Mucosal biofilm formation on middle-ear mucosa in the chinchilla model of otitis media.
BACKGROUND
Chronic otitis media with effusion (OME) has long been considered to be a sterile inflammatory process. The previous application of molecular diagnostic technologies to OME suggests that viable bacteria are present in complex communities known as mucosal biofilms; however, direct imaging evidence of mucosal biofilms associated with OM is lacking.


OBJECTIVE
To determine whether biofilm formation occurs in middle-ear mucosa in an experimental model of otitis media.


METHODS
A total of 48 research-grade, young adult chinchillas weighing 500 g were used for 2 series of animal experiments: one to obtain specimens for scanning electron microscopy and the other to obtain specimens for confocal laser scanning microscopy using vital dyes. In each series, 21 animals were bilaterally injected with viable Haemophilus influenzae bacteria and 1 was inoculated to account for expected mortality. Three served as negative controls. Effusions and mucosal specimens were collected from 2 infected animals that were euthanized at 3, 6, 12, and 24 hours and at days 2, 4, 5, 10, 16, and 22 after inoculation.


METHODS
Images were analyzed for biofilm morphology, including presence of microcolony formation and for presence of bacteria on tissue surfaces.


RESULTS
Scanning electron microscopy demonstrated that biofilm formation was evident in all specimens from animals beginning 1 day after infection and was present through 21 days. Confocal laser scanning microscopy indicated that bacteria within the biofilms are viable.


CONCLUSIONS
These preliminary findings provide evidence that mucosal biofilms form in an experimental model of otitis media and suggest that biofilm formation may be an important factor in the pathogenesis of chronic otitis media with effusion.
Ehrlich
Garth D
GD
Center for Genomic Sciences, Allegheny Singer Research Institute, Pittsburgh, PA 15212, USA. gehrlich@wpahs.org
Veeh
Richard
R
Wang
Xue
X
Costerton
J William
JW
Hayes
Jay D
JD
Hu
Fen Ze
FZ
Daigle
Bernie J
BJ
Ehrlich
Miles D
MD
Post
J Christopher
JC
D000818:Animals; D018441:Biofilms; D002682:Chinchilla; D004195:Disease Models, Animal; D004432:Ear, Middle / Q000382:microbiology* / Q000473:pathology; D006193:Haemophilus influenzae; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D009092:Mucous Membrane / Q000382:microbiology / Q000473:pathology; D010033:Otitis Media / Q000382:microbiology* / Q000473:pathology