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Resumen:
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Background: Due to the highly toxic nature of standard drugs used in the treatment of cutaneous leishmaniasis (CL), and overlapping clinical features of CL with ulcers due to fungal and mycobacterial infections, confirmatory diagnostic testing must be undertaken. We evaluated the performance characteristics of a handheld battery operated device for differentiation of Leishmania from known fungal and mycobacterial causes of cutaneous ulcers. Methods & Materials: Using ATCC strains of Leishmania (L. V. braziliensis, L. V. panamensis, L. V. guyanensis), mycobacteria (M. abscessus complex) and fungi (Paracoccidioides brasiliensis), we validated PalmPCR for detection of Leishmania, fungal, and mycobacterial species known to cause cutaneous ulcers.We further validated the device for detection of Leishmania from clinical specimens including filter paper lesion impressions, cytology brushes, and tissue. Respective primers targeted a conserved region of kinetoplast DNA (kDNA) for detection of Leishmania, pan-mycobacterial Hsp65, and pan-fungal ITS3/4 regions. PCR products were visualized using the EGel Go reader, a portable battery-operated system for agarose electrophoresis. Outcome measures were sensitivity and specificity, where conventional end-point or real time PCR was the reference standard. Results: Compared to the reference standard, the PalmPCR device detected 100% of ATCC strains of Leishmania, fungi, and mycobacteria. There was no cross-reactivity of primers with any negative control. The PalmPCR device accurately categorized reference specimens as positive or negative for Leishmania 91.3% of the time (42/46 specimens), yielding sensitivity and specificity of 90% and 91.7%, respectively. Sensitivity of point-of-care PalmPCR for detection of Leishmania in a clinical field setting enrolling patients with suspected CL was 100% compared to reference real time PCR. In 56% of field patients with CL, pan-mycobacterial and/or pan-fungal primers detected co-colonization with species such as Malassezia spp., Aspergillus spp., and Cladosporium spp. In one patient with CL, Mycobacterium doricum was also detected in the ulcer.
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