Actinomyces israelii in radicular cysts: a molecular study

The role of Actinomyces spp. and related organisms in cervicofacial infections: Pathomechanism, diagnosis and therapeutic aspects

Members of the Actinomyces genus and Actinomyces-like organisms (ALOs; namely Actinotignum, Arcanobacterium, Schaalia and Varibaculum) are Gram-positive, non-spore-forming rods that are commensal members of the human oral cavity, gastrointestinal tract, female genital tract and skin microbiota. Cervicofacial actinomycosis or "lumpy jaw syndrome" - the chronic, suppurative granulomatous disease caused by Actinomyces spp. And ALOs - is characterized by an initially slow and unspecific disease-presentation, which often mimics other pathologies, followed by the formation of painful abscesses and severe tissue destruction. Actinomycosis has been described as a rare disease, however, reliable epidemiological data are lacking. In addition, there is increasing awareness regarding the role of Actinomyces spp. in the development of osteoradionecrosis and medication-related osteonecrosis of the jaw. The aim of this narrative review is to succinctly summarize the current advances regarding the microbiological, clinical, diagnostic and therapeutic aspects of cervicofacial actinomycosis, in addition to the roles of Actinomyces species and ALOs as members of the oral microbiota and in dental biofilm, in other dental infections (caries, root canal infection, periapical infection, periodontitis) and osteonecrosis of the jaw, in the context of recent taxonomic changes affecting the genus. Our paper aims to be a blueprint for dentists, other physicians, microbiologists and researchers regarding the multifaceted field of cervicofacial actinomycosis.

Bacteria and virulence factors in periapical lesions associated with teeth following primary and secondary root canal treatment

AIM

This cross-sectional study aimed to investigate the microbial profile and to quantify the levels of endotoxins (LPS) and lipoteichoic acid (LTA) present in periapical lesions associated with root filled teeth and those that had received root canal retreatment. It also aimed to investigate the association between microorganisms and their virulence factors with clinical and radiographic features.

METHODOLOGY

Patients with periapical lesions in teeth with post-treatment endodontic disease following primary root canal treatment (n = 19) and unsuccessful root canal retreatment (n = 13) were treatment planned for endodontic microsurgery, where the periapical lesions were collected. Clinical and radiographic data were also collected. For microbiological analysis, nested polymerase chain reaction was used to detect 17 bacterial species. Levels of LPS and LTA were determined using limulus amebocyte lysate and enzyme-linked immunosorbent assays, respectively. The Student t-test or Wilcoxon-Mann-Whitney tests were applied to compare the data on LPS and LTA with clinical and radiographic features. The associations between the clinical and radiographic features and the bacterial species were analysed using the Fisher's exact test. A significance level of 5% was adopted.

RESULTS

Bacterial DNA, LPS and LTA were detected in all samples. Parvimonas micra was the most commonly detected species in all groups, followed by Enterococcus faecalis, Fusobacterium nucleatum and Porphyromonas endodontalis. The type of endodontic treatment, whether a primary root canal treatment or retreatment, was not associated with the presence of any bacterial species in periapical lesions. The levels of LPS and LTA in periapical lesions of root filled teeth were not significantly different from those that had been retreated. Associations between the levels of LPS and LTA with clinical signs and symptoms were found. No association was found between specific bacteria and clinical features.

CONCLUSION

Periapical lesions associated with teeth after primary root canal treatment and retreatment had similar polymicrobial composition. The levels of LPS and LTA in periapical lesions associated with teeth after primary root canal treatment and retreatment were similar, and both were associated with the same symptomatology.

Clinicopathological and ultrastructural characterization of periapical actinomycosis

Background

The aim of the present study was to analyze the clinicopathological and the ultrastructural features of periapical actinomycosis (PA) cases.

Material and Methods

Data from the files of an oral pathology laboratory were retrieved and the findings of histopathological analysis were evaluated. Hematoxylin–eosin (HE), a modified Brown & Brenn, and Grocott stains as well as ultrastructural analysis using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were utilized.

Results

Six cases were obtained, 4 females and 2 males, with a mean age of 34 year-old. Two cases were symptomatic, lower teeth and the anterior region were more commonly affected, and all cases were characterized by periapical radiolucencies. All cases presented sulfur granules with a ray-fungus or club-shaped pattern of the Splendore-Hoeppli phenomenon in HE-stained sections, with filamentous gram-positive bacteria aggregates highlighted by the modified Brown & Brenn stain. SEM analysis revealed abundant packed rod-like and filamentous bacteria associated with an extracellular amorphous material. EDX analysis showed predominant picks of calcium and sulfur in actinomycotic colonies.

Conclusions

Our findings suggest that PA manifests either clinically and radiologically as a non-specific and heterogeneous condition and that the actinomycotic colonies consist in a calcium- and sulfur-rich matrix. Furthermore, the results highlight the importance of submitting periapical specimens after surgical removal to histopathological analysis.

Key words:Actinomyces, actinomycosis, periapical diseases.

Apical periodontitis: preliminary assessment of microbiota by 16S rRNA high throughput amplicon target sequencing

Background

Apical periodontitis includes periapical granulomas and radicular cysts, which are histologically distinguished by the absence and the presence of an epithelial lining, respectively. The main cause of apical periodontitis is the bacterial colonization of the root canal space. This research aimed at assessing whether and how periapical granulomas and radicular cysts differ in terms of microbiota using high throughput amplicon target sequencing (HTS) techniques.

Methods

This study included 5 cases of Periapical Granulomas (PGs) and 5 cases of Radicular Cysts (RCs) selected on the base of histology out of 37 patients from January 2015 to February 2016. Complete medical history, panoramic radiograms (OPTs) and histologic records of each patient were assessed. Only lesions greater than 1 cm in diameter and developed in proximity to teeth with bad prognosis were included. The microbiota present in periapical granulomas and radicular cysts thus retrieved was finely characterized by pyrosequencing of the 16S rRNA genes.

Results

The core of OTUs shared between periapical granulomas and radicular cysts was dominated by the presence of facultative anaerobes taxa such as: Lactococcus lactis, Propionibacterium acnes, Staphylococcus warneri, Acinetobacter johnsonii and Gemellales. L. lactis, the main OTUs of the entire datasets, was associated with periapical granuloma samples. Consistently with literature, the anaerobic taxa detected were most abundant in radicular cyst samples. Indeed, a higher abundance of presumptive predicted metabolic pathways related to Lipopolysaccharide biosynthesis was found in radicular cyst samples.

Conclusions

The present pilot study confirmed the different microbial characterization of the two main apical periodontitis types and shade light on the possible role of L. lactis in periapical granulomas.