For microbiological cultures biopsies immediately placed in thioglycolate medium (to protect anaerobic microbes from oxygen exposure) will be further manipulated in an anaerobic hood filled with C02:H2 (95:5) atmosphere. Biopsies will be washed in sterile dye-gassed saline solution supplemented with 0.016% dithioerythritol to remove the mucus and following cell hypotonic lysis in sterile water, seeded in proper agar plates to evaluate the superficial microflora. [35]. Samples will be seeded on non-selective (Brain Heart Infusion Agar, BHA) and selective media for Enterobacteriacae spp (MacConkey agar) and Lactobacillus spp (Rogosa SL agar).