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Central nervous system infections

Performance of the rapid molecular assay BIOFIRE® Meningitis/Encephalitis (ME) Panel for the diagnosis of CNS infections: a one-year evaluation in a tertiary care hospital

May 18 • P0239

O. Opota1, Z. Naseri1, R. Brouillet1, L. Senn2, G. Prod’hom1, G. Greub1, K. Jaton1

1) University of Lausanne and University Hospital of Lausanne, Institute of Microbiology, Lausanne, Switzerland
2) University of Lausanne and University Hospital of Lausanne, Service of hospital preventive medicine, Lausanne, Switzerland

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.

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ME Panel

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