Influence of Subinhibitory Concentrations of Disinfectants on Hydrophobicity, Alginate Production, and Motility of Pseudomonas aeruginosa

The ability of subinhibitory concentrations (sub-MICs) of disinfectant substances to interfere with some important aspects of bacterial cell function, such as surface hydrophobicity, production of alginate, and motility was investigated. Hydrophobicity of the tested P. aeruginosa strain was evaluated by the method of adherence to hydrocarbon – xylene and by the salt aggregation test of ammonium sulfate. All of the substances tested inhibited the adherence to xylene except for Hexaquart plus. From pure quaternary ammonium compounds (QACs) (Group A) the most effective substances were FD 312, Triquart, and Neoquat S mainly at 1/4 of the MIC. From QACs with other ingredients (Group B) the most effectively reduced adherence Lysoformin 3000, TPH 5225, and ID 212 in the whole concentration range. Sub-MICs of disinfectants had no significant effect on the production of alginate. Divoquat forte (from Group A) and Microbac forte (from Group B) reduced the excretion of this virulence factor at 1/4 of the MIC to 65.3 % and 75.6 %, respectively. The inhibitory behaviour of both groups of disinfectant substances concerning motility was similar, while Triquart and Benzalkonium chloride (Group A) and Hexaquart S and Diesen forte (Group B) were the most effective at 1/4 of the MIC.