Serological diagnosis of paracoccidioidomycosis using a Paracoccidioides spp. comercial antigen and the counterimmunoelectrophoresis method

Cocio, Tiago Alexandre; Martinez, Roberto

doi:10.1016/j.bjid.2021.101607

ABSTRACT

Purpose:

In-house Paracoccidioides spp. antigens are commonly used in the serological diagnosis of paracoccidioidomycosis (PCM). The sensitivity and specificity of a commercial Paracoccidioides spp. antigen was assessed for PCM serological testing.

Method:

Counterimmunoelectrophoresis and double immunodiffusion were used to evaluate the Paracoccidioides ID Antigen reagent in sera from PCM cases and patients with other diseases.

Results:

All active PCM sera (n=24) were reactive using counterimmunoelectrophoresis (sensitivity = 100%), including 11 cases of infection by P. brasiliensis sensu stricto and one by P. americana. Fifteen (88%) out of 17 sera from patients on treatment or cured were reactive, including one case of P. lutzii infection. One to three bands of antigen-antibody precipitate were observed on the agarose gel, with a predominance of two to three bands in the test with untreated PCM sera or at the beginning of antifungal therapy. All sera from patients with histoplasmosis (n=7), aspergillosis (n=5), and other diseases (n=27) tested negative (specificity = 100%). The overall sensitivity and specificity using the commercial antigen and double diffusion test were 75% and 100%, respectively.

Conclusion:

The commercial antigen performed satisfactorily and may contribute to the dissemination of the use of serological tests for the PCM diagnosis.

Keywords:
Paracoccidioidomycosis; Paracoccidioides; Fungal antigen; Counterimmunoelectrophoresis

[1] * Corresponding author. E-mail addresses: alexocio@gmail.com (T.A. Cocio), rmartine@fmrp.usp.br (R. Martinez).

	Detection of antibodies - N° of sera (%)
Disease type	CIEP		DID		Total
	Positive	Negative	Positive	Negative
Paracoccidioidomycosis - active disease^a a Patients without treatment or with up to three months of use of antifungals.	24 (100)	0 (0)	15 (63)	9 (37)	24 (100)
Paracoccidioidomycosis in regression or clinical cure^b b Patients with antifungal therapy higher than 3 months or already completed.	15 (88)	2 (12)	15 (88)	2 (12)	17 (100)
Histoplasmosis	0 (0)	7 (100)	0 (0)	7 (100)	7 (100)
Aspergillosis	0 (0)	5 (100)	0 (0)	5 (100)	5 (100)
Other diseases^c c Patients without systemic fungal infection.CIEP, counterimmunoelectrophoresis; DID, double immunodiffusion.	0 (0)	27(100)	0 (0)	27 (100)	27 (100)