Porphyromonas gingivalis heat shock protein vaccine reduces the alveolar bone loss induced by multiple periodontopathogenic bacteria

OBJECTIVES

Heat shock protein (HSP) can be utilized as a vaccine to cross-protect against multiple pathogenic species. The present study was performed to evaluate Porphyromonas gingivalis heat shock protein 60 (HSP60) as a vaccine candidate to inhibit multiple bacteria-induced alveolar bone loss.

MATERIAL AND METHODS

Recombinant P. gingivalis HSP60 was produced and purified from P. gingivalis GroEL gene. Rats were immunized with P. gingivalis HSP60, and experimental alveolar bone loss was induced by infection with multiple periodontopathogenic bacteria.

RESULTS

There was a very strong inverse relationship between postimmune anti-P. gingivalis HSP immunoglobulin G (IgG) levels and the amount of alveolar bone loss induced by either P. gingivalis or multiple bacterial infection (p=0.007). Polymerase chain reaction data indicated that the vaccine successfully eradicated the multiple pathogenic species.

CONCLUSIONS

We concluded that P. gingivalis HSP60 could potentially be developed as a vaccine to inhibit periodontal disease induced by multiple pathogenic bacteria.

Zwitterionic polysaccharides stimulate T cells with no preferential V beta usage and promote anergy, resulting in protection against experimental abscess formation

Zwitterionic polysaccharides (Zps) from pathogenic bacteria, such as Bacteroides fragilis, are virulence factors responsible for abscess formation associated with intra-abdominal sepsis. The underlying cellular mechanism for abscess formation requires T cell activation. Conversely, abscess formation can be prevented by prophylactic s.c. injection of purified Zps alone, a process also dependent on T cells. Hence, the modulatory role of T cells in abscess formation was investigated. We show that Zps interact directly with T cells with fast association/dissociation kinetics. Vbeta repertoire analysis using RT-PCR demonstrates that Zps have broad Vbeta usage. Zps-specific hybridomas responded to a variety of other Zps, but not to a nonzwitterionic polysaccharide, indicating cross-reactivity between different Zps. Furthermore, Zps-reactive T cell hybridomas could effectively transfer protection against abscess formation. Analysis of the proliferative capacity of T cells recovered from Zps-treated animals revealed that these T cells are anergic to subsequent stimulation by the different Zps or to alloantigens in an MLR. This anergic response was relieved by addition of IL-2. Taken together, the data show that this class of polysaccharides interacts directly with T cells in a nonbiased manner to elicit an IL-2-dependent anergic response that confers protection against abscess formation.

CD4+ T cells mediate abscess formation in intra-abdominal sepsis by an IL-17-dependent mechanism

Abscess formation associated with intra-abdominal sepsis causes severe morbidity and can be fatal. Previous studies have implicated T cells in the pathogenesis of abscess formation, and we have recently shown that CD4(+) T cells activated in vitro by zwitterionic capsular polysaccharides from abscess-inducing bacteria such as Staphylococcus aureus and Bacteroides fragilis initiate this host response when transferred to naive rats. In this study, we show that mice deficient in alphabetaTCR-bearing T cells or CD4(+) T cells fail to develop abscesses following challenge with B. fragilis or abscess-inducing zwitterionic polysaccharides, compared with CD8(-/-) or wild-type animals. Transfer of CD4(+) T cells from wild-type mice to alphabetaTCR(-/-) animals reconstituted this ability. The induction of abscesses required T cell costimulation via the CD28-B7 pathway, and T cell transfer experiments with STAT4(-/-) and STAT6(-/-) mice demonstrated that this host response is dependent on STAT4 signaling. Significantly higher levels of IL-17, a proinflammatory cytokine produced almost exclusively by activated CD4(+) T cells, were associated with abscess formation in Th2-impaired (STAT6(-/-)) mice, while STAT4(-/-) mice had significantly lower levels of this cytokine than control animals. The formation of abscesses was preceded by an increase in the number of activated CD4(+) T cells in the peritoneal cavity 24 h following bacterial challenge. Confocal laser-scanning microscopy analysis revealed that CD4(+) T cells comprise the abscess wall in these animals and produce IL-17 at this site. Administration of a neutralizing Ab specific for IL-17 prevented abscess formation following bacterial challenge in mice. These data delineate the specific T cell response necessary for the development of intra-abdominal abscesses and underscore the role of IL-17 in this disease process.

Alteration of V beta usage and cytokine production of CD4+ TCR beta beta homodimer T cells by elimination of Bacteroides vulgatus prevents colitis in TCR alpha-chain-deficient mice

A major pathogenic factor for the development of inflammatory bowel disease (IBD) is the breakdown of the intestinal homeostasis between the host immune system and the luminal microenvironment. To assess the potential influence of luminal Ags on the development of IBD, we fed TCR alpha(-/-) mice an elemental diet (ED). ED-fed TCR alpha(-/-) mice showed no pathologic features of IBD, and their aberrant mucosal B cell responses were suppressed. Similar numbers of CD4(+), TCR betabeta homodimer T cells (betabeta T cells) were developed in the colonic mucosa of ED-fed mice; however, Th2-type cytokine productions were lower than those seen in diseased regular diet (RD)-fed mice. The higher cytokine production in diseased RD-fed mice could be attributed to the high incidence of Bacteroides vulgatus (recovered in 80% of these mice), which can induce Th2-type responses of colonic CD4(+), betabeta T cells. In contrast, ED-fed TCR alpha(-/-) mice exhibited a diversification of Vbeta usage of betabetaT cell populations from the dominant Vbeta8 one associated with B. vulgatus in cecal flora to Vbeta6, Vbeta11, and Vbeta14. Rectal administration of disease-free ED-fed mice with B. vulgatus resulted in the development of Th2-type CD4(+), betabeta T cell-induced colitis. These findings suggest that the ED-induced alteration of intestinal microenvironments such as the enteric flora prevented the development of IBD in TCR alpha(-/-) mice via the immunologic quiescence of CD4(+), betabeta T cells.

