SOURCE OF SUSPECTED PERIODONTAL PATHOGENS REEMERGING AFTER PERIODONTAL TREATMENT

To clarify the source of re-emerging periodontal pathogens after treat ment, we compared the ribotypes of Actinobacillus actinomycetemcomitan s, Porphyromonas gingivalis, Prevotella intermedia/Prevotella nigresce ns group and Campylobacter rectus before and after treatment in 7 peri odontitis patients and in 6 of the spouses. The patients harbored A. a ctinomycetemcomitans, P. gingivalis, P. intermedia/P. nigrescens group of C. rectus in their subgingival or salivary samples before treatmen t. The respective bacterial species were not detected 1 month after tr eatment, but reappeared by 6 months later. When available, 4 random co lonies of each of the 4 species were isolated from both subgingival an d salivary samples at each sampling occasion, the isolates were subcul tured, identified and typed applying pheno- and genotypic intraspecies characterization methods. Altogether 90 stains of A. actinomycetemcom itans, P. gingivalis, P. intermedia/P. nigrescens group and C. rectus were available from 2, 3, 2 and 4 patients, respectively. The pre- and post-treatment ribotypes of A. actinomycetemcomitans-, P. gingivalis- and P. intermedia/P. nigrescens group-isolates were identical in all respective patients. The pre- and post-treatment ribotypes of C. rectu s were identical in 1 of 4 patients, whereas 2 patients harbored a pre viously not detected post-treatment ribotype. To study the possibility that periodontitis patients may acquire strains from the spouse after treatment, isolates of A. actinomycetemcomitans, P. gingivalis, P. in termedia/P. nigrescens group and C. rectus (n = 95) from the patients' spouses were ribotyped and compared with those of the patients. The p atient exhibited his own post-treatment ribotypes, different from thos e of the spouse, of A. actinomycetemcomitans and P. gingivalis in 1 co uple and of P. intermedia/P. nigrescens group and C. rectus in 1 coupl e. In the 2 patients who harbored a previously not detected post-treat ment ribotype of C. rectus, on patient shared the new ribotype with th e spouse, whereas the other one did not. Although an exogenous source cannot be fully ruled out, the patient's own oral flora seems to be th e main source of re-emerging periodontal pathogens after treatment.