Microbiological and Clinical Aspects of Actinomyces Infections: What Have We Learned?

Gut microbiota's influence on erysipelas: evidence from a two-sample Mendelian randomization analysis

Background

Previous studies have suggested a link between gut microbiota and skin diseases, including erysipelas, an inflammatory skin condition. Despite this, the precise nature of the relationship between erysipelas and gut microbiota remains unclear and subject to debate.

Methods

We conducted a Mendelian Randomization (MR) analysis using publicly available summary data from genome-wide association studies (GWAS) to explore the potential causal relationship between gut microbiota and erysipelas. Instrumental variables (IVs) were identified using a comprehensive set of screening methods. We then performed MR analyses primarily using the Inverse Variance Weighted (IVW) method, complemented by alternative approaches such as MR Egger, weighted median, simple mode, and weighted mode. A series of sensitivity analyses, including Cochran's Q test, MR-Egger intercept test, Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO) test, and a leave-one-out test, were executed to ensure the robustness and validity of our findings.

Results

We identified potential associations between erysipelas and various gut microbiota, including Alcaligenaceae (OR 1.23; 95% CI 1.06-1.43; p=0.006), Rikenellaceae (OR 0.77; 95% CI 0.67-0.90; p=0.001), and others. Notably, associations with Actinomyces, Lachnospiraceae NC2004 group, Ruminiclostridium 9, Ruminococcaceae UCG014, Odoribacter, and Actinobacteria were also observed. Sensitivity analyses confirmed the robustness of these associations.

Conclusion

Our MR analysis suggests both potentially beneficial and harmful causal relationships between various gut microbiota and the incidence of erysipelas. This study provides new theoretical and empirical insights into the pathogenesis of erysipelas and underscores the potential for innovative preventive and therapeutic approaches.

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.

Unmasked immune reconstitution inflammatory syndrome towards B-cell non-Hodgkin lymphoma during treatment of esophageal actinomycosis in a patient with advanced HIV: a case report

BACKGROUND

Actinomycosis is an unusual chronic bacterial infection, even rarer in people living with HIV. It is not considered an AIDS-defining disease. However, the role in co-presentation or overlap with other opportunistic conditions of advanced HIV is unknown.

CASE PRESENTATION

A 49-year-old Peruvian male presented with a 4-month history of dysphagia, odynophagia, hyporexia and wasting. He underwent an upper digestive endoscopy, in which ulcers with a necrotic center were observed, therefore, the initial diagnostic assumption was esophageal cancer. Subsequent pathology report excluded neoplasms and confirmed the diagnosis of actinomycosis. Serology for human immunodeficiency virus was requested, yielding a positive result. Antimicrobial treatment with amoxicillin and antiretroviral therapy were indicated, with slow clinical improvement. After 4 months, epigastric discomfort presented, for which a new upper digestive endoscopy was performed, revealing a deep gastric ulcer, which was compatible with diffuse large B-cell non-Hodgkin lymphoma.

CONCLUSION

Esophageal actinomycosis in people living with HIV is very rare. We suggest HIV-associated immunosuppression is not enough to allow for actinomycosis to develop, and masked underlying entities should be sought. The existence of such entities in people living with HIV should raise awareness of the possibility of unmasked immune reconstitution inflammatory syndrome once treatment has started.

A rare case of male Fournier's gangrene with mixed Actinomyces turicensis infection

BACKGROUND

Fournier's gangrene (FG), a urological emergency with high mortality, is an infectious necrotizing fasciitis of the perineal and genital regions. The majority of FG is caused by polymicrobial organisms involving mixed aerobes and anaerobes but rarely reveals Actinomyces species.

CASE PRESENTATION

We report a healthy 67-year-old Asian male who presented with rapidly progressive painful swelling of the scrotum. Clinically diagnosed with FG, the patient underwent an emergency radical debridement, followed by broad-spectrum antibiotics and negative pressure wound therapy. The identification of the causative microorganisms showed Actinomyces turicensis and the antibiotic treatment was adjusted accordingly. After wound bed preparation, we took split-thickness skin grafts to cover the scrotal wound. Active management to minimize faecal contamination was applied throughout the whole course of treatment and repair. The patient was satisfied with the outcome. This was an extremely rare case of A. turicensis as the main causative pathogen of FG.

CONCLUSIONS

FG due to Actinomyces species is rarely reported, but we should still consider this pathogenic microorganism that has long been neglected.