The effect of cyclosporine and tacrolimus on indigenous bacterial flora in human skin grafts.

Abstract Allogeneic skin transplants require intensive immunosuppressive therapy. Treatment protocols used for parenchymal organ grafts are not satisfactory to prevent skin graft rejection. Another factor responsible for the destruction of allogeneic skin transplants is bacterial inflammation. Temporary ischemia and the allogeneic reaction in transplanted skin cause increased permeability of the epidermis and the dermal capillaries, making skin grafts vulnerable to bacterial penetration. Moreover, immunosuppressive therapy compromises the host immune response. The present study assessed the effects of immunosuppression by cyclosporine (CsA) or tacrolimus (Tac) on the indigenous bacterial flora of transplanted human skin. We found that a 6-day course of treatment with CsA or Tac was followed by an increased prevalence of bacterial isolates, mostly evidenced by a change in the spectrum of graft bacterial flora from Staphylococcus aureus and coagulase-negative staphylococci toward more pathogenic strains such as Escherichia coli, Enterococcus faecium, micrococcus, and pseudomonas. The mouse skin adjacent to the graft remained sterile, precluding the possibility of graft contamination with mouse flora.