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BLACK-PIGMENTED GRAM-NEGATIVE ANAEROBES IN BRAZILIAN ADULTS WITH PERIODONTAL DISEASE

Rodrigues, P.H.*, Carvalho, S.A., Carvalho, M.A.R., Farias, L.M., Petrillo-Peixoto, M.L.
Laboratório de Microbiologia Oral e Anaeróbios, Departamento de Microbiologia/ICB/UFMG - Belo Horizonte, Minas Gerais, Brasil.

The aim of the present study was to determine by standard cultivation procedures the frequency of black-pigmented Gram-negative anaerobes detection from periodontal pockets of Brazilian patients. Thirty three patients with periodontal disease were included in this study (24 female, 9 male; mean age 26 years). The clinical specimens were collected with paper points that were immediately immersed in Ringer-PRAS solution. Serial 10-fold dilutions were performed and an aliquot of each dilution was cultivated in Tryptic Soy Agar supplemented with 5% human blood, hemin 5 mg/mL and menadione 10 mg/mL. The plates were incubated in anaerobic chamber (85% N₂, 5%C0₂ and 10% H₂) at 37 °C for up to 21 days. All the procedures were performed under anaerobic conditions. The bacterial isolates identification was made as described by Summanen et a. (1993). One hundred fifty six strains were isolated and identified as: Prevotella intermedia/Prevotella nigrescens group (84.6%), Porphyromonas gingivalis (11.5%), and Prevotella sp. (3.9%). All P. gingivalis strains were isolated together with P. intermedia/P. nigrescens group. Black-pigmented Gram-negative anaerobes were not isolated from 2 patients. The frequencies of detection of P. intermedia/P. nigrescens group, P. gingivalis, and Prevotella sp. were 93.9,12.1 and 6%, respectively. Our results showed a high frequency of detection of Prevotella intermedia/Prevotella nigrescens from periodontal pockets of Brazilian patients with periodontal disease and a low recovery of P. gingivalis. There are very few reports concerning the frequencies of detection of black-pigmented Gram-negative anaerobes in the Brazilian population. The development of this kind of study is very important because it allows us to know better about the prevalence of the different pathogens involved in periodontal disease in our country. Studies to further characterize the physiology of those isolates are under way.

Supported by FAPEMIG, CNPq, CAPES and PRPq/UFMG.