The main objective of this work was to analyse, by different typing methods, the molecular epidemiology of strains of S. pneumoniae isolated from paediatric patients in Cordoba, Argentina. To this end, 10 b-lactam (bL) resistant and 10 bL susceptible capsulated clinical strains were characterized by multilocus sequence typing (MLST). Six bL resistant and four bL susceptible strains were included within Spain 9V3 clonal complex. The Spain 9V3 pneumococcal clone is one of approximately twenty international clones, and it is widely disseminated in European countries. The capsule biosynthesis is performed by enzymes that are codified by a cluster of capsular genes (cps), which are flanked by the dexB and pbp1a genes. This DNA region is a target for frequent capsular recombination and presents multiple divergences in its DNA sequence. We used the cpsB and pbp1a sequence analysis to characterize genotypically serotype-14 clinical strains, and to compare them with the Spain 9V3 clone. In our strains, the cpsB and pbp1a sequences were identical, but markedly different from those of European 9V3 variants, which present these genetic markers divergent from the original Spain 9V3 clone. The serotype 14 variants could be differentiated from the Spain 9V3 clone through the analysis of cpsB and pbp1a DNA sequences, but not by MLST. In conclusion, the Spain 9V3 clone dissemination in Cordoba present the same clonal origin, and indicate that this serotype 14 variant is genetically stable compared with the European 9V3 clones.
