Analysis of leukotoxin gene types of Actinobacillus actinomycetemcomitans in brazilians with aggressive periodontitis

Abstract

Actinobacillus actinomycetemcomitans (Aa) is considered a major etiologic agent of aggressive periodontitis but this species has also been associated with other forms of periodontal disease. Further, highly leukotoxic strains are related to severity of disease. The purpose of this study was to determine the prevalence of Aa and the occurrence of the leukotoxin gene 530-bp deletion in patients with generalized aggressive periodontitis (GAP) from a Brazilian population. Thirty periodontally healthy and 29 GAP subjects participated in the study. Full-mouth periodontal examination including probing pocket depth (PPD), clinical attachment level (CAL), supragingival biofilm (SB) and bleeding on probing (BOP) was carried out at 6 sites/tooth for all subjects. Whole saliva samples were collected for bacterial DNA isolation. The detection of Aa and the presence of the 530-bp genetic deletion were determined directly in the samples by polimerase chain reaction. Differences on clinical and microbiological parameters between the two groups were sought using the Mann-Whitney, Fisher´s exact and Chi-square tests. Associations between clinical and microbiological parameters were tested using the Pearson correlation coefficient. Aa was detected significantly more often in GAP patients (96.6%) than healthy subjects (76.7%) (χ 2 = 4.9; p < 0.05). The genetic deletion was observed in 16 of the 28 (57.1%) GAP patients who were positive for Aa. However, none of the samples from individuals with periodontal health presented this deletion (χ 2 = 19.15; p < 0.001). Strong correlations between the presence of the deletion and PPD (r=0.312, p<0.05), CAL (r=0.409, p<0.01), SB (r=0.278, p<0.05) and BOP (r=0.406, p<0.01) were found. A high frequency of Aa was observed in Brazilians with GAP and periodontal health. However, the highly leukotoxic genotype was observed only in subjects with generalized aggressive disease.

Periodontal microbiology in Latin America

“…Traditional PCR identifies the presence or absence of a microorganism, and real-time PCR provides quantitative results (112). PCR is widely used in periodontal microbiology to identify specific microorganisms and their virulence traits (12,64,67,88,161). Loop mediated isothermal amplification (LAMP) is a point-of-care assay, which may be used to screen for periodontal pathogens in large geographic areas and populations (124).…”

“…In chronic periodontitis, the prevalence of A. actinomycetemcomitans periodontitis was 18% with a predominance of biotype II . Leukotoxic strains of A. actinomycetemcomitans (JP2 clone, serotype b) were a common finding in aggressive periodontitis in South America, with a particularly high prevalence in Brazil . Cortelli et al.…”

“…Overall, the chlorhexidine rinse treatment showed a significant reduction in the proportions of red and orange bacterial complexes nance of biotype II (125). Leukotoxic strains of A. actinomycetemcomitans (JP2 clone, serotype b) were a common finding in aggressive periodontitis in South America, with a particularly high prevalence in Brazil (84,161). Cortelli et al (42) found a higher occurrence of A. actinomycetemcomitans and of highly leukotoxic strains in Brazil than in other South American countries, and linked highly leukotoxic strains to a greater loss of periodontal attachment compared with minimally leukotoxic strains.…”