Risk Factors Associated With Invasive Fungal Infections in Kidney Transplant Patients.

BACKGROUND: Kidney transplant recipients are at increased risk for developing invasive fungal infections (IFI). We queried the United States Renal Data System (USRDS) for risk factors for IFI in these patients. METHODS: Patients who underwent a kidney transplant between 2005 and 2008 were queried for an IFI diagnosis using ICD-9 codes. An IFI was defined as at least one documented diagnosis from one of the following: (1) Candida (candidemia); (2) Histoplasmosis; (3) Aspergillosis; (4) Cryptococcosis; (5) "Other" mycoses. Potential risk factors included demographics, certain comorbidities and immunosuppressive medications. To examine the relative risk (RR), simple bivariate models were used, followed by a comprehensive full model to estimate the adjusted RR (aRR). RESULTS: Of 57,188 kidney transplant patients, 1,218 had 1,343 IFI diagnoses, with a median time to infection of 495 days. "Other" mycoses accounted for the most IFI diagnoses (37%), followed by aspergillosis (22%). The risk for any IFI was increased with age ≥65 years. Diabetes (aRR = 1.71), bacterial pneumonia (aRR = 1.62) and UTI (aRR = 1.34) were the top 3 clinical risk factors for infection. Each of the IFI groups was also associated with individual risk factors. Therapy with mycophenolate mofetil was associated with a decreased risk of candidemia. CONCLUSIONS: Risk factors for IFI in renal transplant patients include demographic, medication-associated and clinical data, as well as organism-specific factors. These results offer an extensive clinical profile of risk for IFI, and may thus help inform the diagnosis and presumptive therapy of invasive fungal infections in renal transplant recipients.

Heterogeneous arsenic enrichment in meta-sedimentary rocks in central Maine, United States.

Arsenic is enriched up to 28 times the average crustal abundance of 4.8 mg kg(-1) for meta-sedimentary rocks of two adjacent formations in central Maine, USA where groundwater in the bedrock aquifer frequently contains elevated As levels. The Waterville Formation contains higher arsenic concentrations (mean As 32.9 mg kg(-1), median 12.1 mg kg(-1), n=38) than the neighboring Vassalboro Group (mean As 19.1 mg kg(-1), median 6.0 mg kg(-1), n=38). The Waterville Formation is a pelitic meta-sedimentary unit with abundant pyrite either visible or observed by scanning electron microprobe. Concentrations of As and S are strongly correlated (r=0.88, p<0.05) in the low grade phyllite rocks, and arsenic is detected up to 1944 mg kg(-1) in pyrite measured by electron microprobe. In contrast, statistically significant (p<0.05) correlations between concentrations of As and S are absent in the calcareous meta-sediments of the Vassalboro Group, consistent with the absence of arsenic-rich pyrite in the protolith. Metamorphism converts the arsenic-rich pyrite to arsenic-poor pyrrhotite (mean As 1 mg kg(-1), n=15) during de-sulfidation reactions: the resulting metamorphic rocks contain arsenic but little or no sulfur indicating that the arsenic is now in new mineral hosts. Secondary weathering products such as iron oxides may host As, yet the geochemical methods employed (oxidative and reductive leaching) do not conclusively indicate that arsenic is associated only with these. Instead, silicate minerals such as biotite and garnet are present in metamorphic zones where arsenic is enriched (up to 130.8 mg kg(-1) As) where S is 0%. Redistribution of already variable As in the protolith during metamorphism and contemporary water-rock interaction in the aquifers, all combine to contribute to a spatially heterogeneous groundwater arsenic distribution in bedrock aquifers.