Biofilm formation by bacteria isolated from upper respiratory tract before and after adenotonsillectomy

Failure of antibiotics to eradicate the microbial pathogens primarily responsible for otorhinolaryngological diseases has led to the hypothesis that these microorganisms may be structured in a biolfilm. Aim of the study was to evaluate the ability to produce biofilm among bacteria isolated from tonsils and/or adenoids and nasopharynx. Biopsies and swabs were collected during surgery and after 3 and 6months in 32 children undergoing adenoidectomy and/or tonsillectomy. Production of biofilm by Staphylococcus aureus, Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae was evaluated in vitro by means of spectrophotometry after growth in microplates and staining with crystalviolet. Of the isolates from intraoperative samples, 44.7% were either moderate or strong biofilm producers compared with 27% of isolates at 6months after surgery. A decrease in biofilm production was observed for H. influenzae and S. aureus. In conclusion, the rate of isolation and ability to form biofilm decreased in bacteria isolated subsequent to adenoidectomy and/or tonsillectomy. This suggests a role for biofilm in pathogenesis of recurrent and chronic pharyngeal diseases and rhinopharingitis.