Costa J M, Ernault P, Gautier E, Bretagne S
Laboratoire de Biologie Moléculaire, Hôpital Américain, BP 109, 92202 Neuilly, France.
Prenat Diagn. 2001 Feb;21(2):85-8. doi: 10.1002/1097-0223(200102)21:2<85::aid-pd18>3.0.co;2-1.
The diagnosis of congenital toxoplasmosis frequently relies on PCR tests of amniotic fluid (AF). A duplex real-time quantitative PCR test based on fluorescence resonance energy transfer was developed to quantify the parasite load and to decrease the risk of contamination. An internal control based on the detection of 10 pg mouse DNA added to the AF was included to check for PCR efficiency. The relationship between the parasite load and the occurrence of ultrasonographic abnormalities in 87 samples of AF was analyzed. Seven AF (8%) had a parasitic load > 10(3); 14 (16%) had > 10(2)-< or =10(3); 26 (30%) had > 10-< or = 10(2); and 40 (46%) had < or = 10 parasites/ml. Four of the six AF with cerebral ventriculomegaly had >10(3) parasites/ml. The other two had 130 and 24 parasites/ml, respectively. No parasitic loads of > 10(3) parasites/ml and no ultrasonographic abnormalities were observed in the 11 AF with maternal toxoplasmosis in the third trimester. Therefore, there is a trend to associate high parasite count with ultrasonographic abnormality, but the main concern remains early maternal infection. The importance of quantification should be better evaluated with postnatal studies. The duplex LightCycler PCR test currently provides rapid and safe results.
先天性弓形虫病的诊断通常依赖于羊水（AF）的PCR检测。开发了一种基于荧光共振能量转移的双重实时定量PCR检测方法，以量化寄生虫载量并降低污染风险。加入了基于检测添加到羊水中的10 pg小鼠DNA的内部对照，以检查PCR效率。分析了87份羊水样本中寄生虫载量与超声异常发生之间的关系。七份羊水样本（8%）的寄生虫载量>10³；14份（16%）>10²-≤10³；26份（30%）>10-≤10²；40份（46%）≤10个寄生虫/ml。六份有脑室扩大的羊水中，四份的寄生虫载量>10³个/ml。另外两份分别有130和24个寄生虫/ml。在孕晚期患有弓形虫病的11份羊水中，未观察到寄生虫载量>10³个/ml且无超声异常。因此，存在将高寄生虫计数与超声异常相关联的趋势，但主要关注点仍然是孕妇早期感染。量化的重要性应通过产后研究进行更好的评估。双重LightCycler PCR检测目前可提供快速且安全的结果。
