Abstract
Background and ObjectivesThe cytolethal distending toxin (Cdt) is a highly conserved exotoxin that are produced by a number of Gram negative bacteria, including Aggregatibacter actinomycetemcomitans, and affects mammalian cells by inhibiting cell division and causing apoptosis. A complete cdt-operon is present in the majority of A. actinomycetemcomitans, but the proportion of isolates that lack cdt-encoding genes (A, B and C) varies according to the population studied. The objectives of this study were to examine serotype, Cdt-genotype, and Cdt-activity in isolates of A. actinomycetemcomitans collected from an adolescent West African population and to examine the association between the carrier status of A. actinomycetemcomitans and the progression of attachment loss (AL).Materials and MethodsA total of 249 A. actinomycetemcomitans isolates from 200 Ghanaian adolescents were examined for serotype and cdt-genotype by PCR. The activity of the Cdt-toxin was examined by DNA-staining of exposed cultured cells and documented with flow cytometry. The periodontal status of the participants was examined at baseline and at a two-year follow-up.ResultsPresence of all three cdt-encoding genes was detected in 79% of the examined A. actinomycetemcomitans isolates. All these isolates showed a substantial Cdt-activity. The two different cdt-genotypes (with and without presence of all three cdt-encoding genes) showed a serotype-dependent distribution pattern. Presence of A. actinomycetemcomitans was significantly associated with progression of AL (OR = 5.126; 95% CI = [2.994–8.779], p<0.001).Conclusion A. actinomycetemcomitans isolated from the Ghanaian adolescents showed a distribution of serotype and cdt-genotype in line with results based on other previously studied populations. Presence of A. actinomycetemcomitans was significantly associated with disease progression, in particular the b serotype, whereas the association with disease progression was not particularly related to cdt-genotype, and Cdt-activity.
Highlights
Colonization of bacteria that adhere to and develop biofilm on teeth and the surrounding tissues are involved in the pathogenesis of periodontitis [1,2]
Presence of all three cdt-encoding genes was detected in 79% of the examined A. actinomycetemcomitans isolates
Presence of A. actinomycetemcomitans was significantly associated with progression of attachment loss (AL) (OR = 5.126; 95% CI = [2.994–8.779], p,0.001)
Summary
Colonization of bacteria that adhere to and develop biofilm on teeth and the surrounding tissues are involved in the pathogenesis of periodontitis [1,2]. More than 700 different bacterial species can be detected in samples from the subgingival plaque biofilm and other sites of the oral cavity [4] The majority of these species can be detected in samples from both healthy and periodontally diseased subjects. Aggregatibacter actinomycetemcomitans is often found in high numbers and proportions in plaque samples from subjects with periodontitis, of its localized aggressive form (LAP) [5]. This Gram-negative capnophilic coccobacillus is genetically heterogeneous and comprises distinct clonal lineages that may have different virulence potentials [6,7,8]. The objectives of this study were to examine serotype, Cdt-genotype, and Cdt-activity in isolates of A. actinomycetemcomitans collected from an adolescent West African population and to examine the association between the carrier status of A. actinomycetemcomitans and the progression of attachment loss (AL)
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