Antibiotic susceptibility of putative periodontal pathogens in advanced periodontitis patients.

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.