Point-of-care Cerebrospinal Fluid Gram Stain For the Management of Acute Meningitis in Adults: A Retrospective Observational Study

Abstract Background: Gram staining of cerebrospinal fluid (CSF) is widely used in the diagnosis of acute meningitis, but is often conducted in the laboratory, as only some hospitals have access to point-of-care Gram stain (PCGS). The purpose of this study was to demonstrate the clinical impact and utility of PCGS in diagnosing and treating both bacterial and aseptic meningitis in adults. Methods: This was a hospital-based, retrospective observational study at a referral center in Okinawa, Japan. We reviewed the records of all patients aged 15 years or older who were admitted to the Division of Infectious Diseases between 1995 and 2015 and finally diagnosed with bacterial (n=34) or aseptic meningitis (n=97). For bacterial meningitis, we compared the treatments that were actually selected based on PCGS with simulated treatments that would have been based on the Japanese guidelines. For aseptic meningitis, we compared the rates of antibiotic use between real cases where PCGS was available and real cases where it was not. Results: PCGS was the most precise predictor for differentiating between bacterial and aseptic meningitis (sensitivity 91.2%, specificity 98.9%), being superior in this regard to medical histories, vital signs and physical examinations, and laboratory data available in the emergency room. In bacterial meningitis, PCGS reduced the frequency of meropenem use (1/34=3.0%) compared with simulated cases in which PCGS was not available (19/34=55.9%) (p=0.000). In real aseptic meningitis cases, the rate of antibiotic administration was lower when PCGS was used (38/97=39.2%) than when it was not (45/74=60.8%) (p=0.006). Conclusions: PCGS of CSF distinguishes between bacterial and aseptic meningitis more accurately than other predictors available in the ER. Patients are more likely to receive narrower-spectrum antimicrobials when PCGS is used than when it is not. PCGS of CSF thus can potentially suppress the empiric use of antimicrobials for aseptic meningitis.