Evaluation of the clinical performance of 2 point-of-care cryptococcal antigen tests in dogs and cats

Background Point-of-care (POC) Cryptococcus antigen assays may provide veterinarians with a more rapid, patient-side diagnosis when compared with traditional laboratory-based latex agglutination tests. Objective To determine the sensitivity and specificity of 2 POC lateral flow cryptococcal serum antigen tests, CrAg LFA (Immy, Norman, OK) and the CryptoPS (Biosynex, Strasbourg, France) for diagnosis of cryptococcosis in dogs and cats, using the cryptococcal antigen latex agglutination system (CALAS) as the reference standard. Animals 102 serum samples from 51 dogs and 40 cats. Methods Specimens were classified as CALAS-positive (n = 25) or CALAS-negative (n = 77). The sensitivity and specificity of each POC assay was calculated by comparing the results to the serologic reference standard results. Results The CrAg LFA assay correctly classified 23/25 CALAS-positive specimens and 69/74 CALAS-negative specimens resulting in a sensitivity of 92.0% (confidence interval [CI], 75.0%-98.6%) and specificity of 93.2% (CI, 85.1%-97.1%). The CryptoPS assay correctly classified 8/10 tested CALAS-positive specimens and 56/59 tested CALAS-negative specimens resulting in a sensitivity of 80.0% (CI, 49.0%-96.5%) and specificity of 94.9% (CI, 86.1%-98.6%). Conclusion and Clinical Importance The POC assays appear to be a sensitive and specific alternative to the traditional CALAS assay with more rapid turnaround times, which may result in earlier diagnosis and treatment.