Emergence of Streptococcus pneumoniae Serotype 12F after Sequential Introduction of 7- and 13-Valent Vaccines, Israel

Abstract

Israel implemented use of 7- and 13-valent pneumococcal vaccine in 2009 and 2010, respectively. We describe results of prospective, population-based, nationwide active surveillance of Streptococcus pneumoniae serotype 12F (Sp12F) invasive pneumococcal disease (IPD) dynamics in the 7 years after vaccine introduction. Of 4,573 IPD episodes during July 2009–June 2016, a total of 434 (9.5%) were caused by Sp12F. Sp12F IPD rates (cases/100,000 population) increased in children 3.9 since 2011–2012, followed by an increase in all ages. During 2011–2016, Sp12F was the most prevalent IPD serotype. Sp12F isolates were mostly penicillin nonsusceptible (MIC >0.06 µg/mL; MIC50 = 0.12) and predominantly of sequence type 3774), a clone exclusively found in Israel (constituting ≈90% of isolates in 2000–2009). The sharp increase, long duration, and predominance of Sp12F IPD after vaccine implementation reflect a single clone expansion and may represent more than a transient outbreak.

Keywords

• Streptocococcus pneumoniae infections
• 12F polysaccharides Streptocococcus pneumoniae
• 7-valent pneumococcal vaccine
• 13-valent pneumococcal vaccine
• emerging infectious diseases
• Israel