Polymicrobial anaerobic bacterial meningitis secondary to dermal sinus: a case report

Anaerobic bacterial meningitis is a rare infectious disease, and there are some special predisposing factors for it. We report a case of polymicrobial anaerobic bacterial meningitis in a nine-month-old boy who visited our hospital due to “fever with drowsiness and vomiting for 2 days”. It was confirmed by the method of sanger sequencing after polymerase chain reaction (PCR) that the purulent meningitis was caused by a mixture of four anaerobic bacteria (Finegoldia magna, Campylobacter ureolyticus, Bacteroides fragilis and Porphyromonas bennonis). Even though there was no obvious structural abnormality on the skin surface, magnetic resonance imaging (MRI) examination suggested the presence of a sacrococcygeal dermal sinus. It was proven that anaerobic bacterial meningitis was secondary to retrograde infection of the dermal sinus. Finally, he was cured by a combination of anti-infection measures and surgical treatment. In conclusion, using appropriate molecular diagnostic techniques may quickly and accurately determine the pathogenic bacteria of anaerobic bacterial meningitis. When anaerobic bacterial meningitis occurs, the presence of structural abnormalities such as dermal sinus needs to be ruled out to avoid recurrence of the disease. In addition to anti-infective treatment, patients with dermal sinuses should undergo surgery as soon as possible to address abnormal structures and their root causes.