An evaluation of reactivity to Coccidioides immitis skin tests in subjects with diabetes mellitus

Persons with diabetes mellitus have an increased incidence of progression and dissemination of infection with Coccidioides immitis. This increased incidence of infection suggests that diabetic subjects may have a defect in cell-mediated immunity (CMI) to coccidioidomycosis. Skin test response is also determined by CMI. A negative coccidioidin skin test is often seen with serious infections and is used as evidence that therapy should be initiated. To evaluate CMI in diabetic subjects we investigated the reactivity to coccidioidin and spherulin of 54 diabetic and 56 nondiabetic subjects. There was no difference between the two groups in the prevalence or size of positive reactions to coccidioidin. These results support the continued use of coccidioidin to evaluate the need for therapy in diabetic subjects who have coccidioidomycosis. Spherulin antigen, however, produced fewer positive reactions in the diabetic group. This decreased spherulin reactivity may be associated with the increased incidence of severe coccidioidal infection in diabetic subjects.