Semi-quantitative analysis of cerebrospinal fluid chemistry and cellularity using urinary reagent strip: An aid to rapid diagnosis of meningitis

Abstract

Background: The examination of the cerebrospinal fluid (CSF) for proteins, glucose, and leukocytes still remains the basic gold standard investigation for the initial diagnosis of meningitis. Early diagnosis and initiation of antibiotics within 3 h can reduce the mortality and morbidity associated with meningitis. Hence, we conducted this study to document the usefulness of urinary reagent strip for the semi-quantitative analysis of CSF chemistry and cellularity.

Materials and methods: All clear CSF samples were subjected for two types of tests, the definitive test and the index test. CSF microscopy and biochemical values are considered as definitive. Combur-10 urinary reagent strip was used as the index test for proteins, glucose, and leukocytes. The diagnostic accuracy of each index test was calculated using different cut-off levels (leukocyte esterase positivity 1+ vs. CSF granulocytes ≥10/cumm, proteins 1+ and 2+ vs. CSF protein ≥30 mg/dl and ≥100 mg/dl, respectively, and glucose 0 vs. ≤40 mg/dl and ≤50 mg/dl). Statistical analysis was performed to derive the specificity, sensitivity, positive predictive value, negative predictive value, likelihood ratio (LR)+, LR-, and area under curve (AUC).

Results: The study subjects comprised 103 cases. The strip showed a high sensitivity and specificity for leukocytes ≥10 cells/cumm. The strip showed a sensitivity of 96% and a specificity of 87.1% for proteins at a cut-off ≥100 mg/dl while the strip was less specific at a cut-off of ≥30 mg/dl. With respect to glucose, the strip was highly specific (100%) and less sensitive at both the cut-off levels. The AUC for leukocytes ≥10 cells/cumm was 99.05%; for proteins ≥30 mg/dl and ≥100 mg/dl, it was 84.86% and 95.69%, respectively; and, for glucose ≤40 mg/dl and ≤50 mg/dl, it was 86.51% and 76.99%, respectively.

Conclusion: The routinely used urinary reagent strip can be utilized for the rapid analysis of CSF. If implemented, this technique will be useful in rural areas. It would also decrease the turnaround time in centers where the facility is available.