Purification and characterization of a phytoalexin elicitor from spores of the saprobe Mucor ramosissimus

Plants accumulate antimicrobial compounds (phytoalexins) in response to a wide variety of microorganisms. Mucor ramosissimus Samutsevitsch is a saprobe capable of inducing phytoalexin production in soybean cotyledons and in the leaves of tropical Rubiaceae on whose surface it has been found. In the present study, the elicitor from M. ramosissimus was partially purified and the activity compared to that of a glucan elicitor isolated from Phytophthora sojae. Optimal isolation of the elicitor (based on fungal growth, yield of spores and elicitor activity) was achieved by autoclaving spores obtained from nine day-old cultures of the fungus. The elicitor was precipitated with ethanol and purified by chromatography on an anion exchange column, which retained the elicitor, and a Concanavalin A-affinity matrix, to which the elicitor did not bind. The purification resulted in a considerable increase (six-fold) in the specific activity of the elicitor. Neutral sugar composition, analyzed by HPLC, revealed the predominance of mannose, followed by glucose and galactose, whereas colorimetric quantification showed the presence of uronic acids. GC-MS analysis of the elicitor revealed the predominance of glucuronic acid and mannose. These results suggest that fragments of mucoran-type polysaccharides are the phytoalexin elicitors present in the spores of the saprobe M. ramosissimus. Our results also indicate for the first time that soybean cotyledon tissues can recognize fragments of glucuronic-acid heteropolymers as phytoalexin elicitors.

Fungal infections in neutropenic patients: a 8-year prospective study

In this paper we report a eight-year prospective study designed to further characterize incidence, epidemiology, specific syndromes, treatment and prognosis associated with fungal infections in neutropenic patients. During the study period 30 fungal infections were diagnosed in 30 patients among 313 episodes of fever and neutropenia (10%). There were 15 cases of candidiasis, 5 pulmonary aspergillosis, 3 sinusitis by Aspergillus fumigatus, 5 infections by Fusarium sp., one infection by Trichosporon sp., and one infection due to Rhodotorula rubra. Blood cultures were positive in 18 cases (60%). The predisposing factors for fungal infection in multivariate analysis were the presence of central venous catheter (p<0.001), longer duration of profound (<100/mm³) neutropenia (p<0.001), the use of corticosteroids (p<0.001), gram-positive bacteremia (p=0.002) and younger age (p=0.03). In multivariate analysis only recovery of the neutropenia (p<0.001) was associated with good prognosis whereas the diagnosis of infection by Fusarium sp. (p=0.006) was strongly associated with a poor outcome. The death rate was 43%. There was no statistically significant difference in the death rate between patients who did receive (52%) or did not receive (50%) antifungal treatment. Identifying patients at risk, specific syndromes and prognostic factors may help to reduce the high mortality associated with disseminated fungal infections in neutropenic patients.

Failure of nitric oxide production by macrophages and decrease in CD4+ T cells in oral paracoccidioidomycosis: possible mechanisms that permit local fungal multiplication

Paracoccidioidomycosis is a chronic granulomatous disease that induces a specific inflammatory and immune response. The participation of nitric oxide (NO), a product of the inducible nitric oxide synthase enzyme (iNOS), as an important fungicidal molecule against Paracoccidioides brasiliensis has been demonstrated. In order to further characterize the Oral Paracoccidioidomycosis (OP), we undertook an immunohistochemical study of iNOS+, CD45RO+, CD3+, CD8+, CD20+, CD68+ cells and mast cells. The samples were distributed in groups according to the number of viable fungi per mm². Our results showed weak immunolabeling for iNOS in the multinucleated giant cells (MNGC) and in most of the mononuclear (MN) cells, and the proportion of iNOS+ MN/MNGC cells in the OP were comparable to Control (clinically healthy oral tissues). Additionally, our analysis revealed a similarity in the number of CD4+ cells between the Control and the OP groups with higher numbers of fungi. These findings suggest that a low expression of iNOS and a decrease in the CD4+ T cells in OP may represent possible mechanisms that permit the local fungal multiplication and maintenance of active oral lesions.

