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

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

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.

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

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.

Identification of bacteria by light microscopy.

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.

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.