Bactericidal activity of disinfectants on Listeria

The bactericidal activity on Listeria spp. of nine disinfectants used in the food industry was studied by previously published methods. The disinfectants were diluted to the test concentration in sterile standard hard water. Various types of chemical agents were evaluated, including phenolic compounds, alcohols, quaternary ammonium compounds, surface-active agents, aldehydes and disochlorine tablets. The following strains isolated from cheese were studied: Listeria innocua, L. welshimeri, L. monocytogenes 1/2a, 1/2b, 1/2c and 4b. The results show that the listerias are not particularly resistant to disinfectants but the efficacy of some agents is affected by organic matter.