The human gut bacteria Bacteroides thetaiotaomicron and Fusobacterium varium produce putrescine and spermidine in cecum of pectin-fed gnotobiotic rats. (9/297)

Pectin is a soluble indigestible polysaccharide that stimulates cecal polyamine formation in rats. Bacteroides and fusobacteria, two numerically dominant bacterial population groups in the large intestine, were found to synthesize in vitro high amounts of spermidine and putrescine. The purpose of this study was to elucidate the effect of pectin on the polyamine production by defined bacterial species in vivo. Germfree male Wistar rats (n = 18) were randomly assigned to one of three treatments: (i) monoassociation with Bacteroides thetaiotaomicron + fiber-free diet; (ii) diassociation with B. thetaiotaomicron + Fusobacterium varium + fiber-free diet or (iii) diassociation with B. thetaiotaomicron + F. varium + fiber-free diet + 10% pectin. The cecal contents of monoassociated rats fed fiber-free diet contained large amounts (1.51+/-0.21 micromol/dry total cecum content) of spermidine which was the major polyamine. The cecum of diassociated rats fed the fiber-free diet contained even higher concentrations of spermidine (2.53+/-0.21 micromol/dry total cecum content) and also putrescine, which was now the dominant polyamine (putrescine 0.32+/-0.28 vs. 3.01+/-0.28 micromol/dry total cecum content; monoassociation vs. diassociation). Pectin consumption by diassociated rats led to an additional increase in the cecal concentrations of all polyamines: putrescine, spermidine and spermine were 40, 37 and 100%, respectively, higher in the diassociated rats consuming the pectin diet than in those consuming the pectin-free diet. Since the microbial counts in the cecum did not differ in the diassociated treatment groups, the elevated concentrations of polyamines observed in the pectin group must have been due to stimulated bacterial polyamine synthesis. The decline of individual polyamines from cecum to feces detected at the end of the study in all treatment groups and the high microbial counts in the cecum and in feces suggest that bacterial polyamines are absorbed in cecum and colon. Pectin stimulates intestinal microbes to synthesize large amounts of polyamines which may be utilized by the host.  (+info)

Review of the in vitro activity of gemifloxacin against gram-positive and gram-negative anaerobic pathogens. (10/297)

Published reports on the in vitro activity of gemifloxacin mesylate (SB 265805), a new fluoronaphthyridone, against anaerobic pathogens are reviewed here. The studies used a variety of media, inocula and antimicrobial agents. Using a proposed breakpoint of 0.5 mg/L, these studies showed that gemifloxacin had generally higher potency against Gram-positive anaerobes (Clostridium perfringens, all Peptostreptococcus spp.) and fusobacteria (Fusobacterium nucleatum, Fusobacterium necrophorum) and moderate but variable potency against Gram-negative anaerobes. Bacteroides stercoris, Bacteroides tectum and many Bacteroides fragilis isolates were inhibited by concentrations of < or =0.5 mg/L, while the other species of the B. fragilis group required higher concentrations for inhibition. Species variability was evident: Porphyromonas asaccharolytica, Porphyromonas canoris, Porphyromonas gingivalis, Porphyromonas macaccae, Prevotella heparinolytica and Prevotella intermedia were susceptible to 0.5 mg/L of gemifloxacin while most other Porphyromonas and Prevotella spp. were not. These data suggest that gemifloxacin may have a clinical role in the treatment of certain dental, head and neck and pleuropulmonary infections in which Gram-positive anaerobes, fusobacteria and some Prevotella and Porphyromonas spp. may predominate.  (+info)

The Fusobacterium nucleatum porin FomA possesses the general topology of the non-specific porins. (11/297)

FomA is a major non-specific porin of Fusobacterium nucleatum with no sequence similarity to other known porins. According to the topology model, the protein consists of 16 transmembrane beta-strands, connected by eight surface-exposed loops and seven periplasmic turns. In this study, the insertion mutagenesis approach was applied to probe the topology model. A Semliki Forest Virus (SFV) epitope was successfully inserted at 11 different sites of the FomA protein and a 6-aa insertion was successfully inserted at two different sites. Correct folding of the mutant proteins and proper incorporation into the outer membrane were assessed by heat modifiability and by an in vivo porin activity assay. Immunofluorescence microscopy analysis of intact cells, using mAbs directed against the inserted SFV epitope, revealed that three of the eight putative extracellular loops are indeed surface-exposed. Trypsin accessibility experiments confirmed the cell surface exposure of two additional loops. The results support the proposed topology model, showing that FomA possesses the general beta-barrel topology of the non-specific porins, with the interesting exception that the third loop does not seem to fulfil the role of a constriction loop.  (+info)

Treatment of anaerobic infections with metronidazole. (12/297)

