[Bactericidal activity of disinfectants against certain bacterial strains of S. aureus]

The bactericidal activity of twenty disinfectants against S. aureus was evaluated by a suspension and capacity test. The effect of interfering substances (organic matter and hard water) on the activity of these disinfectants was investigated by a number of experimental trials. The sensibility of S. aureus to sodium laurylsulfate and zinc pyrithione was affected by proteins. The interference of proteins was not evident for the other disinfectants. The polyvinylpyrrolidone-iodine 7% and the cresol saponatum tolerated the presence of proteins in distilled water, but they were influenced by them in hard water; on the contrary, the zinc pyrithione was more active in hard water than in distilled water. Generally, the second and third incremental addition of microorganisms did not practically alter the bactericidal effect of the majority of disinfectants.