infections developing secondary to appendicitis. In order to assess the part played by B. fragilis in the aetiology of appendicitis, quantitative aerobic and anaerobic culture studies of the contents of 49 inflammated appendices were performed. Anaerobic gram-negative non-sporing rods were cultivated from 43 appendices in the range 10(3)-10(9)/g. A total of 1,473 isolates was differentiated by biochemical methods, and 1,374 cultures were found to belong to the saccharolytic species of the genus Bacteroides (B. fragilis, B. thetaiotaomicron, B. vulgatus, B. distasonis etc.). B fragilis was detected in 31 appendices; the species predominated in 18 samples. B theraiotamicron, recovered from 27 samples, was prevalent in 4 appendices. In one sample, B. fragilis and B. thetaiotaomicron outnumbered the other appendicular bacterial. B. vulgatus was cultivated from 12 appendices, but did once constitute the prevalent group. It has been previously shown that B. vulgatus (43% of intestinal isolates) and B. thetaiomicron predominate in the normal narge bowel flora. On the other hand, approximately 80% of pyrogenic Bacteroides strains belong to B. fragilis, B. thetaiotaomicron accounting for 19% and B. vulgatus being virtually absent. From these striking differences in species distribution the conclusion was drawn that B. fragilis possesses the highest virulence for man. Species distribution within the 1,374 appendicular isolates of saccharolytic Bacteroides (percentages of 62, 19 and 4.3 for B. fragilis, B. thetaiotaomicron, and B. vulgatus, respectively) was very similar to that encountered in clinical specimens. From the results obtained it becomes evident that pyrogenic Bacteroides, in particular B. fragilis, plays an important role in nearly 50% of cases of appendicitis.

Adolescent↗
PubMed1980

[In vitro activity of the oxa-beta-lactam LY 127935 against Bacteroides fragilis and other anaerobic gram-negative rods (author's transl)].

The susceptibility of 115 Bacteroidaceae strains to LY 127935 was determined by broth dilution, agar dilution and agar diffusion tests. Simultaneously, the strains were tested for degradation of the oxa-beta-lactam. Only five strains (3 Bacteroides fragilis and 3 Bacteroides oralis/Bacteroides bivius) partially degraded LY 127935. No major discrepancies between the results of the agar dilution and broth dilution tests were observed. According to the results obtained by the agar dilution method, 50 strains of B. fragilus were inhibited by concentrations of less than or equal to 8 microgram oxa-beta-lactam per ml. Members of the Bacteroides melaninogenicus group of organisms had agar dilution MICs of less than or equal to 0.5 microgram LY 127935 per ml and Fusobacterium/Sphaerophorus species were inhibited by less than or equal to 64 microgram/ml. Strains of Bacteroides thetaiotaomicron, B. oralis/B. bivius and Bacteroides spp. were less susceptible. Due to the narrow range of MICs observed with B. fragilis strains, no regression line could be computed for the relationship between MIC and zone size.

Bacteroides↗
PubMed1984

Expression in Escherichia coli of cryptic tetracycline resistance genes from bacteroides R plasmids.

The putative clindamycin resistance region of the Bacteroides fragilis R plasmid pBF4 was cloned in the vector R300B in Escherichia coli. This 3.8-kb EcoRI D fragment from pBF4 expressed noninducible tetracycline resistance in E. coli under aerobic but not anaerobic growth conditions. The fragment does not express tetracycline resistance in Bacteroides, a strict anaerobe. The separate tetracycline resistance transfer system in the Bacteroides host strain V479-1 has no homology to the cryptic determinant on pBF4. In addition, this aerobic tetracycline resistance determinant is not homologous to the three major plasmid mediated tetracycline resistance regions found in facultative gram-negative bacteria, represented by R100, RK2, and pBR322. A similar cryptic tetracycline resistance fragment was cloned from pCP1, a separate clindamycin resistance plasmid from Bacteroides that shares homology with the EcoRI D fragment of pBF4. This study identifies cryptic drug resistance determinants in Bacteroides that are expressed when inserted into an aerobically growing organism.

Aerobiosis↗
PubMed1992

Heterologous gene expression in Bacteroides fragilis.

Bacteroides fragilis and other gastrointestinal tract Bacteroides are unusual gram-negative eubacteria in that genes from other gram-negative eubacteria are not expressed when introduced into these organisms. To analyze gene expression in Bacteroides, expression vector and promoter probe (detection) vector systems were developed. The essential feature of the expression vector was the incorporation of a Bacteroides insertion sequence element, IS4351, which possesses promoter activity directed outward from its ends. Genes inserted into the multiple cloning site downstream from an IS4351 DNA fragment were readily expressed in B. fragilis. The chloramphenicol acetyltransferase (cat) structural gene from Tn9 was tested and conferred chloramphenicol resistance on B. fragilis. Both chloramphenicol resistance and CAT activity were shown to be dependent on the IS4351 promoters. Similar results were obtained with the Escherichia coli beta-glucuronidase gene (uidA) but activity was just 30% of the levels seen with cat. Two tetracycline resistance determinants, tetM from Streptococcus agalactiae and tetC from E. coli, also were examined. tetC did not result in detectable tetracycline resistance but the gram-positive tetM gene conferred high-level resistance to tetracycline and minocycline in Bacteroides hosts. Based on the cat results, promoter probe vectors containing the promoterless cat gene were constructed. These vectors were used to clone random B. fragilis promoters from partial genomic libraries and the recombinants displayed a range of CAT activities and chloramphenicol MICs in B. fragilis hosts. In addition, known E. coli promoters (Ptet, Ptac, Ptrc, Psyn, and P1P2rrnB) were tested for activity in B. fragilis. No chloramphenicol resistance or CAT activity was observed in B. fragilis with these promoters.

Bacteroides fragilis↗