The intensive, unreasonable use of antibiotics makes resistant strains growing particularly in hospital areas where the selection pressure is important. During the last years, the outstanding event was the emergence of resistant strains against 3rd generation of cephalosporin. In many cases this resistance is linked with Extended broad spectrum Beta-lactamase. After the description of a simple method to detect these particular strains, the authors report the epidemiologic situation in Hopital Principal of Dakar from February 1992 to January 1993. The emergence of these resistant strains creates heavy problems in intensive care services and Pediatrics. As conclusion, principal measures to prevent this phenomen are exposed.