Research Of Test Method For The Antibacterial Activity Of Antibacterial Soaps

This paper aimed to improve and perfect the test method in the national standard GB19877.3-2005"special soap" that evaluating antibacterial activities of soaps. The method has some problems on four aspects, which are the concentration of test bacteria suspension, the applicability for the activity concentration of samples, culture methods of work strains and the preincubation time of test plates, respectively.The bacterial suspension concentration was set at1×x104cfu/plate～9×104cfu/plate based on the relevant industry standards QB/T2738-2012"the evaluation method on the antibacterial effect of daily chemical products".For the applicability about the activity concentration, the study checked the antibacterial activity of five various soaps against Staphylococcus aureus, Escherichia coli or Candida albicans. Minimum inhibitory concentration (MIC) of soaps was determined by agar dilution method in GB19877.3-2005. Inhibition rate of soaps was determined by suspension quantitative test method in QB/T2738-2012. One plain soap was used as control to compare its activity with antibacterial soaps.. In the list of soaps, safeguard with triclocarban and liushen with triclosan were found with higher efficacy against Staphylococcus aureus at the standard concentration of1000mg/L. However, shanghai soap with cresol or sulfur and liushen with artemisia argyi had obvious antibacterial efficacy at4000mg/L or5000mg/L. It might be possible that only soaps with high effective antimicrobial agents (such as TCC, TCS) achieve the requirement of antibacterial products at1000mg/L.In terms of MIC of six soaps, the results were same with the stains incubated for24h on agar slant culture medium and subcultured continuously for3times in broth medium. It shows that strains activated by agar slant culture medium for24h could be used in test to shorten the experimental cycle effectively.It is determined that agar plates incubated and dried for18h-24h could be used for test under strict ascetic environment In order to consider antibacterial or inhibitory composition effect on the antibacterial performance of antibacterial soaps, the study researched the bacteriostasis effect of triclocarban and cresol in soaps. It showed that the soap with0.03%triclocarban had better bacteriostasis effect, whereas the dosage of cresol was much higher to achieve the same effect. With the minimum inhibitory concentration of antibacterial soap increasing, the dosage of cresol would reduce significantly.Meanwhile, the results confirm that soaps with anti/bacterial ingredients have greater antibacterial effect than plain soaps (P<0.05).