We report on the microbiological and clinical effects of mechanical debridement in combination with metronidazole plus amoxicillin therapy in 118 patients with Actinobacillus actinomycetemcomitans‐associated periodontitis. Patients were categorized into 3 groups: 28 had localized periodontitis; 50 had generalized periodontitis, and 40 had refractory periodontitis. After initial treatment and metronidazole plus amoxicillin therapy 114 of 118 (96.6%) patients had no detectable A. actinomycetemcomitans. Significant reduction in pocket probing depth and gain of clinical attachment were achieved in almost all patients. Four patients were still positive for A. actinomycetemcomitans after therapy. Metronidazole resistance (MIC > 25 μg/ml) was observed in 2 of 4 strains from these patients. Patients still positive for A. actinomycetemcomitans or Porphyromonas gingivalis showed a significant higher bleeding tendency after therapy. It was concluded that mechanical periodontal treatment in combination with the metronidazole plus amoxicillin therapy is effective for subgingival suppression of A. actinomycetemcomitans in patients with severe periodontitis. J Periodontol 1992;63:52–57.

The potential use of an adjunctive therapy of metronidazole plus amoxycillin for the subgingival elimination of Actinobacillus actinomycetemcomitans in periodontitis patients was investigated. 22 patients participated in this study, 11 with localized juvenile periodontitis (LJP) and 11 with rapidly progressive periodontitis (RPP). 14 patients had received periodontal treatment in the past. All patients were subgingivally infected with A. actinomycetemcomitans. After mechanical subgingival debridement in combination with the antibiotic treatment, elimination of A. actinomycetemcomitans was achieved in all patients but one. With this one exception, clinical improvements were observed in all patients, resulting in reduced pocket probing depths as well as in a significant reduction in bleeding on probing. Re-examination of 16 patients after 9-11 months revealed that A. actinomycetemcomitans was still undetectable and further clinical improvement was observed. It was concluded that the combination of metronidazole plus amoxycillin is a valuable adjunct to mechanical therapy in A. actinomycetemcomitans associated periodontal infections.

The purpose of this study was to assess whether an intensive oral hygiene regimen practised during pregnancy results in a clinically healthy gingival state, and to assess whether experimentally-induced gingivitis differs in severity during pregnancy as compared to post-partum. In addition, levels of black-pigmented Gram negative anaerobes at subgingival and oral mucosal sites and plasma concentrations of free estrogens and prosterone were determined. These parameters were studied during a 14-day episode of experimental gingivitis induced in the 25th week of pregnancy, and again 6 months post-partum. The subjects were selected on shallow pockets < or = 4 mm and interproximal loss of attachment not exceeding 2 mm. As a result of controlled oral hygiene, the gingival condition improved both during pregnancy and post-partum. At day 0 during pregnancy, however, gingival swelling, redness, and bleeding on probing were found to be higher than post-partum. Free plasma levels of estrogens and progesterone were found to be normal throughout the study. It was hypothesized that the increase in severity of gingival symptoms during pregnancy reflect microvascular physiologic effects of increased levels of these hormones. During pregnancy, more swelling, redness and bleeding on probing developed during experimental gingivitis than post-partum, whereas the amount of plaque was similar in both phases. This suggests that as a result of dental plaque accumulation, gingival inflammation develops superimposed on pregnancy-associated physiologic alterations. Microbiological evaluation showed that the mean proportions of Prevotella intermedia in subgingival plaque increased during experimental gingivitis performed during pregnancy, whereas no increase of this micro-organism was found post-partum.

Today, 10 black‐pigmented Bacteroides (BPB) species are recognized. The majority of these species can be isolated from the oral cavity. BPB species are involved in anaerobic infections of oral and non‐oral sites. In the oral cavity. BPB species are associated with gingivitis, periodontitis, endodontal infections and odontogenic abscesses. Cultural studies suggest a specific role of the various BPB species in the different types of infection. Bacteroides gingivalis is closely correlated with destructive periodontitis in adults as well as in juveniles. Bacteroides intermedius seems to be less specific since it is found in gingivitis, periodontitis, endodontal infections and odontogenic abscesses. The recently described Bacteroides endodontalis is closely associated with endodontal infections and odontogenic abscesses of endodontal origin. There are indications that these periodontopathic BPB species are only present in the oral cavity of subjects suffering from periodontal breakdown, being absent on the mucosal surfaces of subjects without periodontal breakdown. BPB species associated with healthy oral conditions are Bacteroides melaninogenicus, Bacteroides denticola and Bacteroides loescheii. There are indications that these BPB species are part of the normal indigenous oral microflora. Many studies in the past have documented the pathogenic potential and virulence of BPB species. This virulence can be explained by the large numbers of virulence factors demonstrated in this group of microorganisms. Among others, the proteolytic activity seems to be one of the most important features. Several artificial substrates as well as numerous biological proteins are degraded. These include anti‐inflammatory proteins such as alpha‐2‐macroglobulin, alpha‐1‐antitrypsin, C3 and C5 complement factors and immunoglobulins. B. gingivalis is by far the most proteolytic species, followed by B. endodontalis. Like other bacteria, the lipopolysaccharide of B. gingivalis has shown to be active in bone resorption in vitro and is capable in stimulating interleukin‐1 production in human peripheral monocytes. Based on the well documented association with periodontal disease and the possession of relevant virulence factors. BPB species must be considered as important micro‐organisms in the etiology of oral infections. B. gingivalis seems to be the most pathogenic and virulent species.

