Issues in cerebrospinal fluid management. Acid-fast bacillus smear and culture

Abstract

Meningeal tuberculosis is an uncommon disease in the United States with an annual incidence of fewer than 200 cases. This study evaluates three approaches to improving the use of the cerebrospinal (CSF) acid-fast bacillus (AFB) smear and culture procedure: (1) education alone; (2) optional screening by which physicians can select to have the AFB analysis stopped if the initial CSF findings are unremarkable; and (3) mandatory screening before the performance of all CSF AFB analyses. With education alone, the CSF AFB culture rate decreased from 20.6% of all CSF acquisitions to 15.7% (P less than 0.001); however, the effect may have been related to a decrease in all types of AFB testing. Optional screening had no impact on the AFB testing rate. Mandatory screening significantly decreased the CSF AFB rate to 6.7% (P less than 0.001), unrelated to changes in other types of AFB testing. Laboratories that employ mandatory screening should report the screening results immediately and have a mechanism whereby physicians can bypass the screen, providing CSF AFB analysis on unremarkable fluid from high-risk patients.