[Evaluation of Rapid Syndromic Molecular Test in the Diagnosis of Patients with Central Nervous System Infections]

The diagnosis of central nervous system (CNS) infections is challenging and time-consuming. The FilmArray meningitis/encephalitis panel (BioFire Diagnostics®, Salt Lake City, UT, United States of America) (FA-ME) is designed for the rapid detection of 14 microorganisms that are common causative agents of community-acquired meningitis/encephalitis. The aim of this study was to evaluate the effectiveness of the FA-ME panel by comparing panel test results of cerebrospinal fluid (CSF) samples of 1588 patients who admitted to our hospital with a preliminary diagnosis of CNS infection between 01.06.2018-31.08.2022 with conventional microbiological tests, CSF biochemical tests, clinical findings and radiological imaging results. The results of the FA-ME panel from the 1588 patients tested were assessed together with Gram staining, culture-antibiogram, cryptococcal antigen tests, other viral multiplex polymerase chain reaction tests performed for confirmation, CSF biochemical test results, clinical findings, and radiological imaging results. The results were obtained through the examination of archive and confirmation test records from our hospital medical microbiology laboratories, as well as electronic patient files. The data were evaluated using IBM SPSS Statistics version 25.0. An average positivity rate of approximately 10% was found among the 1588 samples. The most frequently detected agent was herpes simplex virus type 1. In this study, 10 samples (7.8%) were evaluated as false positive and 17 positive samples (13.4%) were found to be clinically insignificant. When evaluating 1488 negative samples, microorganisms not included in the panel were identified in 27 cases using conventional methods. Additionally, one Cryptococcus neoformans was assessed as a false negative. The neurology clinic was the department sending the most samples (728) with 28 positive samples but this number decreased to 14 when false positive and clinically insignificant results were excluded. The average time from sample acceptance in the laboratory to diagnosis was found to be 3.2 hours (200 minutes). When the FA-ME panel results obtained from the CSF samples of 1588 patients were evaluated together with traditional test results, the overall positivity rate was determined approximately as 10% which was consistent with the literature. In the analysis of corrected positive results, it was found that the positivity rate was significantly higher in male patients (p= 0.008), which was consistent with the literature. In neurology patients, when considering modified Reller criteria, the positivity of the FA-ME panel did not indicate a true CNS infection, leading to the conclusion that the test was unnecessarily applied to exclude infection. By ensuring that the FA-ME test requested only upon the opinion of an infectious disease specialist, unnecessary use of an expensive test was prevented. It has been concluded that human herpesvirus-6 positivity detected in the panel should be carefully evaluated with the patient’s age, symptoms, immunosuppression status, laboratory findings and radiological imaging results. Furthermore, negative panel results for C.neoformans/Cryptococcus gattii should be carefully evaluated along with the patient’s clinical findings, necessary conventional tests and radiological imaging. In 27 cases, microorganisms identified as causes of meningitis/encephalitis by conventional methods were detected which were not included in the panel. Therefore, it has been concluded that using the panel when necessary, by evaluating the patient’s clinical findings and symptoms, would be an effective approach in terms of diagnosis and cost. Although careful evaluation of the results is required, it has been determined that the panel successfully detects pathogens directly and rapidly from CSF on a large scale.