Performance Evaluation of CLIA for Treponema Pallidum Specific Antibodies Detection in Comparison with ELISA

Treponema pallidum PCR screening at mucosal sites of asymptomatic men who have sex with men taking HIV pre-exposure prophylaxis

Early detection and treatment of syphilis will reduce the infectious period and transmission. We aimed to determine whether screening men who have sex with men (MSM) taking HIV pre-exposure prophylaxis (PrEP) for syphilis using Treponema pallidum polymerase chain reaction (PCR) could detect syphilis before the appearance of syphilis antibodies in serology. MSM attending 3-monthly PrEP clinic visits in Melbourne, Australia, were screened with a PCR assay targeting the polA gene of T. pallidum from an anal swab and an oral rinse between November 2019 and March 2020. Participants were serologically screened for syphilis using chemiluminescence immunoassay. A total of 309 asymptomatic participants provided an anal swab and oral rinse sample for T. pallidum PCR screening. Two syphilis cases (0.6%) were detected: one man had a positive serology only; another man had T. pallidum detected by PCR from an anal swab and a positive serology. PCR positivity was 0.3% (n = 1) for anal swabs and 0% (n = 0) for oral rinse. In this study, T. pallidum PCR screening at routine PrEP clinic visits did not identify additional cases of early syphilis over serological screening performed at these visits. IMPORTANCE With the ongoing syphilis epidemic in men who have sex with men (MSM), we investigated the role of using Treponema pallidum polymerase chain reaction (PCR) testing at the oral cavity and anus in MSM taking pre-exposure prophylaxis for the early detection of syphilis. We evaluated whether the PCR tests from these mucosal sites can detect syphilis infection early, before the development of syphilis antibodies in serology. Our study found two syphilis cases among 309 MSM, and only one syphilis case had a positive anal PCR swab, although serology was positive. We conclude that additional PCR testing is likely to be expensive and would not be cost effective for individuals who regularly screen for syphilis. However, future studies with a larger sample size are required.

Performance characteristics of the Mindray chemiluminescence anti-Müllerian hormone assay

BACKGROUND

The aim of this study was to define the performance characteristics of the Mindray chemiluminescence assay for anti-Müllerian hormone (AMH) detection.

DESIGNS AND METHODS

Intra-assay and total imprecision, analytical sensitivity, linearity, and interference were compared between the Mindray and Roche assays using pools of human serum according to Clinical and Laboratory Standards Institute protocols. Additionally, male and female reference intervals were established using serum specimens collected from otherwise healthy groups and patients with polycystic ovary syndrome (PCOS).

RESULTS

The intra-assay and total imprecision percent coefficients of variation for low and high AMH serum levels were 2.74%/ 3.01% and 5.41%/5.35% respectively. The limits of blank, detection, and quantitation were 0.007, 0.01, and 0.03 ng/ml, respectively. The assay displayed good linearity over the range of 0.01-23 ng/ml. The coefficient of determination (R² ) of the Mindray versus Roche assays was 0.9713 with 411 samples with AMH concentrations ranging from 0.014 to 22.1 ng/ml. The slope and intercept of the regression equation were 0.9687 and 0.3419, respectively. There was no significant interference from triglycerides (up to 3000 mg/dl), bilirubin (up to 50 mg/dl), hemoglobin (up to 500 mg/dl), or total protein (up to 10 g/dl). Reference intervals showed the expected decrease in serum AMH levels with age in healthy women and increased levels in women with PCOS.

CONCLUSION

The Mindray AMH assay demonstrated acceptable analytical performance under routine conditions and is suitable for determining AMH levels in serum samples.

Comparative Evaluation and Measure of Accuracy of ELISAs, CLIAs, and ECLIAs for the Detection of HIV Infection among Blood Donors in China

Background

Enzyme-linked immunosorbent assay (ELISA) is the only serological method approved for blood screening in China. Automated chemiluminescence immunoassay (CLIA) and electrochemiluminescence immunoassay (ECLIA) had been used in clinical laboratories but not applied to screen HIV among blood donors. This study aimed to evaluate the performance of ELISA, CLIA, and ECLIA, focusing on the feasibility of CLIA/ECLIA for blood screening.

Method

1029 blood donations from 14 blood centers screened by ELISA were enrolled in the study. All plasma samples were tested by eight ELISA assays in 16 blood centers, followed by the detection of CLIA and ECLIA methods in the National Center for Clinical Laboratories (NCCL), further confirmed by nucleic acid testing (NAT) and Western blot (WB).

