Development, standardization and testing of a bacterial wound infection model based on ex vivo human skin

PLoS One. 2017 Nov 15;12(11):e0186946. doi: 10.1371/journal.pone.0186946. eCollection 2017.

Abstract

Current research on wound infections is primarily conducted on animal models, which limits direct transferability of these studies to humans. Some of these limitations can be overcome by using-otherwise discarded-skin from cosmetic surgeries. Superficial wounds are induced in fresh ex vivo skin, followed by intradermal injection of Pseudomonas aeruginosa under the wound. Subsequently, the infected skin is incubated for 20 hours at 37°C and the CFU/wound are determined. Within 20 hours, the bacteria count increased from 107 to 109 bacteria per wound, while microscopy revealed a dense bacterial community in the collagen network of the upper wound layers as well as numerous bacteria scattered in the dermis. At the same time, IL-1alpha and IL-1beta amounts increased in all infected wounds, while-due to bacteria-induced cell lysis-the IL-6 and IL-8 concentrations rose only in the uninfected samples. High-dosage ciprofloxacin treatment resulted in a decisive decrease in bacteria, but consistently failed to eradicate all bacteria. The main benefits of the ex vivo wound model are the use of healthy human skin, a quantifiable bacterial infection, a measureable donor-dependent immune response and a good repeatability of the results. These properties turn the ex vivo wound model into a valuable tool to examine the mechanisms of host-pathogen interactions and to test antimicrobial agents.

MeSH terms

  • Colony Count, Microbial
  • Humans
  • In Vitro Techniques
  • Models, Biological*
  • Pseudomonas Infections / microbiology
  • Pseudomonas Infections / pathology*
  • Pseudomonas aeruginosa / isolation & purification
  • Skin Diseases, Bacterial / microbiology
  • Skin Diseases, Bacterial / pathology*
  • Wound Infection / microbiology
  • Wound Infection / pathology*

Grants and funding

We hereby disclose that the authors CS and ML are employees of the federal Robert Koch Institute of Germany, JJ, UBP, AV and FR are employees of the Charité – Universitätsmedizin of the city of Berlin, and NGT is an employee of the private company MJR PharmJet GmbH. Each of the above mentioned institutions/company received an equal part of the federal funding grant [KF2928204MD4], which was granted to the authors CS, NGT and FR. The funders provided support in the form of research materials and salaries for authors [Robert Koch Institute: CS, ML - Charité: UBP, AV, FR - MJR PharmJet GmbH: NGT – grant salary support [KF2928204MD4]: CD, JJ]. However, any of the funders had an additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.