In vitro and ex vivo skin flora models to study antibiotic resistance

Background

The human skin is colonized by millions of bacteria, fungi and viruses creating the skin microbiota.  This essential barrier acts as an additional barrier against disease-causing microorganisms (so-called pathogens) and under certain circumstances can be disrupted by environmental influences, such as the use of skin products containing various chemicals, antimicrobial substances or biocides. The change in the microbiota can on the one hand lead to an imbalance in the microbiota and on the other hand affect the development and selection of antimicrobial resistance.

Aims

In this project, we will investigate the impact of extended exposure to skincare products on the microbial dynamics and the emergence of antibiotic resistance applying an in vitro model by utilizing a simulated bacterial community, as well as ex vivo models including frozen pig skin and a human skin model.

Methodology

The in vitro methodology employs a simulated bacterial community that mimics the mixture of bacteria found on the skin. This community consists of six commensal bacterial strains: Acinetobacter johnsonii, Corynebacterium striatum, Micrococcus luteus, Cutibacterium acnes, Staphylococcus epidermidis, and Streptococcus mitis. By culturing the bacteria under different environmental conditions (pH, temperature, oxygen, and nutrient composition), it is possible to simulate various locations on the body. Samples will be collected at different time points and the bacteria dynamics will be tested using qPCR, metagenomic sequencing, and potentially RNA sequencing.

Protocols for inducing and selecting antibiotic resistance using bacterial strains relevant to wound infections (Staphylococcus aureus and Pseudomonas aeruginosa) will be applied to identify the risks of given skincare products to promote antibiotic resistance.  

Once the testing protocols are established, the frozen pig skin and human Nativeskin® model will be used as ex vivo systems for the same purpose. 

Needs

Model systems for studying bacterial dynamics on the skin will enable the identification of critical effects caused by prolonged exposure to skincare products, including changes in the microbial structure that are linked to disease and the prevention of antibiotic resistance. This knowledge can provide strategies for improving currently skincare products.