Representative images of a mucosal biopsy from a child suffering with rAOM. Middle ear fluid culture and Ply PCR negative, showing biofilm and intracellular infection. Child 4. FISH: EUB338 (yellow), M. catarrhalis (green), H. influenzae (pink) and Hoechst 33342 (nuclei stain - Blue). A) H. influenzae is the predominant pathogen, with other non-identified bacteria also evident (yellow arrows). Maximum projection image (Z = 29 μm), scale bar = 10 μm. B) Intracellular H. influenzae are apparent throughout the tissue as nuclei associated bacterial clusters (white arrows), as well as in biofilm. Maximum projection image (Z = 40 μm), scale bar = 20 μm.