braz j infect dis 2 0 1 7; 2 1(4) :433–440 www.elsevier.com/locate/bjid The Brazilian Journal of INFECTIOUS DISEASES Original article Serotype changes and antimicrobial nonsusceptibility rates of invasive and non-invasive Streptococcus pneumoniae isolates after implementation of 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in Bulgaria Lena Setchanova a,* , Marianna Murdjeva b , Iglika Stancheva c , Alexandra Alexandrova a , Maria Sredkova d , Temenuga Stoeva e , Magda Yoneva f , Anna Kurchatova g , Ivan Mitov a a Medical University of Sofia, Faculty of Medicine, Department of Medical Microbiology, Sofia, Bulgaria b Medical University of Plovdiv, University Hospital, Department of Microbiology, Plovdiv, Bulgaria c UMBAL “Q. Ioanna-ISUL”, Department of ENT Diseases, Sofia, Bulgaria d Medical University of Pleven, University Hospital, Department of Medical Microbiology, Pleven, Bulgaria e Medical University of Varna, University Hospital, Department of Microbiology, Varna, Bulgaria f Tokuda Hospital, Laboratory of Microbiology, Sofia, Bulgaria g National Centre of Infectious and Parasitic Diseases, Department Epidemiology and CD Surveillance, Sofia, Bulgaria a r t i c l e i n f o Article history: Received 2 December 2016 Accepted 9 March 2017 Available online 1 May 2017 Keywords: Streptococcus pneumoniae Invasive and non-invasive isolates Serotypes Antimicrobial nonsusceptibility a b s t r a c t The 10-valent pneumococcal conjugate vaccine (PCV10) has been included in Bulgarian Childhood Immunization Program since 2010. This study aimed to assess serotype distribu- tion and antimicrobial resistance of 198 invasive and non-invasive Streptococcus pneumoniae strains that had been isolated in Bulgaria during 2011–2016 from patients with invasive (IPD) and non-invasive (NIPD) pneumococcal diseases. The most common invasive serotypes were 3 (10.1%), 19F (4.0%), and 7F (3.0%). A significant decrease in the proportion of invasive vac- cine types (VTs) from 64.2% to 35.2% was found in comparison with pre-vaccine era. The most common serotypes among middle ear fluids were 3, 19A and 19F (5.6% each), and VTs fell down from 66.4% to 40.0% in post-PCV10 period. Among respiratory isolates, the most prevalent serotypes were some emergent serotypes such as 15A/B/C (5.0%), 19A, and 6C (4.0% each). VTs decreased significantly (16.3%) among vaccinated children compared to unvaccinated children and adults (44.0%). Two non-VTs (19A and 6C) have increased sig- nificantly more (p < 0.05) in vaccinated children than in unvaccinated patients. The rates of antibiotic nonsusceptible S. pneumoniae in Bulgaria remained high in post-PCV10 era. ∗ Corresponding author. E-mail address: lenasetchanova@hotmail.com (L. Setchanova). http://dx.doi.org/10.1016/j.bjid.2017.03.011 1413-8670/© 2017 Sociedade Brasileira de Infectologia. Published by Elsevier Editora Ltda. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).