Division of Dermatology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
Mediprobe Research Inc., London, ON, Canada.
Int J Dermatol. 2022 Nov;61(11):1385-1389. doi: 10.1111/ijd.16241. Epub 2022 May 10.
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.
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.
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.
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.
聚合酶链反应（PCR）方法已广泛用于检测真菌，包括非皮肤真菌（NDM）。然而，PCR 方法尚未被用于评估持续性甲真菌病的治疗结果。
在整个研究期间，通过 KOH/培养和 PCR 方法评估了 28 名接受局部依氟康唑治疗的患者的指甲样本。在基线和研究结束时（24 个月[M24]），通过 PCR 检测微生物，将其与培养法进行比较。根据 100%目标趾甲完全清除的临床治愈情况，评估两种方法检测真菌的结果。
根据培养法，所有 28 名患者在治疗前均为皮肤癣菌阳性；仅 4/28 例还显示出一种非皮肤真菌微生物。根据 PCR，24/28 名患者在治疗前为皮肤癣菌阳性，25/28 例还显示出非皮肤真菌。在 M24，18/28（64.3%）患者的 KOH/培养结果为阴性，而 4/28（14.3%）患者的 PCR 结果为阴性。PCR 显示，与基线和 M24 相比，NDM 的检测率更高。比较 KOH/培养与 PCR 的诊断效用的计算结果发现，两种方法的阳性检测可靠地表明存在甲真菌病，但阴性 PCR 与 KOH/培养相比，与甲真菌病的治愈相关性更好。
PCR 法在治疗前确认了大量 NDM 的存在，并在 M24 时仍存在 NDM，其意义未知，需要进一步研究。尽管 KOH/培养和 PCR 都具有诊断局限性，但 PCR 法在预测甲真菌病局部治疗结果方面比培养法具有更好的整体效用，应更强烈地考虑用于评估局部治疗。
