Microflora of the nasopharynx in Caucasian and Maghrebian subjects with and without nasopharyngeal carcinoma.

: The possible role of bacteria in the etiology of nasopharyngeal carcinoma (NPC) was studied by bacteriological and biochemical analyses of nasopharyngeal swabs collected in the cavum and in the fossa of Rosenmuller of NPC patients and healthy controls in France and Algeria. Counts of total bacteria and of total nitrate-reducing bacteria, mainly enterobacteria, were higher in the Maghrebians than in the Caucasians. The composition of the bacterial flora was different: in Maghrebians, enterobacteria were present in five of 17 control subjects and eight of 15 NPC patients, while the prevalence was only one out of 15 control subjects in Caucasians. Twelve of 32 bacterial species isolated from Caucasians and Maghrebians with normal or tumorous nasopharyngeal microflora were able to catalyse nitrosation of morpholine in vitro. This result suggests that colonization of the nasopharynx by microflora that contain nitrate-reducing microorganisms which can form N-nitroso compounds might represent a risk factor for NPC in Maghrebian populations.