Department of Clinical Pathology & Immunology, Institute of Endemic Diseases, University of Khartoum, Medical Campus, Qasr Avenue, P,O, Box 45235, Postal code 11111, Khartoum, Sudan.
BMC Public Health. 2013 Dec 5;13:1128. doi: 10.1186/1471-2458-13-1128.
Most people exposed to M. tuberculosis show no evidence of clinical disease. Five to 10% of individuals with latent infection progress to develop overt disease during their life time. Identification of people with latent TB infection will increase case detection rates and may dictate new treatment policies to control tuberculosis. This study aimed to determine LTBI point prevalence in a population from Sudan using two different diagnostic methods: the tuberculin skin test (TST) and the IFN-γ release assay (IGRA).
This was a prospective, community-based and case-controlled study. Following informed consent, household contacts (HHCs; n = 98) of smear-positive index cases and Community controls (CCs; 186), were enrolled. Tuberculin skin test (TST), whole blood stimulation with ESAT-6/CFP-10 ± TB7.7 antigens or purified protein derivative (PPD) and IFN-γ levels determination with ELISA were performed. The levels of IFN-γ and TST induration between the CCs and the HHCs were compared using student t-test, Chi-square and Kappa coefficient. Pearson correlation test was used to compare TST and IFN-γ. P levels of <0.05 were considered significant.
TST induration of ≥ 10 mm gave an LTBI point prevalence of 327 cases/1000 individuals among HHCs compared to 126 cases/1000 individuals among CCs (p = 0.000). PPD-induced IFN-γ release assay gave an LTBI point prevalence of 418 cases/1000 individuals among HHCs compared to 301 cases/1000 individuals among CCs (p =0.06). On the other hand ESAT-6/CFP-10 ± TB7.7-induced IFN-γ gave an LTBI point prevalence of 429 cases/1000 individuals among HHCs compared to 268 cases/1000 individuals among CCs (p = 0.01). IFN-γ productions levels induced by ESAT-6/CPF-10 ± TB7.7 antigens in HHCS and CCs were not significantly different from those induced by PPD (p = 0.7).
IFN-γ release assay (IGRA) gave higher LTBI point prevalence compared to TST in HHCs and CCs. PPD gave comparable results to ESAT-6/CFP-10 ± TB7.7 antigens in whole blood IFN-γ release, making it a cheap alternative to the recombinant antigens.
大多数接触结核分枝杆菌的人没有临床疾病的证据。5%至 10%的潜伏感染者在其一生中会发展为显性疾病。鉴定潜伏性结核感染人群将提高病例检出率，并可能决定新的治疗政策以控制结核病。本研究旨在使用两种不同的诊断方法：结核菌素皮肤试验（TST）和干扰素-γ释放试验（IGRA），确定苏丹人群中的 LTBI 点患病率。
这是一项前瞻性、基于社区的病例对照研究。在获得知情同意后，纳入了痰涂片阳性病例的家庭接触者（HHCs；n=98）和社区对照者（CCs；186）。进行结核菌素皮肤试验（TST）、全血刺激 ESAT-6/CFP-10±TB7.7 抗原或纯化蛋白衍生物（PPD）以及酶联免疫吸附试验测定 IFN-γ水平。使用学生 t 检验、卡方检验和 Kappa 系数比较 CCs 和 HHCs 之间的 IFN-γ和 TST 硬结水平。使用 Pearson 相关检验比较 TST 和 IFN-γ。p 值<0.05 被认为具有统计学意义。
TST 硬结≥10mm 时，HHCs 的 LTBI 点患病率为 327 例/1000 人，而 CCs 为 126 例/1000 人（p=0.000）。PPD 诱导的 IFN-γ释放试验中，HHCs 的 LTBI 点患病率为 418 例/1000 人，而 CCs 为 301 例/1000 人（p=0.06）。另一方面，ESAT-6/CFP-10±TB7.7 诱导的 IFN-γ在 HHCs 中的 LTBI 点患病率为 429 例/1000 人，而 CCs 为 268 例/1000 人（p=0.01）。HHCs 和 CCs 中 ESAT-6/CPF-10±TB7.7 抗原诱导的 IFN-γ产生水平与 PPD 诱导的 IFN-γ产生水平无显著差异（p=0.7）。
与 TST 相比，IGRA 在 HHCs 和 CCs 中检测 LTBI 点患病率更高。PPD 在全血 IFN-γ释放方面与 ESAT-6/CFP-10±TB7.7 抗原具有相当的结果，是重组抗原的廉价替代品。
