Utility of multiplex PCR blood culture for microbiological diagnosis of nosocomial infections of central nervous system in critical patients

Abstract

Background and objective: To determine the usefulness of a molecular biology technique for nucleic acid amplification using real-time polymerase chain reaction (PCR) originally designed for microbiological diagnosis in blood cultures, when applied to cerebrospinal fluid (CSF) samples. Materials and methods: Retrospective, observational, single-center study, carried out between January 2017 and February 2024 in a 28-bed multipurpose critical care unit. All patients with suspected postneurosurgical infection and CSF cytochemical alterations were included. In addition to the microbiological study of the CSF by traditional methods, the BioFire® Blood Culture Identification 2 (BCID) panel was applied directly to CSF samples. Traditional culture methods were considered as the reference standard for microbiological identification. The main variable of interest was the percentage of concordance of microbial identification between traditional cultures and BCID. Results: 29 patients were included. The diagnosis of central nervous system infection was confirmed in 14 cases (48.2%), 7 post-neurosurgical meningitis, 6 infections associated with ventriculostomy and 1 subdural empyema. The most frequently found microorganisms were Acinetobacter baumannii and Klebsiella pneumoniae. No discordances were found between PCR and cultures, so both the positive (14/14) and negative identification concordance (15/15) were 100% between both methods. Conclusions: In patients with suspected post-neurosurgical infection and compatible CSF alterations, multiplex PCR blood cultures applied directly to CSF samples could be considered a useful and accurate tool for rapid microbiological diagnosis in infections of the central nervous system.