Actinomycetoma due to Nocardia brasiliensis with extension to the ovaries

Xanthogranulomatous inflammation caused by K. pneumonia and nocardiosis mimicking a uterine tumor and invading the ureter and colon: A case report and review of the literature

OBJECTIVE

To present a rare case of xanthogranulomatous inflammation (XI) mimicking a uterine sarcoma and invading the ureter and colon.

CASE REPORT

A 66-year-old woman presented with lower abdominal pain. Pelvic examination showed tenderness over the lower abdominal region without cervical discharge. Per-rectal examination showed a hard tumor on the posterior uterine wall, while ultrasonography showed a tumor-like mass extending from the posterior uterine wall to the rectum. Magnetic resonance imaging showed signs of endometrial cancer invading the rectum. However, the tumor markers carbohydrate antigen (CA) 125, CA199, and carcinoembryonic antigen were in the normal range. Cystoscopy, panendoscopy, and colonoscopy showed no significant findings. On performing exploratory laparotomy, we observed pus and severe adhesion on the posterior uterine wall and rectum. Hysterectomy, bilateral adnexectomy, colectomy, and partial left ureter resection were performed. The final pathology showed XI. The pus culture revealed Klebsiella pneumonia and PCR revealed nocardiosis. The patient received 2 weeks of antibiotic treatment and was discharged thereafter.

CONCLUSION

XI in elderly women is rare, and hence, differential diagnoses should be carefully considered.

Isolated Nocardiosis, an Unrecognized Primary Immunodeficiency?

Nocardiosis is an infectious disease caused by the gram-positive bacterium Nocardia spp. Although it is commonly accepted that exposure to Nocardia is almost universal, only a small fraction of exposed individuals develop the disease, while the vast majority remain healthy. Nocardiosis has been described as an "opportunistic" disease of immunocompromised patients, suggesting that exposure to the pathogen is necessary, but a host predisposition is also required. Interestingly, increasing numbers of nocardiosis cases in individuals without any detected risk factors, i.e., without overt immunodeficiency, are being reported. Furthermore, a growing body of evidence have shown that selective susceptibility to a specific pathogen can be caused by a primary immunodeficiency (PID). This raises the question of whether an undiagnosed PID may cause nocardiosis affecting otherwise healthy individuals. This review summarizes the specific clinical and microbiological characteristics of patients with isolated nocardiosis published during the past 30 years. Furthermore, it gives an overview of the known human immune mechanisms to fend off Nocardia spp. obtained from the study of PIDs and patients under immunomodulatory therapies.

Identification and Mobilization of a Cryptic Antibiotic Biosynthesis Gene Locus from a Human-Pathogenic Nocardia Isolate

The genus Nocardia contains >50 human pathogenic species that cause a range of illnesses from skin and soft tissue infections to lung and brain infections. However, despite their membership in the most prominent family of secondary metabolite producers (the Actinomycetes), the ability of Nocardia species, especially those that cause human infections, to produce secondary metabolites has not been as well studied. Using genome mining, we have investigated cryptic secondary metabolite biosynthesis gene clusters from Nocardia species and identified a conserved locus within human pathogenic strains of Nocardia brasiliensis and Nocardia vulneris. Direct capture and heterologous expression in a Streptomyces host activated the biosynthetic locus, revealing it to be the source of the brasiliquinones, benz[a]anthraquinone antibiotics whose biosynthetic pathway has remained hidden for over two decades, until now. Our findings highlight these hitherto neglected human pathogenic Nocardia as a source of diverse and important natural products.