16S rRNA Gene PCR/Sequencing of Cerebrospinal Fluid in the Diagnosis of Post-operative Meningitis

INTRODUCTION: Post-operative meningitis (POM) is a life-threatening complication of neurosurgery. Diagnosis is often difficult due to pre-existing inflammation and antecedent antimicrobial use. Bacterial cerebrospinal fluid (CSF) cultures may reveal no growth, but empiric antibiotics are typically given due to the high morbidity and mortality associated with POM. 16S rRNA gene PCR/sequencing is a molecular methodology that can identify the presence of bacteria regardless of viability for culture. CASE PRESENTATION: A patient presented with a rapid onset of fever associated with headache, neck pain, nausea and altered mental status 11 days after undergoing laser interstitial thermal therapy for treatment of recurrent astrocytoma at another hospital. Based on clinical presentation and imaging, POM was suspected, and empiric antibacterial therapy was started. Microbiological stains and cultures of CSF were negative. Due to persistent fevers, 16S rRNA gene PCR/sequencing was done on CSF; it detected a member of the order Enterobacteriales most closely resembling Serratia species. All antimicrobials were stopped except for cefepime, which was given for 2 weeks. The patient’s mental status fully recovered. CONCLUSION: The application of 16S rRNA gene PCR/sequencing in the setting of POM is of value by improving the quality of patient care and decreasing costs by antimicrobial de-escalation. Further studies regarding the positive and negative predictive values of this test are required.