Nocardia farcinica brain abscess in an immunocompetent patient with isolated hemianopsia

Nocardia farcinica is an uncommon cause of brain abscess, most often in immunocompromised hosts. Increasingly, cases in immunocompetent individuals are reported, but diagnosis remains challenging and mortality is high.

We report a 63-year-old diabetic male with sudden altered mental state and right temporal hemianopsia. Initial CT and FDG-PET/CT suggested a tumour, delaying suspicion of infection. MRI later revealed a cerebral abscess, and stereotactic aspiration yielded purulent material. Direct microscopy showed branching Gram-positive rods; culture identified Nocardia spp. within 1 week. MALDI-TOF confirmed N. farcinica, resistant to meropenem. Empirical ceftriaxone/metronidazole was switched to high-dose trimethoprim-sulfamethoxazole (TMP-SMX) and amoxicillin-clavulanate. The patient developed severe hyperkalaemia (7.7 mEq/L) necessitating TMP-SMX dose reduction and discontinuation of spironolactone. Follow-up MRI at 13 weeks showed complete resolution, with full recovery of visual function. Total therapy duration was 6 months.

Although high-dose TMP-SMX remains the standard for CNS nocardiosis, toxicity is common. A recent multicenter cohort by Yetmar et al. found that in non-disseminated pulmonary nocardiosis, lower TMP-SMX doses achieved similar outcomes with significantly fewer adverse events, questioning whether universally high doses are necessary. While CNS involvement generally warrants aggressive therapy, our case highlights the need for individualized dosing and close monitoring. Early stereotactic drainage, rapid microbiological work-up, and timely therapy adjustments likely contributed to the excellent outcome in this high-risk patient.

This case underscores diagnostic challenges, therapeutic dilemmas, and potential for full recovery in N. farcinica brain abscess. It also emphasizes the importance of balancing efficacy and safety when determining TMP-SMX dosing.