Pulsed field gel electrophoresis in Streptococcus pneumoniae isolated in France and Portugal

During a multicenter surveillance study on Streptococcus pneumoniae resistant to antibiotics in Portugal we have analyzed, within the predominant serotypes of penicillin G resistant strains, the chromosomal DNA restriction profiles by pulsed field gel electrophoresis. The aim of this work was to compare the PFGE restriction profiles of penicillin resistant pneumococci isolated in France with those of Portuguese strains within each serotype. We have studied fifteen penicillin resistant strains isolated in different geographical regions of France, and representing equally the three predominant resistant serotypes 23F, 9V and 14. In general we observed an important homogeneity of profiles within each serotype, in the two countries. In serotype 23F, the five French strains studied show subtypes of a pattern called A, also detected in the majority of 23F Portuguese strains; similarly 4 of the 5 serotype 9V strains belong to subtypes of the pattern G, also common within 9V Portuguese strains; 4 of the 5 strains of serotype 14 show a subtype of profile H, found often in Portuguese strains. The observed homogeneity of chromosomal DNA restriction profiles within each serotype in the two countries, confirms the importance of geographic spread of pneumococcal resistant clones, previously described.