Increasing Incidence of Streptococcus pneumoniae Serotype 19A and Emergence of Two Vaccine Escape Recombinant ST695 Strains in Liguria, Italy, 7 Years after Implementation of the 7-Valent Conjugated Vaccine

Abstract

Two serotype 19A (ST695) Streptococcus pneumoniae vaccine escape recombinant strains attributable to capsular switching events were detected by a laboratory surveillance system that is an integral part of a vaccination program begun in Liguria, Italy, in May 2003, an Italian administrative region with long-lasting high coverage, an unusual occurrence in Europe. To our knowledge, this is the first detection of an occurrence of capsular switching outside the United States.