Methods: 52 C. periodontii clinical isolates in subgingival specimens from severe periodontitis (51) and peri-implantitis (1) adult subjects were identified from flat, transparent, rapidly-spreading, non-corroding, colonies with irregular borders on anaerobically-incubated enriched Brucella blood agar as large, gram-negative, non-spore forming, obligately anaerobic, catalase-negative, multi-flagellated, serpentine motile rods with a centipede-like appearance in wet-mount darkfield microscopic preparations (Lai et al. 1983). Species identification was confirmed with whole chromosomal C. periodontii-specific DNA probe dot-blot testing on a subset of isolates. The organisms were tested in vitro for susceptibility to doxycycline at 2 µg/ml, amoxicillin at 2 µg/ml, and metronidazole at 4 µg/ml, with C. periodontii drug resistance noted when clinical isolate growth occurred on both antibiotic-supplemented and non-antibiotic supplemented enriched Brucella blood agar plates (van Winkelhoff et al. 2000; Rams et al. 2011).
Results: C. periodontii in subjects averaged 1.2 ± 0.2 (SE) % (range 0.01-9.1%) of total cultivable subgingival anaerobic counts on non-antibiotic supplemented plates. In vitro C. periodontii resistance to doxycycline at 2 µg/ml was detected in 2 (3.9%) clinical isolates. No in vitro resistance to amoxicillin at 2 mg/ml or metronidazole at 4 mg/ml was found among any of the 52 C. periodontii clinical isolates studied.
Conclusions: C. periodontii clinical isolates appear to be highly susceptible in vitro to therapeutic concentrations of antibiotics frequently used in the treatment of severe human periodontitis and peri-implantitis lesions.
Keywords: Antimicrobials, Bacterial, Human, Periodontal disease and Periodontal organisms
See more of: Periodontal Research - Therapy