Diagnostic performance of molecular and conventional methods for identification of dermatophyte species from clinically infected Arabian horses in Egypt.

This research article details a study comparing the effectiveness of different methods for identifying the fungus species (dermatophytes) that cause skin diseases in Arabian horses. The traditional methods of direct microscopy and culture, though reliable, can take weeks to provide results, so this study involved the introduction of a PCR (Polymerase Chain Reaction) method using hair samples and culture isolates to allow quicker diagnosis.

Objective and Methodology

• The main aim of the study was to identify the prevalent pathogenic dermatophytes affecting Arabian horses and to compare the effectiveness of different diagnostic methods, ranging from traditional culture and microscopy to modern PCR techniques.
• Samples like hair and skin crusts from Arabian horses with skin lesions were collected every month. These samples were divided into three parts, each for microscopic examination, culture, and PCR amplification.
• The PCR method used focused on amplifying the Intergenic Spacer (ITS) regions of the DNA to identify the dermatophytes.

Results of the Study

• From the 200 horses studied, 35% showed signs of skin diseases caused by dermatophytes.
• Direct microscopy revealed that 70.4% of the samples were positive for fungal elements and culture testing showed an 85.7% positive result.
• The species causing these infections were identified as Microsporum canis, Trichophyton verrucosum, T. mentagrophytes var. mentagrophytes, and M. equinum.
• The test results from 25 selected samples displayed DM, culture, PCRculture, and PCRhair positivity rates of 64%, 92%, 91.3%, and 52%, respectively.

Conclusions from the Study

• The study concluded that the most common species of dermatophytes causing skin infections in Arabian horses were M. canis, T. verrucosum, T. mentagrophytes var. mentagrophytes, and M. equinum.
• Based on the small sample size, the study suggested that ITS-based PCR could serve as a viable diagnostic tool when combined with culture methods. This conclusion hints at the potential faster and effective diagnosis with this combination compared to traditional methods.