Bacterial antigen testing in CSF

Medical Laboratory Observer, March, 2007 by Daniel M. Baer

Q What is the recommendation for performing bacterial antigen testing on a cerebro-spinal fluid (CSF) specimen that is clear and colorless?

A Many bacterial antigen tests are available for the reported rapid and accurate diagnosis of bacterial meningitis. In general, these tests have not proven useful in the clinical microbiology laboratory. They do not have high sensitivity and specificity, and have not been shown to be cost-effective; thus, they should not be performed routinely. They may prove to be helpful when CSF cell counts are abnormal, the Gram stain is negative for organisms, and the patient has already been treated with antibiotics. Certainly, if a CSF specimen is clear and colorless, it is very unlikely to be positive for bacteria or their antigens.

--Susan E. Sharp, PhD, (DABMM)

Director of Microbiology

Kaiser Permanente Pathology

Regional Laboratory; Associate Professor

Oregon Health and Science University

Portland, OR

Suggested Reading

Sewell DL, MacLowry JD. Laboratory management. In: Patrick R, Baron EJ, Jorgensen JH, Pfaller MA, Yolken RH, eds. The Manual of Clinical Microbiology. 8th ed. Washington, DC: ASM Press; 2003:12.

Edited by Daniel M. Baer, MD

MLO's "Tips from the Clinical Experts" provides practical, up-to-date solutions to readers' technical and clinical issues from a panel of experts in various fields. Readers may send questions to Dan Baer by e-mail at tips@mlo-online.com.