Staphylococcus aureus triggers a protective inflammatory response against secondary Cryptococcus gattii infection in a murine model.

Prior infections can provide protection or enhance susceptibility to a subsequent infection through microorganism's interaction or host immunomodulation. Staphylococcus aureus (SA) and Cryptococcus gattii (CG) cause lungs infection, but it is unclear how they interact in vivo. This study aimed to study the effects of the primary SA lung infection on secondary cryptococcosis caused by CG in a murine model. The mice's survival, fungal burden, behavior, immune cells, cytokines, and chemokines were quantified to evaluate murine cryptococcosis under the influence of a previous SA infection. Further, fungal-bacterial in vitro interaction was studied in a culture medium and a phagocytosis assay. The primary infection with SA protects animals from the subsequent CG infection by reducing lethality, improving behavior, and impairing the fungal proliferation within the host. This phenotype was associated with the proinflammatory antifungal host response elicited by the bacteria in the early stage of cryptococcosis. There was no direct inhibition of CG by SA, although the phagocytic activity of macrophages was reduced. Identifying mechanisms involved in this protection may lead to new approaches for preventing and treating cryptococcosis.

Hypervirulence and cross-resistance to a clinical antifungal are induced by an environmental fungicide in Cryptococcus gattii.

The increasing human population requires ongoing efforts in food production. This is frequently associated with an increased use of agrochemicals, leading to environmental contamination and altering microbial communities, including human fungal pathogens that reside in the environment. Cryptococcus gattii is an environmental yeast and is one of the etiological agents of cryptococcosis. Benomyl (BEN) is a broad-spectrum fungicide used on several crops. To study the effects of agrochemicals on fungal pathogens, we first evaluated the susceptibility of C. gattii to BEN and the interactions with clinical antifungals. Antagonistic interaction between BEN and fluconazole was seen and was strain- and concentration-dependent. We then induced BEN-resistance by culturing strains in increasing drug concentrations. One strain demonstrated to be more resistant and showed increased multidrug efflux pump gene (MDR1) expression and increased rhodamine 6G efflux, leading to cross-resistance between BEN and fluconazole. Morphologically, BEN-adapted cells had a reduced polysaccharide capsule; an increased surface/volume ratio; increased growth rate in vitro and inside macrophages and also higher ability in crossing an in vitro model of blood-brain-barrier. BEN-adapted strain demonstrated to be hypervirulent in mice, leading to severe symptoms of cryptococcosis, early mortality and higher fungal burden in the organs, particularly the brain. The parental strain was avirulent in murine model. In vivo cross-resistance between BEN and fluconazole was observed, with mice infected with the adapted strain unable to present any improvement in survival and behavior when treated with this antifungal. Furthermore, BEN-adapted cells cultured in drug-free media maintained the hypervirulent and cross-resistant phenotype, suggesting a persistent effect of BEN on C. gattii. In conclusion, exposure to BEN induces cross-resistance with fluconazole and increases the virulence of C. gattii. Altogether, our results indicate that agrochemicals may lead to unintended consequences on non-target species and this could result in severe healthy problems worldwide.

Hospitalisations for mycoses as an indicator of socio-environmental vulnerability in the Brazilian Amazon-Savanna transition region.

BACKGROUND: The infections caused by fungi represent a global concern and an important cause of hospital admissions in endemic areas. The influence of socio-environmental factors in infectious diseases has been documented; however, this phenomenon remains unclear regarding mycoses. OBJECTIVES: This study aimed to analyse the spatio-temporal dynamics of hospitalisations for mycoses (HM) and the association with socio-economic and climate data in the Amazon-Savanna Transition Region in the state of Maranhão, Brazil. METHODS: In this study, Spearman's correlation was applied to determine the correlation between HM, socio-economic and climatic data obtained from national databases in the period from 1998 to 2016. Hospitalisations for mycoses data were spatialised and analysed using the local Moran's index. RESULTS: Our data revealed a negative and significant correlation between HM and socio-economic data regarding population, demographic density, human development index, health facilities and sanitary sewage. Significant correlations were observed between HM and precipitation, maximum temperature and minimum temperature. The main modulating climatic variable was the minimum temperature. The spatial autocorrelation analysis showed the dynamics of HM in municipalities belonging to the different regions of the state influenced by socio-economic conditions. We observed the presence of municipalities with high incidence of HM surrounded by others with low HM cases and vice versa. CONCLUSIONS: Our results indicate that hospitalisations for mycoses represent an important indicator of socio-environmental vulnerability in the Amazon-Savanna transition region in Brazil. We encourage the adoption of measures to mitigate social and environmental impact on these diseases, especially in municipalities with low socio-economic status.

