Background:Broad-spectrumβ-lactams are used for empirical therapy of severe infections with non-typhoidSalmonellaserotypes; however, activities of these drugs against the strains producing differentβ-lactamase is not so clear. This study investigated the prevalence ofβ-lactamase genes among isolates ofS. entericaserovars from human faecal samples and determined their diversity in activity against differentβ-lactams. Methods:Antimicrobial resistance of faecal isolates ofS. entericato extended-spectrum cephalosporins was analysed and MIC values were determined for the strains presenting extended-spectrumβ-lactamases (ESBLs) phenotypes. Theβ-lactamase genes were identified by PCR and sequencing.β-lactamase activity of theSalmonellastrains exhibiting ESBL phenotype was detected by biological, iodometric, spectrophotometry and nitrocefin assays. Results:Out of 202S. entericaisolates, ESBLs phenotype was detected among 3.4% (7/202) of the strains.blaTEM-1andblaCTX-M-15were among the frequentβ-lactamase genes. Detection ofblaTEM-169inS. entericaserovar Typhimurium andS. entericaserovar Bredeney andblaPER-1inS. entericaserovar Infantis was a new finding in this experiment. Location ofblaCTX-M-15/blaTEM-169/blaPER-1genes on plasmid was confirmed in a transformation experiment. While crude extracts of the enzymes from each strain showed higher activity against cephalothin and cefotaxime, the lowest activity was detected against ceftazidime. The greatest synergistic activity was seen in a strain ofS. entericathat carriedblaCTX-M-15andblaPER-1genes compared with those presentingblaCTX-M-15/blaTEM-169orblaCTX-M-15/blaTEM-1genotypes. Conclusions:The results show dissemination of ESBLs encoding genes and their combined activity among different serovars ofS. entericathat are a threat for future treatment options. [ABSTRACT FROM PUBLISHER]