Leite, A.A.; Ortega, L.S*.; Macedo, A.M.; Carvalho, M.A.R., Moreira, E.S.A.
Universidade Federal de Minas Gerais, Minas Gerais, Brasil.

Actinobacillus actinomycetemcomitans is a Gram-negative capnophilic cocobacillus which can cause certain forms of human periodontal disease, including localized juvenile periodontitis and severe extra-oral infections. The microorganism can be isolated from the oral cavities of non-human primates as well as from human beings. The mechanisms behind the pathogenicity of A. actinomycetemcomitans are not known, but the microorganism produces an assemblage of potential virulence properties and determinants. Recent evidence suggesting variation in the pathogenicity of different strains within bacterial species introduces a second layer of complexity. Defining the clonal nature of periodontal pathogens and discrimination of virulent from nonvirulent strains may provide a clue to the mechanism of breakdown of periodontal tissue. In the present study, restriction endonuclease analysis and arbitrarily primed PCR were used to fingerprint 30 strains of A. actinomycetemcomitans (14 isolated from human patients, 14 strains from marmosets and the reference strains ATCC 29523 e FDC Y4). Restriction enzymes suitable for strain discrimination were identified and then used to assess the genetic diversity. The endonuclease Hae III divided the marmoset strains in two groups and the human strains in six groups. Hybridization assays using the multifocus probe 33.15 (5'... AGAGGTGGGCAGGTGG...3') allowed the distinction of five groups among the marmoset isolates and seven groups for the human isolates. PCR amplification reactions using (GT11 as a primer resulted in DNA banding patterns that generally consisted of 16 to 24 amplicons ranging in size from 0.5 to 1.5 Kb. (GT11 detected five genotypes among the human isolates of A. actinomycetemcomitans. The question of whether a single clone or multiple clones of a bacterial species can colonize an individual is relevant. Our results indicates the presence of more than one clonal type isolated from the same host.

Supported by FAPEMIG and CNPq.               ABSTRACT FORM Surname: ORTEGA First Name: LEILA SADDI Institution: UNIVERSIDADE FEDERAL DE MINAS GERAIS Department: MICROBIOLOGY Address: Avenida Antônio Carlos, 6627 - CXP 486 Zip Code, City: 31270 - 901 / BELO HORIZONTE - MG Country: BRAZIL Tel.: (031) 499 2754 Fax: (031) 499 2525 or (031) 449 2730 E-mail: spangler@mono.icb.ufmg.br Presentation preferred: Poster