Vaccination and periodontitis: myth or reality

In most industrialised countries approximately 15% of the population has enhanced risk for moderate to severe periodontitis. The disease is caused by infection by gram-negative, anaerobic bacteria including Porphyromonas gingivalis and Bacteroides forsythus. There is evidence that P. gingivalis is a key pathogen. Using ligature-induced periodontitis in the non-human primate Macaca fascicularis as a model, we immunised 10 animals using intact killed P. gingivalis and SAF-M adjuvant and 10 controls using adjuvant only. The vaccine, containing 250 microg protein/ml, was injected subcutaneously in the neck and into the deltoid muscle (0.5 ml each site) at baseline and weeks 3, 6, and 16, and the mandibular posterior teeth ligated at week 16. At weeks 30 and 36 changes in alveolar bone, measured using digital subtraction radiography, were used as the outcome measure. Even though periodontitis in humans and in this animal model is a polymicrobial disease, immunisation with a vaccine containing a single bacterial species, P. gingivalis, induced protection. Of all the P. gingivalis components that have been studied, the cysteine proteases have the greatest potential as vaccine antigens. In a pilot study using the same protocol, we have shown that porphypain-2 purified from P. gingivalis is effective in inducing protection. Although opsonisation and bacterial cell killing may be involved in protection, other mechanisms such as antibody mediated reduction of levels of inflammatory mediators such as PGE2 and neutralisation of virulence factors may be important. In neither the whole cell vaccine nor the purified cysteine protease vaccine studies were signs of toxicity observed. In light of the increasing evidence that periodontitis significantly increases risk for potentially fatal diseases such as coronary heart disease, stroke and complications from diabetes mellitus a successful vaccine for periodontitis could have health benefits far exceeding the prevention of periodontitis.

Effect of molecular size on the ability of zwitterionic polysaccharides to stimulate cellular immunity

The large-molecular-sized zwitterionic capsular polysaccharide of the anaerobe Bacteroides fragilis NCTC 9343, designated polysaccharide (PS) A, stimulates T cell proliferation in vitro and induces T cell-dependent protection against abscess formation in vivo. In the present study, we utilized a modification of a recently developed ozonolytic method for depolymerizing polysaccharides to examine the influence of the molecular size of PS A on cell-mediated immunity. Ozonolysis successfully depolymerized PS A into structurally intact fragments. PS A with average molecular sizes of 129.0 (native), 77.8, 46.9, and 17.1 kDa stimulated CD4+-cell proliferation in vitro to the same degree, whereas the 5.0-kDa fragment was much less stimulatory than the control 129.0-kDa PS A. Rats treated with 129.0-kDa, 46.9-kDa, and 17.1-kDa PS A molecules, but not those treated with the 5.0-kDa molecule, were protected against intraabdominal abscesses induced by challenge with viable B. fragilis. These results demonstrate that a zwitterionic polysaccharide as small as 22 repeating units (88 monosaccharides) elicits a T cell-dependent immune response. These findings clearly distinguish zwitterionic T cell-dependent polysaccharides from T cell-independent polysaccharides and give evidence of the existence of a novel mechanism for a polysaccharide-induced immune response.

Protection against experimental intraabdominal sepsis by two polysaccharide immunomodulators

Two immunomodulating polysaccharides, poly-(1-6)-beta-glucotriosyl-(1-3)-beta-glucopyranose (PGG)-glucan and Bacteroides fragilis polysaccharide A (PS A), were evaluated for the prevention of mortality and abscess formation associated with experimental intraabdominal sepsis. Prophylactic treatment with a combination of these compounds significantly reduced mortality (8% vs. 44% in the saline-treated control group) and the incidence of abscesses (30% vs. 100% in the saline-treated control group) after challenge with rat cecal contents. These compounds were also effective when administered therapeutically after bacterial contamination of the peritoneal cavity. PS A treatment conferred long-term protection against abscess formation and resulted in significantly fewer total aerobes and anaerobes in the peritoneal fluid of animals challenged with cecal contents. These data demonstrate the usefulness of two immunomodulatory polysaccharides in preventing experimental intraabdominal sepsis in the absence of antimicrobial therapy and may represent a new adjunct to antibiotic regimens currently used to prevent clinical cases of this disease.

Effect of adjuvants on antibody responses of sheep immunised with recombinant pili from Dichelobacter nodosus

OBJECTIVE

To compare the effects of two oil emulsion adjuvants (incomplete Freunds adjuvant and a proprietary oil adjuvant), DEAE-dextran, L-tyrosine particles and Quil A on the humoral immune responses of sheep immunised with recombinant pili of Dichelobacter Nodosus (strain A).

PROCEDURE

Antibody titres were studied for up to 32 weeks and were measured by bacterial agglutination and ELISA. The relative avidity of antibodies for pili was determined and the incidence and severity of adverse reactions at the site of injection of vaccines were recorded.

RESULTS

The oil emulsion adjuvants and Quil A were more effective than either DEAE-dextran or L-tyrosine at stimulating antibodies in sheep. The incidence and severity of adverse reactions was lower in sheep which received vaccines containing either Quil A or DEAE-dextran than in sheep which received vaccines containing oil emulsion adjuvants. L-tyrosine had no adverse effects.

