Mycological and histological investigations in humans with middle ear infections

The aim of our investigations was to characterize fungal colonization of the ear in immunocompetent patients. From 1993 to 2000, 128 patients supposed to suffer from otomycosis were included. Mycological examination conducted by direct microscopy and fungal cultures was performed on 139 specimens. Among these, 115 patients suffered from chronic otitis media with persisting tympanum perforation and otorrhea. A further 13 patients had clinical signs of an otitis externa only. Out of 139 samples, fungi were identified in the auditory canal (n = 54), on the tympanic membrane (n = 5), and in the middle ear (n = 5). Two-thirds were as moulds and one-third yeasts. The dominating species were Aspergillus niger and Candida parapsilosis. Samples from 15 patients supposed to have mastoiditis or cholesteatoma were examined histologically. Fungal hyphae were observed in the middle ear cavity and/or between horny lamellae of cholesteatoma in four patients. In the middle ear of immunocompetent patients chronic-hyperplastic (polypoid) inflammation was detected with increased production of mucus, which probably promotes colonization by pathogenic fungi in the middle ear as well as in the auditory canal. Invasive fungal growth into the subepithelial connective tissue was not observed.