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.