Taylor-Robinson D, Thomas B J
Division of Sexually Transmitted Diseases, Clinical Research Centre, Middlesex, UK.
Genitourin Med. 1991 Jun;67(3):256-66. doi: 10.1136/sti.67.3.256.
Yolk-sac inoculation of embryonated eggs was superseded 25 years ago by the use of cell cultures (often McCoy) for the isolation of Chlamydia trachomatis. Centrifugation of specimens onto the cell monolayers was shown to increase sensitivity, but little of late has further improved sensitivity which is at least ten-fold greater than that of eggs. However, culture is slow and labour intensive so that non-cultural techniques without these drawbacks have come to dominate. Direct fluorescent antibody (DFA) tests are rapid and have sensitivities that range from 70% to 100% for men and 68% to 100% for women, and specificities that range from 87% to 99% for men and 82% to 100% for women; if the tests are read by competent observers the values are at the top end of the ranges. The detection rate may be enhanced even further by relatively low-speed centrifugation of specimens before staining. Skilled reading is not a feature of enzyme immunoassays (EIAs) which according to the literature have sensitivities that range from 62% to 97% for men and 64% to 100% for women, and specificities that range from 92% to 100% for men and 89% to 100% for women. However, comparison against poor reference tests is responsible for most of the higher values and the clinician should not be misled into believing that EIAs have excellent sensitivity; the lower values in the ranges are closer to reality. Furthermore, EIAs that are being designed for use by general practitioners should be regarded with the greatest caution since lack of sensitivity means that chlamydia-positive patients will go undetected. The polymerase chain reaction (PCR) is not bedevilled by insensitivity but it is no more sensitive than the most sensitive cell culture or DFA tests. PCR is unsuitable for routine diagnosis but has a place as a research tool. For men, examination of "first-catch" urine samples by the best of the non-cultural procedures provides an acceptable non-invasive approach to diagnosis; for women, the value of examining urine may be less, but needs to be thoroughly tested. However, there is little doubt that a Cytobrush used to obtain cervical specimens holds no practical advantage over a swab. Serological tests are reliant on the provision of paired sera for making a diagnosis; high antibody titres in single sera may be suggestive of an aetiological association in deep-seated chlamydial infections (epididymitis, arthritis, salpingitis, etc), but unequivocal interpretation is unusual, particularly in an individual case, since the distinction between a current and past infection is problematical.
25年前，用于分离沙眼衣原体的鸡胚卵黄囊接种法已被细胞培养法（通常为 McCoy 细胞）所取代。将标本离心接种到细胞单层上可提高敏感性，但近年来很少有方法能进一步提高敏感性，目前的敏感性至少比鸡胚法高十倍。然而，培养法耗时且费力，因此没有这些缺点的非培养技术开始占据主导地位。直接荧光抗体（DFA）检测速度快，男性的敏感性范围为70%至100%，女性为68%至100%；男性的特异性范围为87%至99%，女性为82%至100%；如果由专业人员判读检测结果，这些数值处于该范围的上限。在染色前对标本进行相对低速离心，可进一步提高检出率。酶免疫测定（EIA）则不需要专业判读，根据文献，男性的敏感性范围为62%至97%，女性为64%至100%；男性的特异性范围为92%至100%，女性为89%至100%。然而，与较差的参考检测方法进行比较导致了大多数较高的数值，临床医生不应被误导而认为EIA具有出色的敏感性；该范围中较低的数值更接近实际情况。此外，为全科医生设计的EIA应格外谨慎对待，因为缺乏敏感性意味着衣原体阳性患者可能会漏诊。聚合酶链反应（PCR）不存在敏感性问题，但并不比最敏感的细胞培养法或DFA检测更敏感。PCR不适合常规诊断，但可作为一种研究工具。对于男性，采用最佳的非培养方法检测“首次晨尿”样本，可提供一种可接受的非侵入性诊断方法；对于女性，检测尿液的价值可能较小，但需要进行全面测试。然而，毫无疑问，使用细胞刷获取宫颈标本相对于拭子并无实际优势。血清学检测依赖于提供配对血清来进行诊断；单份血清中高抗体滴度可能提示在深部衣原体感染（附睾炎、关节炎、输卵管炎等）中有病因学关联，但明确的解读并不常见，尤其是在个体病例中，因为区分当前感染和既往感染存在问题。
