Fig 1.
Initial histologic examination of intact skin, induced wounds and infected wounds.
(A and B) Richardson stained section of intact human skin (abdomen), shortly after the cosmetic surgery. (C and D) Induced superficial wound: the epidermis was removed with a ball shaped milling cutter. (E-G) Wound, intradermally infected with P. aeruginosa. The bacteria (visible as black dots—arrow 1) are found scattered in the upper woundlayers (F) as well as in deeper wound regions (G).
Fig 2.
Wound histology in the light microscope, twenty hours after the infection.
(A-B). The Richardson stained sections show a dense layer of bacteria that takes up the upper part of the wound (circle 1). (C and D) Lower skin layers—close to the subcutis—reveal scattered bacteria.
Fig 3.
Wound histology in the electron microscope, twenty hours after the infection.
(A) Scanning electron microscopic image of the skin wound profile: the wound surface is entirely covered with layers of bacteria (circle 1), (B) whose hill-like structures consist of collagen bundles (arrow 1) colonized by bacteria (arrow 2). (C and D) (Transmission electron microscopic images) Ultrathin sectioning reveals the organization of the bacteria within the collagen bundles and physical contact between bacteria and collagen fibers (arrow 1).
Fig 4.
Imaging the spread of the infection.
(A and B) The edge zone of the wound shows a thin bacterial layer on its surface (arrow 1). (C) Outside the wound, the skin morphology is intact and no obvious signs of an infection are visible. (D) All uninfected wound control samples still show common dermal cells after 20 hours (arrow 1).
Fig 5.
Bacteria quantification and antimicrobial treatment.
(A) Bacteria counts of uninfected and infected wounds after 0 and 20 hours (●,▴, ■ and ◆ represent triplicates of donors 1–4). (B) Bacteria counts of infected wounds with and without topical ciprofloxacin treatment (10 μL, 375 μg mL-1, 20 hours,) (●,▴ and ■ represent triplicates of donors 5–7). *** p < 0.001.
Fig 6.
Quantification of selected interleukins in infected and uninfected wounds.
(A) IL-1α, (B) IL-1β*, (C) IL-6, and (D) IL-8 concentrations of uninfected and infected wounds after 0 and 20 hours. (●,▴ and ■ represent triplicates of donors 1–3) (*Due to the limited volume of the testing material, triplicates had to be pooled). * p> 0.05, **p>0.01, *** p < 0.001.