Background
Acute upper respiratory tract infections (URIs) that are caused by a diverse range of viral and bacterial pathogens are one of the most common illnesses observed in humans.1, The morbidity, mortality and economic burden associated with all types of URIs have been demonstrated significant, with influenza virus being the focus of identification as a causative pathogen for URIs in ambulatory clinical settings.1,2 Traditional diagnostic testing methods for URIs including antigenic methods, cell culture, and serology have limitations with regard to sensitivity, specificity, and/or turn-around-times, rendering them relatively limited for routine use in ambulatory care settings.3-5
Recent technological advances have led to the development of multiplexed molecular amplification assays that are capable of detecting multiple common causes of URI pathogens from a single nasopharyngeal swab (NP). Although these methods have been shown to be rapid, highly sensitive, and specific,6-9 uptake for routine practice remains relatively limited to research studies, due in part to lack of available treatment options for non-influenza respiratory viruses and added expense of employing multiplex molecular methods.6 On the other hand, these assays afford new opportunities to better understand the etiologic distribution, prevalence, and rates of co-infections associated with URIs. Several recent studies employing multiplex technologies have been conducted with specific select populations, including patients with community-associated pneumonia (CAP),10-12 hospitalized patients,10-14 military personnel,15-17 relatively healthy outpatients7, 18-20 and selected pediatrics cohorts.21-23
To date, there is limited data regarding the etiology of non-influenza, non-RSV, URI viral and bacterial pathogens in unselected ambulatory populations considered at high risk for respiratory virus related complications. Such research could be helpful not only for understanding the epidemiology and etiology of acute URIs, but also could help inform future research to address antibiotic stewardship.7, 22, 23
Our aim was to contribute to the existing knowledge regarding the epidemiology and etiology of acute URIs in a broad ambulatory population of patients considered to be at high-risk of influenza complications,24, 25 who were tested for influenza, but were not tested for other respiratory pathogens. We collected residual waste samples from patients who presented to 4 geographically disparate EDs, who had already been tested for influenza with a single target influenza assay24 and subsequently tested them utilizing the multiplex Genmark ePlex respiratory panel (RP) research use only (RUO) platform.