From the environment to the host: How non-azole agrochemical exposure affects the antifungal susceptibility and virulence of Cryptococcus gattii.

Agrochemicals such as the non-azoles, used to improve crop productivity, poses severe undesirable effects on the environment and human health. In addition, they induce cross-resistance (CR) with clinical drugs in pathogenic fungi. However, till date emphasis has been given to the role of azoles on the induction of CR. Herein, we analyzed the effect of a non-azole agrochemical, pyraclostrobin (PCT), on the antifungal susceptibility and virulence of the human and animal pathogens Cryptococcus gattii and C. neoformans. We determined the minimum inhibitory concentration (MIC) of fluconazole (FLC), itraconazole, ravuconazole, amphotericin B, and PCT on colonies: (i) that were not exposed to PCT (non-adapted-NA-cultures), (ii) were exposed at the maximum concentration of PCT (adapted-A-cultures) and (iii) the adapted colonies after cultivation 10 times in PCT-free media (10 passages-10p-cultures). Our results showed that exposure to PCT induced both temporary and permanent CR to clinical azoles in a temperature-dependent manner. With the objective to understand the mechanism of induction of CR through non-azoles, the transcriptomes of NA and 10p cells from C. gattii R265 were analyzed. The transcriptomic analysis showed that expression of the efflux-pump genes (AFR1 and MDR1) and PCT target was higher in resistant 10p cells than that in NA. Moreover, the virulence of 10p cells was reduced as compared to NA cells in mice, as observed by the differential gene expression analysis of genes related to ion-metabolism. Additionally, we observed that FLC could not increase the survival rate of mice infected with 10p cells, confirming the occurrence of permanent CR in vivo. The findings of the present study demonstrate that the non-azole agrochemical PCT can induce permanent CR to clinical antifungals through increased expression of efflux pump genes in resistant cells and that such phenomenon also manifests in vivo.

Environmental Triazole Induces Cross-Resistance to Clinical Drugs and Affects Morphophysiology and Virulence of Cryptococcus gattii and C. neoformans.

Cryptococcus gattii and Cryptococcus neoformans are environmental fungi that cause cryptococcosis, which is usually treated with amphotericin B and fluconazole. However, therapeutic failure is increasing because of the emergence of resistant strains. Because these species are constantly isolated from vegetal materials and the usage of agrochemicals is growing, we postulate that pesticides could be responsible for the altered susceptibility of these fungi to clinical drugs. Therefore, we evaluated the influence of the pesticide tebuconazole on the susceptibility to clinical drugs, morphophysiology, and virulence of C. gattii and C. neoformans strains. The results showed that tebuconazole exposure caused in vitro cross-resistance (CR) between the agrochemical and clinical azoles (fluconazole, itraconazole, and ravuconazole) but not with amphotericin B. In some strains, CR was observed even after the exposure ceased. Further, tebuconazole exposure changed the morphology, including formation of pseudohyphae in C. neoformans H99, and the surface charge of the cells. Although the virulence of both species previously exposed to tebuconazole was decreased in mice, the tebuconazole-exposed colonies recovered from the lungs were more resistant to azole drugs than the nonexposed cells. This in vivo CR was confirmed when fluconazole was not able to reduce the fungal burden in the lungs of mice. The tolerance to azoles could be due to increased expression of the ERG11 gene in both species and of efflux pump genes (AFR1 and MDR1) in C. neoformans Our study data support the idea that agrochemical usage can significantly affect human pathogens present in the environment by affecting their resistance to clinical drugs.

A new method for studying cryptococcosis in a murine model using 99mTc-Cryptococcus gattii.

Cryptococcus gattii is one of the etiologic agents of cryptococcosis, a systemic mycosis that occurs in healthy and immunosuppressed humans and animals worldwide. Primary pulmonary infection caused by C. gattii is usually followed by fungal dissemination to the central nervous system, resulting in high mortality rates. In this context, animal models of cryptococcosis are useful in the study of fungal pathogenesis and host response against the pathogen, and for testing novel therapeutic options. The most frequently applied method to study fungal dissemination from the lungs to other organs is by culturing tissues, which is not accurate for the detection and quantification of fungal load at early stages of the infection. To overcome this problem, the purpose of this study was to develop a new method for the quantification of Cryptococcus dissemination. One C. gattii strain was efficiently radiolabeled with technetium-99m (99mTc), without affecting viability of the cells. Further, the 99mTc-C. gattii (111 MBq) strain was used to infect mice by intratracheal and intravenous route for biodistribution studies. 99mTc-C. gattii was successfully used in detection of the yeast in the brain of mice 6 hours postinoculation, while the detection using colony forming units was possible only 24 hours postinfection. Our results provided an alternative method that could be applied in further investigations regarding the efficacy of antifungals, fungal virulence, and host-pathogen interactions.

