Multilocus sequence types of invasive pneumococcal isolates from Danish infants (0–90 days) 2003–2013

BACKGROUND: A pneumococcal conjugate vaccine (PCV) has been part of the Danish childhood immunization programme since October 2007. It is administered at the ages of 3, 5 and 12 months and healthy infants younger than 90 days are consequently not vaccinated. Initially the PCV-7 vaccine was used but this was replaced by the PCV-13 in April 2010. Vaccination coverage in Denmark is approximately 90 %.The aim of this study was to present multilocus sequence typing (MLST) profiles of Streptococcus pneumoniae isolates from Danish infants (0–90 days) with invasive pneumococcal disease (IPD) in the period 2003–2013. FINDINGS: 32 IPD isolates were investigated for their MLST profiles. The identified sequence types (STs) had previously been observed in other European countries. Among the clones were ST 306 (serotype 1), ST 180 (serotype 3) and ST 191 (serotype 7F). CONCLUSIONS: The ST profile distribution in this study is similar to that observed in other European studies and show a variety of STs. Our data show that the majority of STs found in Denmark is also observed in other European countries, indicating that the IPD isolates were from clones generally circulating in Europe.