- Autores: Ardanuy C, de Lencastre H, Goossens H, Henriques-Normark B, Linares J, Rolo D, Sá-Leão R, Simões AS, Tavares DA
- Ano de Publicação: 2016
- Journal: Diagnostic Microbiology & Infectious Disease
- Link: http://www.dmidjournal.com/article/S0732-8893(16)30072-4/fulltext
Streptococcus pneumoniae and LytA methods
Surveillance studies detected 11 isolates displaying conflicting or novel results when characterized by widely accepted phenotypic (optochin susceptibility and bile solubility) and genotypic (lytA-BsaAI-RFLP and MLST) identification methods.
The authors aimed to determine the genetic basis for the unexpected results given by lytA-BsaAI-RFLP. They also wanted to investigate the accuracy of the WHO recommended lytA real-time PCR assay to classify these 11 isolates. They found three novel lytA-BsaAI-RFLP signatures (one in pneumococcus and two in S. mitis).
In addition, one pneumococcus displayed the atypical lytA-BsaAI-RFLP signature characteristic of non-pneumococci. Moreover, two S. pseudopneumoniae displayed the typical lytA-BsaAI-RFLP pattern characteristic of pneumococci. lytA real-time PCR misidentified these three isolates.
In conclusion, the use of the method lytA, in both real-time PCR and based methodologies, for identification of pneumococci may lead to false results. This has particular relevance in the increasingly frequent colonization studies relying solely on culture-independent methods.