Antibody responses to Mycoplasma pneumoniae: role in pathogenesis and diagnosis of encephalitis?

The current diagnostic algorithm of the "Consensus Statement of the International Encephalitis Consortium" [12] recommends for the diagnosis of M. pneumoniae infection in children with encephalitis (1) serology and polymerase chain reaction (PCR) from throat samples (routine studies), and if positive test results and/or respiratory symptoms are present, then (2) additionally PCR in cerebrospinal fluid (CSF) (conditional studies). The detection rate of M. pneumoniae by PCR in the CSF of M. pneumoniae encephalitis patients is relatively low (0%-14%) [9], [10], [25], [26]. [...]various cases with M. pneumoniae encephalitis in which bacterial DNA could not be detected in the CSF had a more prolonged duration of respiratory symptoms before the onset of encephalitis (>5-7 days) [10], [25], [27]. [...]while PCR and serology may be of limited value in the diagnosis of M. pneumoniae encephalitis, the detection of intrathecal antibodies to M. pneumoniae, including cross-reactive antibodies against GalC and gangliosides, may be regarded as a promising new diagnostic tool.