Serotype changes in adult invasive pneumococcal infections in Portugal did not reduce the high fraction of potentially vaccine preventable infections

Vaccine. 2012 Jan 5;30(2):218-24. doi: 10.1016/j.vaccine.2011.11.022. Epub 2011 Nov 17.


We determined the serotype and antimicrobial susceptibility of 1100 isolates responsible for adult invasive pneumococcal infections (IPD) in Portugal between 2006 and 2008. Serotypes 3 (13%), 1 (12%), 7F (11%), 19A (10%) and 14 (7%) were the most frequent causes of IPD and the two later serotypes accounted for the majority of erythromycin and penicillin nonsusceptible isolates. Serotype 1 was associated with younger adults whereas serotype 3 was associated with older adults. Despite the availability of the 23-valent polysaccharide vaccine (PPV23) in Portugal since 1996, the proportion of PPV23 preventable IPD remained stable and above 80%. Comparing with previous data from Portugal, we showed a continued decline of the serotypes included in the 7-valent conjugate vaccine (PCV7) in adult IPD and a rise of serotypes included in the 13-valent conjugate vaccine, increasing its potential coverage of adult IPD to 70% in 2008. Penicillin non-susceptibility remained stable (17%) whereas erythromycin resistance (18%) has continued to rise in the post-PCV7 years.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age Factors
  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / pharmacology
  • Female
  • Humans
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Pneumococcal Infections / epidemiology*
  • Pneumococcal Infections / microbiology*
  • Pneumococcal Vaccines / immunology*
  • Portugal / epidemiology
  • Serotyping
  • Streptococcus pneumoniae / classification*
  • Streptococcus pneumoniae / drug effects
  • Streptococcus pneumoniae / isolation & purification*
  • Young Adult


  • 13-valent pneumococcal vaccine
  • 23-valent pneumococcal capsular polysaccharide vaccine
  • Anti-Bacterial Agents
  • Pneumococcal Vaccines