| Objective: Chlorhexidine gluconate is an inefficient disinfectant with broad spectrum antimicrobial activity.It is widely used in the disinfection of skin,mucous membranes and hands of the medical institutions.It is less irritating and less likely to cause skin allergic reactions.However,because of its inefficient disinfection,CHG compounding with other disinfectants can enhance its bactericidal effect.75% ethanol is widely used as a disinfectant,but the strict transportation and storage conditions of ethanol make it too troublesome to store and transport.CHG with ethanol can greatly enhance its bactericidal effect and is easy to use.There are few studies on low concentration of CHG and ethanol compound disinfectant at home and abroad,and it also lacks the systematic evaluation of its best ratio,bactericidal effect and influencing factors.In this study,factorial design was used to screen the optimal formulation of chlorhexidine gluconate-ethanol compound disinfectant.The orthogonal design was used to study the effect of temperature,pH value and organic interference concentration on the bactericidal effect of CHG-EtOH,to determine the influence rule of each factor and to find the best sterilization conditions.The disinfection properties of the best formula CHG-EtOH were also studied systematically.The research on the factors that affect the disinfection of CHG-EtOH in depth is of great practical value and instructive significance for expanding its application in the field of disinfection.Methods: 1.The study used factorial design test to screen the best formula,choosing 2 factors of 4 level to arrange test.It used "Disinfection Technical Specification"(2002 version)2.1.1.7.4 to do quantitative suspension sterilization test to compare the killing effect of each group of test bacteria.2.The effects of single factor reaction temperature,pH value and organic interference concentration on the bactericidal effect of the best formulation of CHG-EtOH were studied by the method of suspension quantitative sterilization test,and the influence law of each factor was determined.(1)Set the reaction temperature to 7levels respectively,test Escherichia coli and Candida albicans,and calculate the kill logarithm to determine the influence law.(2)The pH values were set to 7 levelsrespectively.Candida albicans and Escherichia coli were tested by the method of suspension quantitative sterilization.The killing logarithm value was calculated and the influence rule was determined.(3)The concentrations of organic interferences were set to 7 levels respectively.Candida albicans and Escherichia coli were tested by the method of suspension quantitative sterilization.The killing logarithm value was calculated and the influence law was determined.3.Orthogonal experiments were used to determine the main order and the best sterilization condition of the effect of temperature,pH value and organic interference concentration on the best formula CHG-EtOH.4.According to the national standard "Disinfection Technical Specification"(2002Edition),test researches were carried out on the related disinfection performance of the best formula CHG-EtOH,including: suspension quantitative germicidal test against E.coli,Staphylococcus aureus,Candida albicans and Pseudomonas aeruginosa,field disinfection test on hand,field disinfection test on skin,disinfection field test on other surface,simulated field disinfection test(cucumber,fabric),metal corrosion test,stability test,acute oral toxicity test,murine bone marrow polychromatic erythrocyte micronucleus test,and one complete skin irritation test.Results: 1.Through the factorial design test,the compound disinfectant with formula of 0.3% CHG and 30% EtOH and compound disinfectant with formula of 0.4%CHG and 30% EtOH had the highest logarithmic killing effect against C.albicans.2.The results were obtained by the suspension quantitative germicidal test: with the increase of temperature and pH value,the optimal formula CHG-EtOH had little effect on the killing of E.coli and C.albicans.The bactericidal effect decreased with the increase of the concentration of organic interference.3.Through orthogonal design,the main order of the optimal formula CHG-EtOH for the bactericidal effect of E.coli and C.albicans was determined as: organic interference concentration,pH value and temperature.The best sterilization conditions for E.coli are: temperature: 40℃,pH: 8,the concentration of organic interference was0%.The best sterilization conditions for C.albicans are: temperature: 30℃,pH: 8,the concentration of organic interference was 0%.4.The antisepsis effects of the best formula CHG-EtOH were :(1)When the effecttime was 1min,the killing value against E.coli,S.aureus and P.Aeruginosa were equal to>5.00.The killing value against C.albicans was equal to >4.00.(2)1min for the hand,3min for the skin,5min for the other surface,the killing logarithm of natural bacteria on the hand surface,natural bacteria on the skin surface and natural bacteria on other surface were all> 1.00.(3)The kill logarithm of E.coli stained on the surface of cucumber and S.aureus stained on the surface of the fabric were> 3.00.(4)the best formula CHG-EtOH is basically non-corrosive to stainless steel,carbon steel,copper and aluminum.(5)after preservation,the effective component content decreased < 10%.(6)Acute oral toxicity test in mice showed LD50 values >5 000 mg/kg(body weight).The best formula CHG-EtOH was negative for micronucleus test of bone marrow polychromatic erythrocytes in mice,and the intact skin irritation index was 0 for white rabbits.Conclusions: 1.The formula of 0.3% CHG,30% EtOH and the formula of 0.4%CHG,30% EtOH are the best formula.Combined with economic factors,choose 0.3%CHG,30% EtOH as the best formula.2.The temperature and pH had little effect on the bactericidal effect of CHG-Et OH.With the increase of the concentration of organic interferences,the bactericidal effect of CHG-EtOH was decreased.The killing effect on E.coli is higher than that on C.albicans.3.In the condition of this experiment,through the orthogonal test,the order of the primary and secondary factors affecting the germicidal efficacy of CHG-EtOH against Escherichia coli and C.albicans is the concentration of organic interferences-pH-temperature.The effect of organic interference concentration on the bactericidal effect of the best formula CHG-EtOH was relatively great,but temperature and pH value had little effect on the bactericidal effect of CHG-EtOH.Under the experimental design,the optimum conditions for killing E.coli were 40℃,pH value 8,and organic interference concentration 0%;and the optimum conditions for killing C.albicans were 30 ℃,pH value 8,and organic interference concentration 0%.4.The best formula CHG-EtOH have a good killing effect against Escherichia coli,Staphylococcus aureus,C.albicans and P.Aeruginosa.It also has a good disinfection effect on hand,skin,other surface,fruits,vegetables and fabric.The best formula CHG-EtOH is a good compound disinfectant for small metal corrosion,good stability,noskin irritation and non-toxicity. |
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