Objective: The objective of the present study was to identify bacterial biofilms in tissue samples obtained from paediatric patients undergoing surgical treatment, for recurrent upper airway infections, frequently associated to effusive otitis media, unresponsive to repeated cycles of selective medical antibiotic and anti-inflammatory therapy and assay the ability of Haemophilus influenzae strains, most frequently identified in our cultural examinations, to grow as biofilm in vitro.
Methods: We examined 18 surgical specimens (18 adenoids) from the upper respiratory tract, obtained from 18 paediatric patients. Tissues were cultured using conventional methods and subjected to scanning electron microscopy for detection of biofilm. Haemophilus influenzae strains, were cultured on 96-sterile well polystyrene microtiter plates (CELLSTAR-greiner bio-one) and stained with 1% crystal violet to quantify biofilm production.
Results: Bacterial cocci attached to the tissue surface and organized in colonies, with a morphology consistent with bacterial coccoid biofilms, were observed in all adenoid (18/18) samples. Haemophilus influenzae isolates from 11/18 (61.1%) of our tissue samples scored a percentual transmittance (%Tbloc) > 50, identifying a high capacity to form biofilms (level 4).
Conclusions: Bacterial biofilms identified in adenoid tissue of paediatric patients with recurrent upper airway inflammatory processes, associated to chronic effusive otitis media, may represent a bacterial "reservoir" responsible of the maintenance of chronic inflammatory mucosal reactions, resistant to selective antibiotic therapy and requiring surgical treatment.