[Evaluating the effect of quaternary ammonium disinfectants on bacterial strains of animal origin]

The authors evaluate two quaternary ammonium compounds, first and second generation, using three methods: minimum bactericide concentration, the suspension test of the German Society for Hygiene and Microbiology and the agar gel diffusion test. The compounds were tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis from sheep and pigs. The results show that quaternary ammonia compounds with dodecyl chains have greater efficacy than benzalconium chloride, and that quaternary ammonium compounds are more effective against gram-positive bacteria. No resistance linked to the strains used in the tests was detected. Finally, the authors demonstrate that all three techniques are valid for the evaluation of quaternary ammonium disinfectants.