• Antimicrobial efficacy (as measured by the percent change in microbial counts from baseline of subjects) [ Time Frame: 10 minutes ] [ Designated as safety issue: No ]
  

• User acceptability (as measured by the total of points received per product from a questionnaire) [ Time Frame: 10 minutes ] [ Designated as safety issue: No ]
  

The objective of this randomized controlled, double blinded, 2x3 experimental study is to evaluate the antimicrobial efficacy of silver nanoparticle gel compared to an alcohol-based hand gel on bacterial counts isolated from the hands of 40 healthy, adult, military student volunteers. The study will be conducted in two phases: the first phase will consist of a methods development period and the second phase will consist of the formal pilot study. For phase I, the first four participants from the sample pool will be assigned into one of two groups (nano-silver gel or alcohol-based gel) whereas in Phase II, the participants will be randomized into one of two groups. Participants in both phases will follow a 7 day washout period where subjects will refrain from using antimicrobial products for a week prior to testing. Testing of participants in both phases will start with a baseline bacterial hand count. This will be accomplished by using a surrogate biomarker (S. Marcescens). This microorganism was selected because it is considered the standard surrogate marker to be used in hand hygiene evaluations and because it produces a characteristic red colony that is easily distinguishable from normal microbial populations of the hands making colony counting more accurate. Sampling of bacterial flora will be accomplished utilizing an established "modified glove juice" technique in which the participant's dominant hand is placed into a large sterile bag containing a sampling solution, which removes the surrogate bacteria. Once baseline samples have been collected, all participants will then complete two additional random ordered timed conditions involving the surrogate biomarker and one of the two test gels. For each test condition, five mL of solution will be withdrawn from the collection bag, diluted, plated, and incubated for 36 hours. For the immediate efficacy testing, a glove juice sampling will be obtained after a 1 minute application of the gel. For the persistent efficacy testing, a glove juice sampling will be obtained after a 10 minute application of the gel. To ensure the biomarker has been removed, all subjects will wash hands with a 70% ethanol surgical handwash. The use of an UV-C light will also be implemented for 20 seconds as an additional precaution. Participants in phase I will have an additional glove juice sampling at the end of degerming to validate the protocol. All participants will end the study by completing a 4 question visual analog questionnaire to determine user acceptability of the gels. The percent difference of total bacterial counts from baseline will be used as the outcome variable. An unpaired Student's t-test (or an appropriate non-parametric test) will be used for data analysis for each of the study aims.