The purpose of this pilot study is to compare the antimicrobial efficacy of silver
nanoparticle gel to a commercialized alcohol-based hand gel on bacterial counts isolated
from the hands of 40 volunteers seeded with Serratia marcescens, a surrogate microbial
marker. Specific aims of this study are: Aim #1: Compare the immediate antimicrobial
efficacy of a one-time application of silver nanoparticle gel (SilvaSorb , AcryMed, Inc.,
Portland, OR) versus an alcohol-based hand gel (Purell, GoJo Industries, Akron, OH) in
reducing transient bacterial counts isolated from hands seeded with S. marcescens.
Aim # 2: Compare the persistent antimicrobial efficacy of a one-time application of silver
nanoparticle gel (SilvaSorb) versus an alcohol-based hand gel (Purell) over a 10 minute time
frame in producing a persistent reduction on transient bacterial counts isolated from hands
seeded with S. marcescens.
Aim # 3: Compare user acceptability of silver nanoparticle gel (SilvaSorb) versus an
alcohol-based hand gel (Purell) using a self-assessment questionnaire.
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.
- Age > 18 years old
- Ability to read and understand English (for consent purposes)
- Free of clinically evident dermatitis, open wounds, sores, or breaks in hand skin
determined by a Visual Skin Scale (VSS).
- Free of hand jewelry or artificial nail enhancements
- Have fingernails that are clean and extend no longer than approximately one (1) mm
past the nail bed
- Anyone directly working in a healthcare, public health, or long term residence
- Currently receiving any antibiotics, or on any other in as investigational drug,
steroids or immunosuppressive therapy.
- Reports cuts, scratches, or skin disorders, or Dermatitis visualized by the PI/AI
using the Visual Skin Scale (VSS).
- Reports any form of current immune disorders such as AIDS, lupus, any cancers (solid
or hematopoietic), or other medical conditions such as diabetes, hepatitis,
rheumatoid arthritis, or an organ transplant recipient.
- Known sensitivities or allergies to silver, alcohol, latex, soap, detergent,
- Any use of artificial nail enhancements or any non-removable rings
- Primary care provider or resident in a setting where someone has known impaired
immunocompetence (currently receiving chemotherapy, HIV positive), requires wound
care or intravenous management.
- Currently pregnant/lactating or taking care of children under the age of 3 or anyone
that requires diaper changing.
Mary S McCarthy, RN, PhD, CNSN
Nurse Researcher, Madigan Army Medical Center