Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland.
University of Basel, Basel, Switzerland.
BMC Microbiol. 2020 Oct 2;20(1):298. doi: 10.1186/s12866-020-01963-9.
Diagnosis of soil-transmitted helminths (STHs) in developing countries is commonly based on microscopic detection of eggs in stool samples, using the Kato-Katz (KK) method, which has a poor sensitivity for detecting light intensity infections. We compared the performance of the KK method and real-time PCR in the framework of a randomized trial, which evaluated four novel treatments against Trichuris trichiura and concomitant STH infections.
Two stool samples obtained from 320 participants were examined at baseline and follow-up with quadruplicate KK and PCR analyses of one of the two samples using "bead-beating" for DNA extraction. At follow-up, 80 samples were negative according to both PCR and KK and 173 were positive with both methods for any of the STHs. Relative to PCR, the calculated sensitivity of KK at follow-up was 83.6%, 43.0% and 53.8% for T. trichiura, for hookworm and for Ascaris lumbricoides, respectively. The sensitivity of PCR compared with KK at this time point was 89.1% for T. trichiura, 72.7% for hookworm and 87.5% for A. lumbricoides. Cure rates (CRs) for T. trichiura and A. lumbricoides were slightly lower with the PCR method. For hookworm CRs with KK were mostly significantly lower, namely 36.7%, 91.1%, 72.2% and 77.8% for moxidectin, moxidectin in combination with tribendimidine, moxidectin in combination with albendazole and albendazole in combination with oxantel pamoate, respectively, whereas with PCR the CRs were 8.3%, 82.6%, 37.1% and 57.1%, respectively.
In conclusion, a single real-time PCR is as sensitive as quadruplicate KK for T. trichiura and A. lumbricoides detection but more sensitive for hookworm, which has an influence on the estimated treatment efficacy. PCR method with DNA extraction using the "bead-beating protocol" should be further promoted in endemic areas and laboratories that can afford the needed equipment. The study is registered at ISRCTN (no. 20398469).
在发展中国家，土壤传播性蠕虫（STH）的诊断通常基于粪便样本中虫卵的显微镜检测，使用加藤厚涂片（KK）法，该方法对轻度感染的检测灵敏度较差。我们在一项随机试验的框架内比较了 KK 方法和实时 PCR 的性能，该试验评估了四种针对 Trichuris trichiura 和伴随的 STH 感染的新疗法。
320 名参与者的两份粪便样本在基线和随访时均进行了四重 KK 检查和其中一份样本的实时 PCR 分析，该样本使用“珠磨”进行 DNA 提取。随访时，80 份样本根据 PCR 和 KK 均为阴性，173 份样本根据两种方法均为任何一种 STH 阳性。与 PCR 相比，KK 在随访时的灵敏度分别为 T. trichiura、钩虫和蛔虫的 83.6%、43.0%和 53.8%。此时点 PCR 与 KK 相比的灵敏度分别为 T. trichiura 的 89.1%、钩虫的 72.7%和蛔虫的 87.5%。T. trichiura 和蛔虫的治愈率（CR）略低用 PCR 法。钩虫的 CR 用 KK 法主要显著降低，分别为莫昔克丁、莫昔克丁联合三苯达唑、莫昔克丁联合阿苯达唑和阿苯达唑联合奥苯达唑的 36.7%、91.1%、72.2%和 77.8%，而用 PCR 法的 CR 分别为 8.3%、82.6%、37.1%和 57.1%。
总之，单次实时 PCR 对 T. trichiura 和蛔虫的检测与四重 KK 一样敏感，但对钩虫的检测更敏感，这会影响估计的治疗效果。在寄生虫病流行地区和有能力购买所需设备的实验室，应进一步推广使用“珠磨”DNA 提取方法的 PCR 方法。该研究在 ISRCTN 注册（编号 20398469）。
