Encephalitis Caused Directly by Mycoplasma pneumoniae

A case of non-fatal encephalitis in a 21-y-old immunocompetent woman is described. High titre serum antibodies against Mycoplasma pneumoniae were found. In addition, Mycoplasma pneumoniae DNA was detected in the cerebrospinal fluid by polymerase chain reaction. Neuroimaging findings by magnetic resonance and computed tomographic scanning of the brain, and laboratory investigations, including a search for serum antibodies to gangliosides, did not support an immune-mediated mechanism. No other pathogens were found. These results strongly suggest that the encephalitis was caused directly by Mycoplasma pneumoniae invasion of the central nervous system. They also indicate that such pathogenetic mechanism may sometimes be sufficient to explain neurological manifestations occurring during the course of Mycoplasma pneumoniae infection. The consequences for therapy are discussed.