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Utility of polymerase chain reaction for assessment of onychomycosis during topical therapy
Aditya K Gupta1,2, Elizabeth A Cooper2, Richard C Summerbell3,4
1Division of Dermatology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
Background:
Increased detection of fungi including non-dermatophyte molds (NDMs) using polymerase chain reaction (PCR) methods is well-established. However, the use of PCR to evaluate ongoing onychomycosis treatment outcome has not been investigated.
Methods:
Nail samples from 28 patients receiving topical efinaconazole were evaluated by both KOH/culture and PCR methods across the study period. Detection of microorganisms by PCR was compared to the culture at baseline and end of study at month 24 (M24). Fungal detection by both methods was evaluated with respect to clinical cure observed as 100% visual clearance of the target toenail.
Results:
By culture, all 28 subjects were dermatophyte-positive at pre-treatment; only 4/28 also exhibited an NDM microorganism. According to PCR, 24/28 subjects were dermatophyte-positive pre-treatment, with 25/28 also exhibiting NDMs. At M24, 18/28 (64.3%) participants had negative KOH/culture results, in contrast to 4/28 (14.3%) negative PCR results. PCR showed higher rates of NDM detection than the culture at baseline as well as M24. Calculations to compare the diagnostic utility of KOH/culture versus PCR found that positive tests with both methods reliably indicate the presence of onychomycosis, but negative PCR correlated better with onychomycosis cure than did KOH/culture.
Discussion:
PCR confirmed a high presence of NDMs pre-treatment, and continued presence of NDMs to M24, with unknown significance requiring further investigation. Though both KOH/culture and PCR have diagnostic limitations, PCR showed better overall utility than culture in predicting onychomycosis topical treatment outcome and should be more strongly considered for evaluation of topical therapies.
Insights
Polymerase chain reaction (PCR) better predicts onychomycosis treatment cure than traditional culture methods. PCR also detected more non-dermatophyte molds (NDMs) in patients undergoing topical efinaconazole treatment.
Area of Science:
- Mycology
- Dermatology
- Clinical Diagnostics
Background:
- Polymerase chain reaction (PCR) enhances fungal detection, including non-dermatophyte molds (NDMs).
- The utility of PCR for assessing onychomycosis treatment outcomes remains unexplored.
Purpose of the Study:
- To evaluate the effectiveness of PCR in monitoring onychomycosis treatment response.
- To compare PCR with traditional KOH/culture methods for diagnosing onychomycosis and predicting treatment success.
Main Methods:
- Nail samples from 28 patients treated with topical efinaconazole were analyzed using KOH/culture and PCR.
- Microorganism detection by PCR and culture was compared at baseline and 24 months (M24).
- Diagnostic results were correlated with clinical cure, defined as 100% visual clearance.
Main Results:
- PCR detected a higher prevalence of NDMs at baseline and M24 compared to culture.
- At M24, 64.3% of participants had negative KOH/culture results, versus only 14.3% with negative PCR results.
- Negative PCR results correlated more strongly with clinical cure than negative KOH/culture results.
Conclusions:
- PCR demonstrates superior utility over culture in predicting topical onychomycosis treatment outcomes.
- PCR's ability to detect persistent NDMs requires further investigation.
- PCR should be strongly considered for evaluating topical antifungal therapies for onychomycosis.
