Higher C6 enzyme immunoassay index values correlate with a diagnosis of noncutaneous Lyme disease

Evaluation of different standard and modified two-tier testing strategies for the laboratory diagnosis of lyme borreliosis in a European setting

BACKGROUND

Diagnosis of Lyme borreliosis (LB) relies on clinical symptoms and detection of Borrelia-specific antibodies. Guidelines recommend a two-tier testing (TTT) strategy for disseminated LB: serological screening with a sensitive enzyme immunoassay (EIA) and confirmation with a specific immunoblot. Searching for the most sensitive and specific approach, this retrospective study evaluated standard (STTT) and modified (MTTT) strategies using a well-defined study population.

METHODS

Cases included patients with active Lyme neuroborreliosis (LNB; n = 29) or Lyme arthritis (LA; n = 17). Controls comprised patients treated for LNB (n = 36) or LA (n = 8), healthy individuals who were either untreated (n = 75) or treated for LB (n = 15) in the past, and patients with potentially cross-reactive diseases (n = 16). Sera were subjected to three EIAs and two immunoblots. Reactive screening results were confirmed by immunoblot (STTT) or EIA (MTTT). Solitary IgM results in the screening assay and effects of antibiotic treatment on isotype-specific seropositivity rates were also assessed.

RESULTS

Sensitivities of STTT strategies ranged from 90%-97% for LNB and were 100% for LA. MTTT strategies were 100% sensitive. Specificities ranged from 89%-95% for STTT and from 88%-93% for MTTT strategies. Differences between STTT and MTTT strategies were not statistically significant. Solitary IgM reactivity was common among controls. Antibiotic treatment significantly reduced IgM/IgG positivity for LNB patients; for LA patients, a decline was only observed for IgM.

CONCLUSION

In conclusion, MTTT strategies showed a slightly higher sensitivity and similar specificity compared to STTT strategies. Since EIAs are more time- and cost-efficient, MTTT strategies seem more favorable for clinical use. IgG testing enhances specificity with minimal sensitivity loss.

Evaluation of Lyme serologic quantitative test indexes: High first-tier test index values predict positive second-tier result in standard and modified 2-tier Lyme testing algorithms

OBJECTIVES

In this study, we evaluated the potential utility of reporting a quantitative Lyme serologic test index to improve the utility of results from first-tier Lyme assays.

METHODS

Serum from consecutive samples sent to our laboratory for Lyme testing were tested on 2 commercial first-tier Lyme assays and evaluated to determine the probability of second-tier confirmation based on the serologic index value.

RESULTS

For both assays, we identified an index value above which 100% of samples confirmed on second-tier testing using both standard and modified 2-tier testing algorithms. Lower rates of confirmation were observed for positive or equivocal samples with lower index values.

CONCLUSION

The use of a Lyme test index value may eliminate the need for confirmatory testing on many positive first-tier samples, providing more rapid turnaround time to a definitive result. This practice would also increase efficiency in the clinical laboratory.

A Prospective Study to Characterize Symptoms and Symptom Severity in Adult Patients with Extracutaneous Manifestations of Lyme Disease: Extracutaneous Lyme Disease

BACKGROUND

Systematic assessments of the presence and severity of particular symptoms over time are relatively uncommon for Lyme disease patients in the United States, and especially for Lyme disease patients with extracutaneous manifestations (ECLD).

METHODS

Symptoms and symptom severity of 12 particular symptoms were evaluated in a prospective study at baseline and at 12 months for 35 adult Lyme disease patients with ECLD, 91.4% of whom were already started on antibiotic therapy, and compared with 52 adult Lyme disease patients with erythema migrans, who were untreated at study entry.

RESULTS

No significant difference in the frequency of having at least 1 symptom out of the 12 evaluated was found between the 2 groups at either the baseline visit or the 12 month evaluation. Demographic variables were also similar between the 2 study groups, except that the ECLD patients were significantly less likely to be Caucasian, 24/35 (68.6%) of the ECLD cases vs 48/52 (92.3%) of the erythema migrans cases, p=0.008.

