Overutilization of cultures of CSF for mycobacteria

Over a five-year period, 1,883 specimens were cultured for mycobacterium tuberculosis (TB) at our hospital. All cultures were negative, and no cases of tuberculous meningitis were diagnosed. Culture rates (percent of CSF specimens cultured for TB) varied from 74% on the Medicine and Neurology services to 6% on the Pediatric service. These culture rates have been stable for five years. These data suggest that on the Medicine and Neurology services, TB cultures of CSF are persistently overutilized. A simple rule of not culturing CSF for TB if results of the CSF analysis are normal (ie, WBC count less than or equal to 4/cu mm, protein level less than or equal to 45 mg/dL, and glucose level greater than or equal to 45 mg/dL) could reduce utilization by at least 50% without adversely affecting quality of care.