Nocardia farcinica Brain Abscess in a Glucocorticoid-Treated Patient with Giant-Cell Arteritis: A Case Report.

BACKGROUND Nocardia species are opportunistic pathogens that primarily cause infections in immunocompromised individuals. Giant-cell arteritis is a granulomatous vasculitis of large- and medium-sized arteries in individuals aged ≥50 years, typically requiring prolonged glucocorticoid therapy, which increases susceptibility to opportunistic infections. CASE REPORT We report the case of a 73-year-old man with giant-cell arteritis treated with prednisolone who developed disseminated nocardiosis. Four months after giant-cell arteritis diagnosis, a new pulmonary nodule was detected on follow-up imaging, followed by acute onset of loss of consciousness. Brain magnetic resonance imaging revealed multiple abscesses, and Nocardia farcinica was identified from aspirated pus. The patient was initially treated with intravenous meropenem and amikacin. Therapy was then transitioned to the first-line oral agent sulfamethoxazole-trimethoprim, but this was discontinued due to renal dysfunction. Long-term oral minocycline and moxifloxacin were subsequently administered, although the latter was later withdrawn because of QT prolongation. He ultimately completed 1 year of antimicrobial therapy and remained recurrence-free without neurological sequelae. CONCLUSIONS This case illustrates that nocardiosis can occur even in the early phase of giant-cell arteritis therapy and at moderate doses of glucocorticoids. Clinicians should maintain vigilance for Nocardia infection when evaluating pulmonary or neurological lesions in patients with giant-cell arteritis. Alternative therapeutic regimens, guided by susceptibility testing, may be required when first-line agents are not tolerated.