Identification of Pathogens from the Upper Respiratory Tract of Adult
Emergency Department Patients at High Risk for Influenza Complications
Abstract
Acute upper respiratory infections (URIs) represent a major source of
annual emergency department (EDs) visits in the United States. However,
the definitive etiology of symptoms is generally not determined as
testing has historically been prioritized for influenza virus and
recently, respiratory syncytial virus (RSV). To elucidate the
prevalence, rates of co-infections, and etiologic composition of URIs
from symptomatic adult ED patients, we evaluated specimens from four
geographically diverse EDs in the United States from 2013-2014 utilizing
a multiplex molecular diagnostic assay. 1941 ED patients who had signs
and/or symptoms of an acute URI and were considered ‘high-risk’ for
influenza related complications according to CDC criteria, were
consecutively enrolled and tested for influenza; influenza prevalence
was 9.4% (183/1941). Among them, 799 nasopharyngeal swab specimens with
sufficient residual volumes were subsequently tested for additional
respiratory pathogens. The overall positivity rate was 30.1% (241/799),
of which 6.6% (16/241) were co-infected. Non-influenza pathogens from
most to least common were: rhinovirus/enterovirus, coronavirus, human
metapneumovirus and RSV, respectively. The ratio of co-infection to
mono-infection was highest amongst those with adenovirus, versus
mon-infections (2.0). Broad differences in disease prevalence and
pathogen distributions were observed across geographic regions; the site
with the highest detection rate (for both mono and co-infections)
demonstrated the greatest pathogen diversity. Adult ED patients at
high-risk for influenza complications were infected with a variety of
respiratory pathogens and geographic variations in the disease
prevalence and co-pathogen type were observed. Further research is
required to evaluate the clinical relevance of these findings.