[Should presumptive meningoencephalitis treatment in adults be active against Mycoplasma pneumoniae?]

Meningoencephalitis is the most common central nervous system complication caused by Mycoplasma pneumoniae. Its frequency is probably underestimated.The study's aim was to determine the retrospectively incidence of M. pneumoniae meningoencephalitis among other cases of encephalitis diagnosed in infectiology, neurology and ICU at the Clermont-Ferrand University hospital in 2004 and 2005.A case of meningoencephalitis was defined by encephalopathy (altered level of consciousness and/or change in personality), with one or more of the following symptoms: fever, seizure, focal neurological findings, meningitis, electroencephalography or neuroimaging findings consistent with encephalitis. Tumor and hematoma diagnosed by scan were excluded. M. pneumoniae was considered as a possible cause when patients had positive serological test (IgM Elisa) and/or positive PCR results for the CSF.Four (8.3%) patients among 48 cases of encephalitis could have been caused by M. pneumoniae. All except one convulsed initially. Pneumopathy was found in two patients. All received a specific treatment later. Antibiotics seemed to influence evolution in only two patients. These 4 cases appeared during an epidemic between November 2004 and August 2005: 48 hospitalized adults had positive serological test for M. pneumoniae in 2005 and 15 in 2004, whereas the number of tests was the same in 2004 and in 2005.M. pneumoniae should be investigated as a cause of meningoencephalitis if initial tests are negative, if patients have respiratory symptoms and in case of epidemic. Presumptive treatment of meningoencephalitis should include an antibiotic active against M. pneumoniae.