Cubitt W D, Ades A E, Peckham C S
Department of Microbiology, Hospital for Sick Children, London.
J Clin Pathol. 1992 May;45(5):435-8. doi: 10.1136/jcp.45.5.435.
To evaluate the suitability of five commercial assays (Toxoreagent, DA, Captia Toxo IgG, Toxenz-G, Toxonostika-G) for screening large numbers of sera for antibodies to Toxoplasma gondii.
Sera from 1000 pregnant women booking for antenatal care at a London hospital were screened in parallel by each test. Sera giving discordant results were retested.
The Captia Toxo IgG enzyme immune assay gave the best specificity on initial screening, with 0/773 false positives and only 2/218 false negatives. The Toxoreagent latex agglutination test performed well provided sera were tested at several dilutions to prevent prozone effects; 0/218 false negatives (greater than 12 IU/ml). Only one evidently false positive result was seen in the 1000 samples tested. The DA test gave no false negative results but produced 23/773 false positives. After repeat testing there were 9/1000 sera which gave equivocal results which were negative by the Captia Toxo IgG test (less than 12 IU/ml) but with low titres of 16 in the Toxoreagent test or 4 IU/ml in the DA test. In this situation women would have been asked for a follow up sample for repeat testing. Only 300 sera were tested by Toxenz-G; initial screening produced 4/58 false negative results and 4/242 false positives.
The Captia Toxo IgG test gave the fewest discordant results on initial screening. Results could be readily expressed in international units using a programmable plate reader, and this may be useful for epidemiological studies. The Toxoreagent test is considerably cheaper, and is a simple and reliable method for screening provided that at least two dilutions are used.
评估五种商业检测方法（Toxoreagent、DA、Captia Toxo IgG、Toxenz - G、Toxonostika - G）用于大量血清弓形虫抗体筛查的适用性。
伦敦一家医院1000名预约产前检查的孕妇血清由每种检测方法进行平行筛查。结果不一致的血清进行重新检测。
Captia Toxo IgG酶免疫检测在初次筛查时特异性最佳，773例无假阳性，仅2例（218例中的）假阴性。若对血清进行多次稀释以防止前带效应，Toxoreagent乳胶凝集试验表现良好；218例无假阴性（大于12 IU/ml）。在检测的1000份样本中仅出现1例明显假阳性结果。DA检测无假阴性结果，但产生23例（773例中的）假阳性。重复检测后，1000份血清中有9份结果不明确，Captia Toxo IgG检测为阴性（小于12 IU/ml），但Toxoreagent检测滴度低至16，DA检测为4 IU/ml。这种情况下会要求女性提供后续样本进行重复检测。仅300份血清由Toxenz - G检测；初次筛查产生4例（58例中的）假阴性结果和4例（242例中的）假阳性结果。
Captia Toxo IgG检测在初次筛查时结果不一致的情况最少。使用可编程酶标仪结果可轻松以国际单位表示，这可能对流行病学研究有用。Toxoreagent检测成本低得多，并且只要使用至少两种稀释度，就是一种简单可靠的筛查方法。
