The paper evaluated antibacterial efficacy of 12 disinfectants on the basis of quaternary ammonium compounds (KAZ) on the isolates of Salmonella enterica serovar Typhimurium of the definitive phage type 104 (DT104). One isolate – 5551/99 – represented the multiresistant phenotype, resistant to ampicillin (A), chloramphenicol (C), streptomycin (S), and tetracycline (T). The second isolate – 577/99 – was sensitive to all antibiotics tested. The present study further examined the capability of sub-MIC concentrations of disinfectants to intervene into surface hydrophobicity and motility of the strains tested.The results showed that all disinfectants under study exhibited high antibacterial activity. It is of interest that the isolate resistant to antibiotics was more sensitive to disinfectants in comparison with the isolate resistant to antibiotics. The most effective substances against strain 5551/99 (R-type) were Sokrena, Triquart,Hexaquart plus, ID213,and Microbac forte,and those most effective against strain 577/99 (S-type) were Benzalkonium chloride and Hexaquart plus (MIC 0.09–0,19 µl/ml). Surface hydrophobicity of both tested strains after the action of sub-MIC (1/16, 1/8, 1/4 of MIC) of disinfectants was not influenced in a more marked way. In the case of strain 5551/99, the highest percentage of inhibition of adherence to xylene, to 69.5 % versus the control, was produced by 1/4 of MIC of the substance Triquart and, in the whole concentration range, by the substance Microbac forte. After the action of most substances to strain 577/99, stimulation of adherence took place. Only substance ID213 induced inhibition of adherence in the whole concentration range.The salt-aggregative capabilities of both strainswere not influenced in amoremarked way. The only exceptions were the action of 1/4 of MIC of the substances Cetrimid, Sokrena, ID212, Forten, and 1/8 of MIC of Hexaquart S on strain 577/99, where a decrease in hydrophobicity was observed.Amoderate inhibition ofmotilitywas found after the action of 1/4 of MIC of Benzalkonium chloride (to 87.5 %) and A.D.L. 007 (to 85.2 %) on strain 5551/99. In the case of sensitive isolate 577/99, the most markedly manifested inhibition effect was that of Sokrena within the whole concentration range and that of 1/4 of MIC ID213. The results can be used in the selection of a suitable disinfectant for decontamination of solid surfaces. The effect of substances under study on surface hydrophobicity and motility of the important, food-transferred pathogen in the sense of inhibition or stimulation points out to intervention into its pathogenic potential.

        Key words: Salmonella enterica serovar Typhimurium DT104 – antibiotics – disinfectants – hydrophobicity – motility