CONCLUSION

Quil A was as effective as oil adjuvants at stimulating high levels of antibodies against recombinant pili in sheep and had the significant advantage of being less irritant after subcutaneous injection.

Polysaccharide-mediated protection against abscess formation in experimental intra-abdominal sepsis

Abscess formation is a major complication of intra-abdominal sepsis that causes significant morbidity and mortality. In such cases, Bacteroides fragilis is the predominant anaerobic isolate. In a rat model of intra-abdominal sepsis, the capsular polysaccharide complex (CPC) from B. fragilis promotes abscess formation and when administered sub-cutaneously, protects against this host response by a T cell-dependent immune mechanism. In the present study, the polysaccharide A (PS A) component of CPC protected animals against challenge with live heterologous bacterial species (mixtures of anaerobes and facultative organisms) that are most commonly isolated from intra-abdominal abscesses in humans. Protection against heterologous bacterial challenge was transferred by T cells. Administration of PS A shortly before or even after challenge with B. fragilis protected against this host response. In experiments designed to simulate fecal contamination of the human peritoneal cavity, PS A protected animals against abscess formation induced by a rat cecal contents inoculum. The surprisingly broad protective activity of PS A indicates that this molecule is likely suppressing a nonspecific host tissue reaction that forms in response to a variety of abscess-inducing organisms and that it might be useful in preventing abscess formation associated with intra-abdominal sepsis in the clinical setting.

Prevention of dry socket with clindamycin. A retrospective study

Clindamycin and other agents were compared for efficacy in preventing the entity "dry socket." A total 765 patients were treated with clindamycin, per os, and 408 patients were treated with other antibiotics or were non-treated controls. All patients underwent surgical removal of impacted mandibular third molars. The incidence of dry socket in untreated control and in non-clindamycin antibiotic-treated patients varied from 15 to 31 percent, while in those patients receiving clindamycin, the incidence was 0.65 percent. The results demonstrate a remarkable effectiveness of clindamycin in reducing the incidence of dry socket following surgical removal of impacted mandibular third molar.

Inadequate levels of metronidazole in subcutaneous fat after standard prophylaxis

The efficacy of antibiotic prophylaxis depends on appropriate tissue levels of the drug being present at the time of potential wound contamination. Metronidazole concentrations in serum, muscle and subcutaneous fat were measured after a single intravenous dose given at two different intervals before operation. Twenty-six patients undergoing abdominal wall procedures were divided into two groups. Patients in group 1 received metronidazole 500 mg intravenously 2 h before surgery, and those in group 2 were given the drug during induction of anaesthesia. Mean plasma levels of metronidazole at the beginning of the procedure were significantly lower (P = 0.01) in group 1 (7.3 (95 per cent confidence interval 5.7-8.9)) micrograms/ml than in group 2 (12.3 (8.9-15.7)) micrograms/ml although in both cases were above the minimum inhibitory concentration for 90 per cent of Bacteroides fragilis. Similar therapeutic concentrations of metronidazole were achieved in plasma and muscle in both groups at the end of the operation. However, patients in both groups had non-therapeutic concentrations of metronidazole in subcutaneous fat: group 1 0.9 (0.6-1.2) micrograms/mg, group 2 1.2 (0.7-1.7) micrograms/mg at the beginning of operation, and 1.2 (0.8-1.6) and 1.5 (0.9-2.1) micrograms/mg respectively at the end of the procedure. It is concluded that infusion of metronidazole 2 h before surgery or during induction of anaesthesia achieved adequate plasma and muscle levels but failed to achieve therapeutic levels in subcutaneous fat.

Aztreonam vs. gentamicin in experimental peritonitis and intra-abdominal abscess formation

The activity of gentamicin is known to be decreased in acidic environments, and both the peritoneum during peritonitis and the interior of abscesses have been shown to be acidic and hypoxic. The activity of beta-lactam antibiotics is felt to be relatively less diminished under the same circumstances. We determined that the minimum inhibitory concentration of gentamicin against one pathogenic strain of Escherichia coli increased eight-fold, to 8 mugm/mL, when testing conditions were changed from normoxic and neutral to hypoxic and acidic, whereas the MIC of aztreonam doubled under the same conditions, to 0.25 mugm/mL. In further experiments in a murine model of mixed Escherichia coli/Bacteroides fragilis intra-abdominal abscesses, we demonstrated that a combination of aztreonam and clindamycin was superior to a combination of gentamicin and clindamycin in terms of completely preventing abscess formation (33% vs. 0%) and eliminating Escherichia coli from abscesses that did form (100% vs. 61%).

Effect of recombinant tissue plasminogen activator on intra-abdominal abscess formation in rats with generalized peritonitis

BACKGROUND

During generalized peritonitis, intraabdominal fibrin deposition is stimulated whereas fibrinolytic activity is reduced, which predisposes intra-abdominal abscess formation. We investigated the effects of increasing the intra-abdominal fibrinolytic activity on abscess formation by intra-abdominal administration of recombinant tissue plasminogen activator (rt-PA). Potential side effects, such as bacteremia and bleeding, were also assessed.

STUDY DESIGN

A rat model of generalized peritonitis, induced by intraperitoneal injection of sterile feces contaminated with 10(4) cfu per mL Escherichia coli (E. coli) and 10(4) cfu per mL Bacteroides fragilis, was used.

