Background: To prevent cross-infection of patients, semicritical devices must be high-level disinfected by a product capable of destroying mycobacteria. Glutaraldehyde is commonly used; however, recent studies showed that glutaraldehyde-resistant mycobacteria could survive treatment with this chemical for extended exposure times. Our study tested hydrogen peroxide, peracetic acid, and a germicide (Cidex PA, Advanced Sterilization Products, Irvine, Calif) containing a mixture of the 2 peroxygen compounds for their ability to kill both glutaraldehyde-resistant and nonresistant (control) mycobacteria.
Methods: Bacterial suspensions were exposed to the test chemicals for various periods followed by neutralization and enumeration of survivors.
Results: Hydrogen peroxide at 10% and acidified hydrogen peroxide at 6% had low activity (<4 log reduction in 60 minutes exposure) against glutaraldehyde-resistant strains and slightly higher activity (4 log to 6 log reduction in 60 minutes) against the control strains. Peracetic acid at 0.07% had low to moderate activity (0.6 log to 6 log reduction in 60 minutes) against the resistant organisms and moderate to high activity (4 log to 6 log reduction in 10 minutes) against the control strains. Cidex PA, which contains a mixture of 0.07% peracetic acid and 1% hydrogen peroxide, had high activity (6 log reduction in 10 minutes) against all organisms. Efficacy of 0.8% phenol, a standard reference solution, did not correlate with efficacy of the peroxygen compounds.
Conclusions: Hydrogen peroxide and peracetic acid had much higher activity toward mycobacteria when combined as a synergistic mixture than when evaluated individually.