Optical Immunoassay Test Research Articles

Rapid Tests for Group B Streptococcus Colonization in Laboring Women: A Systematic Review

We set out to determine the accuracy and rapidity of various intrapartum group B Streptococcus (GBS) colonization tests. We performed a systematic review of test-accuracy studies, which were identified without language restriction from Medline and Cochrane databases; bibliographies of known primary and review articles; and contact with authors, experts, and manufacturers. Studies were selected if they tested pregnant women intrapartum for GBS colonization and confirmed by "gold-standard" laboratory cultures. Two reviewers independently selected studies and extracted data on their characteristics, quality, and results. Accuracy data were used to form 2 x 2 contingency tables. Heterogeneity was assessed, and LRs for positive and negative test results were pooled in subgroups of studies of various tests. There were 29 test-accuracy studies in 15,691 women, evaluating 6 different tests: polymerase chain reaction (PCR), optical immunoassay (OIA), DNA hybridization, enzyme immunoassay, latex agglutination, and Islam starch medium tests. The methodologic quality of the studies was generally poor. The most accurate was the real-time PCR test, but it was less rapid than OIA test. Real-time PCR took 40 minutes to complete, whereas the OIA took 30 minutes. Real-time PCR and OIA are candidates for rapid near patient intrapartum GBS testing to determine the need for antibiotic prophylaxis to prevent neonatal GBS disease. Before implementation in practice, a robust technology assessment of their accuracy, acceptability, and cost-effectiveness is required.

Diagnosis and management of adults with pharyngitis. A cost-effectiveness analysis.

Rheumatic fever has become uncommon in the United States while rapid diagnostic test technology for streptococcal antigens has improved. However, little is known about the effectiveness or cost-effectiveness of various strategies for managing pharyngitis caused by group A beta-hemolytic streptococcus (GAS) in U.S. adults. To examine the cost-effectiveness of several diagnostic and management strategies for patients with suspected GAS pharyngitis. Cost-effectiveness analysis. Published literature, including systematic reviews where possible. When costs were not available in the literature, we estimated them from our institution and Medicare charges. Adults in the general U.S. population. 1 year. Societal. Five strategies for the management of adult patients with pharyngitis: 1) observation without testing or treatment, 2) empirical treatment with penicillin, 3) throat culture using a two-plate selective culture technique, 4) optical immunoassay (OIA) followed by culture to confirm negative OIA test results, or 5) OIA alone. Cost per lost quality-adjusted life-days (converted to life-years where appropriate) and incremental cost-effectiveness. Empirical treatment was the least effective strategy at a GAS pharyngitis prevalence of 10% (resulting in 0.41 lost quality-adjusted life-day). Although the other four strategies had similar effectiveness (all resulted in about 0.27 lost quality-adjusted life-day), culture was the least expensive strategy. Results were sensitive to the prevalence of GAS pharyngitis: OIA followed by culture was most effective when GAS pharyngitis prevalence was greater than 20%. Observation was least expensive when prevalence was less than 6%, and empirical treatment was least expensive when prevalence was greater than 71%. The effectiveness of strategies was also very sensitive to the probability of anaphylaxis: When the probability of anaphylaxis was about half the baseline probability, OIA/culture was most effective; when the probability was 1.6 times that of baseline, observation was most effective. Only at an OIA cost less than half of baseline did the OIA alone strategy become less expensive than culture. Results were not sensitive to other variations in probabilities or costs of diagnosis or treatment of GAS pharyngitis. Observation, culture, and two rapid antigen test strategies for diagnostic testing and treatment of suspected GAS pharyngitis in adults have very similar effectiveness and costs, although culture is the least expensive and most effective strategy when the GAS pharyngitis prevalence is 10%. Empirical treatment was not the most effective or least expensive strategy at any prevalence of GAS pharyngitis in adults, although it may be reasonable for individual patients at very high risk for GAS pharyngitis as assessed by a clinical decision rule.

Evaluation of the Strep B OIA Test Compared to Standard Culture Methods for Detection of Group B Streptococci

Objective:This study evaluated the accuracy of the commercial product Strep B OIA (optical immunoassay) compared to the standard agar and broth culture methods for detecting vaginal colonization with group B streptococcus (GBS).Methods:Preoperative vaginal cultures were obtained from 141 nonpregnant gynecological patients undergoing major gynecologic surgery. Major gynecologic surgery was defined as benign gynecologic, gyne-oncology, and urogynecologic procedures. The results of the Strep B OIA test were compared to the results obtained from SXT agar (selective for GBS), colistin-nalidixic acid (CNA) agar, and Todd-Hewitt broth cultures.Results:The prevalence of vaginal GBS colonization in this population was 20.6%. The sample sensitivity and specificity of the OIA method were 58.6% and 85.7%, respectively. These values are lower than the sensitivity and specificity of 85.4% and 91.5%, respectively, given in the OIA package insert. Although the sample negative predictive value was fairly high (88.9%), the positive predictive value was low (51.5%).Conclusion:Although a previous study stated that the product Strep B OIA reduces the time required to obtain results (30 minutes versus days) and can, therefore, function as a useful diagnostic tool in the management of early-onset GBS disease, the present study's finding of low sensitivity and low positive predictive value indicates that this test may have very limited clinical value. Infect. Dis. Obstet. Gynecol. 7:202–205, 1999.