RESULTS

Rats treated with rt-PA dissolved in methyl hydroxy propyl cellulose (MHPC) gel (0.5 mg per mL), had significantly less intra-abdominal abscesses than rats in the control group, treated with either Ringer's lactate solution or MHPC gel alone (p < 0.01). Other than E. coli, cultures of abscesses revealed species originating from the intestine, demonstrating bacterial translocation. The mortality rate was significantly higher in the rats treated with rt-PA as compared with rats in the control group (p < 0.01), which was surprising considering the absence of bacteremia. By challenging the rats with a higher dose of E. coli, early bacteremia was observed in the rats treated with rt-PA, not related to increased mortality rates. Intraabdominal use of rt-PA was not associated with an increased incidence of bleeding events.

CONCLUSIONS

Recombinant tissue plasminogen activator prevents abscess formation in rats with generalized peritonitis. However, early bacteremia and increased mortality rates are serious drawbacks of the intra-abdominal use of rt-PA in this rat model.

Bacterial structure and functional relation to abscess formation

The capsular polysaccharide complex (CPC) of Bacteroides fragilis exhibits unusual biologic properties. This polysaccharide complex promotes the formation of abscesses and prevents abscess induction in a rat model of intra-abdominal sepsis. Each of these biologic properties is mediated by a T cell-dependent immune mechanism. The CPC consists of two distinct polysaccharides, PS A and PS B, each with repeating units that have positively charged amino groups and negatively charged carboxyl or phosphate groups. Analysis of these polysaccharides as well as other charged carbohydrates before and after chemical modification revealed that these oppositely charged groups are required for promotion of intra-abdominal abscesses as well as for protection against abscess induction. These studies provide a structural rationale for the distinct properties associated with the B. fragilis CPC, and delineate one mechanism by which this host response occurs.

Use of cephalosporins for prophylaxis and therapy of polymicrobial infection in mice

Cefoxitin, cefotetan, and cefmetazole were compared in 10-day therapy of intra-abdominal and subcutaneous infections caused by three organisms: Bacteroides fragilis and Bacteroides thetaiotaomicron combined with either Escherichia coli or Staphylococcus aureus. Intra-abdominal infection was caused by B. fragilis plus B. thetaiotaomicron plus E. coli. Therapy was initiated immediately before inoculation or was delayed for 8 h. Mortality was 14 of 30 (47%) for saline-treated mice, and all survivors developed abscesses. Immediate therapy reduced mortality and the percentage of mice with abscesses (in survivors), respectively, to 17 and 20% with cefoxitin, 0 and 13% with cefotetan, and 0 and 17% with cefmetazole, and the numbers of all bacteria were reduced by all the cephalosporins. Delayed therapy reduced mortality and abscess formation, respectively, to 20 and 8% of mice with cefoxitin, 10 and 93% with cefotetan, and 7 and 96% with cefmetazole. B. thetaiotaomicron survived in all abscesses treated with cefotetan and cefmetazole. Subcutaneous abscesses were caused by each organism alone or in combinations of one aerobe (S. aureus or E. coli) and one or two Bacteroides species. Early therapy reduced the numbers of all bacteria independent of their in vitro susceptibility. All agents reduced the number of each Bacteroides species with either E. coli or S. aureus. However, when therapy was delayed, cefotetan and cefmetazole were less effective than cefoxitin against B. thetaiotaomicron. Cefotetan was the most active agent against E. coli, and cefmetazole was the most effective against S. aureus. These data illustrate the efficacy of all tested cephalosporins in the prophylaxis of polymicrobial infections.

Increasing antibiotic dose decreases polymicrobial infection after hemorrhagic shock

Hemorrhagic shock has been shown to increase the susceptibility to infection despite the administration of conventionally accepted doses of antimicrobial drugs. The efficacy of increasing antibiotic dose in a model of mixed gram-negative infection, both with and without hemorrhagic shock, was examined. Shock was induced by bleeding rats to a mean arterial pressure of 45 millimeters of mercury for 45 minutes followed by resuscitation with shed blood and saline solution. One hour after shock or sham, the rats were inoculated with 1 x 10(8) Escherichia coli plus 1 x 10(9) Bacteroides fragilis in a fecal suspension subcutaneously. Rats were given either no antibiotic (CONTROL) or cefoxitin at 30 milligrams per kilogram (STANDARD) or 200 milligrams per kilogram (HIGH) intraperitoneally, 30 minutes before and at six and 12 hours after inoculation. Tissue cefoxitin concentrations were measured 30 minutes before and at six and 12 hours after inoculation. Tissue cefoxitin concentrations were measured 30 minutes after the initial dose. STANDARD reduced abscess diameter by 58 percent compared with CONTROL in rats that were not shocked, but only by 26 percent after shock (p < 0.05 shock versus sham). HIGH further decreased abscess diameter and weight (4 +/- 1 millimeter and 22 +/- 22 milligrams) after shock compared with STANDARD (9 +/- 1 millimeter and 230 +/- 90 milligrams; both p < 0.05). Peak tissue cefoxitin levels were greater than 19 times the minimal inhibitory concentration for each bacteria for HIGH compared with eight times for STANDARD. These data demonstrate that an increased dose of cefoxitin was superior to a conventional dose in controlling a mixed gram-negative infection after shock and suggest that altering traditional antibiotic use may decrease the incidence of infection after shock and hemorrhage.

