Site-specific growth of Nocardia asteroides in the murine brain.
The growth of Nocardia asteroides GUH-2 and two mutants (NG-49 and I-38-syn) in regions of the brains of BALB/c mice was determined by microdissection and viable counting. GUH-2 grew throughout the murine brain but at different growth rates that depended on the specific location. The rate of increase in total CFU per brain during GUH-2 infection was unaffected by the inoculum size; however, in five of eight brain regions, an alteration in the inoculum size resulted in altered nocardial growth rates. Mutant NG-49 showed a significantly slower rate of increase in total CFU per brain than did the parental strain, GUH-2, and significantly decreased growth rates in seven brain regions. Mutant I-38-syn showed a rate of increase in total CFU per brain similar to that of the parental strain; however, this mutant grew significantly faster in the cerebellum and pons-medulla. Growth appeared to be a necessary precursor to the cellular damage that resulted in the variety of neurological disorders observed in mice infected with N. asteroides GUH-2, because mutant NG-49 exhibited a decreased ability to grow in specific regions of the brain and did not induce signs of neurological damage. In contrast, mutant I-38-syn induced neurological signs in a larger percentage of the infected animals than did parental strain GUH-2 and grew better in certain regions of the brain than did the parental strain. Furthermore, there appeared to be a relationship between the growth of N. asteroides in the substantia nigra and the induction of an L-dopa-responsive head shake that was observed in some of the mice following a sublethal intravenous injection of N. asteroides GUH-2.
Ogata
S A
SA
Department of Medical Microbiology and Immunology, School of Medicine, University of California, Davis 95616.
Beaman
B L
BL
D000818:Animals; D001921:Brain / Q000382:microbiology*; D005260:Female; D007980:Levodopa / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D009069:Movement Disorders / Q000209:etiology; D009154:Mutation; D009616:Nocardia asteroides / Q000235:genetics / Q000254:growth & development*; D013378:Substantia Nigra / Q000382:microbiology
D007980:Levodopa