Association of cell-adherent glycocalyx and endocarditis production by viridans group streptococci.

To assess the role of glycocalyx production in the pathogenesis of endocarditis caused by viridans group streptococci in adult patients, glycocalyx production was examined for 49 blood culture isolates. The tryptophan assay, a quantitative spectrophotometric test, was used to measure cell-adherent glycocalyx production. Absorbance values of the isolates that produced endocarditis were significantly higher (means, 0.166 versus 0.060 [P less than 0.001]). At a breakpoint of absorbance of 0.120, the sensitivity of the test was 0.83, the specificity was 0.96, and the predictive value was 0.95. These data suggest that the in vitro tryptophan assay of glycocalyx production by viridans group streptococci has potential value as a predictor of clinical pathogenicity.