Fungal agents in different anatomical sites in Public Health Services in Cuiabá, state of Mato Grosso, Brazil

INTRODUCTION: A contribution to the regional epidemiological profile of the most common fungal agents in Public Health Services in Cuiabá, state of Mato Grosso, including university hospitals and polyclinics. METHODS: Clinical specimens (n = 1,496) from 1,078 patients were collected, submitted to direct mycological exam (potash or stick tape method) and cultured in specific mediums. Dermatophytic and non-dermatophytic agents were identified according to micromorphology (Ridell technique). RESULTS: The majority of the 1,496 specimens were skin (n = 985) and nail exams (n = 472). Of the 800 positive cultures, 246 (30.8%) corresponded to dermatophytes and 336 (42%) to yeasts of the genus Candida, 190 (23.7%) to other yeasts, 27 (3.4%) to non-dermatophytic filamentous fungi and one (0.1%) the agent of subcutaneous mycosis. Lesions considered primary occurred in greater numbers (59.5%) than recurrent lesions (37.4%), with a greater concentration of positivity occurring on the arms and legs. CONCLUSIONS: Comorbidities, allergies and diabetes mellitus were conditions associated with greater positivity in direct mycological exams and cultures. Positive culture was considered a definitive diagnosis of fungal infection and confirmed 47.8% of diagnostic hypotheses.

DISSEMINATED FUNGAL INFECTION WITH ADRENAL INVOLVEMENT: REPORT OF TWO HIV NEGATIVE BRAZILIAN PATIENTS

Paracoccidioidomycosis and histoplasmosis are systemic fungal infections endemic in Brazil. Disseminated clinical forms are uncommon in immunocompetent individuals. We describe two HIV-negative patients with disseminated fungal infections, paracoccidioidomycosis and histoplasmosis, who were diagnosed by biopsies of suprarenal lesions. Both were treated for a prolonged period with oral antifungal agents, and both showed favorable outcomes.

Mycetoma fungal infection: multiple organisms as colonizers or pathogens?

We describe a patient with mycetoma or Madura foot, in which histopathological stains of the bone and surface cultures suggested three different organisms including Nocardia species as the cause. Criteria for the diagnosis of the organisms, differentiation between colonizer and pathogen, and significance of mixed infections are discussed.

In vitro predatory activity of conidia of fungal isolates of the Duddingtonia flagrans on Angiostrongylus vasorum first-stage larvae

INTRODUCTION: Angiostrongylus vasorum is a nematode that parasitizes molluscs, dogs, and even man. METHODS: The objective was to evaluate the predatory activity of the conidia of two fungal isolates of Duddingtonia flagrans (AC001 and CG722) on first-stage larvae (L1) of A. vasorum in laboratory conditions. RESULTS: At the end of the experiment, there were significant reductions (p<0.01) of 74.5% and 63.2%, on average, in the A. vasorum L1 recovered in the AC001 and CG722 treatment conditions, respectively. CONCLUSIONS: The two isolates of fungi were efficient in the capture and destruction of A. vasorum L1.

Assessment of microbiological air quality in hemato-oncology units and its relationship with the occurrence of invasive fungal infections: an integrative review

Worldwide aging of the human population has promoted an increase in the incidence of neoplasia, including hematological cancers, which render patients particularly vulnerable to invasive fungal infections. For this reason, air filtration in hemato-oncology units has been recommended. However, scarce literature has assessed the impact of microbiological air quality on the occurrence of fungal infections in this population. We performed an integrative review of studies in the MEDLINE database that were published between January 1980 and October 2012, using the following combinations of keywords: air × quality × HEPA, air × quality × hematology, and airborne fungal infections. The search yielded only 13 articles, suggesting that high-efficiency filtering of the ambient air in hemato-oncology units can prevent the incidence of invasive fungal infections. However, no randomized clinical trial was found to confirm this suggestion. Currently, there is no consensus about the maximum allowable count of fungi in the air, which complicates filtration monitoring, including filter maintenance and replacement, and needs to be addressed in future studies.

Fungal infections in the immunocompromised host

In recent years many remarkable changes occurred in our way of life, producing opportunities for microbes. All these changes are related to the recent emergence of previously unrecognized diseases, or the resurgence of diseases that, at least in developed countries, were thought to be under control. This concept is reviewed regarding fungal infections and their agents in the immunocompromised host. The changing pattern of these infections, the portals of entry of fungi into the human host, fungal pathogenicity and the main predisposing factors are analyzed. Opportunistic fungal infections in cancer, organ transplant and acquired immunodeficiency syndrome patients are reviewed, specially candidiasis and aspergillosis.