MiraVista Blastomyces Antigen EIA Advantage

Joe Wheat | John Witt | Heather Largura | Deborah Blue | Andrew Hanzlicek

Background

Blastomycosis is endemic in the United States around the Great Lakes, St. Lawrence seaway, southeastern states, and less frequently elsewhere. Clinical findings include pulmonary disease alone or accompanied by disseminated disease. Antigen detection is a rapid method for diagnosis with recognition that cross reactions occur in histoplasmosis. From MiraVista’s review of data, urine antigen is positive in 4.2% and serum antigen 3.2% of large customers from Wisconsin, Minnesota, Arkansas, Tennessee, and Iowa, which are endemic for blastomycosis. Reviews by Drs. Smith and Kauffman on blastomycosis are recommended resources [1, 2].

Performance

The MiraVista Blastomyces antigen enzyme immunoassay (EIA) was introduced in 2003 [3] and modified for quantification in 2011 [4], table 1. The sensitivity for detection of antigen in urine is 90% and 57% in serum [4], table 1. Specificity is 99% in controls with non-fungal diseases and healthy subjects and cross reactions occurred in 96% of patients with histoplasmosis. Day-to-day reproducibility (figures 1 and 2) and precision are excellent (table 2).

The EIA also is used for detection of antigen in bronchoalveolar lavage (BAL). The galactomannan antigen detected in histoplasmosis and blastomycosis is identical and cross reactions in the Histoplasma antigen EIA occurred in 80% (8/10) of BAL specimens from patients with blastomycosis [5]. Blastomyces antigen also may be detected in CSF in patients with Blastomyces meningitis, table 3 [6].

Monitoring Treatment

Serial testing is used as an aid in judging success of treatment. Results of testing on different days exhibit reliable reproducibility, figure 1. Change in antigen concentration between current and prior specimens also show strong agreement, (R2 0.9338, slopes 0.8454, Y intercept 0.0401), figure 2. Testing at 3 months intervals during and at least one year after stopping treatment is recommended.

Gotham Blastomyces Antigen EIA

The Gotham EIA was introduced in 2021 [7]. Results from testing are compared to those in the Gotham EIA. Positive agreement was 97.4% and negative agreement was 100%, but agreement of antigen concentration was low (y= 0.6067x + 2.4889, R2 0.2031). Urine from 4 patients with blastomycosis were positive in the MiraVista and Gotham EIA. Urine was tested from 9 patients with histoplasmosis, and antigen was detected in 5 (55.5%) in the Gotham EIA and 7 (77.7%) in the MiraVista EIA.

Advantages of MiraVista EIA

MiraVista has been offering its Blastomyces EIA for over 17 years. It has been validated for testing serum, urine, and BAL and is also offered for testing CSF as a rare specimen type pending validation, Table 4. These improvements have increased the sensitivity for diagnosis of different forms of blastomycosis.

Turn-around time is 1 day in 92%, 2 days in 98% and 3 days in 99%, providing rapid results permitting accurate diagnosis earlier, table 5.

Recommendations for Diagnosis

  1. Testing urine and serum provides the most sensitive method for diagnosis, table 6
  2. BAL should be tested if bronchoalveolar lavage is performed, table 4
  3. CSF should be tested if meningitis is suspected, table 4
  4. Send directly to MiraVista for results in 1-3 days in 99% of cases, table 5

Table 1. Sensitivity and specificity

Specimen type Sensitivity Specificity1 Reference
Urine 85% 100% [8]
Serum 82% 100% [8]
Urine 93% 100% [3]
Serum Not done Not done [3]
Urine 90% 99% [4]
Serum 57% Not done [4]
Urine 87% Not done [9]
Serum 67% Not done [9]
BAL 80% 100% [5]

1 Excludes cross-reactive galactomannan (histoplasmosis, paracoccidioidomycosis, talaromycosis)

 

Table 2. Precision MiraVista Blastomyces antigen EIA

Calibrator Mean (ng/mL) Standard deviation (ng/mL) Coefficient variation percent
High 11.92 0.71 5.91
Moderate/high 8.42 0.48 5.66
Moderate 2.87 0.21 7.16
Moderate/low 0.77 0.07 9.19
Low 0.19 0.03 14.00

