Evaluation of a sequential enzyme immunoassay testing algorithm for Lyme disease demonstrates lack of test independence but high diagnostic specificity

Performance of two modified two-tier algorithms for the serologic diagnosis of Lyme disease

We compared the performance of a new modified two-tier testing (MTTT) platform, the Diasorin Liaison chemiluminescent immunoassay (CLIA), to the Zeus enzyme-linked immunoassay (ELISA) MTTT and to Zeus ELISA/Viramed immunoblot standard two-tier testing (STTT) algorithm. Of 537 samples included in this study, 91 (16.9%) were positive or equivocal by one or more screening tests. Among these 91 samples, only 57 samples were concordant positive by first-tier screening tests, and only 19 of 57 were concordant by the three second-tier methods. For IgM results, positive percent agreement (PPA) was 68.1% for Diasorin versus 89.4% for Zeus compared to immunoblot. By contrast, the PPA for IgG for both Diasorin and Zeus was 100%. Using a 2-out-of-3 consensus reference standard, the PPAs for IgM were 75.6%, 97.8%, and 95.6% for Diasorin, Zeus, and immunoblot, respectively. The difference between Zeus MTTT and Diasorin MTTT for IgM detection was significant (P = 0.0094). PPA for both Diasorin and Zeus MTTT IgG assays was 100% but only 65.9% for immunoblot STTT (P = 0.0005). In total, second-tier positive IgM and/or IgG results were reported for 57 samples by Diasorin MTTT, 63 by Zeus MTTT, and 54 by Viramed STTT. While Diasorin CLIA MTTT had a much more rapid, automated, and efficient workflow, Diasorin MTTT was less sensitive for the detection of IgM than Zeus MTTT and STTT including in 5 early Lyme cases that were IgM negative but IgG positive.

IMPORTANCE

The laboratory diagnosis of Lyme disease relies upon the detection of antibodies to Borrelia species. Standard two tier testing (STTT) methods rely upon immunoblots which have clinical and technical limitations. Modified two-tier testing (MTTT) methods have recently become available and are being widely adopted. There are limited independent data available assessing the performance of MTTT and STTT methods.

Laboratory Diagnosis of Lyme Borreliosis

Lyme borreliosis is caused by a growing list of related, yet distinct, spirochetes with complex biology and sophisticated immune evasion mechanisms. It may result in a range of clinical manifestations involving different organ systems, and can lead to persistent sequelae in a subset of cases. The pathogenesis of Lyme borreliosis is incompletely understood, and laboratory diagnosis, the focus of this review, requires considerable understanding to interpret the results correctly. Direct detection of the infectious agent is usually not possible or practical, necessitating a continued reliance on serologic testing. Still, some important advances have been made in the area of diagnostics, and there are many promising ideas for future assay development. This review summarizes the state of the art in laboratory diagnostics for Lyme borreliosis, provides guidance in test selection and interpretation, and highlights future directions.

Lyme Disease Pathogenesis

Lyme disease Borrelia are obligately parasitic, tick- transmitted, invasive, persistent bacterial pathogens that cause disease in humans and non-reservoir vertebrates primarily through the induction of inflammation. During transmission from the infected tick, the bacteria undergo significant changes in gene expression, resulting in adaptation to the mammalian environment. The organisms multiply and spread locally and induce inflammatory responses that, in humans, result in clinical signs and symptoms. Borrelia virulence involves a multiplicity of mechanisms for dissemination and colonization of multiple tissues and evasion of host immune responses. Most of the tissue damage, which is seen in non-reservoir hosts, appears to result from host inflammatory reactions, despite the low numbers of bacteria in affected sites. This host response to the Lyme disease Borrelia can cause neurologic, cardiovascular, arthritic, and dermatologic manifestations during the disseminated and persistent stages of infection. The mechanisms by which a paucity of organisms (in comparison to many other infectious diseases) can cause varied and in some cases profound inflammation and symptoms remains mysterious but are the subjects of diverse ongoing investigations. In this review, we provide an overview of virulence mechanisms and determinants for which roles have been demonstrated in vivo, primarily in mouse models of infection.

