[Ubiquity of plasmids belonging to incompatibility group B (author's transl)].

An Algerian strain of Salmonella typhi (56/75), resistant to tetracyclines and minocycline has been studied in our laboratory. Conjugation, transduction and spontaneous loss experiments suggest that these resistance characters are mediated by one R plasmid, referred to as pPA4. This "Tb" plasmid is incompatible with plasmids from groups incB (Grindley), com10 (Scavizzi) and inc0 (Datta). These results suggest that incompatibility group B is world-wide distributed.