ACTINOBACILLUS-ACTINOMYCETEMCOMITANS AND PORPHYROMONAS-GINGIVALIS IN YOUNG CHINESE ADULTS

The aim of this study was to determine the presence or absence of Acti nobacillus actinomycetemcomitans and Porphyromonas gingivalis in young Chinese adults and to examine the A. actinomycetemcomitans is elates from positive subjects with regard to the serotype distribution, prese nce of the leukotoxin gene lktA and the promoter for the leukotoxin op eron as well as the incidence of phage Aa phi 23. Sixty subjects, work ing in a knitting factory in the Province of Guangzhou, People's Repub lic of China, were investigated. Subgingival microbial samples were ta ken from both upper first molars. They were cultured both anaerobicall y and in 5% CO2. P. gingivalis was found in 33 subjects. On average, i t constituted 7% of the total anaerobic cultivable counts. A. actinomy cetemcomitans was detected in 37 subjects of which seven yielded count s >10(5). Twenty-one subjects were positive for both organisms. A. act inomycetemcomitans serotype a was found in 9 subjects, serotype c was found in 23 and serotype e in 5. A. actinomycetemcomitans sero-types b and d were not detected in any subjects. Presence of the leukotoxin g ene lktA was demonstrated for all A. actinomycetemcomitans isolates; h owever, none of the A. actinomycetemcomitans strains from the present study had a deletion in the promoter region of the leukotoxin operon. The results of this investigation show a high frequency of the putativ e periodontal pathogens P. gingivalis and A. actinomycetemcomitans and corroborate the concept that there is variation in virulence and path ogenic potential among isolates from different subjects.