检测特异抗体胶体金免疫层析试条诊断内脏利什曼病患者现场评价

目的 在现场评价检测内脏利什曼病特异抗体的胶体金免疫层析试条诊断内脏利什曼病患者的效果。方法 2013年采集动物源型内脏利什曼病流行区(四川省、甘肃省)和人源型内脏利什曼病流行区(新疆喀什市)疾病预防控制中心门诊就诊的病人血样和骨髓样本,用镜检法、内脏利什曼病试条和rK39试条进行平行测试,以镜检法为金标准,比较两种试条法检测的敏感性和特异性有无差异。结果 内脏利什曼病试条和rK39试条检测镜检确诊的97例内脏利什曼病患者的敏感性分别为98.87%(96/97),97.94%(95/97),二者无统计学差异(χ²=0.34,P>0.05)。两种试条检测非内脏利什曼病病例145例, 均有2例假阳性反应,特异性为98.62(143/145)。对来自动物源型内脏利什曼病流行区和人源型内脏利什曼病流行区的内脏利什曼病患者分别统计阳性率,结果显示内脏利什曼病试条和rK39试条法检测动物源型和人源型流行区的内脏利什曼病患者血样之间阳性率的差异均无统计学意义(χ²=0.22 /0.01,P>0.05)。两种试条法检测动物源型和人源型内脏利什曼病流行区非内脏利什曼病患者血样之间特异性的差异也均无统计学意义(χ²=0.29,P>0.05)。结论 快速检测内脏利什曼病的胶体金免疫层析试条适用于检测动物源型内脏利什曼病流行区患者血样中的特异性抗体。     

Evaluation of a rapid point-of-care fecal antigen detection test for Entamoeba histolytica

Amebiasis is a major cause of morbidity and mortality in the developing world. A reliable point-of-care test would help to improve diagnosis and early treatment. We evaluated a novel rapid fecal antigen detection test for E. histolytica (E. HISTOLYTICA QUIK CHEK; TechLab, Inc., Blacksburg, VA), in a cohort of children in Bangladesh where amebiasis is endemic. This point-of-care test had a sensitivity of 100% and a specificity of 100% when compared with enzyme-linked immunosorbent assay antigen detection.     

快速检测内脏利什曼病特异抗体胶体金免疫层析试条方法的建立与效果评价

目的 建立快速、简便地检测内脏利什曼病特异抗体的胶体金免疫层析试条方法,并评价效果. 方法 采用柠檬酸三钠还原法制备胶体金,用以标记链球菌G蛋白（streptococcal protein G,SPG）,并将其吸附于交联释放垫上;将杜氏利什曼原虫前鞭毛体粗抗原作为包被抗原,包被于硝酸纤维素膜适当位置,制成检测特异抗体的免疫层析试条.用该试条检测病原学确诊的内脏利什曼病（129例）、疟疾（20例）、细粒棘球蚴病（10例）、日本血吸虫病（10例）、并殖吸虫病（5例）、华支睾吸虫病（5例）等患者血清,以及健康者（40例）血清,评价其敏感性和特异性.同时用酶联免疫吸附试验（enzyme-linked immunosorbent assay,ELISA）进行平行检测. 结果 试条法检测129份黑热病患者血清,124份为阳性,敏感性为96.1％;与疟疾患者血清存在10.0％ （2/20）的交叉反应;与日本血吸虫病患者血清存在10.0％ （1/10）的交叉反应;与健康者血清存在2.5％ （1/40）的假阳性反应;与10份细粒棘球蚴病患者血清,5份并殖吸虫病患者血清和5份华支睾吸虫病患者血清均无交叉反应,总特异性为95.6％ （86/90）.该方法与ELISA法的符合率为99.2％,二者阳性检出率之间的差异无统计学意义（x2=0.12,P＞0.05）,二者特异性之间的差异也无统计学意义（x2=0.42,P＞0.05）. 结论 成功建立快速检测内脏利什曼病的胶体金免疫层析试条,该试条敏感性、特异性均较高.     

