Evaluation of disinfectants commonly used by the commercial poultry industry under simulated field conditions

The correct usage of disinfectants is an important component of a successful biosecurity program. The objective of this study was to determine the effect of time, temperature, and organic matter (OM) on disinfectant efficacy. Staphylococcus aureus and Salmonella Typhimurium were used to represent gram-negative and gram-positive bacteria commonly found in commercial poultry housing. The first study evaluated the effect of temperature (4, 20, 32, or 43 degrees C) and time (1, 2, 3, 4, 6, 8, 12, 16, 20, 24, and 30 wk) on the efficacy of disinfectants diluted to working concentrations. The second study determined the effect of OM on the efficacy of working concentrations of freshly prepared disinfectants against the bacteria. For the third study, we compared the bactericidal properties of freshly prepared disinfectants and 30-wk-old disinfectants in the presence of OM. Quaternary ammonium-, chlorhexidine-, phenolic-, and binary ammonium-based solutions represented disinfectants commonly used within the poultry industry. In the first study, all of the disinfectants were effective against S. aureus and Salmonella Typhimurium regardless of treatment. However, the phenolic compound had reduced (P <or= 0.05) efficacy against Salmonella Typhimurium after 6 wk of storage at the highest temperature of 43 degrees C and after 16 wk at the second highest temperature of 32 degrees C. All of the disinfectants were effective against S. aureus regardless of temperature treatment. In the second study, the addition of sterile chicken litter had deleterious effects on all 4 classes of disinfectants against Salmonella Typhimurium. Of the disinfectants tested, the phenolic compound retained efficacy against S. aureus. In the third study, the presence of OM significantly reduced (P <or= 0.05) the efficacy of the 30-wk-old quaternary ammonium and phenolic compound against Salmonella. The fresh quaternary ammonium and binary compound achieved a greater kill (P <or= 0.05) of Staphylococcus, relative to the 30-wk-old disinfectant. These results emphasize the need to use fresh disinfectants and that OM should be removed before disinfection.