Dynamics of Colonization of Streptococcus pneumoniae Strains in Healthy Peruvian Children

• Type of Material: Article
• Authors: Kristin Nelson, Emory University; Carlos G. Grijalva, Vanderbilt University School of Medicine; Sopio Chochua, Emory University; Paulina Hawkins, Emory University; Ana I Gil, Instituto de Investigación Nutricional; Claudio F. Lanata, Instituto de Investigación Nutricional; Marie R. Griffin, Vanderbilt University School of Medicine; Kathryn M. Edwards, Vanderbilt University School of Medicine; Keith P Klugman, Emory University; Jorge Vidal Graniel, Emory University
• Language: English
• Date: 2018-03
• Publisher: Oxford University Press (OUP)
• Publication Version: Final Published Version
• Copyright Statement: © The Author(s) 2018. Published by Oxford University Press on behalf of Infectious Diseases Society of America.
• Final Published Version (URL): http://dx.doi.org/10.1093/ofid/ofy039
• Title of Journal or Parent Work: Open Forum Infectious Diseases
• ISSN: 2328-8957
• Volume: 5
• Issue: 3
• Start Page: ofy039
• End Page: ofy039
• Grant/Funding Information: This work was supported by a Vanderbilt University Clinical and Translational Science Award (National Institutes of Health grant UL1 RR024975 to C.G.G.); the Thrasher Research Fund (grant 02832-9 to C.G.G.); Pfizer investigator-initiated research grants (IIR WS1898786 [0887X1-4492] to C.G.G and IIR WS2079099 to J.E.V.); and the National Institutes of Health (R21AI112768-01A1 to J.E.V.).
• Keywords: pneumococcal disease; asymptomatic carriage; pneumococcal conjugate vaccine; pneumococcal colonization; pneumococcal carriage; pneumoniae; Streptococcus
• Research Categories: Health Sciences, Public Health; Health Sciences, Epidemiology

Abstract

Background: Although asymptomatic carriage of Streptococcus pneumoniae (Spn) is common, acquisition of the bacteria is the first step in disease pathogenesis. We examined the effect of introduction of the 7-valent pneumococcal vaccine on Spn carriage patterns in a cohort of Peruvian children. Methods: We used data from a prospective cohort study that collected monthly nasopharyngeal samples from children under 3 years of age. Spn isolates were serotyped using Quellung reactions, and bacterial density was determined by quantitative polymerase chain reaction. Changes in Spn carriage patterns, including the rate of carriage and number and density of serotypes carried over time, were evaluated before (2009) and after widespread vaccination with PCV7 (2011). Using all pneumococcal detections from each child and year, we identified serotypes that were present both at first and last detection as "persisters" and serotypes that replaced a different earlier type and were detected last as "recolonizers." Results: Ninety-two percent (467/506) of children in 2009 and 89% (451/509) in 2011 carried Spn at least once. In 2009 and 2011, rates of carriage were 9.03 and 9.04 Spn detections per person-year, respectively. In 2009, 23F, a serotype included in PCV7, was the only type identified as a persister and 6A, 15B, and 19A were identified as recolonizer serotypes. In 2011, 6B and 7C were persister serotypes and 13 was a frequent recolonizer serotype. Conclusions: Overall Spn carriage among children under 3 in Peru was similar before and after introduction of PCV7; however, serotype-specific rates and longitudinal carriage patterns have shifted.