Risk factors for nosocomial Salmonella infection among hospitalized horses.

OBJECTIVE: To identify risk factors for nosocomial Salmonella infections among hospitalized horses. DESIGN: Longitudinal study. ANIMALS: 1,583 horses hospitalized in an intensive care unit between January 1992 and June 1996. PROCEDURE: Survivor functions were used to estimate time to shedding salmonellae for various Salmonella serotypes. Survival analysis was then used to determine how variables associated with patient management, environmental conditions, hospital conditions, and other disease processes affected the risk of nosocomial Salmonella infection. RESULTS: 78 horses shed Salmonella organisms: 35 shed Salmonella krefeld, 26 shed S typhimurium, and 17 shed other Salmonella serotypes. Mean time from admission to shedding was significantly longer for horses shedding S krefeld or S typhimurium than for horses shedding other Salmonella serotypes. Therefore, infection with S krefeld or S typhimurium was considered nosocomial. Seven variables were found to be significantly associated with risk of nosocomial Salmonella infection: mean number of horses in the hospital shedding S krefeld during the 4 days prior to and the day of admission, mean number of horses shedding S typhimurium during this period, a diagnosis of large colon impaction, withholding feed, number of days fed bran mash, duration of treatment with potassium penicillin G, and mean daily ambient temperature. CLINICAL IMPLICATIONS: Results suggest that risk of nosocomial Salmonella infections is greater for horses with large colon impactions. In addition to implementing hospital protocols that minimize cross contamination between patients, strategies to reduce the risk of nosocomial Salmonella infection should include minimizing use of potassium penicillin G and regulation of environmental temperature in the hospital.     

Effects of deep placement of controlled-release nitrogen fertilizer on soybean growth and yield under sulfur deficiency

Sulfur (S) and Nitrogen (N) metabolisms in plants are interacted and it is known that S deficiency decrease N absorption and metabolism. In leguminous plants S deficiency also decreases N₂ fixation by rhizobia in the nodules. Deep placement of a controlled-release N fertilizer is a good method to provide nitrogen to soybean without inhibiting N₂ fixation; thus, it was hypothesized that this method is able to provide nitrogen effectively to sulfur-deficient soybean plants. In this study effects of deep placement of coated urea on S-N physicological interaction, growth and productivity in soybean plants were examined using pot experiments. Soybean plants were grown with sulfate concentrations of 30, 100, or 1000 μM, with or without deep placement of coated urea. Shoot weights at the developing stage were not affected by S deficiency. SPAD values of leaves during the flowering stage decreased with S deficiency and increased with the deep placement of coated urea. S deficiency decreased seed weight per plant at the harvesting stage, but this decrease was attenuated by the deep placement of coated urea. N and S content in shoots at the developing stage increased with the deep placement of coated urea, whereas in seeds, only the N content increased. N₂ fixation activity based on the relative ureide-N content in xylem sap indicated that the deep placement of coated urea did not inhibit N₂ fixation activity at the early flowering stage. Without deep placement of coated urea, the relative ureide-N content decreased under S deficiency at the seed filling stage. These results suggest that the deep placement of coated urea is an efficient method to supply N to support soybean yield under S deficiency.

Abbreviations: Deep+: with deep placement of coated urea; Deep–: without deep placement of coated urea