CONCLUSION

Lyme disease patients with ECLD had a similar frequency of symptoms at baseline compared to patients with erythema migrans . ECLD subjects, however, were significantly less like to be Caucasian raising the question of whether a preceding erythema migrans skin lesion may have been missed in persons with a darker skin color. An important limitation of our study, however, is that we did not record skin color per se, which should be considered for future studies.

Empiric antibiotics for children with suspected Lyme disease

In our prospective cohort of children undergoing evaluation for non-cutaneous Lyme disease, 02 (13.9% of those with Lyme disease) were not initially treated with an appropriate antibiotics and 356 (13.3% without Lyme disease) received potentially unnecessary antibiotics. Rapid and accurate diagnostics are needed to further improve initial antibiotic treatment decisions.

Optimizing use of multi-antibody assays for Lyme disease diagnosis: A bioinformatic approach

Multiple different recombinant and peptide antigens are now available for serodiagnosis of Lyme disease (LD), but optimizing test utilization remains challenging. Since 1995 the Centers for Disease Control and Prevention (CDC) has recommended a 2-tiered serologic approach consisting of a first-tier whole-cell enzyme immunoassay (EIA) for polyvalent antibodies to Borrelia burgdorferi followed by confirmation of positive or equivocal results by IgG and IgM immunoblots [standard 2-tiered (STT) approach]. Newer modified 2-tiered (MTT) approaches employ a second-tier EIA to detect antibodies to B. burgdorferi rather than immunoblotting. We applied modern bioinformatic techniques to a large public database of recombinant and peptide antigen-based immunoassays to improve testing strategy. A retrospective CDC collection of 280 LD samples and 559 controls had been tested using the STT approach as well as kinetic-EIAs for VlsE1-IgG, C6-IgG, VlsE1-IgM, and pepC10-IgM antibodies. When used individually, the cutoff for each kinetic-EIA was set to generate 99% specificity. Utilizing logistic-likelihood regression analysis and receiver operating characteristic (ROC) techniques we determined that VlsE1-IgG, C6-IgG, and pepC10-IgM antibodies each contributed significant diagnostic information; a single-tier diagnostic score (DS) was generated for each sample using a weighted linear combination of antibody levels to these 3 antigens. DS performance was then compared to the STT and to MTT models employing different combinations of kinetic-EIAs. After setting the DS cutoff to match STT specificity (99%), the DS was 22.5% more sensitive than the STT for early-acute-phase disease (95% CI: 11.8% to 32.2%), 16.0% more sensitive for early-convalescent-phase disease (95% CI: 7.2% to 24.7%), and equivalent for detection of disseminated infection. The DS was also significantly more sensitive for early-acute-phase LD than MTT models whose specificity met or exceeded 99%. Prospective validation of this single-tier diagnostic score for Lyme disease will require larger studies using a broader range of potential cross-reacting conditions.

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.

Challenges in the Diagnosis and Treatment of Lyme Disease

PURPOSE OF REVIEW

Since recognition in 1975, Lyme disease has become the most common vector-borne illness in North America and Europe. The clinical features are well-characterized and treatment is usually curative, but misperceptions about morbidity persist. The purpose of this review is to examine advances in the diagnosis and treatment of Lyme disease, as well as ongoing management challenges.

RECENT FINDINGS

It is useful to recognize that Lyme disease occurs in stages, with early- and late-stage disease. Clinical expression is in part determined by Borrelial variability. For example, some strains of Borrelia burgdorferi, the causative organism in North America, are particularly arthritogenic. Most patients with early Lyme disease can be cured with a single course of oral antibiotic therapy, in contrast to some patients with Lyme arthritis, a late-stage manifestation, who are more antibiotic refractory and require other treatment strategies. Successful treatment of Lyme disease begins with successful diagnosis and with an understanding of the emergence, clinical features, and impact of Lyme disease over the past half century.

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.