The aim of the study is to determine the mechanisms of antibiotic resistance of Escherichia coli (E. coli), the prevalence of extended spectrum betalactamase (ESBL) circulating strains of E. coli, establishing genotypes, phylogenetic groups of E. coli ESBL in the Republic of Moldova. On the basis of the data of local microbiological monitoring and using the phenotypic and molecular-genetic methods the genetic determinants (beta-lactamase), which cause the formation of resistance to beta-lactamase antibiotics have been identified. By polymerasis chaine reaction and the sequencing method the prevalence of E. coli strains producing ESBL in the urine probes has been identified. Such studies are unique for the Republic of Moldova and can serve as a basis for the establishment of the concept of causal and empirical treatment in our country. Urinary tract infections have been primarily (85%) determined by the E. coli species, followed by Enterococcus faecalis, Klebsiella pneumoniae, etc. The enzymes ESBL identified in the strains of E. coli in most of the cases have been of CTX-M type, the fact that explains the evolution and dissemination of E. coli producing ESBL. E. coli, a representative of the intestinal microflora, can serve as a reservoir of antibiotic resistance of microbic germs involved in the etiology of urinary tract infections. The detection of the type of beta-lactamase and the unification of the different subtypes of resistance to microorganisms are possible with the help of molecular biology techniques, by contrast with the phenotypic routine tests, the fact that is shown by the model of E. coli producing ESBL.