| Objective To compare the resistance differences of 18 kinds of bacterial strains and 2 biological indicators to chlorine-containing disinfectants, hydrogen peroxide, and quaternary ammonium compounds. Methods Strains were selected from food, environment and human sources, including gram-negative bacteria, gram-positive bacteria, and spore-forming bacteria (6 strains per category). Species identification was performed using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) and biochemical assays. 2 biological indicators, namely Staphylococcus aureus ATCC6538 and Escherichia coli 8099 were used as reference strains. Bacterial suspensions (2.0×108~10.0×108 CFU/mL) were prepared to test their tolerance to sodium hypochlorite (available chlorine 0.00400%~0.00499%), hydrogen peroxide (7.5%), and benzalkonium bromide (3.996 mg/mL). All bacterial strains were treated with disinfectants for 3 minutes. The resistance differences were evaluated based on Killing Log Value(KL). Results The bactericidal efficacy ranked as sodium hypochlorite, hydrogen peroxide, benzalkonium bromide. Differernt species showed significant variations in resistance to disinfectants. Among the three types of bacterial strains (Gram-negative bacteria, Gram-positive bacteria, and spore-forming bacteria), there are strains within each category that exhibit higher resistance to disinfectants than the two biological indicators.Conclusion Sodium hypochlorite and hydrogen peroxide exhibit superior bactericidal effects compared to benzalkonium bromide. Bacteria The resistance to disinfectant of bacterias is species-specific and cannot be predicted solely by Gram classification.The screening scope for biological indicators should be expanded based on actual needs. |
