Patterson Kristine, Olsen Bonnie, Thomas Christopher, Norn Dora, Tam Milton, Elkins Christopher
Department of Medicine, Division of Infectious Diseases, University of North Carolina, 547 Burnett-Womack Building, Chapel Hill, NC 27599-7030, USA.
J Clin Microbiol. 2002 Oct;40(10):3694-702. doi: 10.1128/JCM.40.10.3694-3702.2002.
Haemophilus ducreyi is the etiologic agent of chancroid, a sexually transmitted disease that increases the rate of transmission of human immunodeficiency virus. Chancroid ulcerations are difficult to distinguish from those produced by syphilis and herpes. Diagnosis based solely on clinical grounds is inaccurate, and culture is insensitive. Highly sensitive PCR has largely superseded culture as the preferred method of laboratory diagnosis; however, neither culture nor PCR is feasible where chancroid is endemic. We developed a rapid (15-min) diagnostic test based on monoclonal antibodies (MAbs) to the hemoglobin receptor of H. ducreyi, HgbA. This outer membrane protein is conserved in all strains of H. ducreyi tested and is required for the establishment of experimental human infection. MAbs to HgbA were generated and tested for cross-reactivity against a panel of geographically diverse strains. Three MAbs were found to be unique and noncompetitive and bound to all strains of H. ducreyi tested. Using an immunochromatography format, we evaluated the sensitivity and specificity of the test using geographically diverse strains of H. ducreyi, other Haemophilus strains, and other bacteria known to superinfect genital ulcers. All H. ducreyi strains were positive, and all other bacteria were negative, resulting in a specificity of 100%. The minimum number of CFU of H. ducreyi detected was 2 x 10(6) CFU, and the minimum amount of purified HgbA protein detected was 8.5 ng. Although this level of sensitivity may not be sufficient to detect H. ducreyi in all clinical specimens, further work to increase the sensitivity could potentially make this a valuable bedside tool in areas where chancroid is endemic.
杜克雷嗜血杆菌是软下疳的病原体，软下疳是一种性传播疾病，会增加人类免疫缺陷病毒的传播率。软下疳溃疡很难与梅毒和疱疹引起的溃疡区分开来。仅基于临床依据进行诊断是不准确的，而且培养法不够灵敏。高灵敏度的聚合酶链反应（PCR）已在很大程度上取代培养法，成为实验室诊断的首选方法；然而，在软下疳流行地区，培养法和PCR都不可行。我们基于针对杜克雷嗜血杆菌血红蛋白受体HgbA的单克隆抗体（MAb）开发了一种快速（15分钟）诊断测试。这种外膜蛋白在所有测试的杜克雷嗜血杆菌菌株中都是保守的，并且是建立实验性人类感染所必需的。我们制备了针对HgbA的单克隆抗体，并测试了其对一组地理分布不同的菌株的交叉反应性。发现三种单克隆抗体具有独特性且无竞争性，能与所有测试的杜克雷嗜血杆菌菌株结合。我们采用免疫层析形式，使用地理分布不同的杜克雷嗜血杆菌菌株、其他嗜血杆菌菌株以及已知会导致生殖器溃疡二重感染的其他细菌，评估了该测试的灵敏度和特异性。所有杜克雷嗜血杆菌菌株均呈阳性，而所有其他细菌均为阴性，特异性达100%。检测到的杜克雷嗜血杆菌的最低菌落形成单位（CFU）数为2×10⁶CFU，检测到的纯化HgbA蛋白的最低量为8.5纳克。尽管这种灵敏度水平可能不足以在所有临床标本中检测到杜克雷嗜血杆菌，但进一步提高灵敏度的工作可能会使它在软下疳流行地区成为一种有价值的床边检测工具。
