Background: The BIOFIRE® Meningitis/Encephalitis (ME) Panel (bioMérieux), is a rapid (1 h) molecular assay for the diagnosis of meningitis and encephalitis. The test provides a qualitative result for 14 pathogens. We aimed to evaluate the reliability and the added-value of this assay one year after its introduction in our hospital.
Materials/methods: In November 2018, the ME Panel was made available for physicians 7/7 days/8am-10pm. Pathogens for which in-house PCRs were available, were retested within 24h; this included Haemophilus influenzae, Listeria monocytogenes, Neisseria meningitidis, Streptococcus agalactiae, Streptococcus pneumoniae, cytomegalovirus, enterovirus, herpes simplex virus 1 and 2, human herpes virus 6 and broad range 16S rRNA gene PCR. Clinico-laboratory assessment was achieved to investigate discrepant results.
Results: We analyzed results (n=144), obtained during a one-year period after the introduction of the ME Panel (Nov. 2018 to Nov. 2019) with the following results: sensitivity 90.9% (30/33), specificity 98.6% (139/141), positive predictive value 93.7% (30/32) and negative predictive value 97.9% (139/142). Two adult patients that tested positive for E. coli K1 with the ME Panel were negative with in-house PCR, among whom only one of them could eventually correspond to a true positive by clinico-laboratory assessment. Two patients with a clinico-laboratory assessment compatible with a viral encephalitis tested negative for HSV-1 with the ME Panel but positive with in-house real-time PCR with very low DNA copy number. One patient with a Listeria monocytogenes rhombencephalitis and bacteraemia tested negative with the ME Panel but positive with in-house real-time PCR.
Conclusions: The overall performance of the test appeared intermediate. However, important unexpected discrepant results – false positive and false negative – occurred. This may be problematic for a first line assay expected to support decision making in the setting of a life-threatening disease. In conclusion, the ME Panel provided rapid results with a better sensitivity than Gram staining. However, our study similarly to previous studies reinforces that: i) a carefully clinico-laboratory assessment is mandatory for the interpretation of any ME Panel results (both negative and positive results) and ii) confirmation with in-house molecular test, ideally quantitative tests, appears to be necessary.