Lack of evidence for Nocardia asteroides in brain specimens from Lewy body-containing disorders

Previous studies have suggested that Nocardia asteroides may play a role in the pathogenesis of Parkinson's disease (PD), including the production of Lewy bodies, the inclusion bodies present in this disorder. This study explored the possible connection between Nocardia and two Lewy body-containing disorders, PD and dementia with Lewy bodies (DLB). Substantia nigra specimens from individuals with PD, DLB, other neurodegenerative disorders, and normal subjects were evaluated for nocardial infection by in situ hybridization, PCR, and Gram staining. Brain specimens from a cynomolgus monkey experimentally infected with N. asteroides for 48 h served as the controls for in situ hybridization and Gram staining, and a nocardial pellet was the PCR control. The organism was detected by in situ hybridization and Gram stain in the experimentally infected monkey brain, and by PCR from the nocardial pellet. However, in situ hybridization reactivity was detected in only three of the 125 human brain specimens (2.4%; one case each of PD, DLB, and Alzheimer's disease), and none of the specimens was positive for Nocardia by PCR or Gram staining. These findings do not support an association of Nocardia with Lewy body-containing disorders.