C6 peptide enzyme immunoassay in Lyme borreliosis serology

The cut-off values used in C6 peptide-based enzyme immunoassay (EIA), a widely used test in Lyme borreliosis (LB) serology, have not been thoroughly analysed. The objective of the study was to examine the performance of the C6 EIA, and to determine optimal cut-off values for the test. The analysed data contained results of 1368 serum samples. C6 EIA index values were compared statistically with the immunoblot (IB) test results. The identified cut-off values were further tested in a well-defined LB patient cohort. Cut-off value 1.6 appeared to be optimal when C6 EIA was used as a stand-alone test. When using C6 EIA as the first-tier test, the optimal cut-off values were 0.9 and 2.4 for negative and positive results. When C6 EIA was used as a second-tier test, samples yielding C6 index values ≥3.0 could be considered positive. The identified cut-off values had also a high sensitivity to identify seropositivity among definite LB patients. The identified cut-off values refine the role of C6 EIA in LB serology. Importantly, the use of C6 EIA leads to a reduction in the number of samples that need to be analysed using an IB, thus also reducing the costs. Two alternative workflows for LB serology including the C6 EIA are suggested.

A Fully Automated Multiplex Assay for Diagnosis of Lyme Disease with High Specificity and Improved Early Sensitivity

Lyme borreliosis is a tick-borne disease caused by the Borrelia burgdorferi sensu lato complex. Bio-Rad Laboratories has developed a fully automated multiplex bead-based assay for the detection of IgM and IgG antibodies to B. burgdorferi The BioPlex 2200 Lyme Total assay exhibits an improved rate of seropositivity in patients with early Lyme infection. Asymptomatic subjects from endemic and nonendemic origins demonstrated a seroreactivity rate of approximately 4% that was similar to other commercial assays evaluated in this study. Coupled to this result was the observation that the Lyme Total assay retained a high first-tier specificity of 96% while demonstrating a relatively high sensitivity of 91% among a well-characterized CDC Premarketing Lyme serum panel. The Lyme Total assay also performs well under a modified two-tier algorithm (sensitivity, 84.4 to 88.9%; specificity, 98.4 to 99.5%). Furthermore, the new assay is able to readily detect early Lyme infection in patient samples from outside North America.

Diagnostic Performance of C6 Enzyme Immunoassay for Lyme Arthritis

OBJECTIVES

In Lyme disease endemic areas, initial management of children with arthritis can be challenging because diagnostic tests take several days to return results, leading to potentially unnecessary invasive procedures. Our objective was to examine the role of the C6 peptide enzyme immunoassay (EIA) test to guide initial management.

METHODS

We enrolled children with acute arthritis undergoing evaluation for Lyme disease presenting to a participating Pedi Lyme Net emergency department (2015-2019) and performed a C6 EIA test. We defined Lyme arthritis with a positive or equivocal C6 EIA test result followed by a positive supplemental immunoblot result and defined septic arthritis as a positive synovial fluid culture result or a positive blood culture result with synovial fluid pleocytosis. Otherwise, children were considered to have inflammatory arthritis. We report the sensitivity and specificity of the C6 EIA for the diagnosis of Lyme arthritis.

RESULTS

Of the 911 study patients, 211 children (23.2%) had Lyme arthritis, 11 (1.2%) had septic arthritis, and 689 (75.6%) had other inflammatory arthritis. A positive or equivocal C6 EIA result had a sensitivity of 100% (211 out of 211; 95% confidence interval [CI]: 98.2%-100%) and specificity of 94.2% (661 out of 700; 95% CI: 92.5%-95.9%) for Lyme arthritis. None of the 250 children with a positive or equivocal C6 EIA result had septic arthritis (0%; 95% CI: 0%-1.5%), although 75 children underwent diagnostic arthrocentesis and 27 underwent operative joint washout.

CONCLUSIONS

In Lyme disease endemic areas, a C6 EIA result could be used to guide initial clinical decision-making, without misclassifying children with septic arthritis.

