Periodontitis is a chronic infectious disease which leads to the destruction of the gingiva
and alveolar bone until tooth loss. The evidence of bacterial specification in periodontitis
patients has led to periodontal instrumentation combined with systemic antibiotic
treatment. The main objectives of the study were 1) to evaluate the efficacy of
instrumentation according to the presence of pathogens, 2) to determine the spectrum of
pathogens and 3) to compare the total degree of colonisation with the number of the
Altogether 140 patients aged 13–68 years were studied. Samples from the
periodontal pockets were placed in anaerobic transport vials; five-fold dilutions were
made and seeded onto the Brucella and BVTS agar plates. The pathogens were identified
according to their colonial and cellular morphology, the potency disk pattern and the
After periodontal instrumentation no pathogens were isolated in 46 patients,
94 were colonised with 1–5 pathogenic species. Fifty-three patients harboured one
pathogen, 27 harboured two, 12 three and two patients harboured 5 pathogens. The total
load of colonisation varied from 0 to 8.4 CFU/mL (median 5.5 CFU/mL), being
positively correlated with the number of isolated pathogens (p<0.001). The P.
intermedia/nigrescens group was present in 37, A. actinomycetemcomitans in 36 P.
micros in 12, P. gingivalis in 7, B. forsythus in 4 and C. rectus in 2 patients. Higher
colonisation with oral bacteria indicates presence of periodontal pathogens. Of these
patients 33% remained pathogen-free, indicating the success of primary mechanical
therapy. However, 67% of the patients were also colonised with one to five different
pathogens. Therefore, for the successful diagnosis and therapy of periodontal diseases,
individual microbiological examination of each patient is recommended.