Disseminated Nocardia farcinica with multiple cerebral abscesses in a patient receiving induction immunosuppression for autoimmune hepatitis: case report.

BACKGROUND: Nocardiosis is an opportunistic infection caused by aerobic, Gram-positive actinomycetes of the genus Nocardia that most often affects patients with impaired cell-mediated immunity, including those receiving corticosteroids or other immunosuppressive therapies. Disseminated disease frequently involves the central nervous system, where a systematic review reported an overall case fatality rate of 22.8%, and Nocardia farcinica is the most commonly identified species. We report a case of disseminated Nocardia farcinica with multiple cerebral abscesses in a patient receiving induction immunosuppressive therapy for autoimmune hepatitis.

CASE REPORT: A 55-year-old man with a history of autoimmune hepatitis and occupational soil exposure presented with 4-5 week history of progressive cognitive impairment, dysarthria, and right upper extremity weakness. Two months earlier, he had been treated with high-dose corticosteroids and azathioprine and prescribed trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis, which had been interrupted for an estimated 2-4 weeks before presentation during ongoing corticosteroid therapy. Upon admission, laboratory tests demonstrated neutrophil-predominant leukocytosis with lymphopenia, and liver function tests showed substantial improvement compared to his initial presentation of autoimmune hepatitis. Neuroimaging revealed multiple ring-enhancing intracerebral lesions with surrounding vasogenic edema. Stereotactic aspiration of a cerebral abscess and drainage of a concurrent retroperitoneal collection grew Nocardia farcinica, confirming disseminated nocardiosis. Antimicrobial therapy was transitioned to imipenem-cilastatin and TMP-SMX based on susceptibility testing. During infection management, azathioprine was paused, and prednisone was continued at a dose of 25 mg/day, followed by a biochemical autoimmune hepatitis flare requiring hepatology-guided monitoring. The patient demonstrated gradual neurologic improvement and was discharged to inpatient rehabilitation after an 18-day hospitalization.

CONCLUSION: Disseminated nocardiosis should be considered for immunosuppressed patients with autoimmune hepatitis presenting with subacute neurological decline and ring-enhancing brain lesions, particularly during outpatient immunosuppression transitions when antimicrobial prophylaxis may be interrupted or incompletely reconciled. The patient demonstrated progressive neurological improvement and radiographic abscess reduction after 3 months of susceptibility-guided combination therapy, reinforcing the importance of early tissue diagnosis and neurosurgical intervention in this population.