The polymicrobial Actinomyces naeslundii and Pseudomonas aeruginosa sepsis in a patient with ulcerative colitis 2 months after colonoscopy

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.

Oral, Cloacal, and Hemipenal Actinomycosis in Captive Ball Pythons (Python regius)

Ball pythons (Python regius) are one of the most commonly kept and bred reptiles in captivity. In a large ball python breeding colony, a unique syndrome characterized by granulomatous inflammation of the cloaca and hemipenes (phalli) was observed in 140 of 481 (29.1%) breeding males, but only one of 1,446 breeding females. Lesions were absent in virgin males (n = 201) and virgin females (n = 293). On postmortem examination (n = 13, 12 males, 1 female), numerous well-defined mucosal and submucosal granulomas were present in the hemipenes (males) and cloaca (males and female). Extension into the coelomic cavity and liver was noted in a subset of these animals. An additional small subset of breeder animals (6/2027; 0.3%) presented with oral and mandibular swellings. Postmortem examination (n = 4, all female) showed oral lesions histologically indistinguishable from the cloacal/hemipenal lesions. Aerobic bacterial culture of a hepatic granuloma of one snake resulted in the isolation of filamentous, Gram-positive bacilli; amplification, and sequencing of the 16S rRNA gene and subsequent phylogenetic analysis of the isolate identified the bacterium as a novel species of Actinomyces. Screening of cloacal and oral granulomas using a specific, heminested 16S rRNA PCR assay confirmed the presence of the agent in all 17 snakes, as well as in cloacal swabs taken at the time of necropsy in 11/13 snakes. The Actinomyces sp. was also identified by PCR of cloacal swabs of unaffected snakes (n = 94) from the affected colony and two unrelated, grossly unaffected breeding colonies. In the affected colony, 65.5% of breeding animals (n = 23) but only 11.9% of virgin animals (n = 42) tested PCR positive, with breeding status being a significant predictor of bacterium presence (P < 0.00001). This study characterizes a granulomatous mucosal disease syndrome of breeding male ball pythons associated with a novel Actinomyces. In stark contrast to male snakes, the presence of the bacterium in both breeding and virgin females was very rarely associated with clinical disease. Though additional studies are necessary, these data suggest a role for the novel bacterium in the disease process, a predilection for clinical disease in male snakes, and the potential for sexual transmission of the disease.

Campylobacter jejuni and Pseudomonas coinfection in the setting of ulcerative colitis

A 66-year-old woman presented with 2 days of fever and severe diarrhoea. She has a history of ulcerative colitis (UC), well controlled with medication. She also has a history of Ehlers-Danlos syndrome, infective endocarditis following aortic valve replacement and pulmonary embolism. She had complained of passing stool with traces of blood about 30 times per day. Stool testing for Clostridium difficile, routine culture and microscopy was done. She was started on ceftriaxone. CT scan revealed thick-walled colon consistent with UC flare. Flexible sigmoidoscopy showed active continuous colitis extending from the rectum to the proximal descending colon. Campylobacter jejuni was isolated from the stool and blood cultures yielded Pseudomonas aeruginosa. The antibiotic was transitioned to intravenous piperacillin/tazobactam and azithromycin followed by 2 weeks of intravenous cefepime. Her diarrhoea was controlled, and she was discharged for follow-up in 2 months.

Actinomycosis: a frequently forgotten disease

Actinomycosis is a rare subacute or chronic, endogenous infection mainly by Actinomyces species, showing low virulence through fimbriae and biofilms. Cervicofacial, thoracic, abdominal, pelvic and sometimes cerebral, laryngeal, urinary and other regions can be affected. Actinomycosis mimics other diseases, often malignancy. Disease risk in immunocompromised subjects needs clarification. Diagnosis is often delayed and 'sulfur granules' are helpful but nonspecific. Culture requires immediate specimen transport and prolonged anaerobic incubation. Imaging, histology, cytology, matrix-assisted laser desorption ionization time-of-flight mass spectrometry and molecular methods improve the diagnosis. Actinomycetes are β-lactam susceptible, occasionally resistant. Treatment includes surgery and/or long-term parenteral then oral antibiotics, but some 1-4-week regimens or oral therapy alone were curative. For prophylaxis, oral hygiene and regular intrauterine device replacement are important.

Actinomyces and related organisms in human infections

Actinomyces israelii has long been recognized as a causative agent of actinomycosis. During the past 3 decades, a large number of novel Actinomyces species have been described. Their detection and identification in clinical microbiology laboratories and recognition as pathogens in clinical settings can be challenging. With the introduction of advanced molecular methods, knowledge about their clinical relevance is gradually increasing, and the spectrum of diseases associated with Actinomyces and Actinomyces-like organisms is widening accordingly; for example, Actinomyces meyeri, Actinomyces neuii, and Actinomyces turicensis as well as Actinotignum (formerly Actinobaculum) schaalii are emerging as important causes of specific infections at various body sites. In the present review, we have gathered this information to provide a comprehensive and microbiologically consistent overview of the significance of Actinomyces and some closely related taxa in human infections.