Parasitic polymorphism of Coccidioides spp.

BACKGROUND: Coccidioides 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. METHODS: We 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. RESULTS: The 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). CONCLUSIONS: The 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.

[An unusual outbreak of histoplasmosis in residents of the state of Mexico]. / Brote inusual de histoplasmosis en residentes del estado de México.

OBJECTIVE: The aim of this study was to establish whether there was a histoplasmosis outbreak among a group of residents of Naucalpan (State of Mexico, a non-endemic area for histoplasmosis) and to ascertain the source through which they were infected. MATERIAL AND METHODS: Anyone associated with the Index Case in the same period with a flu-like infection was considered as a suspected case. Diagnosis was confirmed by clinical examination positive, cultures and positive immunological tests. Date and form of potential exposure were obtained through interviews. Material potentially contaminated with bird or bat droppings was sought and analyzed by PCR. RESULTS: The outbreak was associated with a trip to El Tamarindo (Veracruz, near the Gulf of Mexico). Patients got sick after digging a hole in the floor inside a house where a treasure had been supposedly buried by a death relative. The pathogen was detected in soil samples at 10 cm below the surface. CONCLUSIONS: The study showed that patients contracted histoplasmosis in El Tamarindo, a community where there had been no prior cases of this disease.

Clinical comparison of two Mexican coccidioidins.

Coccidioidin, an extract from the saprophytic mycelial form of Coccidioides spp., has been a very useful antigen preparation both for skin and serological tests for coccidioidomycosis. Unfortunately, coccidioidin is not currently available for skin testing in the United States. Coccidioidin has been produced commercially in Mexico by a vaccine and reagents laboratory of the Mexican Federal Government. It also has been produced at the Microbiology Laboratory of the Faculty of Medicine, Universidad Nacional Autónoma de México exclusively as an antigen for research projects. The objective of the study was to compare both coccidioidins in their reactivity and safety when applied in humans. One hundred and eighty-four volunteers were tested; median age was 33 (range 14-82). When the cutoff point is set in 5 mm, 88 subjects (47.8%) had a positive test for the commercial coccidioidin and 76 (41.3%; CI(95%) 0.50, 1.15; P = 0.20) were positive with the research antigen. Seventy-five subjects were positive for both antigens and 96 were negative for both. Fifty-nine subjects (31.3%) reported an adverse reaction after the application of the antigen; they were mostly very mild local reactions. Mexican research coccidioidin is a safe and reliable antigen that can be used for the detection of coccidioidomycosis infection in mammals.

Actinomycetoma in arm disseminated to lung with grains of Nocardia brasiliensis with peripheral filaments.

Actinomycetomas represent 97.8% of mycetomas in Mexico, where 86.6% are produced by Nocardia brasiliensis. We report a case of actinomycetoma in the arm by Nocardia brasiliensis disseminated to lung. Uncommon grains were observed which present outside peripheral filaments and also numerous filaments loosing the grains. These characteristics of the grains are due probably because for the long treatment with antibiotics of the patient. In situ antibiotic action against the microcolonies is discussed.