Parasitic polymorphism of Coccidioides spp.

Bertha Muñoz-Hernández,María Angeles Martínez-Rivera,Carlos Cabello-Gutiérrez,Gabriel Palma-Cortés

doi:10.1186/1471-2334-14-213

Bertha Muñoz-Hernández, María Angeles Martínez-Rivera + Show 2 more

Open Access

https://doi.org/10.1186/1471-2334-14-213

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Abstract

BackgroundCoccidioides spp. is the ethiological agent of coccidioidomycosis, an infection that can be fatal. Its diagnosis is complicated, due to that it shares clinical and histopathological characteristics with other pulmonary mycoses. Coccidioides spp. is a dimorphic fungus and, in its saprobic phase, grows as a mycelium, forming a large amount of arthroconidia. In susceptible persons, arthroconidia induce dimorphic changes into spherules/endospores, a typical parasitic form of Coccidioides spp. In addition, the diversity of mycelial parasitic forms has been observed in clinical specimens; they are scarcely known and produce errors in diagnosis.MethodsWe presented a retrospective study of images from specimens of smears with 15% potassium hydroxide, cytology, and tissue biopsies of a histopathologic collection from patients with coccidioidomycosis seen at a tertiary-care hospital in Mexico City.ResultsThe parasitic polymorphism of Coccidioides spp. observed in the clinical specimens was as follows: i) spherules/endospores in different maturation stages; ii) pleomorphic cells (septate hyphae, hyphae composed of ovoid and spherical cells, and arthroconidia), and iii) fungal ball formation (mycelia with septate hyphae and arthroconidia).ConclusionsThe parasitic polymorphism of Coccidioides spp. includes the following: spherules/endospores, arthroconidia, and different forms of mycelia. This knowledge is important for the accurate diagnosis of coccidioidomycosis. In earlier studies, we proposed the integration of this diversity of forms in the Coccidioides spp. parasitic cycle. The microhabitat surrounding the fungus into the host would favor the parasitic polymorphism of this fungus, and this environment may assist in the evolution toward parasitism of Coccidioides spp.

Highlights

Coccidioides spp. is the ethiological agent of coccidioidomycosis, an infection that can be fatal
In that work we presented socio-economics, co-morbidities, and clinical data, in addition to microbiological and radiological studies, finding an operational definition that included all of the cases: "Patients with pulmonary coccidioidomycosis with evolution of 2.5 years to 8 months, which included cough, hemoptysis, radiographic evidence of cavitary lesion and type 2 diabetes mellitus developed parasitic mycelial forms of the fungus", and we proposed the integration of this diversity of forms into the parasitic cycle of Coccidioides spp. [7,8]
The diversity of the parasitic forms of Coccidioides spp. observed in clinical specimens were the following: i) spherules/endospores at different maturation stages; ii) pleomorphic cells, septate and branched hyphae, hyphae composed of ovoid, rectangular, and spherical cells); iii) arthroconidia; and iv) fungal ball formation, the parasite polymorphism of Coccidioides spp. includes this morphological diversity

Summary

Introduction

Coccidioides spp. is the ethiological agent of coccidioidomycosis, an infection that can be fatal. The "atypical" hyphal forms of Coccidioides spp. can be confused with other fungal infections such as aspergillosis, hyalohyphomycosis, etc., and rounded fungal arthroconidia can be confused with blastoconidia, parasitic forms of Blastomyses dermatititdis, the ethiological agent causative of blastomycosis; we recommend confirmation of the diagnosis by searching for the typical parasitic structures of Coccidioides spp. spherules/endospores of this infection. If they are not observed in specimens, it is necessary to support the diagnosis with clinical and epidemiological data, with serological studies, or by isolation of the fungus. The diversity of the parasitic forms of Coccidioides spp. observed in clinical specimens were the following: i) spherules/endospores at different maturation stages; ii) pleomorphic cells, septate and branched hyphae, hyphae composed of ovoid, rectangular, and spherical cells); iii) arthroconidia (spherical, triangular, ovoid, or barrel-shaped); and iv) fungal ball formation (mycelium with septate hyphae and arthroconidia), the parasite polymorphism of Coccidioides spp. includes this morphological diversity

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