Distribution of biotypes and leukotoxic activity of Aggregatibacter actinomycetemcomitans isolated from Brazilian patients with chronic periodontitis

Abstract

Aggregatibacter actinomycetemcomitans is an important etiologic agent of the periodontitis and is associated with extra-oral infections. In this study, the detection of the ltxA gene as well as the ltx promoter region from leukotoxic A. actinomycetemcomitans isolated from 50 Brazilian patients with periodontitis and 50 healthy subjects was performed. The leukotoxic activity on HL-60 cells was also evaluated. Leukotoxic activity was determined using a trypan blue exclusion method. The 530 bp deletion in the promoter region was evaluated by PCR using a PRO primer pair. A. actinomycetemcomitans was detected by culture and directly from crude subgingival biofilm by PCR using specific primers. By culture, A. actinomycetemcomitans was detected in nine (18%) of the periodontal patients and one (2%) healthy subject. However, by PCR, this organism was detected in 44% of the periodontal patients and in 16% of the healthy subjects. It was verified a great discrepancy between PCR detection of the ltx operon promoter directly from crude subgingival biofilm and from bacterial DNA. Only one periodontal sample harbored highly leukotoxic A. actinomycetemcomitans. Moreover, biotype II was the most prevalent and no correlation between biotypes and leukotoxic activity was observed. The diversity of leukotoxin expression by A. actinomycetemcomitans suggests a role of this toxin in the pathogenesis of periodontal disease and other infectious diseases.

Chemokine Receptor 2 (CXCR2) Gene Variants and Their Association with Periodontal Bacteria in Patients with Chronic Periodontitis

“…Although A. actinomycetemcomitans is more often associated with AgP than with CP, Gaetti-Jardim et al [43] detected the bacteria by the PCR method in 44% of CP patients. In the Brazilian study, the IL-4 haplotypes, but not the IL-8 haplotypes, were associated with the presence of A. actinomycetemcomitans in CP patients [41].…”

Periodontal microbiology in Latin America

“…Another study by Cortelli et al. recovered the highly leukotoxic genotype from young subjects with aggressive periodontitis and suggested a role for A. actinomycetemcomitans leukotoxic strains in the development of the disease, and possibly also in chronic periodontitis . Cortelli et al.…”

“…The leukotoxin may be a particularly potent virulence factor in young individuals, who may not yet have developed effective immunity against the organism (92,134,142). However, individuals colonized by A. actinomycetemcomitans clones other than the JP2 clonal type can also develop periodontitis (6,44,74,89,137). Subgingival A. actinomycetemcomitans was detected in 26% of subjects with chronic periodontitis from the Umutina Indian Reservation at the Mato Grosso region of Brazil, and none of the A. actinomycetemcomitans isolates was of the leukotoxic phenotype (202).…”

Aggregatibacter actinomycetemcomitans: Patógeno importante en la periodontitis

“…Su nula acción, sobre determinadas células como epitelio, fibroblastos, plaquetas, eritrocitos, esta comprobado de estudios in vitro. 8,9,15,16 Toxina de distensión citoletal (CDT): Esta toxina es codificado por el operón cdtABC, e inhibe la progresión del ciclo celular en G2, llevándola a una apoptosis celular. Así también puede inhibir la proliferación de linfocitos CD4, impidiendo una respuesta adecuada del sistema inmune.…”