In vivo probiotic and antimicrobial photodynamic therapy as alternative therapies against cryptococcosis are ineffective.

Cryptococcosis, an invasive fungal infection distributed worldwide that affects both domestic and wild animals, has incredible rates regarding treatment failure, leading to the necessity of the development of new therapies. In this way, we aimed to evaluate the probiotic (Saccharomyces boulardii, Lactobacillus paracasei ST-11, and Lactobacillus rhamnosus GG) and antimicrobial photodynamic alternative therapies against Cryptococcus gattii in a murine model. Although previous studies suggest that these therapies can be promising against cryptococcosis, our experimental conditions for both probiotic and antimicrobial photodynamic therapies (aPDT) were not able to improve the survival of mice with cryptococcosis, even with the treatment combined with fluconazole. Our results may help other researchers to find the best protocol to test alternative therapies against Cryptococcus gattii.

A subdose of fluconazole alters the virulence of Cryptococcus gattii during murine cryptococcosis and modulates type I interferon expression.

Cryptococcosis is an invasive infection caused by yeast-like fungus of the genera Cryptococcus spp. The antifungal therapy for this disease provides some toxicity and the incidence of infections caused by resistant strains increased. Thus, we aimed to assess the consequences of fluconazole subdoses during the treatment of cryptococcosis in the murine inflammatory response and in the virulence factors of Cryptococcus gattii. Mice infected with Cryptococcus gattii were treated with subdoses of fluconazole. We determined the behavior of mice and type 1 interferon expression during the treatment; we also studied the virulence factors and susceptibility to fluconazole for the colonies recovered from the animals. A subdose of fluconazole prolonged the survival of mice, but the morbidity of cryptococcosis was higher in treated animals. These data were linked to the increase in: (i) fluconazole minimum inhibitory concentration, (ii) capsule size and (iii) melanization of C. gattii, which probably led to the increased expression of type I interferons in the brains of mice but not in the lungs. In conclusion, a subdose of fluconazole altered fungal virulence factors and susceptibility to this azole, leading to an altered inflammatory host response and increased morbidity.

Epidemiology and phospholipase activity of oral Candida spp. among patients with central nervous system diseases before and after dental cleaning procedure

Patients suffering of diseases that affect central nervous system may be considered more susceptible to the infectious diseases of mouth. Sixty-nine patients suffering of cerebral palsy, Down's syndrome and metal retardation were submitted to saliva examination for the presence of Candida spp. before and after a procedure of dental cleaning. The isolates were submitted to assay for verifying phospholipase production. 55.10 percent of the patients provided isolation of Candida spp. The frequency of isolation obtained before dental procedure was: C. albicans (83.33 percent), C. krusei (8.33 percent) and C. kefyr, C. parapsilosis and C. glabrata (2.78 percent each). The frequency after the procedure was: C. albicans (68.57 percent), C. parapsilosis (11.43 percent), C. krusei and C. kefyr (8.57 percent each) and Candida glabrata (2.86 percent). We verified significantly difference (p < 0.01) between populations obtained at the two examinations. Phospholipase production was verified only among C. albicans strains and the proportion of producers was higher when testing isolates obtained after dental cleaning procedure. Studies focused on Candida spp. isolation are useful for better comprehension of the role of these yeasts on the oral flora from patients with cerebral palsy, Down's syndrome and metal retardation.

Epidemiology and phospholipase activity of oral Candida SPP. Among patients with central nervous system diseases before and after dental cleaning procedure.

Patients suffering of diseases that affect central nervous system may be considered more susceptible to the infectious diseases of mouth. Sixty-nine patients suffering of cerebral palsy, Down's syndrome and metal retardation were submitted to saliva examination for the presence of Candida spp. before and after a procedure of dental cleaning. The isolates were submitted to assay for verifying phospholipase production. 55.10% of the patients provided isolation of Candida spp. The frequency of isolation obtained before dental procedure was: C. albicans (83.33%), C. krusei (8.33%) and C. kefyr, C. parapsilosis and C. glabrata (2.78% each). The frequency after the procedure was: C. albicans (68.57%), C. parapsilosis (11.43%), C. krusei and C. kefyr (8.57% each) and Candida glabrata (2.86%). We verified significantly difference (p < 0.01) between populations obtained at the two examinations. Phospholipase production was verified only among C. albicans strains and the proportion of producers was higher when testing isolates obtained after dental cleaning procedure. Studies focused on Candida spp. isolation are useful for better comprehension of the role of these yeasts on the oral flora from patients with cerebral palsy, Down's syndrome and metal retardation.