Serotype distribution and antimicrobial resistance of invasive Streptococcus pneumoniae isolates in Bulgaria before the introduction of pneumococcal conjugate vaccine.

AbstractThe 10-valent pneumococcal conjugate vaccine (PCV10) was introduced as a mandatory vaccine in Bulgaria in April 2010. We report on the serotype distribution and the antimicrobial resistance of 222 invasive Streptococcus pneumoniae isolates collected from all age groups before the introduction of PCV10. PCV7, PCV10, and PCV13 covered 43·7, 59·9, and 78·8% of all invasive pneumococcal strains, and 64·2, 79·1, and 89·6% of isolates involving children less than 5 years of age. Penicillin resistance was found in 30·1% of the isolates responsible for meningitis and in 5·0% of isolates responsible for other invasive infections. Overall, erythromycin resistance was found in 19·4% of all invasive strains. The erm(B) was the most prevalent pneumococcal macrolide resistance genotype (63·2%) and dual mechanisms of both genes the erm(B) and mef(E) were detected in 15·8% of 19 erythromycin resistant isolates during the period 2006–2010. The prevalence and spread of serotypes 19F, 6B, and 19A during the last per...