Evaluation of an optical immunoassay test for rapid detection of influenza A and B viral antigen

An optical immunoassay test, FLU OIA (BIOSTAR, USA), was evaluated for the diagnosis of influenza viral infection. The reactivity of the FLU OIA test was evaluated using 42 influenza strains (25 human influenza A, 12 human influenza B, 2 swine influenza A and 3 avian influenza A strains). The FLU OIA test showed positive results for all influenza strains. There was no evidence that cross-reactivity occurred with non-influenza viruses. The detection limit of the FLU OIA test was found to be 3.0-6.5 x 10(4) pfu/assay for human influenza A and B strains. The sensitivity and specificity of the FLU OIA test compared to isolation in cell culture was 89.7% and 76.0% for testing of 54 nasopharyngeal aspirate specimens. The FLU OIA test is rapid and easy for the detection of influenza A and B viral antigen and provide a valuable tool for the rapid diagnosis of influenza viral infection.

Evaluation of a new rapid antigen detection kit for group A beta-hemolytic streptococci.

To evaluate the use of a new rapid antigen-detection kit for group A beta-hemolytic streptococcus and compare results with previously published studies. Throat swabs were obtained prospectively from patients, aged one to 18 years, presenting to the emergency department, acute concerns clinic, and walk-in clinic of an urban tertiary care children's hospital. Throat swabs were first inoculated on a 5% sheep blood agar plate and then used for the streptococcus A optical immunoassay (OIA) kit. Results of both the throat culture and the rapid antigen-detection test were then compared. Two-hundred thirty-three patients were enrolled. Seventy-three patients had a positive culture and 63 patients had a positive OIA. Fifteen patients had a false negative result for the OIA kit and five patients had a false positive result. Test sensitivity was 79.5%, specificity was 96.9%, positive predictive value was 92.1%, and negative predictive value was 91.2% Although previous studies have demonstrated OIA kit sensitivities as high as 98.9% and authors have, as a result, recommended that the performance of a backup throat culture for a negative OIA test is unnecessary, our results do not support this. A sensitivity of 79.5% is not sufficiently high to justify omission of a standard throat culture. Accordingly, all OIA tests that are negative should be confirmed by the performance of a throat culture.

Use of Optical Immunoassay to Diagnose Streptococcal Pharyngitis

<h3>To the Editor.</h3> —In the article by Dr Gerber and colleagues¹reporting an office-based multicenter investigation of the optical immunoassay (OIA) test for group A β-hemolytic streptococcal (GABHS) pharyngitis, the authors concluded that "with adequately trained personnel, negative OIA test results may not always need to be routinely confirmed with blood agar plate (BAP) cultures." We believe the authors' conclusions are based less on the quality of the testing personnel or the performance specifications of the OIA and more on the quality of the BAP culture procedure used in the study. Presumptive differentiation of GABHS and non—group A streptococci may be accomplished by the bacitracin test, in which a zone of inhibition is noted on a pure subculture of β-hemolytic colonies. Bacitracin disks placed on primary cultures on nonselective media, as was done in this study, may detect as little as 54% of group A streptococci.²We compared

Optical Immunoassay Test for Group A β-Hemolytic Streptococcal Pharyngitis

To compare the accuracy of an optical immunoassay (OIA) for the rapid diagnosis of group A streptococcal pharyngitis with blood agar plate (BAP) culture. Blinded comparison with criterion standard. A total of 6 private pediatricians' offices, 3 in Connecticut and 3 in Chicago, III. A total of 2113 consecutive patients with acute pharyngitis, 983 in Connecticut and 1130 in Chicago. The sensitivities and specificities of OIA and BAP culture (both performed and interpreted in the office) were determined using a research laboratory's interpretation of a combination of BAP culture and Todd-Hewitt broth (THB) culture of transport tube pledget as criterion standard. Among patients in Connecticut, the sensitivities of the OIA and BAP culture were 94% and 89%, respectively (P=.004), while the specificities were 96% and 99%, respectively (P=.001). Among patients in Chicago, the sensitivities of the OIA and BAP culture were 79% and 72%, respectively (P<.001), while the specificities were 89% and 99%, respectively (P<.001). In each of the 6 pediatricians' offices, the OIA was more sensitive than the BAP culture. Combining the data from Connecticut and Chicago, the overall sensitivities of the OIA and BAP culture were 84% and 78%, respectively (P<.001), while the specificities were 93% and 99%, respectively (P<.001). The results of this comprehensive office-based investigation suggest that with adequately trained personnel, negative OIA test results may not always need to be routinely confirmed with BAP cultures.

Rapid detection of group B streptococcal antigen from vaginal specimens using a new Optical ImmunoAssay technique

A total of 531 vaginal specimens were used to evaluate a new Optical ImmunoAssay (OIA) screening technique for the rapid detection of group B streptococcal antigen. The results of the OIA test, the ICON Strep B membrane immunoassay (Hybritech ICON), and conventional culture on sheep blood agar (direct TSA) were compared to broth enhanced culture. Results obtained from the OIA test, ICON, and direct TSA yielded 72, 39, and 68 positives, respectively, as compared to 100 positives using the Lim broth culture method as the standard. The Optical ImmunoAssay technique is as sensitive as the conventional plating method and is capable of providing results in 30 minutes.