A case of invasive penicilliosis in Hong Kong with immunologic evaluation

A 53-yr-old Chinese sailor developed prolonged pyrexia with unresolved lobar pneumonia, cervical lymphadenopathy, generalized subcutaneous abscesses, and pericardial effusion. Penicillium marneffei was isolated from pericardial fluid and subcutaneous pus and was demonstrated on histologic sections of lymph nodes and lung tissue. The penicilliosis was treated successfully with amphotericin B, ketoconazole, and 5-fluorocytosine. Subsequently, he also developed other T-lymphocyte-related opportunistic infections such as disseminated cutaneous herpes zoster and chronic osteomyelitis of sternum caused by Salmonella typhimurium. He was also a chronic carrier of cytomegalovirus. Further investigations showed that he had persistent depression of T-lymphocyte function and enhancement of B-lymphocyte activity, the cause of which was undetermined.     

Comparative evaluation of seven commercial tests for detection of heterophile antibody in infectious mononucleosis

Detection of heterophile antibodies in infectious mononucleosis is the most rapid and cost-effective method for confirming the clinical diagnosis of the disease. This study compared seven commercial test kits (the Oxoid Infectious Mononucleosis Kit [Oxoid Ltd], Immunoscan Im-Latex [Baxter Travenol], Mono-Latex [Wampole Laboratories], Monospot and Im Screen Test [Ortho Diagnostics], Immunoscan Im-RBC Test [Baxter Travenol], and Infectious Mononucleosis Test [NCS Diagnostics]) to the Davidsohn differential test. All of the kits were shown to be acceptable for use, with specificities and sensitivities greater than 96.5% and 95.5%, respectively.     

Field application and evaluation of a rapid immunochromatographic test for detection of Plasmodium falciparum infection among the inhabitants of Lao PDR

Field application and evaluation of a rapid immunochromatographic test (ICT) for detection of Plasmodium falciparum infection were performed in 13 villages in a southern province of Lao PDR in 1999. More than 2,000 inhabitants, accounting for 61.8% of the total estimated population, were examined. Malaria infection was confirmed in all villages surveyed by ICT and microscopic diagnosis. The positive rates of P. falciparum malaria by microscopy ranged from 9.7% to 59.2% (mean 27.2%), whereas by ICT they were from 11.6% to 64.5% (mean 29.8%). The positive rates by ICT were generally higher in 8 out of 13 villages. However, a significant difference between the positive rates by microscopy and ICT was not observed in all villages. Plasmodium falciparum infection was actually confirmed by microscopy in 84.1% of specimens that tested positive by ICT. The results by ICT were consistent with those of the microscopic diagnosis, the discrepancy of the results was less than 10% (141/2,066). The ICT was falsely-positive in 4.7% and falsely-negative in 2.1% of the test cases. These results showed the efficacy of ICT not only in the diagnosis of the respective cases, but also in the mass-examination in the field.     

Use of a quantitative point-of-care test for the detection of serum cardiac troponin T in patients with suspected acute coronary syndromes

We compared a third generation quantitative cardiac troponin T (cTnT) point-of-care testing (POCT) from Roche Diagnostics with the laboratory assay (Roche Elecsys 2010 immunoassay analyser). Heparin-treated blood and serum were collected simultaneously in 133 unselected patients (mean age 62 +/- 14 years, 38% females) presenting to our hospital with possible cardiac chest pain. Results of the POCT were measured against the laboratory-based assay considered as the gold standard. There were 18 POCT positive versus 24 laboratory assay positive (> or = 0.03 ng/mL) patients. POCT was falsely negative in six patients, with values between 0.03 and 0.1 ng/mL. The POCT had a sensitivity of 75%, specificity of 100%, positive predictive value of 100%, negative predictive value of 95% and a total accuracy of 95%; kappa = 0.831 (P < 0.001). There was good correlation between the values of POCT and the laboratory assay: Y = 1.195X + 0.002, r2 = 0.94 (P < 0.0001). Whereas cTnT levels > 0.1 mg/mL were reliably detected with this current generation of POCT, cTnT levels between 0.03 and 0.10 ng/mL were not. Future generations of devices will need to improve sensitivity to reliably risk stratify patients with suspected acute coronary syndromes.     

