QUALITY ASSURANCE STUDY OF BACTERIAL-ANTIGEN TESTING OF CEREBROSPINAL-FLUID

Bacterial antigen testing (BAT) of cerebrospinal fluid (CSF) by latex agglutination is a low-yield procedure in patients whose CSF specimens have normal laboratory parameters. Between August 1992 and August 199 4, we evaluated 287 bacterial antigen (BA) test requests to determine whether yields could be improved and whether patient costs could be re duced by canceling BAT for those patients with normal CSF parameters ( cell count, protein, glucose) after consultation with physicians. A to tal of 171 (68%) BA tests were canceled by this approach. None of thes e CSF specimens was culture positive for an organism detectable by BAT , Of the remaining 116 CSF specimens tested, only 3 were positive by B AT, one each for Neisseria meningitidis, Streptococcus pneumoniae, and group B streptococcus. Only 43 of the CSF specimens tested had at lea st two abnormal parameters; the 3 positive CSF specimens were included in this group. In light of the low rate of positivity, the number of BA tests can be further reduced by establishing criteria that must be met before a CSF specimen is accepted for BAT. After review of our dat a and the literature concerning this topic, we concluded that only spe cimens with leukocyte counts of greater than or equal to 50 cells per mm(3) should be tested. Of 287 specimens evaluated in our study, only 36 met this criterion, including the 3 BA-positive specimens. Enacting such a restriction would have reduced the total number of BA tests by 251 (87%) without compromising patient care. A laboratory cost saving s of $6,500 per year would have been realized, with a substantial redu ction in the cost per positive test, Patient charges would have been r educed by $12,500 per year.