251. Development of an Improved Antibody Detection EIA for use in Detection of Coccidioidomycosis
Session: Poster Abstract Session: Diagnostics: Mycology
Thursday, October 8, 2015
Room: Poster Hall
Background: Coccidioidomycosis is a mycoses caused by Coccidioides spp., which are endemic to the southwestern U.S., northern mexico and regions of South America. Coccidioidomycosis often presents as community acquired pneumonia (CAP) and is estimated to be the cause of 15-30% of such infections in endemic areas. However infections can range from subclinical to life-threatening disseminated disease. Serology is the most common technique used for diagnosis, specifically the detection of IgG and IgM antibodies by immunodiffusion (ID) and enzyme immunoassay (EIA), followed by IgG quantification by complement fixation (CF) or ID. Commercial EIAs demonstrate enhanced sensitivity compared to classical methods, but require confirmation and often result in IgM+/IgG- where the clinical significance is controversial.

Methods: Microplates were coated with Coccidioides antigen and used for testing serums from patients with proven or probable coccidioidomycosis and controls. Standards and controls containing anti-Coccidioidesantibodies were used and the results were reported in antibody units (AU).

Results: IgG antibodies were detected in 88.7% (n=80) of samples from subjects with coccidioidomycosis, for a specificity of 93.6% (n=203). Detection of IgM antibodies resulted in a sensitivity of 63.8% and specificity of 98%, but did not enhance assay sensitivity.  The positive likelihood ratio was 14.0 and the negative likelihood ratio was 0.12. Compared to the commercially available IMMY kit, the two assays were both positive in 55 cases (68.8%), the MiraVista assay alone was positive in 16 cases (20%), the IMMY assay alone was positive in one case (1.3%)  and 8 cases (10%) were not detected by either assay. Additionally, 11 of the detected cases (19.6%) were positive only by IgM using the IMMY assay compared to 0 cases with the MVD EIA.

Conclusion: The MiraVista Coccidioides antibody detection EIA is sensitive and specific for use with patient sera. The EIA demonstrates improved sensitivity compared toIMMY EIA and an additional improvement by minimizing cases identified by IgM alone. The use of this assay has the potential to aid in the diagnosis of coccidioidomycosis by providing increased sensitivity compared to currently available EIAs, and improved throughput and turnaround time compared to classical serology methods.

Eric D. Holbrook, PhD1, Tirdad Zangeneh, DO2, Joshua Malo, MD3, Christopher Strawter, MD3, Eyal Oren, PhD4, Ian Robey, PhD3, Heidi Erickson, RN3, Racquel Chahal, BS5, Cynthia Thompson, HSD5, Neil M. Ampel, MD, FIDSA6, L. Joseph Wheat, MD, FIDSA1 and Kenneth S. Knox, MD3, (1)MiraVista Diagnostics, Indianapolis, IN, (2)Infectious Disease, University of Arizona College of Medicine Tucson, Tucson, AZ, (3)University of Arizona College of Medicine, Tucson, AZ, (4)University of Arizona College of Public Health, Indianapolis, AZ, (5)University of Arizona, Tucson, AZ, (6)Medicine, University of Arizona College of Medicine, Tucson, AZ

Disclosures:

E. D. Holbrook, MiraVista Diagnostics: Employee , Salary

T. Zangeneh, None

J. Malo, None

C. Strawter, None

E. Oren, None

I. Robey, None

H. Erickson, None

R. Chahal, None

C. Thompson, None

N. M. Ampel, None

L. J. Wheat, MiraVista Diagnostics: Employee , Salary

K. S. Knox, None

Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 7th with the exception of research findings presented at the IDWeek press conferences.