Confirmation of psaA in all 90 serotypes of Streptococcus pneumoniae by PCR and potential of this assay for identification and diagnosis

The gene encoding the pneumococcal surface adhesin A (PsaA) protein, psaA w as confirmed in all Streptococcus pneumoniae serotypes by a newly developed PCR (psaA PCR) assay. Eighty-nine of the 90 serotypes amplified produced a n 838-bp fragment; the exception nas a serotype 16F strain acquired from th e American Type Culture Collection (ATCC). analysis of 20 additional 16F st rains from the United States and Brazil showed that the gene was amplified in all 16F strains, implying that the serotype 16F ATCC strain must be a va riant. The specificity of the assay was verified by the lack of signal from analysis of heterologous bacterial species (n = 30) and genera (n = 14), i ncluding viridans group streptococci, The potential of the assay far clinic al application was shown by its ability to detect pneumococci in culture-po sitive nasopharyngeal specimens. Demonstration of psaA in all 90 serotypes and lack of amplification of heterologous organisms suggest that this assay could be a useful tool for detection of pneumococci and diagnosis of disea se.