[Tissue diffusion of amoxicillin-clavulanic acid for antibiotic prophylaxis in colorectal surgery]

Tissue penetration of amoxicillin and clavulanic acid given for antibiotic prophylaxis was studied in 15 patients. On induction of anesthesia patients were given 2 g amoxicillin and 200 mg clavulanic acid. The same dose was given two hours later. At time of surgical incision amoxicillin and clavulanate levels were 15.9 +/- 7.7 micrograms/g and 2.23 +/- 2.69 micrograms/g in abdominal wall fat and 16.6 +/- 10.5 and 1.72 +/- 1.35 micrograms/g in epiploic fat, respectively. Similar levels were measured at time of closure of the abdomen. In colonic wall, amoxicillin et clavulanate levels were 22.7 +/- 13.4 micrograms/g and 2.65 +/- 2.35 micrograms/g. By comparison with blood levels, tissue penetration of both drugs was 20 to 30 p. cent into fatty tissues and 60 to 70 p. cent into colonic wall.

Abdominal surgical wound infection is lowered with improved perioperative enterococcus and bacteroides therapy

Perioperative antibiotics decrease surgical wound infection (SWI) in trauma patients requiring abdominal exploration. This investigation evaluated 24 hours of cefoxitin or ampicillin/sulbactam used for early therapy in such patients. Patients were randomly assigned to one of two treatment groups. The primary endpoint evaluated was SWI, which was defined as purulent drainage or active wound treatment. Five hundred ninety-two patients were evaluated: 283 received ampicillin/sulbactam and 309 received cefoxitin. The incidence of wound infection among the ampicillin/sulbactam patients was 2% and among cefoxitin patients it was 7% (p < 0.004). The cefoxitin patients with colon injuries were analyzed (p < 0.007). The major difference between the two groups was an increased incidence of enterococcal infections in the cefoxitin-treated patients. A single broad-spectrum antibiotic given for 24 hour perioperatively effectively controls SWI. Use of ampicillin/sulbactam results in a significantly lower SWI rate than use of cefoxitin, which may be a result of improved enterococcal and Bacteroides coverage.

Species specific monoclonal antibodies to Bacteroides fragilis lipopolysaccharide protect mice from severe infection

Four monoclonal antibodies which reacted in a species specific manner with Bacteroides fragilis were isolated. They recognised at least two different epitopes of B. fragilis lipopolysaccharide. The monoclonal antibodies protected non-immune mice from longlasting bacteraemia and abscess formation induced by the intraperitoneal administration of B. fragilis in combination with an infection-potentiating agent. The monoclonal antibodies were as efficient as an anti-B. fragilis hyperimmune serum. Only antibodies administered intraperitoneally or intramuscularly were protective.

Immunization with Porphyromonas (Bacteroides) gingivalis fimbriae protects against periodontal destruction

Adhesive fimbriae from Porphyromonas gingivalis are cell surface structures which may be important in the virulence of this oral pathogen and thus may serve as a critical or target antigen. Immunization with highly purified 43-kDa fimbrial protein protected against periodontal tissue destruction when tested in the P. gingivalis-infected gnotobiotic rat model. A similarly highly purified 75-kDa cell surface component did not provide protection. Heat-killed whole-cell and sonicated cell surface extracts which contain the 43-kDa protein as well as the 75-kDa component were protective also. This study indicates that the fimbrial protein may serve as a model for the development of effective vaccines against periodontitis, a major human oral disease.

Porphyromonas gingivalis virulence in mice: induction of immunity to bacterial components

Selected cell envelope components of Porphyromonas gingivalis were tested in a BALB/c mouse model in an attempt to elucidate further the outer membrane components of this putative oral pathogen that might be considered as virulence factors in host tissue destruction. Lipopolysaccharide (LPS), outer membrane, and outer membrane vesicles of P. gingivalis W50, ATCC 53977, and ATCC 33277 were selected to examine an immunological approach for interference with progressing tissue destruction. Mice were actively immunized with heat-killed (H-K) or Formalin-killed (F-K) whole cells or with the outer membrane fraction, LPS, or outer membrane vesicles of the invasive strain P. gingivalis W50. The induction of invasive spreading lesions with tissue destruction and lethality were compared among different immunization groups in normal, dexamethasone-treated (dexamethasone alters neutrophil function at the inflammatory site), and galactosamine-sensitized (galactosamine sensitization increases endotoxin sensitivity) mice after challenge infection with the homologous strain (W50) and heterologous strains (ATCC 53977 and ATCC 33277). Enzyme-linked immunosorbent assay analyses revealed significantly elevated immunoglobulin G and M antibody responses after immunization with H-K or F-K cells or the outer membrane fraction compared with those of nonimmunized mice. The killed whole-cell vaccines provided significantly greater protection against challenge infection in normal mice (decreased lesion size and death) than did either the outer membrane fraction or LPS immunization. The lesion development observed in dexamethasone-pretreated mice was significantly enhanced compared with that of normal mice after challenge with P. gingivalis. Immunization with P. gingivalis W50 provided less protection against heterologous challenge infection with P. gingivalis ATCC 53977; however, some species-specific antigens were recognized and induced protective immunity. Only viable P. gingivalis induced a spreading lesion in normal, dexamethasone-treated, or galactosamine-sensitized mice; F-K or H-K bacteria did not induce lesions. The F-K and outer membrane vesicle immunization offered greater protection from lesion induction than did the H-K immunogen after challenge infection simultaneous with galactosamine sensitization. The H-K cell challenge with galactosamine sensitization produced 100% mortality without lesion induction, suggesting that LPS or LPS-associated outer membrane molecules were functioning like endotoxin. Likewise, P. gingivalis W50 LPS (1 micrograms per animal) administered intravenously produced 80% mortality in galactosamine-sensitized mice. In contrast to the effects of immunization on lesion development, immunization with H-K or F-K cells or LPS provided no protection against intravenous challenge with LPS; 100% of the mice died from acute endotoxin toxicity.(ABSTRACT TRUNCATED AT 400 WORDS)

Influence of immunization on Porphyromonas gingivalis colonization and invasion in the mouse chamber model

