Analysis of Nasopharyngeal Microbiota in Patients With Respiratory Infections

Respiratory tract infections represent the most frequent infectious pathology in community environments and when of bacterial origin, imply a morbid state generally supported by a pathogenic bacterial species predominant on the commensal flora of the airways. Among the most frequent bacterial infections of the upper respiratory tract in pediatric age we find acute bacterial pharyngitis or pharyngotonsillitis caused by Streptococcus pyogenes (β-hemolytic group A), for which antimicrobial therapy is clearly indicated, and which manifests itself with an onset sudden fever. It should also be remembered that some forms of pharyngitis are caused by Chlamydia pneumoniae, Mycoplasma pneumoniae, Bordetella pertussis and Legionella, commonly responsible for lower respiratory tract infections but recently also associated with upper respiratory tract infections. In childhood, a viral or bacterial infection of the upper respiratory tract (in particular pharyngitis, laryngitis) can easily lead to an infection of the lower respiratory tract (pneumonia). In fact, the inflammatory process triggered by a previous infection, generally viral, determines an impairment of mucociliary clearance which facilitates the proliferation not only of pathogenic bacteria but also of the commensal bacterial flora, normally non-pathogenic. An altered local microbial flora can, therefore, contribute to the pathogenesis of new infections or itself be responsible for invasive infections. The microbiota of the upper airways may therefore be a further factor influencing the susceptibility, frequency and severity of acute respiratory diseases. The oropharyngeal microbiota is in fact made up of numerous bacterial species which, by colonizing this anatomical tract, interact with the mucosa of the pharynx and therefore with the immune system, contributing to the homeostasis of the upper respiratory tract and consequently also preserving the integrity of the lower respiratory tract. As observed for other anatomical sites, the composition of the oropharyngeal microbiota is conditioned by external events, among which we find the use of antibiotics or oral disinfectant drugs which can favor the development of pathogenic microorganisms. Characterizing the oropharyngeal microbiota in a state of acute and/or chronic respiratory infection could increase knowledge on the microbiological signature associated with such infections and ineffective antibiotic treatments. Greater knowledge of it, also with future corrective purposes, as has now been demonstrated for other body areas, could be of great help in reducing the risk of acute recurrent disease and/or chronic consequences.