The results of treatment of 10 patients with anaerobic infections with metronidazole are presented. Six patients were cured, three showed initial good response but circumstances required a change to another drug, and one patient did not respond. The unique spectrum of the drug, its pharmacology, and limitations are discussed. The results indicate that further clinical trials to determine the efficacy of metronidazole in the treatment of anerobic infections are indicated.  (+info)

Indirect fluorescent antibody procedure for the rapid detection and identification of Bacteroides and Fusobacterium in clinical specimens. (13/297)

An indirect fluorescent antibody (IFA) technique was evaluated as a procedure for rapid detection and identification of members of the Bacteroidaceae. Antisera were prepared against 31 members of this family, including species of Bacteroides and Fusobacterium commonly isolated from human infections. The antisera had demonstrated species and/or subspecies specificity. Thirty clinical specimens were studied. Of 13 specimens yielding Bacteroidaceae, for which antisera were available, 23 were presumptively diagnosed by IFA to contain subspecies of B. fragilis and/or Fusobacterium species. Of 17 specimens yielding negative culture results, two were positive by IFA on direct smear. Frequently the in vivo morphology of cells detected in direct smears by this procedure closely mimicked that of cellular debris, tissue cells, and leukocytes. Polyvalent antisera pools facilitated use of the IFA procedure as a practical tool for rapid diagnosis of infections involving the Bacteroidaceae.  (+info)

Anaerobic specimen transport device. (14/297)

A device is described and evaluated for the anaerobic transport of clinical specimens. The device limits the amount of oxygen entering with the sample to a maximum of 2%, which is rapidly removed by reacting with hydrogen in the presence of a palladium catalyst. The viability on swabs of 12 species of anaerobes, four strains of facultative anaerobes and a strain of Pseudomonas aeruginosa, was maintained during the length of the tests (24 or 48 h). The results demonstrated that this device protected even the more oxygen-sensitive clinical anaerobes from death due to oxygen exposure. This device can be used for swabs as well as for anaerobic collection and liquid and solid specimens.  (+info)

Characterization of endotoxin from Fusobacterium necrophorun. (15/297)

Endotoxic lipopolysachharide (LPS) was obtained from phenol-water extraction of cell walls prepared from mass-cultivated Fusobacterium necrophorum. The LPS was relatively free of nucleic acids and low in protein, and constituted about 4% of the cell walls. Upon acid hydrolysis, some of the components detected were hexosamines (7.0%), neutral and reducing sugars (50.5%), heptose (6.4%), 2-keto-3-deoxyoctonate (0.8%), lipid A (21.0%), and phosphorus (1.7%). Under electron microscopy the LPS appeared mainly as ribbon-like trilaminar structures, and upon chemical treatment it displayed a behavior resembling that reported in certain enterobacterial LPS. The LPS was lethal to mice, 11-day-old chicken embryos, and rabbits. Endotoxicity in mice was enhanced at least 1,380-fold by the addition of 12.5 mug of actinomycin D. Induced tolerance to lethal effect of the endotoxin and rapidly acquired resistance to infection by F. necrophrum viable cells were also demonstrated in mice. The endotoxin produced both localized and generalized Shwartzman reactions as well as biphasic pyrogenic responses in rabbits. These results firmly establish the presence of a classical endotoxin in F. necrophorum, thus providing strong support to our recent suggestion that cell wall-associated components may contribute significantly to the pathogenicity of F. necrophorum.  (+info)

Biological characterization of Fusobacterium necrophorum. Cell fractions in preparation for toxin and immunization studies. (16/297)

Fusobacterium necrophorum isolated from bovine liver abscesses was grown in bulk at 37 C for 24 h under a strict anaerobic atmosphere. Harvested washed cells were disrupted ultrasonically and fractionated by differential centrifugation into the intracellular (cytoplasm) and cell wall fractions. Both intact cells and cell fractions induced generalized cytopathic effect on primary pig kidney cultures and caused a variety of signs of illness and/or death of intraperitoneally injected mice. The intact cells, disrupted cells, and cell walls produced necrotic lesions and erythema on intradermally injected guinea pigs and rabbits, whereas the cytoplasm mainly erythema. By contrast, the used culture medium (culture filtrate) of F. necrophorum did not show any detectable toxicity. The toxic component of the cytoplasm appears to be associated with nondialyzable, hemolytic, high-molecular-weight proteins and its toxicity is reduced by trypsin and pronase. Heating at 60 C for 10 min decreased markedly its erythemal and cytotoxic ability, wheras the toxicity of the cell walls appeared to be only slightly affected even when heated at 100 C for 1 h. These results suggest that at leasttwo distinct cell-bound toxic factors are present in F. necrophorum cells.  (+info)