Helicobacter pylori is involved in gastritis, gastric and duodenal ulcers, gastric adenocarcinoma, and mucosaassociated lymphoid tissue lymphoma. Earlier studies already suggested a role for autoimmune phenomena in H. pylori-linked disease. We now report that lipopolysaccharides (LPS) of H. pylori express Lewis y, Lewis x, and H type I blood group structures similar to those commonly occurring in gastric mucosa. Immunization of mice and rabbits with H. pylori cells or purified LPS induced an anti-Lewis x or y or anti-H type I response, yielding antibodies that bound human and murine gastric glandular tissue, granulocytes, adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma cells. Experimental oral infections in mice or natural infection in humans yielded anti-Lewis antibodies also. The ␤ chain of gastric H ؉ ,K ؉ -ATPase, the parietal cell proton pump involved in acid secretion, contained Lewis y epitopes; gastric mucin contained Lewis x and y antigenic determinants. Growth in mice of a hybridoma that secretes H. pylori-induced anti-Lewis y monoclonal antibodies resulted in histopathological evidence of gastritis, which indicates a direct pathogenic role for anti-Lewis antibodies. In conclusion, our observations demonstrate that molecular mimicry between H. pylori LPS and the host, based on Lewis antigens, and provide understanding of an autoimmune mechanism for H. pylori-associated type B gastritis.

Twenty-eight odontogenic abscesses were examined for the presence of black-pigmented Bacteroides spp. Of the 28 samples, 26 were found to contain one or more species of black-pigmented Bacteroides. Abscesses were divided into three categories according to the tissue of origin: endodontal, periodontal, and pericoronal. Four abscesses which developed after extraction were also examined. It was found that Bacteroides endodontalis, a newly described species of asaccharolytic black-pigmented Bacteroides, was isolated almost exclusively from periapical abscesses of endodontal origin. B. intermedius proved to be the most frequently isolated species in all of the samples. B. gingivalis was present in all of the periodontal abscesses studied, as well as in two endodontal abscesses. B. melaninogenicus was recovered once from a pericoronal abscess. Precautions for the isolation of B. endodontalis are discussed. Abscesses in the maxillofacial region are the most frequently occurring pyogenic infections in oral surgery. These infections are almost always of odontogenic origin. They may be classified according to the primarily infected tissues: endodontal (periapical), periodontal, and pericoronal. Other infections may be postoperative or may be caused by needleborne infections, jaw fractures, skin lesions, or extractions. Early research on the bacteriology of these kinds of infections suggested a major role for the viridans streptococci (13, 14). However, since the improvement of anaerobic sampling and cultivation techniques it was found that the majority of the microbiota of these abscesses consisted of obligately anaerobic microorganisms (1, 3, 5, 11). Within this group of bacteria gram-negative rods often are encountered. In addition, many other types of bacteria can be isolated, e.g., facultative and obligately anaerobic cocci and rods. Until now, few attempts have been made to correlate the different forms of dental abscesses with certain bacterial floras or specific combinations of bacterial species. Researchers in bacteriology often did not differentiate among the various forms of odontogenic abscesses, making correlation with the microbial flora involved impossible. Oguntebi and co-workers (12) found Fusobacterium spp. and Strepto

In this study, we evaluated the microbiological and clinical effects of mechanical debridement in combination with metronidazole and amoxicillin therapy in 48 patients with Actinobacillus actinomycetemcomitans‐associated periodontitis, 3 months and at least 24 months after active treatment. The results of this study showed that 47 out of 48 patients were still negative for A. actinomycetemcomitans subgingivally, at the mucous membranes, the tonsillar area and in the saliva, 2 years after therapy. The clinical results showed that a reduction of probing pocket depth, probing attachment level, bleeding index and plaque index was not only seen in the time between baseline and 3 months after therapy, but further clinical improvement was observed between 3 and 24 months after active treatment. We conclude that combined mechanical debridement and metronidazole plus amoxicillin therapy is very effective in suppressing A. actinomycetemcomitans below cultivable levels over a long period of time, suggesting elimination of this organism, and that recolonization of A. actinomycetemcomitans seems to be a rare event. The elimination of A. actinomycetemcomitans is paralleled by a further improvement of the periodontal status of the patients, even up to 24 months after active treatment.

Lactoferrin (LF), a cationic 80-kDa protein present in polymorphonuclear leukocytes and in mucosal secretions, is known to have antibacterial effects on gram-negative bacteria, with a concomitant release of lipopolysaccharides (LPS, endotoxin). In addition, LF is known to decrease LPS-induced cytokine release by monocytes and LPS priming of polymorphonuclear leukocytes. Its mechanism of action is incompletely understood. We have now demonstrated by in vitro-binding studies that LF binds directly to isolated lipid A and intact LPS of clinically relevant serotypes of the species which most frequently cause bacteremia (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa), as well as to lipid A and LPS of mucosal pathogens (among others, Neisseria meningitides and Haemophilus influenzae). Binding to LPS was inhibitable by lipid A and polymyxin B but not by KDO (3-deoxy-D-manno-octulosonate), a glycoside residue present in the inner core of LPS. Binding of LF to lipid A was saturable, and an affinity constant of 2 x 109 M-1 was calculated for the LF-lipid A interaction. Our data may explain, in part, the mechanism whereby LF exerts its antibacterial and anti-endotoxic effects. Further studies on the ability of LF to block the detrimental effects of LPS, both in vitro and in vivo, are warranted.