Evaluation of sequential multiplex PCR for direct detection of multiple serotypes of Streptococcus pneumoniae from nasopharyngeal secretions.

Sequential multiplex PCR was evaluated for detection of multiple Streptococcus pneumoniae serotypes directly from nasopharyngeal secretions. A total of 279 nasopharyngeal swab samples were tested blindly. When limited to the 29 serotypes identifiable by the molecular method, the mean number of serotypes identified by the conventional latex/Quellung method was 0.85, which was significantly lower than that by the molecular method (P <0.0001). The multiplex PCR method identified significantly more serotypes than the latex/Quellung method if limited to the 29 serotypes (P=0.001 and P=0.014, respectively).