Density Interactions between Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus in the Nasopharynx of Young Peruvian Children

• Type of Material: Article
• Authors: Yu-Wen Chien, Emory University; Jorge Vidal Graniel, Emory University; Carlos G. Grijalva, Vanderbilt University School of Medicine; Catherine Bozio, Emory University; Kathryn M. Edwards, Vanderbilt University School of Medicine; John V. Williams, Vanderbilt University School of Medicine; Marie R. Griffin, Vanderbilt University School of Medicine; Hector Verastegui, Instituto de Investigación Nutricional; Stella M. Hartinger, University of Basel; Ana I. Gil, Instituto de Investigación Nutricional; Claudio F. Lanata, Instituto de Investigación Nutricional; Keith P Klugman, Emory University
• Language: English
• Date: 2013-01
• Publisher: Lippincott, Williams & Wilkins
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2013, (C) 2013 Lippincott Williams
• Final Published Version (URL): http://journals.lww.com/pidj/pages/articleviewer.aspx?year=2013&issue=01000&article=00023&type=abstract
• Title of Journal or Parent Work: Pediatric Infectious Disease Journal
• ISSN: 0891-3668
• Volume: 32
• Issue: 1
• Start Page: 72
• End Page: 77
• Grant/Funding Information: This study was supported in part by Vanderbilt University, the Vanderbilt CTSA grant UL1 RR024975-01 from NCRR/NIH and Pfizer (IIR WS1898786(0887X1-4492)).
• Keywords: Streptococcus pneumoniae; nasopharyngeal carriage; interaction
• Research Categories: Health Sciences, Public Health

Abstract

Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus are commonly carried in the nasopharynx (NP) of young children, and have been speculated to interact with each other. Although earlier studies used cultures alone to assess these interactions, the addition of real-time quantitative polymerase chain reaction (qPCR) provides further insight into these interactions. We compared results of culture and qPCR for the detection of these three bacteria in 446 NP samples collected from 360 healthy young children in a prospective cohort study in the Peruvian Andes. Patterns of concurrent bacterial colonization were studied using repeated measures logistic regression models with generalized estimating equations. Spearman correlation coefficients were employed to assess correlations among bacterial densities. At a bacterial density <105 colony forming units (CFU)/ml measured by qPCR, culture detected significantly less carriers (P<0.0001) for all three pathogens, than at a bacterial density >105 CFU/ml. In addition, there was a positive association between S. pneumoniae and H. influenzae colonization measured by both culture (OR 3.11 – 3.17, p < 0.001) and qPCR (OR 1.95 – 1.97, p < 0.01). The densities of S. pneumoniae and H. influenzae, measured by qPCR, were positively correlated (correlation coefficient 0.32, p < 0.001). A negative association was found between the presence of S. pneumoniae and S. aureus in carriage with both culture (OR 0.45, p = 0.024) and qPCR (OR 0.61, p < 0.05). The impact of density on detection by culture and the observed density-related interactions support use of qPCR in additional studies to examine vaccine effects on diverse bacterial species.