Results

Of 1029 samples, 136 were confirmed as HIV positive. CLIA and ECLIA assay had similar sensitivities with ELISAs but showed higher specificity (CLIA: 99.1%, 885/893; ECLIA: 99.0%, 884/893), concordance rate (CLIA: 99.2%, 1021/1029; ECLIA: 99.1%, 1020/1029), and positive predictive value (PPV) (CLIA: 94.4%, 136/144; ECLIA: 93.8%, 136/145) than most of ELISA kits (>5 ELISAs) (P < 0.05). Kappa values of CLIA (0.967) and ECLIA (0.963) were the highest among all the serologic assays. Among 451 samples with initial ELISA reactivity, 315 were negatives, of which 307 (97.5%) and 306 (97.1%) were detected as nonreactive by CLIA (8 nonspecific reactions) and ECLIA (9 nonspecific reactions), respectively.

Conclusion

Compared with ELISA, CLIA and ECLIA are more specific and accurate in detecting HIV antibody/antigen and can keep more nonspecifically reactive donors detected by ELISA. CLIA and ECLIA can be used for the improvement of serological blood screening strategy to avoid the unnecessary loss of blood donors.

The evaluation of the reverse algorithm for syphilis screening in blood donors

Background: In Turkey, prior to transfusion and apheresis, it is mandatory to screen blood for HBsAg, anti-HCV, anti-HIV 1/2, and syphilis. In recent years, efforts have been made to create effective diagnostic algorithms for screening, and as a screening strategy, many countries have switched from traditional algorithms to reverse algorithms. This study was carried out to evaluate the results we obtained after changing to chemiluminescence immunoassay (CLIA) based reverse algorithm, which is more sensitive and specific than the traditional algorithm and VDRL test we currently use for syphilis screening.

Methods: The screening algorithm was initiated with the treponemal CLIA method. The reactive samples were tested using a nontreponemal test VDRL and a second treponemal test TPHA. In the descriptive analyses, the averages, numbers, and percentage distributions were calculated. The group comparisons were undertaken with the chi-square test, accepting p < 0.05 as statistically significant.

Results: Of the 5,053 samples that were tested with CLIA syphilis TPA assay 5,043 were negative (99.802%) and 10 were positive reactive (0.198%), and the difference between the two was statistically significant (p < 0.001). Ten samples that were recurrently reactive were analyzed by VDRL and TPHA tests simultaneously. VDRL was negative in all 10 samples, whereas TPHA was negative in one sample, but positive in nine samples at a titer of ≥1/160.

Conclusion: Based on the results of this study, we decided to use the CLIA method and reverse algorithm instead of using the traditional algorithm and VDRL as the initial screening method.

Comparison of Roche Elecsys and Sysmex HISCL immunoassays for the screening of common blood-borne pathogens

Background

We conducted a comprehensive comparison in the sensitivity, specificity, dilution sensitivity, and precision between two immunoassay systems, Roche Elecsys Cobas e 601 and Sysmex HISCL 5000, for the detection of hepatitis B virus surface antigen (HBsAg), antibody to hepatitis C virus (anti-HCV), treponemal antibodies (anti-TP), and human immunodeficiency virus (HIV).

Methods

One thousand unselected samples and 100 reserved weak reactive samples were tested by the two systems. Sensitivity and specificity were then calculated for each system. Seroconversion panels were used to assess the sensitivity in early stage detection. Dilution sensitivity was evaluated by dilution tests of several seroconversion panel samples. Evaluation of within-run and intermediate precision was conducted following EP-15A protocol.

Results

The consistency rates of the two systems for the detection of four pathogens were all over 99% among unselected samples. Both Elecsys and HISCL were observed to have high sensitivity and specificity in unselected samples and weak reactive samples. Seroconversion panel tests showed that Elecsys could identify positive results earlier than HISCL in HBsAg (1 out of 4), anti-TP (1 out of 2) and HIV (1 out of 12) panels. The results of the anti-HCV panels were comparable. In dilution tests, Elecsys could detect lower concentrations than HISCL in two anti-HCV samples and one anti-TP sample. The two systems had similar performance in dilution tests of HBsAg and HIV samples. Both Elecsys and HISCL had qualified intra-assay and inter-assay precision.

Conclusions

Both Elecsys and HISCL have good performance in the screening of four common bloodborne pathogens. The two systems are comparable and considered adequate for clinical use.

