Isolation of Actinomyces viscosus from two patients with clinical infections

Clinical Characteristics of Actinomyces viscosus Bacteremia

Background and Objectives: Actinomyces species are part of the normal flora of humans and rarely cause disease. It is an uncommon cause of disease in humans. The clinical features of actinomycosis have been described, and various anatomical sites (such as face, bones and joints, respiratory tract, genitourinary tract, digestive tract, central nervous system, skin, and soft tissue structures) can be affected. It is not easy to identify actinomycosis because it sometimes mimics cancer due to under-recognition. As new diagnostic methods have been applied, Actinomyces can now more easily be identified at the species level. Recent studies have also highlighted differences among Actinomyces species. We report a case of Actinomyces viscosus bacteremia with cutaneous actinomycosis. Materials and Methods: A 66 years old male developed fever for a day with progressive right lower-leg erythematous swelling. Blood culture isolates yielded Actinomyces species, which was identified as Actinomyces viscosus by sequencing of the 16S rRNA gene. In addition, we searched for the term Actinomyces or actinomycosis cross-referenced with bacteremia or "blood culture" or "blood stream" from January 2010 to July 2020. The infectious diseases caused by species of A. viscosus from January 1977 to July 2020 were also reviewed. Results: The patient recovered well after intravenous ampicillin treatment. Poor oral hygiene was confirmed by dental examination. There were no disease relapses during the following period. Most cases of actinomycosis can be treated with penicillin. However, clinical alertness, risk factor evaluation, and identification of Actinomyces species can prevent inappropriate antibiotic or intervention. We also compiled a total of 18 cases of Actinomyces bacteremia after conducting an online database search. Conclusions: In summary, we describe a case of fever and progressive cellulitis. Actinomyces species was isolated from blood culture, which was further identified as Actinomyces viscosus by 16S rRNA sequencing. The cellulitis improved after pathogen-directed antibiotics. Evaluation of risk factors in patients with Actinomyces bacteremia and further identification of the Actinomyces species are recommended for successful treatment.

Pyothorax Caused by Anaerobic Organisms

Pyothorax was caused by anaerobic organisms including Actinomyces viscosus, anaerobic streptococcus species, and Bacteroides species in a 67-year-old man. Despite administration of antibiotics and continuous irrigation of the abscess cavity with a povidone iodine solution, the pyothorax was complicated by pneumonia and the patient died of sepsis caused by methicillin-resistant Staphylococcus aureus on the 44th hospital day. This case is the 10th report of thoracic Actinomyces viscosus infection in English literature.

Isolation of Wolinella recta and Actinomyces viscosus from an actinomycotic chest wall mass

In this Note we describe a patient with an actinomycotic chest wall mass from which large numbers of Wolinella recta and Actinomyces viscosus organisms were isolated. This is the first reported association of W. recta with extraoral infection and the tenth report of lung infection by A. viscosus.