True recurrence - all of the following:
(1) 2 or more episodes of meningitis
(2) The interval between episodes is >= 3 weeks (21 days) after completion of therapy for the previous episode (sufficient for convalescence and full recovery).
(3) The infection may be due to a different or the same bacterial species.
where:
• The 3 week interval is somewhat arbitrary but is a consensus for the various reports in the medical literature.
• The presence of totally different isolates would tend to favor a new infection (provided that it was not missed or misidentified on the original culture).
• If the same species is isolated it may be beneficial to see just how closely related they are. The presence of the same isolate and demonstration of resistance to the antibiotic used for treatment would favor treatment failure with relapse.
Special categories for a recurrent meningitis:
(1) associated with a CSF leak
(2) associated with foreign body
Exclusions:
(1) tuberculous meningitis
