Meningoencephalitis Caused by Porphyromonas gingivalis: A Case Report and Literature Review

Anaerobic bacteria are a rare cause of adult bacterial meningitis.We report the case of a 48-year-old man who presented with fever, confusion, headache, and word-finding difficulty approximately two weeks after molar extraction performed in the setting of periodontal disease.Cerebrospinal fluid (CSF) analysis showed findings consistent with bacterial meningitis, while routine cultures remained negative.Additional broadrange eubacterial polymerase chain reaction (PCR) of the initial CSF sample detected Porphyromonas gingivalis DNA, leading to targeted antimicrobial therapy with ceftriaxone and metronidazole.Periodontal source control was achieved through extraction of multiple molars.The patient showed gradual neurological improvement but required prolonged inpatient rehabilitation due to persistent dizziness, ultimately achieving independent ambulation and complete resolution of headaches.This case highlights the importance of considering a possible odontogenic source in patients presenting with meningitis following recent dental procedures.Molecular diagnostics may aid pathogen identification when CSF findings suggest bacterial infection despite negative cultures.In this patient, source control and antimicrobial therapy were followed by a favorable neurological outcome.