Field evaluation of the ICT Malaria Pf/Pv immunochromatographic test for the detection of asymptomatic malaria in a Plasmodium falciparum/vivax endemic area in Thailand

Rapid antigen assays provide an effective tool for the detection of malaria in symptomatic patients. However, the efficacy of these devices for detecting asymptomatic malaria, where parasite levels are normally significantly lower than in symptomatic patients, is less well established. We evaluated the efficacy of a new combined Plasmodium falciparum-Plasmodim vivax immunochromatographic test (ICT Malaria Pf/Pv) in a cross-sectional malaria survey of the village of Ban Kong Mong Tha, Kanchanaburi Provice, Thailand, from August to December 2000. A total of 1,976 bleeds were made from 559 individuals over the course of the study. Blinded microscopy of thick and thin blood films was used as the gold standard; all discordant and 10% of concordant results were cross-checked. Of 1,976 ICT Malaria Pf/Pv dipsticks tested, 98.3% (n = 1,943) performed as expected, as evidenced by the appearance of the control line. The ICT Malaria Pf/Pv test was both sensitive (100.0%) and specific (99.7 %) for the diagnosis of falciparum malaria with parasitemias of > or = 500 trophozoites/microL; however, only 15.9% (13/82) of infected individuals had parasitemia rates this high. When P. falciparum parasitemia rates were < 500/microL, the sensitivity of the diagnosis was only 23.3%, with a positive predictive value (PPV) and a negative predictive value (NPV) of 76.2 and 97.2%, respectively. The ICT Malaria Pf/Pv test was specific, but not sensitive, for the diagnosis of vivax malaria with parasite rates of > or = 500 trophozoites/microl, with sensitivity, specificity, PPV, and NPV of 66.7%, 99.9%, 66.7%, and 99.9%, respectively. At parasite rates of < 500/microL, corresponding values were 0.0%, 99.9%, 0%, and 95.1%. Because of the relatively high cost of these assays, low parasite rates found in the majority of asymptomatic individuals, and low sensitivity of this assay with rates of < 500/microl, use of this assay as a tool for active case detection is of limited value in western Thailand.     

Evaluation of a monoclonal antibody-based rapid immunochromatographic test for direct detection of rabies virus in the brain of humans and animals

Rabies diagnosis uses a direct fluorescent antibody test (FAT) that is difficult, costly, and time-consuming, and requires trained personnel. We developed a rapid immunochromatographic test (RICT) for the diagnosis of rabies. The efficacy of the RICT was compared with that of the FAT. Brain samples were collected from humans, dogs, cats, and other animals in Sri Lanka (n = 248), Bhutan (n = 27), and Thailand (n = 228). The sensitivity (0.74-0.95), specificity (0.98-1.0), positive predictive value (0.98-1.0), negative predictive value (0.75-0.97), accuracy (0.91-0.98), and kappa measure of agreement (0.79-0.93) were all satisfactory for animal samples and samples preserved in 50% glycerol saline solution. Because the RICT showed high sensitivity but low specificity with human brain samples, it is unsuitable for confirming rabies in humans. No amino acid substitutions were found in the antibody attachment sites of the nucleoprotein gene with FAT-positive, RICT-negative samples. The RICT is reliable, user friendly, rapid, robust, and can be used in laboratories with a modest infrastructure.     

Comparison of a rapid field immunochromatographic test to expert microscopy for the detection of Plasmodium falciparum asexual parasitemia in Thailand.

We assessed a rapid, Plasmodium falciparum histidine rich protein 2 (PfHRP2)-based immunochromatographic test (ICT Malaria Pf Test), for detection of asexual P. falciparum parasitemia in 551 subjects in three groups: (1) symptomatic patients self-referring for diagnosis, (2) villagers in a screening survey, and (3) patients recently treated for P. falciparum malaria. Expert light microscopy was the reference standard. ICT test performance was similar for diagnostic and screening modes. Four findings emerged: (1) test sensitivity correlated directly with parasite density, (2) test band intensity correlated directly with parasite density, (3) persistent test positivity after parasite clearance precludes its use for monitoring early therapeutic responses, and (4) a false negative test at 18,000 parasites/microl is unexplained. We conclude that a strong positive ICT test is highly predictive of falciparum asexual parasitemia for the diagnosis of new cases of falciparum malaria in Thailand, but a negative test result is inadequate to exclude parasitemia < 300/microl, and in some instances, even a higher parasitemia.     

