Molecular diagnosis of Nocardia farcinica from a cerebral abscess.

Histopathology and special stains of a brain biopsy specimen from a 42-year-old man revealed numerous gram-positive bacilli arranged in branching filaments, suggesting Nocardia infection. Antibiotic therapy with trimethoprim-sulfamethoxazole markedly decreased the abscess size, and the patient improved. DNA was analyzed from formalin-fixed sections of the cerebral abscess by a 16S ribosomal DNA polymerase chain reaction assay demonstrating the presence of either Nocardia farcinica or N otitidiscaviarum.