Evaluation of the selection of cerebrospinal fluid testing in suspected meningitis and encephalitis.

Diagnostic stewardship interventions can decrease unnecessary antimicrobial therapy and microbiology laboratory resources and costs. This retrospective cross-sectional study evaluated factors associated with inappropriate initial cerebrospinal fluid (CSF) testing in patients with suspected community-acquired meningitis or encephalitis. In 250 patients, 202 (80.8%) and 48 (19.2%) were suspected meningitis and encephalitis, respectively. 207 (82.8%) patients had inappropriate and 43 (17.2%) appropriate testing. Any inappropriate CSF test was greatest in the immunocompromised (IC) group (n = 54, 91.5%), followed by non-IC (n = 109, 80.1%) and HIV (n = 44, 80%). Ordering performed on the general ward was associated with inappropriate CSF test orders (adjOR 2.81, 95% CI [1.08-7.34]). Laboratory fee costs associated with excessive testing was close to $300,000 per year. A stepwise algorithm defining empiric and add on tests according to CSF parameters and patient characteristics could improve CSF test ordering in patients with suspected meningitis or encephalitis.