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.

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.

Systemic ofloxacin as adjunct to open flap surgery is able to suppress A. actinomycetemcomitans below detectable level in patients harboring this organism at baseline.

A. actinomycetemcomitans (Aa) can be transmitted among family members. The purpose of the present study was, to evaluate, whether A. actinomycetemcomitans is able to persist for a prolonged period of time in periodontally healthy subjects following elimination of this pathogen from diseased family members. In 14 periodontitis patients harboring Aa as well as in their 37 family members, the clinical (PPD, PAL, P1I, GI) and microbiological status (TSBV) was evaluated. After study patients received mechanical, surgical and antibiotic (3x375 mg amoxicillin+3x250 mg metronidazole/7 d) treatment, they, as well as their family members, were reassessed 3, 6, 9 and 12 months following therapy. From 13 spouses, 4 (31%) had periodontitis associated with Aa, 4 (31%) had periodontitis and no Aa, 2 (15%) were periodontally healthy and harbored Aa, 3 (23%) were healthy with no detection of Aa. From 24 off-springs, one (4%) had periodontitis associated with Aa, 8 (33%) were healthy and harbored Aa, 15 (63%) were healthy with no detection of Aa. In the 2 spouses and in 7 of the 8 offsprings being healthy, but harboring Aa, this pathogen still persisted at the 12-month appointment, after it had been eliminated from the diseased family members. Only one child became negative for Aa after 12 months. The results of this study indicate that A. actinomycetemcomitans is able to persist in the oral habitats of periodontally-healthy subjects for at least 12 months, after this pathogen had been eliminated from diseased family members. This might suggest that also in healthy family members, A. actinomycetemcomitans as a source of transmission should be eliminated to prevent reinfection.