The oropharyngeal aerobic gram-negative bacillary carriage, uncommon in healthy people, is high in patients with head and neck cancer. A marked increase in oral Gram-negative enterobacteria and pseudomonads has particularly been shown during the period of radiation therapy. Irradiation-induced oral mucositis in patients with cancer of the head and neck is associated with changes in this oropharyngeal microflora, but this change is very unlikely to be a causative one. The aim of the study was to ascertain whether there was any change in the Gram positive and Gram negative oropharyngeal flora...