The effects of immunization with invasive or noninvasive Porphyromonas (Bacteroides) gingivalis strains on the pathogenesis of infection in a mouse chamber model were examined. BALB/c mice were immunized by a single injection of heat-killed P. gingivalis invasive strain A7436 or W83 or noninvasive strain 33277, HG405, or 381 directly into subcutaneous chambers. P. gingivalis-specific antibody was detected in chamber fluid 21 days postimmunization, and mice were subsequently challenged by injection of exponential-phase P. gingivalis into chambers. Immunization with A7436 or W83 followed by challenge with A7436 protected mice against secondary abscess formation and death; however, P. gingivalis persisted in chambers for up to 14 days postchallenge. Immunization with noninvasive strain 33277, HG405, or 381 followed by challenge with invasive strain A7436 or W83 protected mice against secondary lesion formation and death. P. gingivalis was cultured from 33277- or HG405-immunized and nonimmunized animals to day 14. All P. gingivalis strains induced an immunoglobulin G response, as measured by an enzyme-linked immunosorbent assay and Western immunoblotting of P. gingivalis whole-cell and outer membrane protein preparations. Western blot analyses indicated that sera from mice immunized with different invasive and noninvasive strains recognized common P. gingivalis antigens. In summary, immunization with invasive P. gingivalis A7436 and W83 or noninvasive P. gingivalis 33277, HG405, and 381 protected mice from secondary lesion formation and death after challenge with invasive P. gingivalis A7436 or W83. P. gingivalis-specific antibody did not, however, inhibit the colonization of P. gingivalis within chambers.

Immunization with Fimbrial Protein and Peptide Protects against Porphyromonas Gingivalis-Induced Periodontal Tissue Destruction

In these studies we have attempted to show that cell surface structures are critical antigens for protection against P. gingivalis-induced periodontal destruction. Fimbrillin, and in particular a synthetic 20-amino-acid fimbrillin peptide, exerts a protective effect in gnotobiotic rats, thus identifying them as potentially useful in the development of a vaccine.

Delayed administration of tissue plasminogen activator reduces intra-abdominal abscess formation

Previous studies demonstrated that intraperitoneal fibrinolysis using tissue plasminogen activator (t-PA) prevented intraabdominal abscess formation in a rat fibrin clot infection model when administered simultaneously with the infecting inoculum. To more closely mimic the clinical setting, the efficacy of delayed administration of t-PA on intra-abdominal abscess formation was examined. A delay of 2, 6, and 18 hours had no effect on the rate of abscess formation but did reduce abscess size, indicating partial fibrinolysis. Since fibrin clots dehydrate in vivo, we hypothesized that a higher concentration of t-PA might be necessary to effect complete abscess resolution. High-dose t-PA (0.1 mg/mL) prevented abscess formation following a 6-hour delay and reduced mean weight following an 18-hour delay. Since heparin sodium may prevent new fibrin deposition and enhance t-PA activity, it was combined with t-PA to investigate potential synergistic effects. Despite adequate anticoagulation with heparin, no synergy with t-PA could be documented. In addition, the combination of antibiotics with t-PA did not affect its efficacy in vivo. We demonstrate that delayed administration of t-PA is effective in preventing abscess formation and may have implications for the clinical setting where initial surgical intervention is usually delayed.

Topical and systemic antibiotics in the prevention of wound infection

We evaluated under controlled conditions the efficacy of topical and systemic antibiotics, alone and in combination, in the prevention of wound infection and measured serum and tissue antibiotic levels in the wound and distant tissue after administration of antibiotics topically, systemically, and in combination. Adult Sprague-Dawley rats were contaminated on the dorsal paravertebral muscles with a preset standardized inoculum of Staphylococcus aureus, Escherichia coli, and Bacteroides fragilis. A second-generation cephalosporin was used; systemic administration was given intramuscularly and topically in powder form. Wound infection was confirmed by the recovery of the organism by culture. Prophylactic antibiotics were effective in preventing wound infection in all groups. Topical antibiotic and a combination (topical/systemic) antibiotic were significantly more effective than was systemic antibiotic alone in preventing wound infection. Adequate levels of antibiotic were achieved in serum and tissue with both topical and systemic antibiotics. Wound tissue concentration of antibiotic was significantly higher when topical antibiotic was used.

Efficacy of a multivalent Bacteroides nodosus vaccine against foot rot in sheep in Britain

A multivalent Bacteroides nodosus foot rot vaccine was tested by comparing the prevalence of foot rot in 317 vaccinated ewes and lambs with the prevalence in 422 unvaccinated control sheep. The vaccine conferred statistically significant protection against foot rot. The vaccine also demonstrated a therapeutic effect in animals with foot rot, after one injection.

Enhancement of survival from murine polymicrobial peritonitis with increased abdominal abscess formation

Muramyl dipeptide (MDP), a purified synthetic immune adjuvant, has been shown to increase murine intraabdominal abscess formation in a monomicrobial model using Bacteroides fragilis. This effect required live bacteria and was abolished by appropriate antibiotics. A polymicrobial model of peritonitis and abdominal abscess formation using Streptococcus fecalis, Escherichia coli, and B. fragilis was initially used to determine mortality rates at various concentrations and obtain an appropriate LD50. Animals were then pretreated with MDP or its inert buffer and underwent intraperitoneal injection of the appropriate bacterial suspension. Mortality and abdominal abscess formation were then assessed at 2 weeks after injection. There was a significant reduction in mortality (P less than 0.03) in mice treated with MDP compared to the controls. In surviving animals, there was also a significant increase in the number of animals forming abscesses (P less than 0.05) following treatment with MDP. This study has shown that nonspecific immune stimulation by MDP provided enhanced protection against a polymicrobial intraperitoneal challenge and paradoxically increased the formation of abdominal abscesses at the same time. This may be regarded as enhancement of the natural history of survival from peritonitis via bacterial containment through intraabdominal abscess formation, a manifestation of beneficial outcome in experimental peritonitis.

