ABSTRACT
Respiratory tract infections represent one of the most common clinical syndromes for which patients present to physicians in North America. Lower respiratory tract infections are a leading cause of morbidity and mortality, and upper respiratory tract infections, while rarely causing death, are commonly associated with significant morbidity. Common infections today command the use of antimicrobial agents and respiratory tract infections in particular have driven the use of empirically prescribed oral antimicrobials.1 The widespread use of antimicrobials in the management of both lower and upper respiratory tract infections has been associated with increasing antibiotic resistance. This has led to the development of extensive surveillance programs worldwide to understand the evolution of resistance.2 However, our understanding of the incidence of pathogens causing respiratory tract infections in the dynamic of changing patient populations has not been as well addressed.3 While many studies have attempted to define the incidence of common bacterial pathogens using culture and, increasingly, molecular diagnostics, less common viral, fungal, or difficult-to-detect pathogens causing disease have remained more elusive.
