Risk Factors for Bacterial Load of Pneumococcal Colonization among Peruvian Children Público

Abstract

Abstract

Background: Streptococcus pneumoniae, and its more than 93 serotypes, is a major cause of child mortality worldwide. Previous studies have established that environmental, biological, social and behavioral factors are important for colonization by S. pneumoniae, especially in the developing world. However, no studies have addressed the influence of these risk factors on pneumococcal carriage density. In this thesis, we quantified S. pneumoniae present in the nasopharynx of healthy children from a rural community in Peru and investigated the influence of risk factors on bacterial density.

Methods: This was a case-control study. Nasopharyngeal (NP) swabs (N=259) were collected from healthy Peruvian children (<3 years old). S. pneumoniae strains were isolated by culture and serotypes were identified. To quantify bacterial load, DNA extracted from NP swabs was analyzed using a lytA-based qPCR assay. Information about risk factors was collected using a questionnaire administered to the children's mothers. To identify risk factors implicated in density, two regression models were constructed: a logistic model that dichotomized the continuous qPCR data into lower and higher bacterial loads and an ordinal logistic regression model that accounted for both colonization status and degree of bacterial load.

Results: The prevalence of pneumococcal colonization among this population was 75.3%, as detected by the qPCR assay. The most prevalent serogroups identified were 6A/B, 15B/C, 23F, 19F, 19A, and 9V/A. In the logistic model, having at least one sibling was a risk factor for density of bacterial colonization (OR=2.79 (95%CI: 1.10-7.06)). In the ordinal logistic model, cooking breakfast for at least 45 minutes (OR=3.24 (95%CI: 1.76-5.98)) and having at least one sibling (OR=1.97 (95%CI: 1.05-3.68)) were also risk factors for pneumococcal density.

Conclusion: Carriage rates of S. pneumoniae in children within this community are very high. Risk factors implicated in S. pneumoniae density include having at least one sibling and cooking breakfast for at least 45 minutes.

Table of Contents

Table of Contents
I. INTRODUCTION..................................................................................................................1
II. METHODS...............................................................................................................................6
Study Design......................................................................................................................................... 6
Study Population ................................................................................................................................. 7
Data Collection .................................................................................................................................... 7
Laboratory Analysis ........................................................................................................................... 8
Statistical Analysis ........................................................................................................................... 11
III. RESULTS .......................................................................................................................... 12
IV. DISCUSSION.................................................................................................................... 13
V. REFERENCES................................................................................................................... 18
VI. TABLES............................................................................................................................. 24

About this Master's Thesis

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School	Rollins School of Public Health
Department	Epidemiology
Subfield / Discipline	Global Epidemiology - MPH & MSPH
Degree	MPH
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Epidemiology
Palabra Clave	Peru density nasopharyngeal pneumococcal risk factors
Committee Chair / Thesis Advisor	Klugman, Keith P, Emory University
Committee Members	Vidal Graniel, Jorge Eugenio, Emory University
Partnering Agencies	Emory University schools, faculty or affiliated programs International Non-governmental organization (e.g., CARE, Inc.) University, college or educational institution (other than Emory)

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