Effectiveness of vaccination in controlling ovine footrot

Efficacy of reducing footrot by use of a commercial vaccine was evaluated over 2 yr with 223 ewes from five crossbred genotypes. Ewes were assigned randomly within genotype, age and initial footrot status to a 2 x 3 factorial array of vaccination in the 1st yr and fall vaccination, winter vaccination or control in the 2nd yr. The flock contained a single Bacteroides nodosus serotype (XV) known to be highly cross-reactive with one of the vaccine serotypes (British serotype H). Vaccination reduced footrot incidence by 61% (P less than .01) in the 1st yr and by 45% (P less than .01) in the 2nd yr. Vaccination of previously uninfected ewes did not significantly reduce the rate of new infection, but vaccination of infected ewes reduced re-infection by 92% (P less than .01). Vaccination in the 1st yr failed to produce any carryover or additive protection in the 2nd yr. Genotypes differed in both footrot incidence (P less than .05) and footrot reduction following vaccination (P less than .05), but the effect was inconsistent between years. Vaccination increased serum antibody titers in both years (P less than .01). Among vaccinates in the 1st yr, infected ewes had lower titer levels than uninfected ewes (P less than .01), but no correlation between titer level and incidence was observed in the 2nd yr.

Effect of ultrasonic instrumentation on Bacteroides intermedius

Two physical mechanisms of ultrasound, cavitation and acoustic streaming, were investigated in an ultrasonic endodontic unit. In addition, the potential of ultrasonic instrumentation for disruption of Bacteroides intermedius was examined at various time intervals. The ultrasonic file could not generate cavitation within the recommended power settings indicated for endodontic purposes. However, there was evidence of acoustic streaming. The latter phenomenon resulted in destruction of 21.6%, 30.4% and 92.9% of test bacteria after 1, 5 and 15 min sonication respectively. It appears that ultrasonic instrumentation of root canals has little bactericidal effect.

Effects of immunization with B. macacae on induced periodontitis--preliminary findings

This preliminary study examined the effects of immunization with Bacteroides macacae, the monkey equivalent of the human species of B. gingivalis on ligature-induced periodontitis. During a 12 week immunization period, 8 out of the 12 Macacae fasicularis monkeys were immunized weekly with B. macacae washed cells and 4 were sham-immunized with saline. At the same time, all were scaled and pumiced weekly to establish gingival health. Following this period, the mandibular first molars were ligated in 8 out of the 12 monkeys to induce periodontitis. The immunized, ligated experimental group, the ligated, sham-immunized control group, and the immunized, non-ligated control group were then followed for a 6 months ligation period while plaque was allowed to accumulate. Gingival indices, attachment levels, pocket depths, plaque indices, radiographs, serum and crevicular fluid antibodies and subgingival bacteria were assessed. Immunization led to elevated antibody levels to B. macacae while ligation increased plaque, gingival inflammation, and bone loss. Following the 6 month ligation period, B. macacae comprised 1.7% of the cultivable flora in the immunized, non-ligated monkeys, 2.1% in the immunized, ligated monkeys, and 5.6% in the sham-immunized, ligated monkeys. Similar differences between the immunized, ligated and and the sham-immunized, ligated groups were not seen for B. intermedius, nor B. melaninogenicus. These results suggest a heightened humoral response to B. gingivalis reduces subgingival re-colonization by this organism and modulates the course of ligature-induced periodontitis.

Prevention of intra-abdominal abscesses by fibrinolysis using recombinant tissue plasminogen activator

We studied whether intraperitoneal fibrinolysis using recombinant tissue plasminogen activator (t-PA) could prevent abscess formation in the rat model of intra-abdominal infection caused by fibrin clots. Single-dose administration of t-PA at concentrations greater than 0.005 mg/mL at surgery or delivered by open lavage within 1 h of surgery completely obviated abscess formation induced by Bacteroides fragilis-infected clots without altering mortality (approximately 0.6%). With mixed Escherichia coli-B. fragilis clots, t-PA increased the mortality rate from the control level of 43.8% to 81.3% but prevented abscesses in survivors. This increased mortality rate was probably due to an acute E. coli bacteremia. Antibiotics plus t-PA prevented both mortality and abscess formation. Intraperitoneal fibrinolysis may be a useful adjunct to antibiotics and appropriate surgery in the management of intra-abdominal infection.

Antibody responses of sheep vaccinated with foot rot vaccines

Enzyme-linked immunosorbent assay (ELISA) and crossed immunoelectrophoresis (IEP) were used to investigate antibody responses of sheep vaccinated with a double adjuvanted or single adjuvanted commercial foot rot vaccine. ELISA detected an antibody response of greater magnitude to the double adjuvant vaccine compared with the single adjuvant vaccine. Sera from sheep vaccinated with double adjuvant vaccine recognised at least six antigens of Bacteroides nodosus in crossed IEP while sera from the single adjuvant vaccinated sheep recognised one antigen. The use of non-denatured antigens of B nodosus in ELISA and crossed IEP enabled quantitative comparisons of antibody responses to the different foot rot vaccines to be made.

