Study On The Germicidal Efficacies And Mechanisms Of Compound Ortho-phthalaldehyde In Killing Nosocomial Infection Bacteria

【Objective】To observe the germicidal efficacy of compound ortho-phthalaldehyde in killing nosocomial infection bacteria , by detecting the disinfectant resisitant gene qacA/B in MRSA and comparing germicidal efficacy of disinfectants against MRSA with and without qacA/B to discover whether MRSA with qacA/B are resistant to compound ortho-phthalaldehyde,to elucidate the bactericidal mechanism of ortho-phthalaldehyde by detecting the leakage of proteins and DNA.【Methods】1 Experimental methodNeutralization tests and suspension quantitative germicidal tests were respectively conducted at 20±1℃by compound ortho-phthalaldehyde against Methicillin-resistant Staphylococcus aureus(MRSA), Methicillin-resistant coagulase-negative staphylococci(MRCNS), Methicillin-susceptible Staphylococcus aureus(MSSA), Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacterium coli, baumanii, Enterobacter cloacae, stenotrophomonas maltophilia, Candida albicans, Candida tropicalis.The disinfectant resistant gene qacA/B was detected by PCR and suspension quantitative germicidal tests was conducted resectively on MRSA with and without qacA/B. The leakage of protein and DNA was detected.2 Statistic methodThe bacterial count alive of experiment groups and control groups was transformed by logarithm, and the logarithm reduction was used to represent the germicidal efficacy. The repeated measure ANOVA was used to deal with the datas of germicidal efficacy and influential factors of compound ortho-phthalaldehyde by SPSS 13.0 for Windows, and the trend of data was analysed by Excel 2003.【Results】1 Study on the germicidal efficacies of compound ortho-phthalaldehydeWhen 100mg/L ,50mg/L,25mg/L OPA in the compound ortho-phthalaldehyde solution had been for 3 minutes,the logarithm mean reduction was respectively 6.77, 3.53,1.19 against Klebsiella pneumoniae, respectively 6.90, 4.58, 2.74 against Pseudomonas aeruginosa, respectively 6.78, 2.94, 0.38 against Candida tropicalis.When 50mg/L,25mg/L,12.5mg/L OPA in the compound ortho-phthalaldehyde solution had been for 3 minutes, the logarithm mean reduction was respectively 6.80, 2.31, 1.77 against baumanii, respectively 7.16, 3.56, 1.34 against stenotrophomonas maltophilia,respectively 6.66, 4.03, 2.02 against MRCNS,respectively 7.12, 2.39, 0.24 against Candida albicans,respectively 7.00, 2.44, 0.31 against Enterobacter cloacae, respectively 7.08, 2.50, 1.25 against MSSA.When 50mg/L,25mg/L,12.5mg/L OPA in the compound ortho-phthalaldehyde solution had been for 5 minutes, the logarithm mean reduction was respectively 6.87, 3.70, 1.89 against Bacterium coli, respectively 6.30, 4.82,1.93 against MRSA(qacA/B positive),respectively 5.77,3.98,2.09 against MRSA(qacA/B negative).2 The detection of disinfectant resistant gene qacA/B in MRSA and comparison of germicidal efficacies of bromogeramine, ortho-phthalaldehyde, compound ortho-phthalaldehyde respectively on the positive and negative strainWhen 250mg/L,125mg/L,62.5mg/L bromogeramine had been for 3 minutes, the logarithm mean reduction was respectively 5.74, 3.64, 3.02 against MRSA(qacA/B positive), respectively 7.38, 5.74,4.04 against MRSA(qacA/B negative),the germicidal efficacy of bromogeramine on the positive strain showed significant difference from the negative strain((P<0.05). When 50mg/L,25mg/L,12.5mg/L ortho-phthalaldehyde had been for 5 minutes, the logarithm mean reduction was respectively 5.15,2.96,0.85 against MRSA(qacA/B positive), respectively 5.32, 3.00, 1.03 against MRSA(qacA/B negative), the germicidal efficacy of ortho-phthalaldehyde on the positive strain showed no significant difference from the negative strain(P>0.05).When 50mg/L,25mg/L,12.5mg/L compound ortho-phthalaldehyde had been for 5 minutes, the logarithm mean reduction was respectively 6.30,4.82,1.93 against MRSA(qacA/B positive), respectively 5.77,3.98,2.09 against MRSA(qacA/B negative), the germicidal efficacy of compound ortho-phthalaldehyde on the positive strain showed significant difference from the negative strain(P<0.05),but to bind the diagram together,we thought that there had no difference between the two groups.3 The leakage of protein and DNA from MRSA, Klebsiella pneumoniae, Candida albicans treated with compound ortho-phthalaldehydeThe leakage of protein and DNA was not detected when those test organisms were treated with 100mg/L, 50mg/L, 25mg/L, 12.5mg/LOPA in the compound ortho-phthalaldehyde for 1min, 3min, 5 min, 10 min, 15 min respectively.【Conclusions】When the temperature was 20±1℃, compound ortho-phthalaldehyde has the quick and high germicidal activity, can effectively kill various kinds of frequent nosocomial infection bacteria, including MRSA with disinfectant resistant gene qacA/B.Although it was resistant to bromogeramine in compound ortho-phthalaldehyde, it was not resistant to compound ortho-phthalaldehyde.The leakage of protein and DNA shows the mechanism that the cell structure was injured to result in the leakage of the cytoplasm content was not the way compound ortho-phthalaldehyde kill bacteria.