Clinical performance of a point-of-care Coccidioides antibody test in dogs

Abstract

Background: Point-of-care (POC) Coccidioides antibody assays may provide veterinarians with rapid and accurate diagnostic information.

Objectives: To determine the agreement of a POC lateral flow assay (LFA), sona Coccidioides (IMMY, Norman, Oklahoma) with the current diagnostic standard, the immunodiffusion assay (agar gel immunodiffusion [AGID]; Coccidioidomycosis Serology Laboratory, University of California, Davis, California).

Animals: Forty-eight sera specimens from 48 dogs.

Methods: Sera specimens were collected from client-owned dogs that had a clinical suspicion for coccidioidomycosis. Animals were classified as Coccidioides antibody-positive (n = 36) based on a positive AGID or Coccidioides antibody-negative (n = 12) based on a negative AGID. The performance of the LFA assay was determined by comparing results to AGID results.

Results: The LFA assay demonstrated agreement in 32 of 36 Coccidioides antibody-positive specimens and 12 of 12 Coccidioides antibody-negative specimens, resulting in a positive percentage agreement of 88.9% (95% confidence interval [CI], 74.7-95.6%) and negative percentage agreement of 100% (95% CI, 75.8-100%) as compared to AGID. A receiver operator characteristic curve was constructed, and the area under the curve was 0.944 (CI, 0.880-1.000).

Conclusion and clinical importance: This LFA is a rapid alternative to the traditional AGID. The LFA provides excellent predictive value for positive results. Positive agreement was lower in dogs with low AGID titers; therefore, confirmatory testing is recommended if a high index of suspicion exists.

Keywords: diagnostic test; fungal; lateral flow; veterinary.