Evaluation of the Modified Two-Tiered Testing Method for Diagnosis of Lyme Disease in Children

Conventional two-tiered testing (CTTT) for Lyme disease includes a first-tier enzyme immunoassay (EIA) followed by a supplemental immunoblot, and modified two-tiered testing (MTTT) relies on two different sequential EIAs without the inclusion of an immunoblot. MTTT has shown promising results as an alternative strategy for the diagnosis of Lyme disease in adults but has not yet been evaluated in children. We performed a cross-sectional study of children and adolescents ≤21 years of age undergoing clinical investigation for suspected Lyme disease. Serum specimens were analyzed with both a whole-cell sonicate (WCS) and a C6 EIA, with a supplemental immunoblot if either EIA was positive or equivocal. We compared CTTT (WCS EIA followed by supplemental immunoblot) to MTTT (WCS EIA followed by C6 EIA) using McNemar's test to evaluate for agreement beyond chance alone. We then used a kappa statistic to measure level of the agreement between testing strategies. We included 1,066 serum specimens, of which 156 (14.6%) had a positive CTTT and 165 (15.5%) had a positive MTTT. There were no significant differences between MTTT and CTTT (P = 0.16). Although the overall agreement between MTTT and CTTT was high (kappa, 0.88; 95% confidence interval, 0.84 to 0.92), 33 children had discordant test results. In a cohort of children and adolescents undergoing investigation for suspected Lyme disease, CTTT and MTTT results agreed in most cases. Since immunoblots are time-consuming, laborious, and challenging to interpret, MTTT provides a promising alternate Lyme disease testing strategy for children.

Investigation of the performance of serological assays used for Lyme disease testing in Australia

Spirochaetes of the Borrelia burgdorferi sensu lato complex, which includes those that cause Lyme disease, have not been identified in Australia. Nevertheless, Australian patients exist, some of whom have not left the country, who have symptoms consistent with so-called “chronic Lyme disease”. Blood specimens from these individuals may be tested in Australian laboratories and in specialist laboratories outside Australia and sometimes conflicting results are obtained. Such discrepancies cause the patients to question the results from the Australian laboratories and seek assistance from the Australian Government in clarifying why the discrepancies occur. The aim of this study was to determine the level of agreement in results between commonly used B. burgdorferi serology assays in specimens of known status, and between results reported by different laboratories when they use the same serology assay. Five immunoassays and five immunoblots used in Australia and elsewhere were examined for the detection of IgG antibodies to Borrelia burgdorferi sensu lato. Predominantly, archived specimens previously tested for Lyme disease were used for the study and included 639 contributed by seven clinical laboratories located either in Australia or in areas endemic for Lyme disease. Also included were 308 prospectively collected Australian blood donor specimens. All clinical specimens were tested in all 10 assays whereas blood donor specimens were tested in all immunoassays and a subset was tested on immunoblots. With the exception of one immunoblot, the results between the assays agreed with each other in a known positive specimen population ≥ 77% of the time and in a known negative population, 88% of the time or greater. The test results obtained during the study were different from the participating laboratory’s less than 2% of the time when the same assay was used. These findings suggest that discordance in results between laboratories is more likely due to variation in algorithms or in the use of assays with different sensitivities or specificities rather than conflicting results being reported from the same assay in different laboratories. In the known negative population, specificities of the immunoassays ranged between 87.7% and 99.7%. In Australia’s low prevalence population, this would translate to a positive predictive value of < 4%.

Revisiting the Lyme Disease Serodiagnostic Algorithm: the Momentum Gathers

Lyme disease is a tick-borne illness caused by Borreliella (Borrelia) burgdorferi, and it is the most common vector-borne disease in the United States, with an estimated incidence of 300,000 cases per year. The currently recommended approach for laboratory support of the diagnosis of Lyme disease is a standard two-tiered (STT) algorithm comprised of an enzyme-linked immunoassay (EIA) or immunofluorescence assay (IFA), followed by Western blotting (WB). The STT algorithm has low sensitivity in early infection, and there are drawbacks associated with the WB use in practice. Modified two-tiered (MTT) algorithms have been shown to improve the sensitivity of the testing in early disease while maintaining high specificity. In this issue of the Journal of Clinical Microbiology, A. Pegalajar-Jurado et al. (J Clin Microbiol 56:e01943-17, 2018, https://doi.org/10.1128/JCM.01943-17) report the results of their evaluation of the Liaison VlsE CLIA, the Captia B. burgdorferi IgG/IgM EIA, and the C6 B. burgdorferi (Lyme) EIA as MTT algorithms compared with results with the STT algorithm using the same tests as the first-tier test and the ViraStripe IgM and IgG WBs as the second-tier test. The results showed that all MTT algorithms had higher sensitivities than STT algorithms and were highly specific. These results showed that MTT approaches are a valid alternative to the currently recommended STT algorithm for serodiagnosis of Lyme disease, opening the door for the development of rapid diagnostics and point-of-care testing that can provide diagnostic information during the initial patient visit.