Pneumococcal Serotypes Colonise the Nasopharynx in Children at Different Densities

Fernanda Rodrigues; Leon Danon; Begonia Morales-Aza; Paulina Sikora; Valtyr Thors; Muriel Ferreira; Katherine Gould; Jason Hinds; Adam Finn

doi:10.1371/journal.pone.0163435

Pneumococcal Serotypes Colonise the Nasopharynx in Children at Different Densities

PLoS One. 2016 Sep 29;11(9):e0163435. doi: 10.1371/journal.pone.0163435. eCollection 2016.

Authors

Fernanda Rodrigues^{1

2}, Leon Danon³, Begonia Morales-Aza⁴, Paulina Sikora⁴, Valtyr Thors⁴, Muriel Ferreira¹, Katherine Gould^{5

6}, Jason Hinds^{5

6}, Adam Finn⁴

Affiliations

¹ Hospital Pediátrico Coimbra, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal.
² Faculty of Medicine, Universidade de Coimbra, Coimbra, Portugal.
³ School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
⁴ School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom.
⁵ Institute for Infection and Immunity, St. George's, University of London, London, United Kingdom.
⁶ BUGS Bioscience, London Bioscience Innovation Centre, London, United Kingdom.

Abstract

Prevalence of pneumococcal serotypes in carriage and disease has been described but absolute serotype colonisation densities have not been reported. 515 paediatric nasal swab DNA extracts were subjected to lytA qPCR and molecular serotyping by microarray. Absolute serotype densities were derived from total pneumococcal density (qPCR cycle threshold and standard curve) and relative abundance (microarray) and varied widely. Compared to all serotype densities observed, the strongest evidence of differences was seen for serotypes 21 and 35B (higher) and 3, 38 and non-typeables (lower) (p<0.05) with a similar hierarchy when only a single serotype carriage was assessed. There was no evidence of any overall density differences between children with single or multiple serotypes detected but serotypes with mid-range densities were more prevalent. The hierarchy of distinct pneumococcal serotype carriage densities described here for the first time, may help explain the dynamics of transmission between children.

Grants and funding

This work was supported by an investigator-led project grant from Pfizer. BMA and PS are supported by the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Evaluation of Interventions at University of Bristol. LD is supported by the NIH (Pepfar supplement) and Canadian Institute of Health Research. JH and KG are not employed by and receive no personal income from BUGS Bioscience. Pfizer had no role in study design, data collection and analysis nor preparation of the manuscript. NIHR provided support in the form of salaries for authors BMA and PS, NIH and Canadian Institute of Health Research provided support in the form of salaries for author LD but in all cases did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.