A 78‐year‐old Caucasian female with a history of hyperlipidemia and pacemaker placement about 2 years prior presented with a chest mass. She noticed a small, non‐tender nodule on the left side of her chest several weeks ago. The nodule was biopsied, and the aspirate was suggestive of an abscess. She was started on a course of Cephalexin. Over the following 2 weeks, the mass significantly increased in size and became tender with yellowish material oozing out of it. She denied fever, nausea, vomiting, or shortness of breath. No history of trauma or insect bite was reported. Upon presentation, she was afebrile with normal vital signs. Physical exam was unremarkable except for a left upper chest wall discharging mass with erythema and tenderness, and an implanted pacemaker just above and lateral to the mass. The chest wall mass was partially drained with ultrasound guidance. Lab work was significant for WBC 19,000 and neutrophilia. The patient was not immuno‐compromised and there was no evidence of diabetes or HIV. Blood cultures, PPD, and histoplasma serology were negative. Chest CT scan showed a large 6.8 x 5.2 cm mass, suggestive of abscess in the left parasternal chest wall with extension into the pectoralis musculature as well as posterior extension into the anterior mediastinum with involvement of the left anterior upper lobe. Pus culture grew aerobic gram positive branching rod that was found to be Nocardia Cyriacigeorgica on further identification. The patient was started on oral Bactrim, and no surgical drainage of abscess was needed. She significantly improved on Bactrim and IV Ceftriaxone as an outpatient.
Nocardiosis is a gram positive bacterial infection caused by aerobic actinomycetes in the genus nocardia. Typically it is described as opportunistic infection, but in rare occasions it can affect immunocompetent patients. The incidence of nocardia infection used to be underestimated because of rarity, diverse presentations, and because it is a not reportable disease.
This case demonstrates how nocardiosis can present in immunocompetent patients. Up to one third of nocardia infections occur with normal immune system. It is extremely unusual to have such an invasive infection in immunocompetenet individuals. Pacemaker placement is likely the organism port of entry, with its leads reaching the abscess; however, as far as we know, pacemaker implantation causing nocardiosis was only reported once. Prolonged antibiotic therapy is the mainstay treatment, and surgical drainage is rarely needed.