RGB Imaging as Tool to Analyze the Growth of Fusarium graminearum in Infected Oats (Avena sativa) and Rice (Oryza sativa)

Fusarium graminearum is a cereal pathogen responsible for economic losses worldwide every year. An understanding of its growth is key to control its infection, but current growth models are limited because their size-based approach provides little information about the mold's metabolism. Recently, a RGB (red, green and blue) imaging analysis demonstrated the predictability of F. graminearum color change as it grows in yeast extract agar (YEA). This study aimed to verify the same phenomenon in oats (aw = 0.94, 0.97 and 0.99) and rice (aw = 0.97, 0.98 and 0.99). Photos were taken using a professional camera and a smartphone (iPhone 6) after incubation and during the subsequent 16 days, and average RGB was quantified using ImageJ software. The photos showed very similar color variations, regardless of the type of grain or aw. The mold first adopted a k-selection strategy by growing as a mycelium and then a r-selection strategy, increasing spore production. All RGB channels showed positive Pearson correlations between them (p < 0.001) and it was possible to design a model showing two lag phases, the first prior to a mycelial phase and the second prior to a sporular phase at the end of the experiment.

Genetic differences between Coccidioides spp. and closely related nonpathogenic Onygenales

Coccidioides spp. are dimorphic, pathogenic fungi that can cause severe human and animal disease. Like the other primary fungal pathogens, animal infection results in a morphologic transformation from the environmental mycelial phase to a tissue phase, known as a spherule. The sequencing and annotation of Coccidioides spp. and the genomes of several nonpathogenic Onygenales species allows comparisons that provide clues about the Coccidioides spp. genes that might be involved in pathogenesis. The analysis in this study is a gene by gene orthology comparison. Although there were few differences in the size of genes families in the Coccidioides spp.-specific group compared to the genes shared by Coccidioides spp. and nonpathogenic Onygenales, there were a number of differences in the characterization of the two types of genes. Many more Coccidioides spp.-specific genes are up-regulated expression in spherules. Coccidioides spp.-specific genes more often lacked functional annotation and were more often classified as orphan genes. Analysis by random forest machine learning confirmed that high numbers of orthologs and high levels of expression in hyphae were predictive of common genes, while high levels of expression in spherules and more nonsynonymous predicted Coccidioides spp.-specific genes. Review of individual genes in the Coccidioides spp.-specific group identified a histidine kinase, two thioredoxin genes, a calmodulin gene and ureidoglycolate hydrolase. Hopefully, identification of these genes will be useful for pursuing potential Coccidioides spp. virulence genes in the future.

In Vitro Activity of Posaconazole against Talaromyces marneffei by Broth Microdilution and Etest Methods and Comparison to Itraconazole, Voriconazole, and Anidulafungin

ABSTRACT We determined the susceptibilities of 57 Talaromyces marneffei strains to anidulafungin, itraconazole, voriconazole, and posaconazole with MICs of 2 to 8, 0.002 to 0.004, 0.016 to 0.063, and 0.001 to 0.002 μg/ml by broth microdilution and >32, ≤0.002 to 0.008, ≤0.002 to 0.008, and ≤0.002 μg/ml by Etest, respectively, at yeast phase; MICs at mycelial phase for anidulafungin and posaconazole were 1 to 2 and 0.004 to 0.063 μg/ml, respectively. The results suggest promising activities of posaconazole. Etest can be used for testing of azoles against T. marneffei.

HISTOPLASMIN SURVEY IN HIV-POSITIVE PATIENTS: RESULTS FROM AN ENDEMIC AREA IN NORTHEASTERN BRAZIL

SUMMARY Background. Disseminated histoplasmosis is common in AIDS patients with advanced immunosuppression in Ceará, Northeastern Brazil. The goal of this study was to determine the prevalence of Histoplasma infection in patients with HIV/AIDS living in Fortaleza, the capital of Ceará. Methods. Intradermal tests with histoplasmin (mycelial phase) were performed in 161 HIV patients with CD4 ≥ 350 cells/mm 3 . Evidence of recent illness was evaluated with immunodiffusion (ID) tests in 76 of these individuals. Results. A total of 11.8% of patients reacted to histoplasmin and 2.63% had ID test positive to Histoplasma. The presence of mango trees (Mangifera indica) in the patient neighborhood (OR = 2.870; 95% CI = 1.081-7.617; p = 0.040) and past activity involving soil (OR = 2.834; 95% CI = 1.045-7.687; p = 0.045) or visits to a farm (OR = 3.869; 95% CI = 1.189-12.591; p = 0.033) were significantly associated with Histoplasma infection. Conclusions. Patients with HIV living in Fortaleza have an expressive prevalence of infection with Histoplasma.

Use of Mycelial-Phase Sporothrix schenckii Exoantigens in an Enzyme-Linked Immunosorbent Assay for Diagnosis of Sporotrichosis by Antibody Detection

ABSTRACT An enzyme-linked immunosorbent assay (ELISA) was developed for specific antibody detection in serum specimens of patients with sporotrichosis. The assay was made with mycelial-phase Sporothrix schenckii exoantigens and was tested against 90 sera from patients with different clinical forms of sporotrichosis. Potential cross-reactions were analyzed with 72 heterologous sera from patients with paracoccidioidomycosis, cryptococcosis, aspergillosis, histoplasmosis, tuberculosis, and American tegumentary leishmaniasis, as well as 76 sera from healthy controls. We found a sensitivity of 97% and a specificity of 89% in this assay. Some cross-reactions were seen, as observed in other immunoassays for the diagnosis of sporotrichosis. The ELISA appears to be especially useful for cutaneous forms of disease, since these are not promptly diagnosed with available immunoprecipitation or agglutination techniques. These results suggest that the ELISA using mycelial-phase S. schenckii exoantigens is a very sensitive diagnostic tool for the serodiagnosis of sporotrichosis and can be used in conjunction with conventional methods of diagnosis, particularly in cases where cross-reactions or false-positive results are experienced with the serodiagnosis.

Identifying Phase-specific Genes in the Fungal PathogenHistoplasma capsulatumUsing a Genomic Shotgun Microarray

A fundamental feature of the fungal pathogen Histoplasma capsulatum is its ability to shift from a mycelial phase in the soil to a yeast phase in its human host. Each form plays a critical role in infection and disease, but little is understood about how these two morphologic phases are established and maintained. To identify phase-regulated genes of H. capsulatum, we carried out expression analyses by using a genomic shotgun microarray representing approximately one-third of the genome, and identified 500 clones that were differentially expressed. Genes induced in the mycelial phase included several involved in conidiation, cell polarity, and melanin production in other organisms. Genes induced in the yeast phase included several involved in sulfur metabolism, extending previous observations that sulfur metabolism influences morphology in H. capsulatum. Other genes with increased expression in the yeast phase were implicated in nutrient acquisition and cell cycle regulation. Unexpectedly, differential regulation of the site of transcript initiation was also observed in the two phases. These findings identify genes that may determine some of the major characteristics of the mycelial and yeast phases.