Actinomyces meyeri: A Rare Cause of Postsurgical Pelvic Actinomycosis

Pulmonary invasive mucinous adenocarcinoma mimicking pulmonary actinomycosis

Background

Primary pulmonary invasive mucinous adenocarcinoma is a rare and distinct subtype of lung adenocarcinoma.

Case presentation

A 72-year-old woman presented with productive cough for two months and fever for six days. Chest computed tomography (CT) showed a mass in the left lower lobe. Sputum culture tested negative for bacteria, but the sequence of Actinomyces meyeri was detected by metagenomic next generation sequencing from the bronchoalveolar lavage fluid. It was considered a pathogenic bacterium as the normalized number of DNA sequencing reads was 10 times higher than the normal level. The patient’s symptoms alleviated quickly, and the chest CT lesion shrank to a third of the original size following treatment with penicillin for two months. However, a repeat chest CT performed after four months of treatment revealed that the lesion had expanded. Positron emission tomography/CT revealed that fluorodeoxyglucose metabolism was increased in the mass with surrounding ground glass density of the left lower lobe. Furthermore, CT-guided percutaneous lung biopsy was performed, and hematoxylin–eosin staining showed columnar tumor cells with abundant mucin in the cytoplasm with a basal nucleus. Finally, the patient was diagnosed with pulmonary invasive mucinous adenocarcinoma and agreed to undergo a thoracoscopic surgery.

Conclusions

Pulmonary invasive mucinous adenocarcinoma is a subset of lung adenocarcinoma with low incidence rate. The clinical features and CT findings are non-specific. A histopathological diagnosis is of fundamental importance in preventing misdiagnosis.

A “Boil” Being the Clue to Think beyond Typical Bacterial Pathogens in Community-Acquired Pneumonia

Empyema necessitans is an exceptionally rare complication of bacterial pneumonia in the pediatric population. It occurs when the infection extends from the lung parenchyma to the chest wall by forming a fistula, which leads to infection of the surrounding soft tissue. In this case, a 13-year-old boy is found to have empyema necessitans caused by Actinomyces meyeri, with a preceding clue to the diagnosis being that he was treated for a superficial chest wall abscess several weeks prior to developing significant respiratory symptoms. Providers should be aware of this entity as it requires obtaining cultures to identify the appropriate pathogen and avoid treatment failure as it has implications for antibiotic choice and length of therapy.

Actinomyces meyeri pleural infection that was difficult to treat due to delayed culture: A case report and literature review of 28 cases

An eighty-three-year-old man suffered from cough, right chest pain, and progressive dyspnea for sixteen days. He had hypoxemia, high white blood cells and C-reactive protein, and moderate right-sided pleural effusion on radiographic imaging. A pleural fluid examination revealed exudate. He was diagnosed with pleural infection and treated with intravenous ampicillin/sulbactam. On the second day of hospitalization, the treatment was changed to levofloxacin and clindamycin due to drug eruption. He improved gradually and was prescribed only oral levofloxacin on the eighteenth day of hospitalization. However, improvements in inflammation and imaging findings were poor. Actinomyces meyeri resistant to fluoroquinolones was cultured from a pleural effusion sample on the twenty-sixth day of hospitalization. The treatment was changed to oral clindamycin, and his medical condition subsequently improved. We reviewed twenty-eight patients with Actinomyces pleural infection and thirty-eight patients with other pleural infection phenotypes from our hospital and published case reports. Actinomyces pleural infection is a long-term process and results in a large amount of pleural effusion compared to other pleural infection phenotypes. These results might be related to the fact that Actinomyces is a slow-growing organism.

The Pathogenic Role of Actinomyces spp. and Related Organisms in Genitourinary Infections: Discoveries in the New, Modern Diagnostic Era

Actinomycosis is a chronic, suppurative, granulomatous infectious disease, caused by different species of Actinomyces bacteria. To date, 26 validly published Actinomyces species have been described as part of a normal human microbiota or from human clinical specimens. Due to the rapid spread of new, modern diagnostic procedures, 13 of 26 of these species have been described in this century and the Actinomycetaceae family has undergone several taxonomic revisions, including the introduction of many novel species termed Actinomyces-like organisms (ALOs). There is scarce data available on the role of these novel bacterial species in various infectious processes in human medicine. The aim of this review is to provide a comprehensive overview of Actinomyces and closely related organisms involved in human diseases-with a special focus on newly described species-in particular their role in genitourinary tract infections in females and males.