Vaccine. 2016 Jun 17. pii: S0264-410X(16)30430-3. doi: 10.1016/j.vaccine.2016.06.017. [Epub ahead of print]

Impact of the 13-valent pneumococcal conjugate vaccine on Streptococcus pneumoniae multiple serotype carriage.

Valente C1, Hinds J2, Gould KA2, Pinto FR3, de Lencastre H4, Sá-Leão R5.

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Abstract

INTRODUCTION:

Pneumococcal multiple serotype carriage is important for evolution of the species and to understand how the pneumococcal population is changing with vaccination. We aimed to determine the impact of the 13-valent pneumococcal conjugate vaccine (PCV13) on multiple serotype carriage.

METHODS AND MATERIALS:

Nasopharyngeal samples from fully vaccinated pneumococcal carriers (4 doses of PCV13, n=141, aged 18-72months) or from non-vaccinated pneumococcal carriers (0 doses of any PCV, n=140, same age group) were analyzed. Multiple serotype carriage was evaluated by DNA hybridization with a molecular serotyping microarray that detects all known serotypes.

RESULTS:

Vaccinated children had a lower prevalence of multiple serotype carriage than the non-vaccinated group (20.6% vs 29.3%, p=0.097), and a significantly lower proportion of PCV13 serotypes (6.4% vs 38.5%, p=0.0001). PCV13 serotypes found among vaccinated children were mostly detected as a minor serotype in co-colonization with a more abundant non-vaccine serotype. Vaccinated children were colonized by a significantly higher proportion of commensal non-pneumococcal Streptococcus spp. (58.2% vs 42.8%, p=0.012). In vaccinated children there were significantly less non-vaccine type (NVT) co-colonization events than expected based on the distribution of these serotypes in non-vaccinated children.

CONCLUSIONS:

The results suggest that vaccinated children have lower pneumococcal multiple serotype carriage prevalence due to higher competitive abilities of non-vaccine serotypes expanding after PCV13 use. This might represent an additional benefit of PCV13, as decreased co-colonization rates translate into decreased opportunities for horizontal gene transfer and might have implications for the evolution and virulence of pneumococci.

Copyright © 2016 Elsevier Ltd. All rights reserved.

KEYWORDS:

Co-colonization; Microarray; Multiple serotype carriage; PCV13; Pneumococcal conjugate vaccine; Streptococcus pneumoniae

PMID: 27325351 [PubMed - as supplied by publisher]