Role of Microbiome and Bacterial Biofilms in the Pathogenesis of Cutaneous Leishmaniasis.

purposeCutaneous leishmaniasis (CL) is a vector-borne parasitic disease characterized by chronic skin lesions. Emerging evidence has highlighted the critical role of the skin microbiome and bacterial biofilms in disease progression. This review discusses the current evidence supporting the involvement of the skin microbiome and bacterial biofilms in the pathogenesis of CL. It further examines the clinical significance of microbiota dysbiosis and bacterial coinfections, reviews emerging biofilm-directed adjunctive therapeutic strategies, and outlines key knowledge gaps for future translational research.

methodsThe available literature on the skin microbiome, bacterial biofilms, microbiota dysbiosis, bacterial coinfections, host immune responses, and emerging biofilm-directed adjunctive therapeutic strategies in cutaneous leishmaniasis was reviewed.

resultsCL lesions are associated with microbial dysbiosis characterized by an increased abundance of opportunistic bacteria including Staphylococcus and Streptococcus species. These alterations contribute to dysregulated host immune responses, including increased production of pro-inflammatory cytokines and enhanced neutrophil recruitment, thereby promoting disease progression and delaying wound healing. Biofilm formation within CL lesions represents an additional factor contributing to disease persistence. Biofilms protect bacteria from host immune defences and limit antimicrobial penetration, thus reducing therapeutic efficacy and contributing to treatment failure. The interplay among Leishmania, bacterial communities, and host immunity creates a complex polymicrobial microenvironment that exacerbates lesion pathology.

conclusionA deeper understanding of these complex interactions may enable the design of more effective therapeutic approaches directed at both the parasite and the polymicrobial wound environment.