The association between bacteria colonizing the upper respiratory tract and lower respiratory tract infection in young children: a systematic review and meta-analysis

Shantelle Claassen-Weitz, Katherine Yl Lim, Christopher Mullally, Heather J Zar, Mark P Nicol

Research output: Contribution to journalReview articlepeer-review

24 Citations (Scopus)

Abstract

BACKGROUND: Bacteria colonizing the upper respiratory tract (URT) of young children play a key role in the pathogenesis of lower respiratory tract infection (LRTI).

OBJECTIVES: To systematically review the literature on the association between bacteria colonizing the URT and LRTI among young children.

DATA SOURCES: MEDLINE, Academic Search Premier, Africa-Wide Information and CINAHL, Scopus and Web of Science.

STUDY ELIGIBILITY CRITERIA: Studies published between 1923-2020, investigating URT bacteria from LRTI cases and controls.

PARTICIPANTS: Children under five years with and without acute LRTI.

METHODS: Three reviewers independently screened titles, abstracts, and full texts. Meta-analysis was done using Mantel Haenszel fixed- or random-effects models.

RESULTS: Most eligible studies (41/50) tested nasopharyngeal specimens when investigating URT bacteria. Most studies were of cross-sectional design (44/50). Twenty-four studies were performed in children in lower- or lower-middle-income countries (LMICs). There was higher prevalence of Haemophilus influenzae [pooled OR: 1.60 (95% CI: 1.23-2.07)] and Klebsiella spp. [pooled OR: 2.04 (95% CI: 1.17-3.55)] from URT specimens of cases versus controls. We observed a positive association between the detection of Streptococcus pneumoniae from URT specimens and LRTI after excluding studies where there was more antibiotic treatment prior to sampling in cases vs. controls [pooled OR: 1.41 (95% CI: 1.04-1.90)]. High density colonization with S. pneumoniae (>6.9log10 copies/mL) was associated with an increased risk for LRTI. The associations between both Streptococcus and Haemophilus URT detection and LRTI were supported, at genus-level, by 16S rRNA sequencing. Evidence for the role of Moraxella catarrhalis and Staphylococcus aureus was inconclusive.

CONCLUSIONS: Detection of H. influenzae or Klebsiella spp. in the URT was associated with LRTI, while evidence for association with S. pneumoniae was less conclusive. Longitudinal studies assessing URT microbial communities, together with environmental and host factors are needed to better understand pathogenesis of childhood LRTI.

Original languageEnglish
Pages (from-to)1262-1270
Number of pages9
JournalClinical Microbiology and Infection : the Official Publication of the European Society of Clinical Microbiology and Infectious Diseases
Volume27
Issue number9
DOIs
Publication statusPublished - Sept 2021

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