Detection of Microsporum canis and Trichophyton mentagrophytes by loop-mediated isothermal amplification (LAMP) and real-time quantitative PCR (qPCR) methods.

ABSTRACT

BACKGROUND: Dermatophytes are infectious zoonotic fungal agents that are common in animals worldwide. A new loop-mediated isothermal amplification (LAMP) method and quantitative (q)PCR can be used for identifying these agents. Both methods have high specificity and sensitivity, and are simple and quick to use. HYPOTHESIS/OBJECTIVES: To develop a LAMP and a rapid multiplex qPCR method for detecting Microsporum canis and Trichophyton mentagrophytes, which are the most common fungal species isolated from cats and dogs. MATERIAL AND METHODS: Both methods targeted the CHS-1 gene. Their specificity and sensitivity were tested using 64 M. canis and 44 T. mentagrophytes field strains. The validation of the methods was performed using 250 clinical fungal-positive hair samples. RESULTS: The specificity value was 100% for both methods. For LAMP, the sensitivity value was 96.9% for M. canis and 93.2% for T. mentagrophytes. For qPCR, the sensitivity values were 98.4% for M. canis and 97.7% for T. mentagrophytes. Similar specificity and sensitivity results were obtained from the validation study using 250 clinical hair samples. LAMP and multiplex qPCR took 30 and 45 min (respectively) for both targets. The limit of detection (LOD) assays for both targets were 10 and 1 spore/mL for LAMP and multiplex qPCR, respectively. CONCLUSION: These findings demonstrate that the LAMP and multiplex qPCR methods targeting CHS-1 gene developed in this study can be used both for point-of-care testing and in the laboratory for detecting M. canis and T. mentagrophytes with high specificity and sensitivity with an internal control.