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Diagnostic Accuracy of PCR Alone and Compared to Urinary Antigen Testing for Detection of Legionella spp.: a Systematic Review.

ABSTRACT: The diagnosis of Legionnaires' disease (LD) is based on the isolation of Legionella spp., a 4-fold rise in antibodies, a positive urinary antigen (UA), or direct immunofluorescence tests. PCR is not accepted as a diagnostic tool for LD. This systematic review assesses the diagnostic accuracy of PCR in various clinical samples with a direct comparison versus UA. We included prospective or retrospective cohort and case-control studies. Studies were included if they used the Centers for Disease Control and Prevention consensus definition criteria of LD or a similar one, assessed only patients with clinical pneumonia, and reported data for all true-positive, false-positive, true-negative, and false-negative results. Two reviewers abstracted data independently. Risk of bias was assessed using Quadas-2. Summary sensitivity and specificity values were estimated using a bivariate model and reported with a 95% confidence interval (CI). Thirty-eight studies were included. A total of 653 patients had confirmed LD, and 3,593 patients had pneumonia due to other pathogens. The methodological quality of the studies as assessed by the Quadas-2 tool was poor to fair. The summary sensitivity and specificity values for diagnosis of LD in respiratory samples were 97.4% (95% CI, 91.1% to 99.2%) and 98.6% (95% CI, 97.4% to 99.3%), respectively. These results were mainly unchanged by any covariates tested and subgroup analysis. The diagnostic performance of PCR in respiratory samples was much better than that of UA. Compared to UA, PCR in respiratory samples (especially in sputum samples or swabs) revealed a significant advantage in sensitivity and an additional diagnosis of 18% to 30% of LD cases. The diagnostic performance of PCR in respiratory samples was excellent and preferable to that of the UA. Results were independent on the covariate tested. PCR in respiratory samples should be regarded as a valid tool for the diagnosis of LD.

SUBMITTER: Avni T

PROVIDER: S-EPMC4733173 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature

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Diagnostic Accuracy of PCR Alone and Compared to Urinary Antigen Testing for Detection of Legionella spp.: a Systematic Review.

Avni Tomer T Bieber Amir A Green Hefziba H Steinmetz Tali T Leibovici Leonard L Paul Mical M

Journal of clinical microbiology 20151209 2

The diagnosis of Legionnaires' disease (LD) is based on the isolation of Legionella spp., a 4-fold rise in antibodies, a positive urinary antigen (UA), or direct immunofluorescence tests. PCR is not accepted as a diagnostic tool for LD. This systematic review assesses the diagnostic accuracy of PCR in various clinical samples with a direct comparison versus UA. We included prospective or retrospective cohort and case-control studies. Studies were included if they used the Centers for Disease Con ...[more]

PMID: 26659202

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Project description:BackgroundQuantitative RT-PCR (RT-qPCR) of nasopharyngeal swab (NPS) samples for SARS-CoV-2 detection requires medical personnel and is time consuming, and thus is poorly suited to mass screening. In June, 2020, a chemiluminescent enzyme immunoassay (CLEIA; Lumipulse G SARS-CoV-2 Ag kit, Fujirebio, Tokyo, Japan) was developed that can detect SARS-CoV-2 nucleoproteins in NPS or saliva samples within 35 min. In this study, we assessed the utility of CLEIA in mass SARS-CoV-2 screening.MethodsWe did a diagnostic accuracy study to develop a mass-screening strategy for salivary detection of SARS-CoV-2 by CLEIA, enrolling hospitalised patients with clinically confirmed COVID-19, close contacts identified at community health centres, and asymptomatic international arrivals at two airports, all based in Japan. All test participants were enrolled consecutively. We assessed the diagnostic accuracy of CLEIA compared with RT-qPCR, estimated according to concordance (Kendall's coefficient of concordance, W), and sensitivity (probability of CLEIA positivity given RT-qPCR positivity) and specificity (probability of CLEIA negativity given RT-qPCR negativity) for different antigen concentration cutoffs (0·19 pg/mL, 0·67 pg/mL, and 4·00 pg/mL; with samples considered positive if the antigen concentration was equal to or more than the cutoff and negative if it was less than the cutoff). We also assessed a two-step testing strategy post hoc with CLEIA as an initial test, using separate antigen cutoff values for test negativity and positivity from the predefined cutoff values. The proportion of intermediate results requiring secondary RT-qPCR was then quantified assuming prevalence values of RT-qPCR positivity in the overall tested population of 10%, 30%, and 50%.FindingsSelf-collected saliva was obtained from 2056 participants between June 12 and Aug 6, 2020. Results of CLEIA and RT-qPCR were concordant in 2020 (98·2%) samples (Kendall's W=0·99). Test sensitivity was 85·4% (76 of 89 positive samples; 90% credible interval [CrI] 78·0-90·3) at the cutoff of 0·19 pg/mL; 76·4% (68 of 89; 68·2-82·8) at the cutoff of 0·67 pg/mL; and 52·8% (47 of 89; 44·1-61·3) at the cutoff of 4·0 pg/mL. Test specificity was 91·3% (1796 of 1967 negative samples; 90% CrI 90·2-92·3) at the cutoff of 0·19 pg/mL, 99·2% (1952 of 1967; 98·8-99·5) at the cutoff of 0·67 pg/mL, and 100·0% (1967 of 1967; 99·8-100·0) at the cutoff of 4·00 pg/mL. Using a two-step testing strategy with a CLEIA negativity cutoff of 0·19 pg/mL (to maximise sensitivity) and a CLEIA positivity cutoff of 4·00 pg/mL (to maximise specificity), the proportions of indeterminate results (ie, samples requiring secondary RT-qPCR) would be approximately 11% assuming a prevalence of RT-qPCR positivity of 10%, 16% assuming a prevalence of RT-qPCR positivity of 30%, and 21% assuming a prevalence of RT-qPCR positivity of 50%.InterpretationCLEIA testing of self-collected saliva is simple and provides results quickly, and is thus suitable for mass testing. To improve accuracy, we propose a two-step screening strategy with an initial CLEIA test followed by confirmatory RT-qPCR for intermediate concentrations, varying positive and negative thresholds depending on local prevalence. Implementation of this strategy has expedited sample processing at Japanese airports since July, 2020, and might apply to other large-scale mass screening initiatives.FundingMinistry of Health, Labour and Welfare, Japan.

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Diagnostic Accuracy of PCR Alone and Compared to Urinary Antigen Testing for Detection of Legionella spp.: a Systematic Review.

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Diagnostic Accuracy of PCR Alone and Compared to Urinary Antigen Testing for Detection of Legionella spp.: a Systematic Review.

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