Abstract
BackgroundTraditional methods of detecting Leishmania from cutaneous lesions involve invasive diagnostic procedures, such as scrapings, which cause discomfort, require technical expertise, and carry risks of invasive procedures. We compared the performance of 2 novel, molecular-based non-invasive methods for the diagnosis of cutaneous leishmaniasis (CL).MethodsConsecutive patients presenting to the Leishmania Clinic at the Hospital Nacional Cayetano Heredia were enrolled. PCR was performed on filter paper lesion impressions (FPLIs), cytology brushes, and lancets for detection of Leishmania DNA. Smears from lesion scrapings and leishmanin skin test were also performed. Outcome measures were sensitivity and specificity. Composite reference standard was any 2 of 5 tests positive. Species identification was performed by PCR assays of positive specimens.ResultsNinety patients with 129 lesions were enrolled, 117 of which fulfilled reference criteria for a diagnosis of CL. Of these 117 lesions, 113 were positive by PCR of lancets used for lesion scrapings versus 116 by PCR of FPLIs (p = 0.930) or 116 by PCR of cytology brushes (p = 0.930). Sensitivity and specificity of PCR on lancets were 96.6% [95% CI 93.3–99.9%] and 100%, respectively. Sensitivity and specificity of FPLI PCR were 99.1% [95% CI 97.4–100%] and 100%, respectively. Sensitivity and specificity of cytology brush PCR were 99.1% [95% CI 97.4–100%] and 100%, respectively. Giemsa-stained lesion smear and leishmanin skin test had inferior sensitivities at 47.9% [95% CI 38.9–57.0%] and 82.3% [95% CI 73.9–90.7%], respectively, compared to PCR of invasive or non-invasive specimens (p<0.001).ConclusionsCytology brush PCR constitutes a sensitive and specific alternative to traditional diagnostic assays performed on invasive specimens such as lesion scrapings. It performs comparatively to non-invasive FPLI PCR. This novel, rapid, and well-tolerated method has the potential for widespread use in the field and in pediatric populations where traditional specimen collection is difficult.
Highlights
Accepted gold standard diagnosis of cutaneous leishmaniasis (CL) involves visualization of parasites either microscopically, or by culture, both of which traditionally involve obtaining diagnostic specimens by invasive means [1,2,3]
Invasive specimen collection techniques cause considerable discomfort, require technical expertise, carry risks of invasive procedures including bleeding and infection, and are difficult to perform in pediatric populations, in remote field settings, and are contraindicated in those with secondary bacterial or fungal infection of their ulcer due to risks of bacteremia or more complicated soft-tissue infection [1]
We have demonstrated that filter paper lesion impression (FPLI) PCR is a sensitive, well tolerated, non-invasive diagnostic approach to CL [7,8]
Summary
Accepted gold standard diagnosis of cutaneous leishmaniasis (CL) involves visualization of parasites either microscopically, or by culture, both of which traditionally involve obtaining diagnostic specimens by invasive means [1,2,3]. Invasive specimen collection techniques cause considerable discomfort, require technical expertise, carry risks of invasive procedures including bleeding and infection, and are difficult to perform in pediatric populations, in remote field settings, and are contraindicated in those with secondary bacterial or fungal infection of their ulcer due to risks of bacteremia or more complicated soft-tissue infection [1]. They pose a risk of body fluid exposure to the healthcare worker via needlestick injury and necessitate sharps biohazard procedures. We compared the performance of 2 novel, molecular-based non-invasive methods for the diagnosis of cutaneous leishmaniasis (CL)
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