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



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.



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.



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.
Laboratory of Molecular Microbiology of Human Pathogens, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
Carina
C
Valente
Institute for Infection and Immunity, St. George's, University of London, London, UK; BUGS Bioscience, London Bioscience Innovation Centre, London, UK.
Jason
J
Hinds
Institute for Infection and Immunity, St. George's, University of London, London, UK; BUGS Bioscience, London Bioscience Innovation Centre, London, UK.
Katherine A
KA
Gould
BioISI - Biosystems & Integrative Sciences Institute, Faculdade de Ciências da Universidade de Lisboa, Lisbon, Portugal.
Francisco R
FR
Pinto
Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal; Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, NY, USA.
Hermínia
H
de Lencastre
Laboratory of Molecular Microbiology of Human Pathogens, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal. Electronic address: rsaleao@itqb.unl.pt.
Raquel
R
Sá-Leão
D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D009305:Nasopharynx / Q000382:microbiology; D011008:Pneumococcal Infections / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000627:therapeutic use; D011174:Portugal; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification
C538862:13-valent pneumococcal vaccine; D022242:Pneumococcal Vaccines
Co-colonization; Microarray; Multiple serotype carriage; PCV13; Pneumococcal conjugate vaccine; Streptococcus pneumoniae