Assessment and comparison of four different methods for Streptococcus pneumoniae serotyping
Pneumococcal serotype identification is essential to monitor pneumococcal vaccine effectiveness and serotype replacement. We compared four different methods: PCRSeqTyping, Quellung reaction, Single-step Multiplex-PCR Assay and S. PneumoStrip of Streptococcus pneumoniae serotyping.
A double blind study was carried out in Donostia University Hospital (northern Spain) where four different techniques were used to compare the serotyping of 18 pneumococcal strains obtained from clinical specimens. PCRSeqTyping to detect 91 different serotypes, Quellung reaction as the Gold Standard, Single-step Multiplex-PCR Assay able to differentiate 92 serotypes and S. PneumoStrip for the identification of 76 pneumococcal serotypes , 42 individually and 34 in pairs.
A 100% correlation of PCRSeqTyping results was observed with PneumoStrip results and Single-step Multiplex-PCR Assay and 15 (83.3%) by Quellung reaction. The quickest technique was PneumoStrip followed by Single-Step multiplex PCR Assay and PCRSeqTyping. Quellung reaction was the slowest technique.
PneumoStrip was an accurate and rapid technique with high reproducibility, as was PCRSeqTyping. Single-step Multiplex-PCR Assay was also a good technique for S. pneumoniae serotyping which does not require culturing the samples unlike PneumoStrip or Quellung reaction. Quellung reaction was also not totally reliable due to its subjective nature.