Effect of soil type and temperature on survival of Salmonella enterica in poultry manure-amended soils.

The effects of soil type and temperature on the survival of a cocktail of five Salmonella enterica serotypes (Enteritidis, Infantis, Montevideo, Typhimurium and Zanzibar) in manure-amended soils under controlled laboratory conditions was assessed. Containers of clay loam or sandy soil, unaltered or amended with 2% (w/w) poultry manure, were inoculated with S. enterica (~5 log10 CFU per gram) and held at 5, 21 or 37°C for 6 weeks. Statistical analysis of the persistence of S. enterica identified a significant three-way interaction between soil type, manure amendment and temperature. Clay loam soils and lower temperatures tended to support S. enterica persistence over 6 weeks with only 1- and 2-log reductions respectively. In contrast, sand and higher temperatures resulted in a 4-log and either 3- to 4-log reductions respectively. Manure amendment had an overarching effect of reducing die-off of S. enterica in comparison with unamended soils. This study highlights that a large component of variation of the rate of S. enterica reduction in soils may be attributed to combinations of environmental factors, in particular, soil type and temperature. It further underscores the importance of risk management strategies and industry guidelines based on local data and that reflect the diversity of prevailing horticultural production environments. SIGNIFICANCE AND IMPACT OF THE STUDY: The persistence of Salmonella enterica in soil environments was shown to be significantly influenced by a range of individual and interacting environmental effects, including temperature, soil type and amendment addition. This indicates that current horticultural food safety management systems which employ a uniform prescribed exclusion period between application of manure and time of harvest may be unfit for purpose under certain conditions by either underestimating or overestimating pathogen die-off. These findings support exclusion periods that account for a range of environmental factors including temperature, soil type and growing region that may be more appropriate to manage microbiological risks associated with soil which has been amended with manure.

Attack on all fronts: functional relationships between aerial and root parasitic plants and their woody hosts and consequences for ecosystems.

This review discusses how understanding of functional relationships between parasitic plants and their woody hosts have benefited from a range of approaches to their study. Gross comparisons of nutrient content between infected and uninfected hosts, or parts of hosts, have been widely used to infer basic differences or similarities between hosts and parasites. Coupling of nutrient information with additional evidence of key processes such as transpiration, respiration and photosynthesis has helped elucidate host-parasite relationships and, in some cases, the anatomical nature of their connection and even the physiology of plants in general. For example, detailed analysis of xylem sap from hosts and parasites has increased our understanding of the spatial and temporal movement of solutes within plants. Tracer experiments using natural abundance or enriched application of stable isotopes ((15)N, (13)C, (18)O) have helped us to understand the extent and form of heterotrophy, including the effect of the parasite on growth and functioning of the host (and its converse) as well as environmental effects on the parasite. Nutritional studies of woody hosts and parasites have provided clues to the distribution of parasitic plants and their roles in ecosystems. This review also provides assessment of several corollaries to the host-parasite association.

Hospital-sponsored rural health clinics: an effective diversification alternative for rural hospitals.

Changes in rural health care are resulting in new challenges for the administrators of rural hospitals. The lack of available care, economic deterioration, and demographic changes in rural America are contributing factors to rural health care problems and are detrimental to the financial well-being of rural hospitals. Diversification is becoming commonplace in these hospitals as administrators seek strategies to gain financial viability for their facilities. The concept of hospital-sponsored rural health clinics is more than a decade old, yet there are fewer than 30 such clinics nationwide. Reasons for the underutilization of such clinics may include the lack of knowledge that such clinics exist as well as inadequate information describing the establishment, operation, and financial feasibility of the clinics. The hospital-sponsored rural health clinic "concept" will be introduced, including potential benefits of such clinics to both the hospital and the communities they serve, factors to be considered in developing such a system, and problems that may arise in this development. This article presents a case study of how one rural hospital incorporated such clinics into its long-range plans.