# Optimizing a Conventional Multiplex PCR for Simultaneous Detection of Granulomatous Skin Infection Agents: Leishmania aethiopica, Mycobacterium leprae, and Mycobacterium tuberculosis

## TL;DR

This study develops a PCR test to detect three skin infections—cutaneous leishmaniasis, skin tuberculosis, and leprosy—with high accuracy.

## Contribution

The study introduces a validated multiplex PCR assay for simultaneous detection of three granulomatous skin infection agents.

## Key findings

- The mPCR showed 100% sensitivity and specificity on control DNA samples.
- Among clinical cases, the mPCR had 75.8% sensitivity and 100% specificity.
- The assay could aid diagnosis in regions where these infections coexist.

## Abstract

Conventional polymerase chain reaction (PCR) assays are well‐established molecular techniques that can be integrated as standard diagnostic tools, especially in referral settings. This study aimed to assess the diagnostic potential of a multiplex PCR (mPCR) assay for the diagnosis of cutaneous leishmaniasis (CL), skin tuberculosis, and leprosy.

A cross‐sectional study was carried out involving 62 patients in the study group, comprising 45 with CL, 9 with leprosy, 4 with skin tuberculosis, and 4 with coinfections. Additionally, 112 positive control DNA samples were analyzed, including 37 of M. tuberculosis, 46 of M. leprae, and 29 of L. aethiopica. The study assessed sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and detection limits.

Sensitivity and specificity of the mPCR on positive and negative control samples were 100% (95% CI: 96.8%–100%) and 100% (95% CI: 94.9%–100%), respectively. Its sensitivity and specificity among the study group were 75.8% (95% CI: 63.3%–85.8%) and 100% (95% CI: 94.9%–100.0%), respectively.

With further validation on more clinical suspects, mPCR has the potential to facilitate diagnosis in settings with coendemic CL, leprosy, and skin tuberculosis.