Primary Actinomycosis in the breast caused by Actinomyces neuii. A report of 2 cases

Non-puerperal Breast Actinomycosis: A Case Report

Breast abscesses can be a complication of infectious mastitis or the first presentation of a breast infection, presenting as pain, erythema, and a lump. Actinomycosis is a rare chronic disease caused by anaerobic branched filamentous gram-positive bacteria belonging to the Actinomyces genus. It is usually found in the human mouth, digestive tract, and genital tract but can also cause breast abscesses. Actinomycosis affecting the breast is a rare condition that typically occurs as a secondary infection resulting from a pulmonary infection. It is primary when inoculation occurs through the nipple. This report describes the case of a 48-year-old institutionalized female with periareolar swelling in the right breast that had been evolving for approximately two months. The abscess was drained, and the aspirated material contained Actinomyces neuii, a gram-positive bacterium. Actinomycosis of the breast can manifest as either a sinus tract or mass-like features that closely resemble malignancy. The clinical presentation can pose challenges in distinguishing between primary actinomycosis, mastitis, and inflammatory carcinoma. Treatment consists of drainage with needle aspiration or surgical drainage and antibiotic therapy.

Comparative genomic analyses of the clinically-derived Winkia strain NY0527: the reassignment of W. neuii subsp. neuii and W. neuii subsp. antitratus into two separate species and insights into their virulence characteristics

Background

Winkia neuii, previously known as Actinomyces neuii, is increasingly recognized as a causative agent of various human infections, while its taxonomy and genomic insights are still understudied.

Methods

A Winkia strain NY0527 was isolated from the hip abscess of a patient, and its antibiotic susceptibility was assessed. The genome was hybrid assembled from long-reads and short-reads sequencing. Whole-genome-based analyses on taxa assignment, strain diversity, and pathogenesis were conducted.

Results

The strain was found to be highly susceptible to beta-lactam antibiotics, but resistant to erythromycin, clindamycin, and amikacin. The complete genome sequences of this strain were assembled and found to consist of a circular chromosome and a circular plasmid. Sequence alignment to the NCBI-nt database revealed that the plasmid had high sequence identity (>90%) to four Corynebacterium plasmids, with 40-50% query sequence coverage. Furthermore, the plasmid was discovered to possibly originate from the sequence recombination events of two Corynebacterium plasmid families. Phylogenomic tree and genomic average nucleotide identity analyses indicated that many Winkia sp. strains were still erroneously assigned as Actinomyces sp. strains, and the documented subspecies within W. neuii should be reclassified as two separate species (i.e., W. neuii and W. anitratus). The core genome of each species carried a chromosome-coded beta-lactamase expression repressor gene, which may account for their broadly observed susceptibility to beta-lactam antibiotics in clinical settings. Additionally, an ermX gene that expresses fluoroquinolone resistance was shared by some W. neuii and W. anitratus strains, possibly acquired by IS6 transposase-directed gene transfer events. In contrast, tetracycline resistance genes were exclusively carried by W. neuii strains. In particular, W. neuii was found to be more pathogenic than W. anitratus by encoding more virulence factors (i.e., 35-38 in W. neuii vs 27-31 in W. anitratus). Moreover, both species encoded two core pathogenic virulence factors, namely hemolysin and sialidase, which may facilitate their infections by expressing poreformation, adhesion, and immunoglobulin deglycosylation activities.

Conclusion

This study highlights the underappreciated taxonomic diversity of Winkia spp. and provides populational genomic insights into their antibiotic susceptibility and pathogenesis for the first time, which could be helpful in the clinical diagnosis and treatment of Winkia spp. infections.

Primary mammary actinomycosis challenged with penicillin allergy

Actinomycosis is a subacute-to-chronic bacterial infection caused by gram-positive, filamentous, non-acid-fast, facultative anaerobic bacteria. It is a normal commensal bacterium found in the oral cavity and the lower reproductive tract of women. We present a case of primary actinomycosis of the breast. A postmenopausal woman, complicated by penicillin allergy, presented with a left breast lump clinically simulating malignancy. The first line of treatment for actinomycosis is penicillin. Due to a penicillin allergy, the patient was initially treated with doxycycline. However, doxycycline was discontinued due to tremors, and was replaced by clindamycin. The patient had a good clinical response with resolution of the abscess.

Actinomyces neuii: a case report of a rare cause of acute infective endocarditis and literature review

BACKGROUND

Infective endocarditis caused by Actinomyces spp. is extremely rare. However, cases by new species of Actinomyces have been increasingly reported due to advances in laboratory techniques, and many of these species do not cause classic presentations of actinomycosis. Actinomyces neuii is reported to have a tendency to cause endovascular infection. The course of infective endocarditis caused by Actinomyces spp. is usually indolent.

CASE PRESENTATION

A 61-year-old man with history of infective endocarditis, end stage renal disease, and monoclonal gammopathy was admitted for an abrupt fever, confusion, dysarthria, and facial droop after hemodialysis. Echocardiogram showed vegetations on both the aortic and mitral valves. Two sets of blood culture grew A. neuii. Brain MRI showed multiple bilateral cerebral infarcts consistent with septic emboli. The patient recovered after valvular surgery and prolonged intravenous and oral antibiotic therapy.

CONCLUSIONS

This case illustrates an unusually acute presentation of A. neuii infective endocarditis. As with other Gram-positive bacilli, Actinomyces spp. isolates are often regarded as a result of contamination. One should keep it in mind as a cause of infective endocarditis in vulnerable patient populations.

Actinomycosis of the breast and lungs

Actinomycosis is a chronic, progressive, and often relapsing granulomatous infection that characteristically crosses tissue planes and forms abscesses and sinus tracts. We report a unique case of a woman with actinomycosis presenting with a breast abscess, a sinus tract spontaneously exiting the sternum, and miliary lung lesions.