Vaccines against toxoplasma gondii : challenges and opportunities

Development of vaccines against Toxoplasma gondii infection in humans is of high priority, given the high burden of disease in some areas of the world like South America, and the lack of effective drugs with few adverse effects. Rodent models have been used in research on vaccines against T. gondii over the past decades. However, regardless of the vaccine construct, the vaccines have not been able to induce protective immunity when the organism is challenged with T. gondii, either directly or via a vector. Only a few live, attenuated T. gondii strains used for immunization have been able to confer protective immunity, which is measured by a lack of tissue cysts after challenge. Furthermore, challenge with low virulence strains, especially strains with genotype II, will probably be insufficient to provide protection against the more virulent T. gondii strains, such as those with genotypes I or II, or those genotypes from South America not belonging to genotype I, II or III. Future studies should use animal models besides rodents, and challenges should be performed with at least one genotype II T. gondii and one of the more virulent genotypes. Endpoints like maternal-foetal transmission and prevention of eye disease are important in addition to the traditional endpoint of survival or reduction in numbers of brain cysts after challenge

Combination therapy of disseminated coccidioidomycosis with caspofungin and fluconazole

BACKGROUND: The current recommended therapy for diffuse coccidioidal pneumonia involves initial treatment with amphotericin B deoxycholate or high-dose fluconazole, followed by an azole after clinical improvement. Amphotericin B is more frequently used as initial therapy if the patient's deterioration is rapid. CASE PRESENTATION: A 31-year-old Korean male with coccidioidomycosis presented to the hospital with miliary infiltrates on chest X-ray (CXR) and skin rash on the face and trunk. Initially, the patient did not respond to amphotericin B deoxycholate therapy. However, following caspofungin and fluconazole combination therapy, the patient showed favourable radiological, serological, and clinical response. CONCLUSION: This appears to be the first case of diffuse coccidioidal pneumonia with skin involvement in an immunocompetent patient who was treated successfully with caspofungin and fluconazole. Combination therapy with caspofungin and fluconazole may, therefore, be an alternative treatment for diffuse coccidioidal pneumonia that does not respond to amphotericin B deoxycholate therapy

The processing and impact of dissolved riverine nitrogen in the Arctic Ocean

© The Author(s), 2011. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Estuaries and Coasts 35 (2012): 401-415, doi:10.1007/s12237-011-9417-3.Although the Arctic Ocean is the most riverine-influenced of all of the world’s oceans, the importance of terrigenous nutrients in this environment is poorly understood. This study couples estimates of circumpolar riverine nutrient fluxes from the PARTNERS (Pan-Arctic River Transport of Nutrients, Organic Matter, and Suspended Sediments) Project with a regionally configured version of the MIT general circulation model to develop estimates of the distribution and availability of dissolved riverine N in the Arctic Ocean, assess its importance for primary production, and compare these estimates to potential bacterial production fueled by riverine C. Because riverine dissolved organic nitrogen is remineralized slowly, riverine N is available for uptake well into the open ocean. Despite this, we estimate that even when recycling is considered, riverine N may support 0.5–1.5 Tmol C year−1 of primary production, a small proportion of total Arctic Ocean photosynthesis. Rapid uptake of dissolved inorganic nitrogen coupled with relatively high rates of dissolved organic nitrogen regeneration in N-limited nearshore regions, however, leads to potential localized rates of riverine-supported photosynthesis that represent a substantial proportion of nearshore production.Funding for this work was provided through NSFOPP- 0229302 and NSF-OPP-0732985.Support to SET was additionally provided by an NSERC Postdoctoral Fellowship

H2S events in the Peruvian oxygen minimum zone facilitate enhanced dissolved Fe concentrations

Dissolved iron (DFe) concentrations in oxygen minimum zones (OMZs) of Eastern Boundary Upwelling Systems are enhanced as a result of high supply rates from anoxic sediments. However, pronounced variations in DFe concentrations in anoxic coastal waters of the Peruvian OMZ indicate that there are factors in addition to dissolved oxygen concentrations (O2) that control Fe cycling. Our study demonstrates that sediment-derived reduced Fe (Fe(II)) forms the main DFe fraction in the anoxic/euxinic water column off Peru, which is responsible for DFe accumulations of up to 200 nmol L-1. Lowest DFe values were observed in anoxic shelf waters in the presence of nitrate and nitrite. This reflects oxidation of sediment-sourced Fe(II) associated with nitrate/nitrite reduction and subsequent removal as particulate Fe(III) oxyhydroxides. Unexpectedly, the highest DFe levels were observed in waters with elevated concentrations of hydrogen sulfide (up to 4 µmol L-1) and correspondingly depleted nitrate/nitrite concentrations (<0.18 µmol L-1). Under these conditions, Fe removal was reduced through stabilization of Fe(II) as aqueous iron sulfide (FeSaqu) which comprises complexes (e.g., FeSH+) and clusters (e.g., Fe2S2|4H2O). Sulfidic events on the Peruvian shelf consequently enhance Fe availability, and may increase in frequency in future due to projected expansion and intensification of OMZs

Results from the ARTEMIS DISK Global Antifungal Surveillance Study, 1997 to 2007: a 10.5-Year Analysis of Susceptibilities of Candida Species to Fluconazole and Voriconazole as Determined by CLSI Standardized Disk Diffusion ▿

Fluconazole in vitro susceptibility test results for 256,882 isolates of Candida spp. were collected from 142 sites in 41 countries from June 1997 to December 2007. Data were collected for 197,619 isolates tested with voriconazole from 2001 to 2007. A total of 31 different species of Candida were isolated. Increased rates of isolation of the common non-albicans species C. glabrata (10.2% to 11.7%), C. tropicalis (5.4% to 8.0%), and C. parapsilosis (4.8% to 5.6%) were noted when the time periods 1997 to 2000 and 2005 to 2007 were compared. Investigators tested clinical isolates of Candida spp. by the CLSI M44-A disk diffusion method. Overall, 90.2% of Candida isolates tested were susceptible (S) to fluconazole; however, 13 of 31 species identified exhibited decreased susceptibility (<75% S), similar to that seen with the resistant (R) species C. glabrata and C. krusei. Among 197,619 isolates of Candida spp. tested against voriconazole, 95.0% were S and 3% were R. About 30% of fluconazole-R isolates of C. albicans, C. glabrata, C. tropicalis, C. rugosa, C. lipolytica, C. pelliculosa, C. apicola, C. haemulonii, C. humicola, C. lambica, and C. ciferrii remained S to voriconazole. An increase in fluconazole resistance over time was seen with C. parapsilosis, C. guilliermondii, C. lusitaniae, C. sake, and C. pelliculosa. Among the emerging fluconazole-R species were C. guilliermondii (11.4% R), C. inconspicua (53.2% R), C. rugosa (41.8% R), and C. norvegensis (40.7% R). The rates of isolation of C. rugosa, C. inconspicua, and C. norvegensis increased by 5- to 10-fold over the 10.5-year study period. C. guilliermondii and C. rugosa were most prominent in Latin America, whereas C. inconspicua and C. norvegensis were most common in Eastern European countries. This survey identifies several less-common species of Candida with decreased susceptibility to azoles. These organisms may pose a future threat to optimal antifungal therapy and underscore the importance of prompt and accurate species identification and antifungal susceptibility testing