Evaluation of three automated Treponema pallidum antibody assays for syphilis screening

The accuracy of the test is critical for the syphilis serology diagnosis. This study aims to evaluate the values of the Elecsys syphilis assay, the Architect syphilis assay, and the Mindray syphilis assay, as syphilis screening tests for pregnant women and patients with syphilis or other diseases. A reverse algorithm was used for the syphilis serology diagnosis. Serum samples (n = 584) were tested with three automated screening assays. All reactive sera by one, two, or three screening assays were further analyzed with the tolulized red unheated serum test (TRUST). Inconsistent results were confirmed by the Treponema pallidum particle agglutination assay (TPPA). The final patient diagnosis was made according to the results of syphilis serology, clinical evidence, and past medical history. The sensitivity, specificity, accuracy, and kappa value of each assay were as follows: for the Elecsys syphilis assay, 100.0%, 98.5%, 98.6%, and 0.927, respectively; for the Architect syphilis assay: 100.0%, 94.5%, 95.0%, and 0.770; and for the Mindray syphilis assay: 100.0%, 97.0%, 97.3%, and 0.862. The McNemar test showed that there were significant differences in the performance between the Elecsys syphilis assay and the Architect syphilis assay (P < 0.001), and between the Mindray syphilis assay and the Architect syphilis assay (P = 0.001). Our study demonstrated that three automated Treponema pallidum antibody assays generally showed high sensitivities and specificities, and so, they are suitable for use in screening for syphilis. The performances of the Elecsys syphilis assay and the Mindray syphilis assay are superior to Architect syphilis assay.

Evaluation of the Lumipulse G TP-N Chemiluminescent Immunoassay as a Syphilis Screening Test

A syphilis diagnosis is often aided by the detection of treponemal and nontreponemal antibodies. Automated treponemal antibody detection systems enable high-volume clinical laboratories to perform syphilis screening at a faster pace with lower labor costs. The Lumipulse G TP-N chemiluminescent immunoassay is an automated system that qualitatively detects IgG and IgM antibodies against Treponema pallidum antigens in human serum and plasma. To assess performance characteristics and workflow efficiency, the Lumipulse G TP-N assay was compared to the Bioplex 2200 Syphilis IgG multiplex flow immunoassay. Among the 4,134 routine and HIV samples tested by the two automated assays, the percentage of agreement was excellent at 99.0% (95% confidence interval [CI], 98.6% to 99.2%; κ, 0.89), with the Lumipulse G TP-N having a shorter time to first and subsequent results. All specimens with reactive syphilis screening results were further tested by rapid plasma reagin (RPR) and Treponema pallidum particle agglutination (TP·PA) testing (n = 231). The results from the RPR-reactive samples (n = 82) showed complete concordance with the two automated assays, while the TP·PA assay displayed some discrepancies. The positive percent agreement (PPA) and negative percent agreement (NPA) between the TP·PA test and the Lumipulse G TP-N test were 98.9% and 77.3%, respectively. The Bioplex 2200 Syphilis IgG immunoassay displayed a similar PPA (100%) but a substantially lower NPA (15.9%). Patient chart reviews of discrepant results suggested that the Lumipulse G TP-N assay produced 27 fewer falsely reactive results and can reduce the amount of additional confirmatory RPR and TP·PA testing needed. The analogous performance characteristics of the two automated systems indicate that the Lumipulse G TP-N assay is suitable for high-throughput syphilis screening.

Evaluation of the HISCL Anti-Treponema pallidum Assay as a Screening Test for Syphilis

The resurgence of syphilis in recent years has become a serious threat to public health worldwide, and the serological detection of specific antibodies against Treponema pallidum remains the most reliable method for laboratory diagnosis of syphilis. This study examined the performance of the recently launched HISCL anti-Treponema pallidum (anti-TP) assay as a screening test for syphilis in a high-volume laboratory. The HISCL anti-TP assay was tested in 300 preselected syphilis-positive samples, 704 fresh syphilis-negative samples, 48 preselected potentially interfering samples, and 30 "borderline" samples and was compared head to head with the commercially available Lumipulse G TP-N. In this study, the HISCL anti-TP assay was in perfect agreement with the applied testing algorithms with an overall agreement of 100%, comparable to that of Lumipulse G TP-N (99.63%). The sensitivity and specificity of the HISCL anti-TP assay were 100% (95% confidence interval [CI], 98.42% to 100%) and 100% (95% CI, 99.37% to 100%), respectively. Considering the excellent ease of use and automation, high throughput, and its favorable sensitivity and specificity, the HISCL anti-TP assay may represent a new choice for syphilis screening in high-volume laboratories.