Location of bacterial biofilm in the mucus overlying the adenoid by light microscopy.

Objective: To determine the location of bacteria and biofilm in adenoid tissue and in mucus overlying the adenoid.

Design: Adenoids removed in 1 piece were oriented to the cephalic and caudal ends. Mucus was fixed by the gradual addition of Carnoy fluid. Consecutive histologic sections were stained with periodic acid-Schiff for visualization of the exopolysaccharide matrix, Giemsa for visualization of bacteria and cells, and fluorescent in situ hybridization with a universal probe for visualization of bacteria.

Setting: Department of Otolaryngology-Head and Neck Surgery, University of Virginia.

Participants: We obtained adenoids from children 10 years or younger who had chronic adenotonsillitis or obstructive sleep apnea. Twenty-seven adenoids were used to develop the fixation method. We examined histologic sections from 9 of 10 adenoids fixed using the final fixation protocol. One adenoid that was missing the surface epithelium was excluded from further evaluation.

Main Outcome Measure: Identification of bacteria by light microscopy.

Results: Bacteria in large numbers were present in the mucus overlying the surface of all 9 adenoids; bacteria were not found in the parenchyma of the adenoids below the epithelial surface. Bacterial biofilms were present on 8 of the 9 adenoids. Sessile (attached) biofilm was present on the caudal end of only 1 adenoid. Multiple planktonic (unattached) biofilms were present on 7 adenoids, always in areas not subject to mucus flow. Biofilms were most common on the caudal portions of adenoids.

Conclusions: Bacteria of the adenoid reside in secretions on the surface and in crypts. Biofilms, predominantly planktonic, were present on 8 of 9 adenoids excised because of hypertrophy. Whether biofilms have a role in the causation of adenoid hypertrophy is not known.