Pathogenicity of exopolysaccharide‐producing Actinomyces oris isolated from an apical abscess lesion

Abstract

Aim To demonstrate a capacity for producing exopolysaccharides (EPSs) and an ability to form biofilm on abiotic materials of Actinomyces oris strain K20. Methodology The productivity of EPSs and the ability to form biofilm of strain K20 were evaluated by measuring viscosity of spent culture media and by scanning electron microscopy (SEM) and the biofilm assay on microtitre plates, respectively. High‐performance liquid chromatography was used to determine the chemical composition of the viscous materials. To examine the role of the viscous materials attributable to the pathogenicity in this organism, the ability of strain K20 to induce abscess formation was compared in mice to that of ATCC 27044. Results The viscosity of the spent culture media of K20 was significantly higher than that of ATCC 27044. Strain K20 showed dense meshwork structures around the cells and formed biofilms on microtitre plates, whereas ATCC 27044 did not. Chemical analysis of the viscous materials revealed that they were mainly composed of neutral sugars with mannose constituting 77.5% of the polysaccharides. Strain K20 induced persistent abscesses in mice lasting at least 5 days at a concentration of 108 cells mL−1, whereas abscesses induced by ATCC 27044 healed and disappeared or decreased in size at day 5. Conclusions Strain K20 produced EPSs, mainly consisting of mannose, and formed biofilms. This phenotype might play an important role for A. oris to express virulence through the progression of apical periodontitis.

Actinomycosis: An infrequent disease in renal transplant recipients?

“…Actinomycosis lacks virulence, and dissemination is mostly locoregional, with a high risk of abscess or fistula. The lack of virulence could be explained by the production of a biofilm composed of exopolysaccharides . This biofilm increases host phagocytic cells without fully eliminating the bacteria and creates local inflammation with neutrophil diapedesis .…”

“…16,17 This biofilm increases host phagocytic cells without fully eliminating the bacteria 16,17 and creates local inflammation with neutrophil diapedesis. 16 Furthermore, co-infecting bacteria, which occur frequently with Streptococci, Staphylococci, or anaerobic bacteria, 5 and granulomatous organization decrease phagocytic activity in the host. 3,16 However, no co-infection was reported in our study.…”

“…16 Furthermore, co-infecting bacteria, which occur frequently with Streptococci, Staphylococci, or anaerobic bacteria, 5 and granulomatous organization decrease phagocytic activity in the host. 3,16 However, no co-infection was reported in our study. Acquired immunity is also involved.…”

“…The In the literature, treatment is lengthy, despite preserved sensitivity to penicillin, 21 because Actinomyces lead to avascular infectious lesions 21 in tissue cages. 16 In 2000, Russo 22 recommended high doses of intravenous penicillin for 2-6 weeks, followed by high doses of oral penicillin for 6-12 months to prevent relapse. Several authors [23][24][25][26] are now in agreement on a recommendation for a shorter treatment and a lower dose in the case of an early diagnosis.…”

A comparative assessment of the antibacterial activity of root canal sealers on 2 Actinomyces species: An in vitro study

“…2 A recent study by Yamane et al showed that Actinomyces species have a capacity to produce exopolysaccharides (EPSs), and thus contribute to biofilm formation, which can be essential to their pathogenic potential and the development of persistent infections in the periapical tissues. 3 Bacterial cells embedded in an extracellular matrix can more easily survive in a nutritionally deprived environment and can evade neutrophilic phagocytosis and other host defense mechanisms. 4 Actinomycotic colonies are known to have low pathogenicity, they also induce a minimal host response in the form of chronic endodontic infections, accompanied by the sinus tract, which discharges bright yellow granules referred to as sulfur granules.…”