 

Table 3. Detection of antigen in the CSF from patients with Blastomyces meningitis

Immunity CSF Culture Antigen n/mL References
Competent Negative 1.82 Walkty [10]
Compromised Positive Positive Bariola [6]
Competent Negative Positive Bariola [6]
Competent Positive Positive Bariola [6]

 

Table 4. Antigen results from a single institution January 2020-June 2021

Specimen Positive Negative Total Positive %
BAL 5 98 103 4.9
CSF 2 51 53 3.8
Serum 35 1061 1096 3.2
Urine 99 2245 2344 4.2
Total 141 3455 3596 3.9

 

Table 5. MiraVista Blastomyces Antigen EIA

Parameter Finding
Years offered 17
Years’ personnel experience 108
Number of EIAs weekly 8
Cross-reactivity Histoplasmosis, 96%
Coccidioidomycosis, ~10%
Aspergillosis, <5%
TAT 1-day 92%, 2-day 98%, 3-days, 99%

 

Table 6. Importance of testing urine and serum: Results single institution

Results Percentage Advantage
Urine Serum Number (%)  
Positive Positive 37 (61.7%) Highest sensitivity testing serum and urine
Positive Negative 10 (16.7%) Urine sensitive single test
Negative Positive 6 (10%) Urine alone misses 10%
Serum >urine 4 (6.7%) Serum better for serial testing 6.7%
Serum positive
Urine BLQ (< 0.2 ng/mL)
3 (5%) Positive serum true positive BLQ

 

Figure 1. Reproducibility of Blastomyces antigen EIA for diagnosis

Reproducibility of Blastomyces antigen EIA for diagnosis

Figure 2. Reproducibility of Blastomyces antigen EIA for monitoring antigen clearance during treatment [4]

Reproducibility of Blastomyces antigen EIA for monitoring antigen clearance during treatment

Reference List:

  1. Smith JA, Kauffman CA. Blastomycosis. Proc Am Thorac Soc 2010 May;7(3):173-80.
  2. Smith JA, Gauthier G. New Developments in Blastomycosis. Semin Respir Crit Care Med 2015 Oct; 36(5):715-28.
  3. Durkin M, Witt J, LeMonte A, Wheat B, Connolly P. Antigen EIA with the potential to aid in diagnosis of blastomycosis. J Clin Microbiol 2004 Oct;42(10):4873-5.
  4. Connolly P, Hage CA, Bariola JR, et al. Blastomyces dermatitidis Antigen Detection by Quantitative Enzyme ImmunoEIA. Clin Vaccine Immunol 2012 Jan; 19(1):53-6.
  5. Hage CA, Davis TE, Fuller D, et al. Diagnosis of Histoplasmosis by Antigen Detection in BAL Fluid. Chest 2010 Mar; 137(3):623-8.
  6. Bariola JR, Perry P, Pappas PG, et al. Blastomycosis of the central nervous system: a multicenter review of diagnosis and treatment in the modern era. Clin Infect Dis 2010 Mar 15; 50(6):797-804.
  7. Theel ES, Rodino KG, Granger D. Detection of Blastomyces dermatitidis antigen in urine using a commercially available, quantitative enzyme immunoEIA. J Clin Microbiol 2021 Aug 4;JCM0144421.
  8. Bariola JR, Hage CA, Durkin M, et al. Detection of Blastomyces dermatitidis antigen in patients with newly diagnosed blastomycosis. Diagn Microbiol Infect Dis 2011 Feb; 69(2):187-91.
  9. Richer SM, Smedema ML, Durkin MM, et al. Development of a Highly Sensitive and Specific Blastomycosis Antibody Enzyme ImmunoEIA Using Blastomyces dermatitidis Surface Protein BAD-1. Clin Vaccine Immunol 2014 Feb; 21(2):143-6.
  10. Walkty A, Keynan Y, Karlowsky J, Dhaliwal P, Embil J. Central nervous system blastomycosis diagnosed using the MVista(R) Blastomyces quantitative antigen enzyme immunoEIA test on cerebrospinal fluid: A case report and review of the literature. Diagn Microbiol Infect Dis 2018 Feb; 90(2):102-4.