THE EFFECTS OF 7 CHICKEN HATCHERY DISINFECTANTS ON A STAPHYLOCOCCUS-AUREUS STRAIN

Seven disinfectants used in commercial hatcheries were evaluated for t heir bactericidal effectiveness on Staphylococcus aureus. These disinf ectants included two quaternary ammonium compounds, three phenolic com pounds, one iodophor compound, and one pine oil compound. Ten-fold ser ial dilutions were made for each disinfectant in sterile distilled wat er. Brain heart infusion (BHI) broth containing from 10(5) to 10(8) co lony-forming units (cfu) of S. aureus was exposed to different concent rations of the disinfectants for three different time periods (10, 20, and 30 min). Six of the seven disinfectants tested were effective at the manufacturers' recommended concentration (MRC). Four of the seven disinfectants tested were also effective at ten and 100-fold dilutions of the MRC; they caused greater than five decimal reductions (DR) of S. aureus. The effectiveness of the disinfectants was reduced to less than 3 DR at a dilution of 1000-fold of the MRC or higher. Effectivene ss was determined as causing five decimal reductions in cfu when compa ring the original cfu and the cfu after disinfectant contact time. Fur thermore, this study showed that a 10-min contact period was sufficien t to kill S. aureus and that longer contact times (20 and 30 min) did not enhance the bactericidal effect of the different disinfectants (P< 0.001). Five of the seven disinfectants were also effective in causin g a greater than 5 DR in a simulated hatchery environment.