Enterobacteriaceae represent more than 11% of bacteria involved in osteoarticular infections in adult and, among them, Enterobacter cloacae is found in 12% of the cases. The increased evolution of the antibiotic resistance rate of this species is worrying. However, all isolates responsible for this type of infection at the University Hospital of Nancy from 1990 to 1994 (24 strains isolated from 22 patients presented an identical antibiotype with especially a natural resistance phenotype to beta-lactam antibiotics except one cephalosporinase-over-producing strain. The DNA of these strains was studied by pulse-field gel electrophoresis after digestion by the restriction enzyme XbuI. The great genomic diversity obtained showed that the stability of the antibiotic susceptibility during the period studied was not due to the existence of unique clone but to that of multiple clones. The analysis of the restriction profiles has permitted to achieve a better differenciation of the strains than biotyping and antibiotyping, which confirms the high discrimination power of this genotypic method.