Serology of coccidioidomycosis

Abstract

Serologic tests have assisted in the diagnosis and prognosis of coccidioidomycosis for a half-century. The causative agent, Coccidioides immitis, is a dimorphic fungus existing in a hyphal form with arthroconidia in nature and in the usual culture. The arthroconidia represent the inhaled infective forms which in vivo and under special laboratory conditions form spherules which endosporulate. The culture filtrate/autolysate (coccidioidin) from the hyphal phase has provided antigens of suitable reliability for currently used serologic tests. These tests are primarily to determine the two major antibody responses: the early immunoglobulin M (IgM) response is useful in the diagnosis of acute primary coccidioidomycosis. Later, IgG is produced and usually outlasts the IgM, persisting in chronic coccidioidomycosis. The IgM is detectable by tube precipitin, a corresponding immunodiffusion, or latex particle agglutination tests. The pertinent antigen(s) is heat stable and pronase resistant and appears to be largely carbohydrate, mainly mannose with some 3-O-methyl mannose. The IgG detectable in the serum and other body fluids by complement fixation and a corresponding immuno-diffusion is useful in diagnosis, and its quantitation provides an indicator of progression of disease (increasing titer) or regression (decreasing titer). The pertinent antigen appears to be a heat-labile, pronase-sensitive protein which in an unreduced form has a molecular weight of 110,000. A third very useful serologic procedure is the exoantigen test for identification of putative cultures of C. immitis.

Increased risk of coccidioidomycosis in patients treated with tumor necrosis factor α antagonists

“…On the basis of this observation, it is believed that 2 of the 13 cases were consistent with a reactivation of a prior coccidioidal infection. Although serologic testing for anticoccidioidal IgM and IgG is useful for detecting acute, active infection, titers of both types of antibodies become negative within months after infection in those patients whose infection is controlled (11,12).…”

Coccidioidomycosis After Renal Transplantation in an Endemic Area

“…Three methods for serologic testing were used, including the enzyme immunoassay ( (10,11). Dr D. Pappagianis at the University of California, Davis provided the antigen used in the complement fixation tests.…”

The Utility of Fine Needle Aspiration for Diagnosis of Extrapulmonary Coccidioidomycosis: A Case Report and Discussion

“…Serologic antibody detection tests for Coccidioides are usually immunodiffusion or complement fixationbased, but they carry the disadvantage of being labor intensive and sometimes lacking sensitivity, particularly in the early stages of infection. [4][5][6] Skin antigen testing is becoming available, but will remain positive in the case of asymptomatic or remote infections. 7,8 Additionally, patients with extensive disease may be anergic.…”