Evaluation of phenotypic and molecular methods for identification of Streptococcus pneumoniae.

Aim: The objective of this study is to compare various Streptococcus pneumoniae identification methods.

Materials & Methods: In total, 1371 putative S. pneumoniae isolates were tested with three phenotypic methods and a molecular-based method targeting a virulence factor (CpsA). We assessed the sensitivity and the specificity of each method and widely used S. pneumoniae identification algorithm.

Results: None of the methods or the identification algorithm used separately was able to correctly identify all S. pneumoniae isolates. Furthermore, a high rate of optochin resistance was found.

Conclusions: We demonstrated the failure of the current S. pneumoniae identification methods and optochin susceptibility-based algorithm. In addition, the high rate of optochin resistance might justify the necessity of a close monitoring of optochin susceptibility.