The Journal of Medical Microbiology, Vol 13, Issue 4 551-560, Copyright © 1980 by Society for General Microbiology
Enzyme immunoassay of the capsular polysaccharide of Streptococcus pneumoniae type III in cerebrospinal fluid in experimental meningitis
C. M. Nolan and W. C. Ulmer Jr
An enzyme immunoassay (EIA) for the capsular polysaccharide of
Streptococcus pneumoniae type III was developed and applied to the
measurement of this antigen in cerebrospinal fluid (CSF) in an experimental
model of pneumococcal meningitis. EIA was performed by a single-antibody
sandwich technique in which the globulin fraction of pneumococcal
type-specific antiserum (antiserum-globulin) was used to coat the solid
phase before antigen attachment and to conjugate with the labelling enzyme,
horseradish peroxidase. Under optimum assay conditions EIA detected
purified pneumococcal type-III capsular polysaccharide in concentrations as
low as 0.15 ng/ml in aqueous buffer. Assayed by EIA, the mean concentration
of type-III capsular polysaccharide in CSF of rabbits with pneumococcal
meningitis increased exponentially from 24 h to 96nh of infection (range
13.9 ng/ml--62 500 ng/ml). Effective antimicrobial therapy of rabbits with
meningitis was associated with a rapid decrease in the CSF concentration of
the capsular antigen, although it was still detected in concentration in
the range 1--10 ng/ml in 100% of animals treated for 4 days. Thus EIA
provides a quantitative and extremely sensitive method of measuring
type-III pneumococcal capsular polysaccharide in CSF.
