Background: Propionibacterium acnes has been reported as a causative agent in a range of serious infections in humans, such as meningitis, infections associated with CSF shunts, wound infections, osteomyelitis, and endocarditis. Nevertheless this bacterium is usually considered of little
significance and is often dismissed as a simple contaminant when isolated in the microbiology laboratory. Indeed the isolation of Propionibacterium from clinical samples such as blood or CSF is often difficult to evaluate, especially in the presence of insidious and non-specific signs or symptoms, as in the case presented in this report.
Case Report: We report a case of meningitis due to Propionibacterium acnes, secondary to neurosurgery in a patient with glioblastoma multiforme. Clinical findings were consistent with a meningeal syndrome characterized by an insidious onset. Microbiological findings highlighted the presence of Gram positive rods on direct microscopic examination of Gram stained cytospin
preparations from the cerebrospinal fluid (CSF), followed by isolation of the bacterium in pure culture. The patient was successfully treated with ampicillin and clindamycin.
Conclusions: This case emphasizes the role of anaerobic bacteria in the etiopathogenesis of meningitis, particularly after neurosurgery, and the consequent need for anaerobic culture of CSF.

Keywords: Propionibacterium acnes, Meningitis, Neurosurgery