Recurrent upper airway infections and bacterial biofilms

Abstract

Background: Bacterial biofilms identified in various medical devices used in otorhinolaryngology, including tympanostomy tubes, voice prostheses, and cochlear implants, can directly colonise mucosal tissues. The upper airways seem to be at high risk for this type of colonisation. Chronic and/or recurrent upper airway infections may be related to the complex structural and biochemical (quorum sensing) organisation of the biofilm which interferes with the activity of antibiotics (including those with proven in vitro efficacy), thus promoting the establishment of a chronic infection eradicable only by surgical treatment. Biofilm formation plays a role in upper respiratory infections: it not only explains the resistance of these infections to antibiotic therapy but it also represents an important element that contributes to the maintenance of a chronic inflammatory reaction.Objectives: To document the presence of biofilms in surgical tissue specimens from patients with recurrent infection diseases, and identify their possible role in the chronicity of these infectious processes.Method: We examined 32 surgical specimens from the upper respiratory tract (tonsils, adenoids, mucosa from the ethmoid and maxillary sinuses) of 28 patients (20 adults, eight children) with upper airway infections that had persisted despite repeated treatment with anti-inflammatory agents and antibiotics with demonstrated in vitro efficacy. Tissues were cultured using conventional methods and subjected to scanning electron microscopy for detection of biofilm formation.Results: Over 80 per cent (26/32; 81.3 per cent) of the tissue specimens were culture-positive. Bacterial biofilms (associated in most cases with coccoid bacteria) were observed in 65.6 per cent of the tissue samples.