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Decrease in Pneumococcal Co-Colonization following Vaccination with the Seven-Valent Pneumococcal Conjugate Vaccine

Valente, C; Hinds, J; Pinto, F; Brugger, SD; Gould, K; Mühlemann, K; de Lencastre, H; Sá-Leão, R (2012) Decrease in Pneumococcal Co-Colonization following Vaccination with the Seven-Valent Pneumococcal Conjugate Vaccine. PLOS ONE, 7 (1). e30235 (1)- e30235 (7). ISSN 1932-6203 https://doi.org/10.1371/journal.pone.0030235
SGUL Authors: Gould, Katherine Ann Hinds, Jason

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Abstract

Understanding the epidemiology of pneumococcal co-colonization is important for monitoring vaccine effectiveness and the occurrence of horizontal gene transfer between pneumococcal strains. In this study we aimed to evaluate the impact of the seven-valent pneumococcal conjugate vaccine (PCV7) on pneumococcal co-colonization among Portuguese children. Nasopharyngeal samples from children up to 6 years old yielding a pneumococcal culture were clustered into three groups: pre-vaccine era (n = 173), unvaccinated children of the vaccine era (n = 169), and fully vaccinated children (4 doses; n = 150). Co-colonization, serotype identification, and relative serotype abundance were detected by analysis of DNA of the total bacterial growth of the primary culture plate using the plyNCR-RFLP method and a molecular serotyping microarray-based strategy. The plyNCR-RFLP method detected an overall co-colonization rate of 20.1%. Microarray analysis confirmed the plyNCR-RFLP results. Vaccination status was the only factor found to be significantly associated with co-colonization: cocolonization rates were significantly lower (p = 0.004; Fisher’s exact test) among fully vaccinated children (8.0%) than among children from the pre-PCV7 era (17.3%) or unvaccinated children of the PCV7 era (18.3%). In the PCV7 era there were significantly less non-vaccine type (NVT) co-colonization events than would be expected based on the NVT distribution observed in the pre-PCV7 era (p = 0.024). In conclusion, vaccination with PCV7 resulted in a lower co-colonization rate due to an asymmetric distribution between NVTs found in single and co-colonized samples. We propose that some NVTs prevalent in the PCV7 era are more competitive than others, hampering their co-existence in the same niche. This result may have important implications since a decrease in co-colonization events is expected to translate in decreased opportunities for horizontal gene transfer, hindering pneumococcal evolution events such as acquisition of antibiotic resistance determinants or capsular switch. This might represent a novel potential benefit of conjugate vaccines.

Item Type: Article
Additional Information: Copyright: 2012 Valente et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Keywords: Child, Child, Preschool, Colony Count, Microbial, Humans, Infant, Multivariate Analysis, Oligonucleotide Array Sequence Analysis, Pneumococcal Vaccines, Polymorphism, Restriction Fragment Length, Reproducibility of Results, Risk Factors, Serotyping, Streptococcus pneumoniae, Vaccination, Science & Technology, Multidisciplinary Sciences, Science & Technology - Other Topics, MULTIDISCIPLINARY SCIENCES, STREPTOCOCCUS-PNEUMONIAE, DAY-CARE, NASOPHARYNGEAL CARRIAGE, HAEMOPHILUS-INFLUENZAE, SEROTYPES, CHILDREN, DISEASE, COCOLONIZATION, TRANSMISSION, REGRESSION, General Science & Technology, MD Multidisciplinary
SGUL Research Institute / Research Centre: Academic Structure > Infection and Immunity Research Institute (INII)
Journal or Publication Title: PLOS ONE
ISSN: 1932-6203
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Dates:
DateEvent
12 January 2012Published
Web of Science ID: WOS:000301357100048
URI: https://openaccess.sgul.ac.uk/id/eprint/107076
Publisher's version: https://doi.org/10.1371/journal.pone.0030235

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