263. Advances in Diagnosis of Progressive Coccidioidomycos: Experience in 164 Cases and 508 Controls

BACKGROUND: Antibody detection is the main method for diagnosis of coccidioidomycosis but has limitations including sensitivity and turnaround time. The MVISTA Coccidioides antigen enzyme immunoassay (EIA) is recommended for testing CSF in suspected Coccidioides meningitis. The early reports on urine and serum antigen testing evaluated small numbers of patients who were mostly immunocompromised with advanced disease. METHODS: A retrospective study, including all patients in whom Coccidioides antigen testing was performed between January 2013 and May 2017, was conducted at Maricopa Integrated Health System (MIHS). Sensitivity and specificity of antigen testing at MiraVista Diagnostics and antibody testing at MIHS or commercial laboratories were evaluated in 164 cases and 508 controls. RESULTS: The sensitivity of antigen testing was 51% and specificity was 99%. The sensitivity of antigen detection was highest if both urine and serum were tested (57%) than if only urine was tested (38%). The sensitivity of antibody testing was 84% and the specificity was 94% by immunodiffusion (ID). The sensitivity and specificity of antigen or ID antibody testing both were 94%. Sensitivity of antigen testing was 57% in proven and 58% in probable cases, ID antibody in 85% of proven and 75% of probable and antigen or ID antibody in 93% of proven and 95% of probable cases. Antigen was detected more often in disseminated (79%) than pulmonary cases (42%) as was ID antibody, 91% and 79%, respectively. Antigen testing was more sensitive in immunocompromised (76%) than non-immunocompromised patients (41%) while ID antibody was less sensitive in immunocompromised (74%) than in non-immunocompromised patients (93%). Combined antigen and ID antibody testing provided the highest sensitivity, 94% in all cases, 94% in immunocompromised and 95% in non-immunocompromised patients. CONCLUSION: These findings support testing urine and serum for Coccidioides antigen and serum for ID antibodies for diagnosis of progressive pulmonary or disseminated coccidioidomycosis. [Image: see text] [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.