Field evaluation of the whole blood immunochromatographic test for rapid bancroftian filariasis diagnosis in the northeast of Brazil

This study evaluated the whole blood immunochromatographic card test (ICT card test) in a survey performed in Northeastern Brazil. 625 people were examined by the thick blood film (TBF) and ICT card test. Residents of a non-endemic area were also tested by the whole blood card test and Og4C3. The sensitivity of the ICT card test was 94.7% overall, but lower in females than males, based on the reasonable assumption that TBF is 100% specific. However, since TBF and other methods have unknown sensitivity, the true specificity of the card test is unknown. Nevertheless, it is possible to estimate upper and lower limits for the specificity, and relate it to the prevalence of the disease. In the endemic area, the possible range of the specificity was from 72.4% to 100%. 29.6% of the card tests performed in the non-endemic area exhibited faint lines that were interpreted as positives. Characteristics of the method including high sensitivity, promptness and simplicity justify its use for screening of filariasis. However, detailed information about the correct interpretation in case of extremely faint lines is essential. Further studies designed to consider problems arising from imperfect standards are necessary, as is a sounder diagnostic definition for the card test.     

Prospective evaluation of a Candida antigen detection test for invasive candidiasis in immunocompromised adult patients with cancer

PURPOSE: Serologic tests to detect invasive candidiasis generally have been unreliable. We prospectively evaluated the clinical utility of a new, promising commercial latex particle agglutination test (i.e., Cand-Tec, Ramco Laboratories, Inc., Houston, Texas). This assay detects Candida antigens in serum. PATIENTS AND METHODS: We examined the reliability of Cand-Tec to diagnose invasive candidiasis in 142 consecutive in-patients intensively treated with chemo-radiation therapy. Serum samples were collected at admission and then weekly, until the patients' death or hospital discharge. Evaluation for clinical utility was done using various reference titers. Twenty-nine patients had invasive candidiasis whereas 113 patients did not have documented invasive candidal infections. RESULTS: At a titer of 1:8, the Cand-Tec test had sensitivity of 38%, specificity of 90%, positive predictive value of 50%, and negative predictive value of 85%. Weekly use of the Cand-Tec test did not improve early detection of invasive candidiasis, providing only a mean interval of 0.4 day from the first positive Cand-Tec result to a definitive diagnosis of invasive candidiasis by blood culture, tissue biopsy, or autopsy. In addition, surveillance cultures from the oropharynx or stool were not helpful in identifying those patients who would develop an invasive fungal infection. CONCLUSION: In the context of current clinical management strategies for suspected fungal infection, the Candida antigen detection assay (Cand-Tec) is not a reliable method for diagnosis of deep candidiasis in neutropenic patients. Until better methods of early detection are available, patients at high risk for the development of invasive candidiasis should continue to receive empiric antifungal agent therapy.     

Establishing CD4 thresholds for highly active antiretroviral therapy initiation in a cohort of HIV-infected adult Chinese in Hong Kong

Studies on the use and outcome of highly active antiretroviral therapy (HAART) in HIV-infected Chinese have been scarce. We evaluated risk of progression to (1) nonaccidental death and (2) new AIDS-defining illness (ADI) or death in 223, 89.9% of 248 HIV-1-infected adult Chinese patients who were first initiated on HAART between 1997 and 2002, and followed through 2003. The study subjects were mostly male (88.3%), aged between 30-49 years (43.9%), and acquired HIV via sexual contact (95.7%). After a median follow-up of 38.6 months, 13 nonaccidental deaths were observed. Overall, 25 patients developed new ADI or died. Using Kaplan-Meier analyses, there was no survival difference of starting HAART at various CD4 strata but a higher risk of progression to new ADI/death in patients with pretreatment CD4 count less than 100 cells per microliter (p = 0.01). On Cox proportional hazards multivariate regression analyses, pretreatment CD4 counts of less than 100 cells per microliter and less than 150 cells per microliter but not higher levels were the cutoffs for increased progression to death (adjusted hazard ratio [HR] = 4.90, 95% confidence interval [CI]: 1.08-22.22) and new ADI/death (adjusted HR = 14.44, 95% CI: 1.95-106.89), respectively. Age 50 years or greater was the only other independent predictor of mortality and new ADI/death after HAART. Further studies are indicated to validate and discern implications of these preliminary findings of a lower CD4 threshold for antiretroviral therapy in a small Chinese HIV cohort.