Resumen:
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 β-lactam (βL) resistant and 10 βL susceptible capsulated
clinical strains were characterized by multilocus sequence typing
(MLST). Six βL resistant and four βL 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.