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Pig skin as test substrate for evaluating topical antimicrobial activity
Abstract:
The feasibility of using pathogen-contaminated pig skin as a model substrate for evaluating skin disinfectants was demonstrated. A test methodology is described that is safe, convenient to use, and adaptable to a variety of hand-washing conditions. The treatment protocol, pathogen contamination conditions, and application technique variables can all be carefully controlled to simulate clinical use conditions. The number of organisms transferred by contact was compared with the total organism count on the pig skin. The quantity of organisms transferred ranged from 10 to 60% of the total organisms, depending on the nature of the contamination conditions. The cumulative results of multiple imprint and stripping measurements were consistent with the concentration of inoculated organisms. Tests with alcohol solutions validated the methodology and clearly showed the dependence of topical antimicrobial activity on both the concentration and structure of the alcohol. Activity increased with increasing alcohol concentration and in the following order: ethanol, isopropanol, and n-propanol. All of the alcohols became less active as the severity of the test conditions was increased, i.e., higher inoculum levels for a longer incubation time before treatment. The contact imprint and stripping methods used to evaluate bacterial growth on the skin clearly showed that the alcohol treatments reduced but did not eliminate the inoculated pathogens. It was found that long lifetimes (several hours) for pathogens on the skin are possible under some environmental conditions. This observation strongly suggests that frequent hand washing is a necessary infection control practice even when opportunities for repeated pathogen contamination have not occurred.
Insights
Pathogen-contaminated pig skin effectively models disinfectant efficacy for hand hygiene. Alcohol-based disinfectants reduce, but do not eliminate, pathogens, underscoring the need for frequent hand washing to control infections.
Area of Science:
- Microbiology
- Infection Control
- Dermatology
Background:
- Evaluating skin disinfectants is crucial for infection control.
- Existing models may not fully replicate clinical hand-washing scenarios.
- Pathogen survival on skin necessitates effective decontamination strategies.
Purpose of the Study:
- To establish the feasibility of using pathogen-contaminated pig skin as a model for evaluating skin disinfectants.
- To develop and validate a safe, convenient, and adaptable test methodology for hand hygiene.
- To assess the efficacy of alcohol-based solutions against inoculated pathogens under controlled conditions.
Main Methods:
- Utilized pathogen-contaminated pig skin as a substrate for disinfectant testing.
- Developed a methodology allowing control over contamination, treatment, and application variables.
- Employed contact imprint and stripping methods to quantify microbial transfer and reduction.
- Validated the model using alcohol solutions of varying concentrations and types.
Main Results:
- The pig skin model demonstrated feasibility, with microbial transfer ranging from 10-60% depending on contamination conditions.
- Alcohol efficacy increased with concentration and followed the order: ethanol < isopropanol < n-propanol.
- Disinfectant activity decreased under more severe test conditions (higher inoculum, longer incubation).
- Alcohol treatments significantly reduced, but did not eradicate, inoculated pathogens, highlighting pathogen persistence.
Conclusions:
- Pathogen-contaminated pig skin serves as a viable model for assessing skin disinfectant performance.
- The developed methodology is adaptable and allows for controlled simulation of clinical hand-washing.
- Frequent hand washing is essential for infection control due to the potential for prolonged pathogen survival on skin.