Evaluation of Less Invasive Sampling Tools for the Diagnosis of Cutaneous Leishmaniasis

Abstract

Background Diagnosis of cutaneous leishmaniasis (CL) usually relies on invasive samples, but whether more patient-friendly tools are good alternatives for diverse lesions when used with PCR is unclear. Methods CL-suspected patients were enrolled consecutively in a prospective diagnostic accuracy study. We compared dental broach, tape disc and microbiopsy with PCR as index tests to PCR on skin slit as reference test. Subsequently, we constructed a composite reference test including microscopy, the three index tests and skin slit PCR, and compared these same tests to the composite reference test. Diagnostic accuracy parameters with 95%CIs for all comparisons were assessed. Results Among 344 included patients, 282 (82.0%) were diagnosed with CL and 62 (18.0%) with CL-absence by skin slit PCR. Sensitivity and specificity of dental broach, tape disc and microbiopsy by PCR were 89.0% (95%CI 84.8–92.1) and 58.1% (95%CI 45.7–69.5), 96.1% (95%CI 93.2– 97.8) and 27.4% (95%CI 17.9–39.6), and 74.8% (95%CI 66.3–81.7) and 72.7% (95%CI 51.8–86.8), respectively. Several reference test negative patients were consistently positive for the index tests. Using the composite reference test, dental broach and skin slit had similar diagnostic performance. Discussion Dental broach seems a less invasive but similarly accurate alternative to skin slit for diagnosing CL when using PCR. Tape discs lack specificity and seem unsuitable for CL diagnosis without cutoff. Reference tests for CL are problematic, since using a single reference test is likely to miss true cases, while composite reference tests are often biased and impractical as they require multiple tests.