JSTOR

Methods

The following alcohol‐based hand rubs were studied: Sterillium rinse (75% [vol/vol] alcohol: 45% 2‐propanol [isopropanol], 30% 1‐propanol, and 0.2% mecetronium ethyl‐sulfate; Rivadis), Sterillium Gel (85% [vol/vol] ethanol; Rivadis), and Manugel Plus gel (70% [vol/vol] alcohol [53% ethanol and 17% isopropanol]; Anios). The antimicrobial activity of the 3 study products was investigated under practical conditions, in accordance with standard EN 12791, in 20 volunteers older than 18 years.⁴ In a crossover design, each volunteer performed surgical hand disinfection with the reference product (60% [vol/vol] n‐propanol) and the study products. Their skin was free of cuts or abrasions. Nails were short and clean. Volunteers did not use antimicrobial soaps or hand rubs during the week before each product was tested.

Briefly, the hands of each volunteer were first washed with a nonmedicated soap (Anios doux; Rivadis) for 1 minute and rinsed with tap water. The pretreatment bacterial count was obtained by rubbing separately the fingertips of the right and left hands in 10 mL of trypticase soy broth (TSB) for 1 minute. The bacterial count was determined after plating serial 10‐fold dilutions of each sample on trypticase soy plates and incubating them for 48 hours at 36° °C.

Then, each volunteer treated their hands with the reference product (60% [vol/vol] n‐propanol) or one of the study products in a randomized order. There was a 1‐week interval between use of each product, which allowed reconstitution of the normal skin flora. Hand rubbing with the study products and the reference product was performed according to a standardized technique. During each test, volunteers rubbed their hands with two 3‐mL quantities of the product and repeated this step, keeping the skin moist for a total of 3 minutes. The immediate posttreatment bacterial count was assessed on 1 randomized hand by rubbing the fingertips for 1 minute in TSB that contained 3% Tween 80, 3% lecithin, 0.1% histidine, and 0.1% cysteine (buffer rinse DNP; AES Laboratoires). The other hand was gloved for 3 hours. After the glove was removed, the sustained antimicrobial effect was assessed by rubbing the fingertips in TSB containing neutralizer for 1 minute. The bacterial count from each fluid sample was determined after plating 0.1 mL of 10‐fold serial dilutions on trypticase soy agar, to measure the immediate and the sustained effects of the product. To determine the posttreatment bacterial count, 1 mL of sample fluid was spread on 5 different trypticase soy agar plates to increase the threshold of detection. Dishes were incubated for 48 hours at 36° °C.

The numbers of bacteria detected before and after treatment were expressed as log₁₀ bacterial counts. For each volunteer, the reduction factor was determined by calculating the difference between the log₁₀ pretreatment and log₁₀ posttreatment counts.

A product is considered to pass the requirement of standard EN 12791 if the immediate antimicrobial activity (ie, the bacterial count immediately after use) and sustained antimicrobial activity (ie, the count 3 hours after use) is not significantly lower than that of the reference product. Statistical analysis was performed using the Wilcoxon matched‐pair signed rank test. Additional statistical analysis (not required by the EN 12791 standard) was performed using analysis of variance and the Tukey multiple comparisons test (GraphPad). Two‐tailed tests were used, and a P value less than .05 was considered statistically significant.

Results

The initial bacterial count on volunteer hands was not significantly different in each group: mean log₁₀ pretreatment counts (±SD) were for n‐propanol, for Manugel Plus gel, for Sterillium rinse, and for Sterillium Gel ( ). The immediate and sustained antimicrobial activities of each study product were not significantly less than those of the reference product, whereas the immediate antimicrobial activity of the study products was significantly greater than that of 60% n‐propanol (Table). Sterillium Gel and rinse were significantly more effective than 60% n‐propanol with respect to the sustained antimicrobial effect. Analysis of variance revealed that Sterillium rinse and Sterillium Gel achieved better sustained antimicrobial activity than Manugel Plus gel ( , by the Tukey test).

Table.  Comparison of the Antibacterial Efficacy of 3 Study Products With That of a Reference Product for Surgical Hand Disinfection, According to European Standard EN 12791

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Discussion

Our main finding is that the study products passed the efficacy requirements of the EN 12791 standard and were suitable for surgical hand disinfection. The EN 12791 standard is a crossover evaluation with 60% (vol/vol) alcohol as a reference product. This reference method is widely used in Europe and has been shown to lead to accurate and reproducible results.^7,8 Our results also indicate that the best results were achieved with Sterillium rinse and Sterillium Gel, which had significantly greater immediate and sustained effects than the reference alcohol. A comparison of the antimicrobial activity of the gels revealed that Sterillium Gel had a greater sustained antimicrobial activity than Manugel Plus gel.

To our knowledge, this study is the second report that assessed the antibacterial efficacy of alcohol‐based gels for surgical hand disinfection. Our results are in accordance with those previously reported by Kampf et al.,⁶ who showed that Sterillium Gel passed the efficacy requirements of the EN 12791 standard and had a significantly greater sustained activity than the reference alcohol. The strong sustained activity of Sterillium Gel might be explained by its strong immediate activity (reduction factor, 3.5), which substantially limits the ability of the resident skin flora to return to pretreatment levels.

The difference in antibacterial effect of the different alcohol‐based products cannot be explained by the duration of hand rubbing, which was similar for all the products. It has been hypothesized that the different antibacterial efficacy observed between gels and rinses depends on the type and the concentration of alcohol included in the formulations.¹ For example, it has been previously shown that ethanol at a concentration of 60% is far less effective against resident hand flora than ethanol at a concentration of 80% or higher.^1,8,9 In a previous study that assessed the antibacterial activity of gels and rinses during routine patient care, we showed that a gel that contained 85% ethanol (Sterillium Gel) was equivalent to a rinse that contained 45% 2‐propanol and 30% 1‐propanol (Sterillium) and that both were significantly more effective than a gel that contained 53% ethanol and 17% isopropanol (Manugel Plus) in reducing bacterial counts on hands.¹⁰ Our results confirm that the antimicrobial activity of a gel that contains 85% ethanol is greater than that of a gel with a lower concentration of alcohol (70%).

In conclusion, Sterillium Gel and Manugel Plus gel, 2 alcohol‐based gels with an alcohol concentration no less than 70% alcohol, were found to be effective against resident flora immediately and 3 hours after application, when tested in accordance with the EN 12791 standard. From a bacteriological point of view, these gels can therefore be considered suitable for surgical hand antisepsis. Apart from the bacterial efficacy of these products, the dermal tolerance, the acceptability, and the impact on surgical site infection rates should be also considered.