Abstract
Background Influenza virus infection is a substantial cause of severe illness, hospitalization, and mortality in children. Infection by influenza can also predispose the host to bacterial infection, including bloodstream infections, which are associated with more severe illness than influenza infection alone. The purpose of this work is to describe the clinical course of children hospitalized for influenza whose illness is complicated by bloodstream infection.
Methods Using active surveillance data of laboratory-confirmed influenza hospitalizations at the 12 Canadian Immunization Monitoring Program Active (IMPACT) hospitals among children 鈮� 16 years old, between 2010-2011 and 2019-2020 influenza seasons. Factors associated with bloodstream infection were identified using multivariable logistic regression analyses. The risk of death associated with a bloodstream infection was explored using a multivariable logistic regression model.
Results We identified 9,179 laboratory-confirmed influenza hospital admissions. Median age was 3.0 years (IQR 1.1, 6.0) and 57% of patients were male. A laboratory-confirmed bacterial infection was present in 3.2% (394/9179) of cases, most frequently bloodstream infection in 87 children (0.9%). Streptococcus pyogenes (22%, 19/87), Staphylococcus aureus (18%, 16/87), and Streptococcus pneumoniae (17%, 15/87) were the most commonly identified organisms causing bloodstream infection. In multivariable logistic regression analyses, cancer (aOR 3.20, 95% CI 1.43-6.40), the presence of a non-bloodstream bacterial infection (aOR 13.9, 95% CI 7.52-21.6), ICU admission (aOR 2.58, 95% CI 1. 58-4.18), and radiographically confirmed pneumonia (aOR 1.76, 95% CI 1.10-2.78) increased odds of bloodstream infection. Separate models with the same covariates, replacing only the measure of disease severity of ICU admission, were also tested. Respiratory support (aOR 3.43, 95% CI 1.99-5.77) and longer hospital LOS (aOR 1.03, 95% CI 1.02-1.04) were each also significantly associated with bloodstream infection. Bloodstream infection was a significant risk factor for death (aOR 13.0, 95% CI 4.84-29.1) in a multivariable logistic model adjusted for age, influenza virus type and the presence of any at-risk chronic condition.
Conclusion Bloodstream infections among pediatric influenza hospitalizations were identified to be associated with increased levels of care, including to ICU admission, invasive mechanical ventilation, hospital length of stay, and in-hospital mortality.