Distinct microbiome profiles and biofilms in Leishmania donovani-driven cutaneous leishmaniasis wounds

Abstract

The endemic strain of Leishmania donovani in Sri Lanka causes cutaneous leishmaniasis (CL) rather than more common visceral form. We have visualized biofilms and profiled the microbiome of lesions and unaffected skin in thirty-nine CL patients. Twenty-four lesions (61.5%) were biofilm-positive according to fluorescence in situ hybridization. Biopsies of biofilm-positive lesions were dominated by Pseudomonas, class Bacilli and Enterobacteriaceae and distinguished by significantly lower community evenness. Higher relative abundance of a class Bacilli OTU was detected in wound swabs versus contralateral skin. Wound swabs and biopsies had significantly distinct microbiome profiles and lower diversity compared to unaffected skin. Greater abundances of potentially pathogenic organisms were observed in wet ulcers, lesions with high parasite loads and large wounds. In summary, more than half of L. donovani associated CL wounds harboured biofilms and the wounds exhibited a distinct, less diverse, microbiome than unaffected skin.

Possible clinical implications and future directions of managing bacterial biofilms in cutaneous leishmaniasis wounds

“…[9]. Under similar settings, we found that the biofilms of ulcerated local CL wounds were mainly composed by class bacilli, family Enterobacteriaceae, and genus Pseudomonas [6]. Pseudomonas is one of the most common biofilm-forming wound pathogens isolated from chronic wounds.…”

“…In this short report, we highlight the importance of investigating the role of biofilms in CL wound healing, their clinical indicators, cost-effective laboratory tests involving less/non-invasive sampling techniques for diagnosing biofilms and potential therapeutic options for these biofilm-containing CL wounds, such as adjunctive application of wound debridement and antimicrobial treatment along with anti-parasitic drugs. The discussion is partly based on our previous findings [6] but more broadly considers recent literature on chronic wound biofilms. We hope that this will introduce the concept of biofilm-specific CL wound management.…”

“…Further, the CL wound microenvironment may play an important role in the formation of these bacterial biofilms, i.e. the observed early formation of the biofilms (< 3 months) [6] could be due to the acidic pH found in CL wounds. Acidic pH levels have been found to facilitate biofilm formation in vitro [14] and further identified as a factor enhancing antibiotic resistance in biofilms formed by Pseudomonas aeruginosa [15].…”

“…Cutaneous leishmaniasis wounds are mostly asymptomatic unless super-infected. The significant association of age of > 40 years, discharge, pain and/or itching in CL wounds [6] could be considered as possible clinical indicators of biofilms in CL wounds and need to be further evaluated. This will facilitate clinical judgement and prompt treatment could be started.…”

“…We have recently investigated biofilm formation in CL wounds [6]. In this study, 39 ulcerated CL wounds, collected over 1 year (2019-2020) from an endemic area of Sri Lanka, were subjected to Gram staining, fluorescent in situ hybridization (FISH) and scanning electron microscopy (SEM) imaging, to visualize bacterial biofilms (Fig.…”