In the present study, the antibiotic susceptibility of most prevalent micro-organisms in advanced periodontitis patients was evaluated. In 56 patients, pooled subgingival plaque samples were taken from the deepest site of each quadrant and were cultivated anaerobically. From each patient, the 4 most frequently encountered types of bacterial colonies were subcultured and identified (Rapid ID 32 A). From all bacterial species identified in the 224 subcultures, the 4 most prevalent were used for susceptibility testing to tetracycline, metronidazole and amoxicillin/clavulanate using the E Test. The most prevalent microorganisms were Fusobacterium nucleatum (38/214), Peptostreptococcus micros (33/214), Prevotella oralis (33/214) and Porphyromonas gingivalis (32/214). Regarding antibiotic susceptibility it could be shown that minimal inhibitory concentration (MIC) in all cases was below antibiotic concentrations achievable in gingival crevicular fluid. However, antibiotic resistance was seen in 3 to 29% of the investigated microorganisms.

Considerable problems have been reported in the eradication of Actinobacillus actinomycetemcomitans from periodontal sites. The present communication describes the 2-year results of a comprehensive combined mechanical/surgical and adjunctive minocycline (200 mg/day for 3 and another 2 weeks) treatment regimen in 28 patients with A. actinomycetemcomitans-associated periodontitis. Elimination of A. actinomycetemcomitans at periodontal sites was a prerequisite for gain of clinical attachment of > or = 2 mm or decrease of probing depth to < or = 4 mm after subgingival scaling plus minocycline (p < 0.01). Whereas 2 years after active treatment A. actinomycetemcomitans could not be detected at monitored sites in 23 patients, the organism was found on buccal mucosa and in saliva in 17 and 12 cases, respectively. One or 2 years after periodontal surgery, there was a significant association between log10-numbers of A. actinomycetemcomitans in buccal samples and numbers of residual pockets of > or = 7 mm as well as gingival sites with overt gingivitis (R2 = 0.687, p < 0.001). Present results indicate failure of an even prolonged administration of adjunctive minocycline to eliminate oral A. actinomycetemcomitans in most cases of A. actinomycetemcomitans-associated periodontitis.

In the present study, a total of 619 subgingival and extracrevicular samples from 66 early-onset periodontitis, 42 adult periodontitis/gingivitis and 36 treated Actinobacillus actinomycetemcomitans-associated periodontitis patients were selectively cultivated for presence of A. actinomycetemcomitans. The organism was recovered from 68% cases with early-onset periodontitis, 24% cases with adult periodontitis/gingivitis and 50% of treated patients. Associations between recovery from pooled subgingival plaque and samples from extracrevicular locations as well as between different extracrevicular samples, were not heterogeneous with regard to different groups with the exception for cheek/saliva comparisons (odds ratios: early-onset periodontitis 825; adult periodontitis 8.1; treated patients 117; 0.05 < p < 0.1). For associations between recovery of A. actinomycetemcomitans from pooled subgingival plaque/extracrevicular samples, Mantel-Haenszel's odds ratios of between 12.2 and 21.6 were calculated (p < 0.0001). The organism was isolated from 17 cheek mucosa samples of 18 patients identified as still harboring the organism after therapy. Present results point to the considerable value of cheek mucosa samples especially in treated patients to diagnose persistent A. actinomycetemcomitans colonization of the oral cavity.

The following communication is a case history of an 11 year-old female patient suffering from Papillon-Lefèvre syndrome. Since a massive occurrence of A. actinomycetemcomitans had been found in the subgingival microflora of the periodontal pockets, the patient was treated with repeated subgingival scaling, with an adjunct Amoxicillin and Metronidazol treatment. A bacteriological examination of the girl's family proved that several brothers and sisters as well as one parent also carried. A. actinomycetemcomitans, showing 3 different strains of this bacterium within the family. An immunohistological examination of the gingival tissue showed a massive inflammatory infiltrate which was dominated by plasma cells. The histological investigation of the first molars did not show morphological abnormalities of the root cementum. Posttreatment clinical and radiographical improvement of the periodontal conditions is reported despite the recurrent finding of A. actinomycetemcomitans.

Multiple periodontal abscesses were reported in medically compromised patients. We examined patients with a non-contributory medical history referred for the treatment of numerous periodontal abscesses. All patients had taken oral broad spectrum antibiotics 1 to 3 weeks prior to the outburst of the abscesses (8 patients: penicillin, 2 patients: tetracycline). The patients suffered from advanced periodontal disease, 82% of the examined sites showed probing depths greater than 3 mm, 56% attachment loss greater than 3 mm. Subgingival plaque samples were analysed from 2 different abscess sites. Bacteroides gingivalis (19/20), Fusobacterium nucleatum (13/20) and Streptococcus intermedius (13/20) were the most prevalent anaerobic microbiota. Strains resistant to the prescribed antibiotic were found in 55% (11/20) of the subgingival plaque samples. It was concluded that in patients with advanced periodontal disease, systemic antibiotic therapy without subgingival debridement may change the composition of the subgingival microbiota, thus favouring the outburst of multiple periodontal abscesses.