Cerebrospinal fluid (CSF) pleocytosis and abnormal protein and glucose levels were not predictive of a positive result on the FilmArray Meningitis/Encephalitis Panel (FA-M/E), according to research presented at American Society of Microbiology (ASM) Microbe 2019 held from June 20-24, 2019 in San Francisco, California.

Researchers conducted the study to assess whether abnormal CSF parameters are appropriate restriction measures for patients at a tertiary care pediatric medical center. Between June 1, 2016, and November 23, 2018, researchers tested 787 CSF samples, and performed chart reviews for CSF parameters, patient demographics, and pathogens detected. Patients were categorized by age as follows: neonate (≤1 month), infant (>1 month to ≤12 months), and children (>12 months). The study cohort had a median age of 2.5 years. To determine its predictive value, CSF glucose, protein and cellularity were compared with FA-M/E results.

Of the 787 samples, positive CSF results were concurrent with FA-M/E in 93 (11.8%). Mean assay turnaround was 2.4 hours.

Viruses were the most commonly identified cause of infection (8.8% of samples, n=69). The most common viruses were enterovirus (n=35), and human herpesvirus-6 (n=20). Bacterial etiology was identified in 23 (2.9%) cases; Streptococcus agalactiae and Streptococcus pneumoniae were the most common bacterial pathogens (n=7 and n=9, respectively).

Pleocytosis was present in 60.7% of virus-positive patients (73.7% [14/19] neonates, 65.2% [15/23] infants, and 42.1% [8/19] children). When a criteria of white blood cells ≥5 cells/mm3 was used for all pathogens, the presence of pleocytosis had a sensitivity and positive predictive value of 68.2% and 24.6% in neonates; 69.0% and 27.4% in infants; and 60.7% and 16.0% in children, respectively.

In patients with bacterial etiology of infection, 82.4% demonstrated pleocytosis in CSF. In neonates, and infants, pleocytosis was present in 1 of 3 cases and 5 of 6 cases, respectively; in children, it was present in all 8 cases.

Five of 26 (19.2%) immunocompromised patients with positive targets had an absence of pleocytosis (2 enterovirus, 1 cytomegalovirus, and 2 HHV-6). The most common etiologic agent in patients with acellular CSF samples was human herpesvirus-6 (n=12), followed by enterovirus (n=6). All 4 cases positive for herpes simplex-1 demonstrated acellular CSF samples, as did 2 of 3 cases positive for parechovirus.

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Abnormal protein levels had a positive predictive value of 5.8% in neonates, 14.3% in infants, and 10.9% in children. Abnormal glucose levels had a positive predictive value of 23.8% in neonates, 22.6% in infants, and 4.8% in children.

Study investigators concluded that “CSF pleocytosis and abnormal glucose/protein was not predictive of positive FA-M/E result. Restricting FA-M/E orders based on pleocytosis or other abnormal CSF parameters would have resulted in a significant number of missed diagnostic opportunities, particularly viral meningitis.”

One author of the study declared an association of consulting and researching connections to BioFire Diagnostics. Please refer to original reference for a full list of authors’ disclosures. 

Reference

Pandey U, Fahit M, Naccache SN, Dien Bard J. CSF parameters are poor predictors of appropriate film array meningitis/encephalitis (FA-M/E) utilization in pediatric patients. Presented at: ASM Microbe 2019; June 20-24, 2019; San Francisco, California. Poster P524.