ARTICLE Molecular characterization of Streptococcus pneumoniae invasive serotype 19A isolates from adults in two Spanish regions (1994–2009) J. M. Marimón & M. Alonso & D. Rolo & C. Ardanuy & J. Liñares & E. Pérez-Trallero Received: 7 June 2011 /Accepted: 18 August 2011 # Springer-Verlag 2011 Abstract From 1994 to 2009, the incidence of invasive serotype 19A pneumococci isolated from adults in Barcelona and San Sebastian almost doubled every 4 years. Genotyping of the 167 invasive isolates studied showed serotype 19A to be highly heterogeneous, with 35 different sequence types (STs) and a different clonal structure in each region and time period. Multiresistance, defined as non-susceptibility to three or more antimicrobials, was found in 86 (51.5%) isolates. The most frequent STwas the multidrug-resistant ST276 (n =28), which is a single-locus variant of the Denmark 14 -ST230 global clone. The ST276 clone, only present in San Sebastian before 2001, was successfully disseminated from 2002 in both cities and was the main contributor to the overall increase of serotype 19A infections. Introduction Infections caused by Streptococcus pneumoniae are among the first causes of morbidity and mortality due to an infectious disease worldwide. After the commercialization of the 7-valent pneumococcal protein conjugate vaccine (PCV7) in 2000, invasive pneumococcal disease (IPD) caused by vaccine serotypes substantially decreased, while non-vaccine serotypes increased [1, 2]. In the last few years, serotype 19A pneumococci as a cause of IPD have increased worldwide. This increase has been observed in countries with and without the introduction of the PCV7 in children [3–5]. Moreover, the increase of multidrug- resistant pneumococci serotype 19A, such as ST320 in the USA, Europe, and Asia, and ST276 in Europe, is especially worrisome [4, 6–13]. The aim of this study was to analyze the evolution of invasive serotype 19A infections in the adult populations of two Spanish cities in the 16 years before the introduction of the new 10-valent (PCV10) and 13-valent (PCV13) conjugate vaccines, which also cover serotype 19A. The possible effect of the introduction of the PCV7 in June 2001 in Spain was also analyzed. Materials and methods This study was simultaneously performed in two cities: San Sebastian, in the north of Spain, and Barcelona, in the northeast of Spain. The two cities are 571 km apart. The study included all S. pneumoniae isolates causing IPD obtained from patients aged ≥15 years old attending Hospital Donostia and Hospital Universitari de Bellvitge between January 1994 and December 2009. IPD was considered when a pneumococcus was isolated from a J. M. Marimón : M. Alonso : E. Pérez-Trallero Hospital Universitario Donostia-Instituto Biodonostia, San Sebastián, Spain J. M. Marimón : D. Rolo : C. Ardanuy : J. Liñares : E. Pérez-Trallero Biomedical Research Center Network for Respiratory Diseases (CIBERES), Madrid, Spain D. Rolo : C. Ardanuy : J. Liñares Hospital Universitari de Bellvitge—IDIBELL, Barcelona, Spain E. Pérez-Trallero Faculty of Medicine, University of the Basque Country, San Sebastián, Spain E. Pérez-Trallero (*) Servicio de Microbiología, Hospital Donostia, Paseo Dr. Beguiristain s/n, 20014 San Sebastián, Spain e-mail: mikrobiol@terra.es Eur J Clin Microbiol Infect Dis DOI 10.1007/s10096-011-1399-3