Prevention of intra-abdominal abscesses with fibrinolytic agents

Fibrin deposition during secondary peritonitis predisposes to abscess formation by protecting bacteria from host-defence mechanisms. To test the hypothesis that local fibrinolytic therapy can prevent the formation of intra-abdominal abscess, daily injections of the fibrinolytic enzymes trypsin and tissue plasminogen activator (t-PA) were administered intraperitoneally to Wistar rats inoculated intraperitoneally with infected fibrin clots. After 5 days, trypsin (1 mg/ml) had significantly (p less than 0.001) reduced abscess formation in animals inoculated with monomicrobial Bacteroides fragilis clots (20% versus 87%) or mixed Escherichia coli-B. fragilis clots (11% versus 91%). Bacteroides fragilis abscesses were also completely prevented with t-PA (0.25 mg/ml). The number of B. fragilis organisms present in residual abscesses in the trypsin-treated group was significantly (p less than 0.05) lower than in the control group (8.2 +/- 0.2, n = 7 versus 5.7 +/- 1.4, n = 4, log CFU/g abscess). In-vitro studies demonstrated that trypsin had no bactericidal effect on B. fragilis, suggesting enhanced clearance of bacteria. From these studies it appears that controlled fibrinolysis at operation may be a useful adjunct to surgery and systemic antibiotics in preventing abscess formation postoperatively.

[Principles of treatment of non-clostridial anaerobic infection in the surgery of inflammatory diseases of the biliary tract]

Based upon the clinico-bacteriological examination of 196 patients with different inflammatory diseases of bile ducts the author has established the role of non-clostridial anaerobic infection in the appearance of these diseases. Clinical symptoms of the infection have been systematically described. New principles of the surgical tactics and antibacterial prophylactics have been developed and used which allowed postoperative lethality to be reduced to 1%. The duration of treatment at the hospital became shorter (8.4 days).

Antibiotics and suction drainage as prophylaxis in vaginal and abdominal hysterectomy

A randomized prospective study compared the efficacy of a three-dose perioperative course of intravenously administered cefuroxime and metronidazole versus suction drainage of the vaginal vault for preventing postoperative infection in abdominal and vaginal hysterectomies. In vaginally operated patients, a significant difference in the rate of vaginal cuff abscess formation was found between the drain group and the antibiotic group (33 versus 0%). In the abdominally operated patients, no significant difference was found (7 versus 0%). The rate of cystitis was not influenced by the prophylactic method. A positive correlation was found between Bacteroides sp isolated from the vaginal fluid and vaginal cuff abscesses in the vaginally operated women. The complications of infection are explained by the decrease in host defense, occurring more frequently in patients treated with the vaginal approach than with the abdominal technique.

Vaccination against lumpy jaw and measurement of antibody response in wallabies (Macropus eugenii)

Successful protection against lumpy jaw disease in a colony of captive wallabies (Macropus eugenii) was induced by vaccination with a commercial ovine footrot vaccine. No mortalities attributable to lumpy jaw were observed in 69 vaccinated animals while six of 42 unvaccinated control wallabies died of the disease. Vaccinated animals exhibited significant increases in antibody titres to Bacteroides nodosus after the first and second doses of vaccine. Titres were measured by an enzyme-linked immunosorbent assay.

Expression of pili from Bacteroides nodosus in Pseudomonas aeruginosa

The pili of Bacteroides nodosus, the causative agent of ovine footrot, constitute the major host-protective immunogen against homologous serotypic challenge. The pilin gene from B. nodosus 198 has been cloned and morphologically expressed as extracellular pili in Pseudomonas aeruginosa by using a plasmid-borne, thermoregulated expression system. B. nodosus pilin could not be detected in cultures of P. aeruginosa grown at 32 degrees C, but after induction at 37 degrees C, B. nodosus pili were expressed on the cell surface of P. aeruginosa to the virtual exclusion of the host cell pili. Pili harvested from induced P. aeruginosa cultures were used to immunize sheep against footrot. The serum agglutinating antibody titers of vaccinated sheep were comparable to those of sheep receiving pili from B. nodosus. Subsequent challenge of the sheep with B. nodosus 198 indicated that the recombinant- DNA-derived pili vaccine and the B. nodosus pili vaccine provided similar levels of protection against footrot.

Efficacy of ofloxacin (HOE 280) in a model of subcutaneous abscess: penetration and prevention of abscess formation

A mouse model of subcutaneous abscess was used to determine the penetration into the abscess and the preventive value of ofloxacin (Hoe 280). Sterile cecal contents were injected subcutaneously combined with three different types of inoculum: Bacteroides fragilis, Escherichia coli and E. coli plus B. fragilis. For penetration studies three doses of 20 mg/kg of ofloxacin were administered intraperitoneally 8 hourly after abscesses had formed. Serum levels at 10, 20, 30, 60 and 90 min after the last dose showed mean values of: 6.9, 4.7, 3.8, 2.35 and 1.08 mg/l respectively. Simultaneously assessed ofloxacin abscess levels were 3.6, 4.1, 2.4, 1.91 and 1.98 mg/kg. In order to evaluate its preventive value, ofloxacin was given intraperitoneally at doses of 20 mg/kg in four regimens. Regimen A: one dose immediately before injection of the inoculum; regimen B: one dose 4 h after the injection of the inoculum; regimen C: one dose immediately before and two doses 8 h and 16 h after injection of the inoculum and regimen D: one dose 4 h, 12 h and 20 h after injection of the inoculum. The results are expressed as the percentage of the reduction in the number of abscesses formed in the survivors versus the control groups: regimens A) 30 to 70%; B) 0 to 40%; C) 50 to 60%, and D) 10 to 60%. The viable bacterial counts in the abscess contents were also assessed.