Review: Are there indigenous Saccharomyces in the digestive tract of livestock animal species? Implications for health, nutrition and productivity traits.

All livestock animal species harbour complex microbial communities throughout their digestive tract that support vital biochemical processes, thus sustaining health and productivity. In part as a consequence of the strong and ancient alliance between the host and its associated microbes, the gut microbiota is also closely related to productivity traits such as feed efficiency. This phenomenon can help researchers and producers develop new and more effective microbiome-based interventions using probiotics, also known as direct-fed microbials (DFMs), in Animal Science. Here, we focus on one type of such beneficial microorganisms, the yeast Saccharomyces. Saccharomyces is one of the most widely used microorganisms as a DFM in livestock operations. Numerous studies have investigated the effects of dietary supplementation with different species, strains and doses of Saccharomyces (mostly Saccharomyces cerevisiae) on gut microbial ecology, health, nutrition and productivity traits of several livestock species. However, the possible existence of Saccharomyces which are indigenous to the animals' digestive tract has received little attention and has never been the subject of a review. We for the first time provide a comprehensive review, with the objective of shedding light into the possible existence of indigenous Saccharomyces of the digestive tract of livestock. Saccharomyces cerevisiae is a nomadic yeast able to survive in a broad range of environments including soil, grass and silages. Therefore, it is very likely that cattle and other animals have been in direct contact with this and other types of Saccharomyces throughout their entire existence. However, to date, the majority of animal scientists seem to agree that the presence of Saccharomyces in any section of the gut only reflects dietary contamination; in other words, these are foreign organisms that are only transiently present in the gut. Importantly, this belief (i.e. that Saccharomyces come solely from the diet) is often not well grounded and does not necessarily hold for all the many other groups of microbes in the gut. In addition to summarizing the current body of literature involving Saccharomyces in the digestive tract, we discuss whether the beneficial effects associated with the consumption of Saccharomyces may be related to its foreign origin, though this concept may not necessarily satisfy the theories that have been proposed to explain probiotic efficacy in vivo. This novel review may prove useful for biomedical scientists and others wishing to improve health and productivity using Saccharomyces and other beneficial microorganisms.

The health enhancer yeast Saccharomyces cerevisiae in two types of commercial products for animal nutrition.

The health enhancer yeast Saccharomyces cerevisiae (SC) is widely used in diets for different animals. Two main types of SC-based products are commercially available, one containing live yeasts and one containing SC fermentation by-products, which are supposedly not dependent on live yeasts for their physiological effects in vivo. Culture-based techniques were applied to study yeasts in two types of commercial products: a product containing live SC (LSC) and a SC fermentation product (SCFP). Three temperatures (25, 30 and 39°C) and two pH levels (4 and 7) were tested. The product with LSC contained an average of 1·21 × 109 colony-forming units (CFUs) of yeasts per g contents (min: 1 × 108 , max: 3 × 109 ). In contrast, the SCFP contained an average of 4·67 × 103 (min: 3 × 102 , max: 1·9 × 104 ) CFUs per g contents (c. 1 million times less than the concentration of yeasts in the product with LSC). Both temperature and pH level affected the number of CFUs but this effect differed between the two products. Biochemical tests identified the two yeasts as SC, which differed in their ability to ferment maltose (negative in the SCFP). This report encourages more research on commercial microbial strains for animal nutrition that can lead to a better understanding of their mode of action in vivo. SIGNIFICANCE AND IMPACT OF THE STUDY: Probiotics (or direct fed microbials) are increasingly popular in Animal Nutrition. Different products containing live micro-organisms or microbial-derived products are commercially available to enhance health and boost commercial traits. The characteristics of these products dictate their physiological effects and determine their potential to increase profitability from livestock. For the first time, this report presents data about the numbers and phenotype of the health enhancer Saccharomyces cerevisiae in two widely available commercial products in Animal Nutrition. These findings may be useful for scientists and producers around the globe and have the potential to open up novel venues for research.

Epstein-Barr virus-specific CD8(+) T lymphocytes from diffuse large B cell lymphoma patients are functionally impaired.

Epstein-Barr virus (EBV) is a persistent virus with oncogenic capacity that has been implicated in the development of aggressive B cell lymphomas, primarily in immunosuppressed individuals, although it can be present in immunocompetent individuals. Changes in the function and clonal diversity of T lymphocytes might be implied by viral persistence and lymphoma development. The aim of the present study was to evaluate the frequency, phenotype, function and clonotypical distribution of EBV-specific T cells after peripheral blood stimulation with a virus lysate in newly diagnosed patients with diffuse large B cell lymphoma (DLBCL) aged more than 50 years without prior histories of clinical immunosuppression compared with healthy controls. Our results showed impaired EBV-specific immune responses among DLBCL patients that were associated primarily with decreased numbers of central and effector memory CD8(+) T lymphocytes. In contrast to healthy controls, only a minority of the patients showed CD4(+)/tumour necrosis factor (TNF)-α(+) T cells expressing T cell receptor (TCR)-Vß17 and CD8(+)/TNF-α(+) T cells with TCR-Vß5·2, Vß9 and Vß18 in response to EBV. Notably, the production of TNF-α was undetectable among TCR-Vß5·3(+), Vß11(+), Vß12(+), Vß16(+) and Vß23(+) CD8(+) T cells. In addition, we observed decreased numbers of CD4(+)/TNF-α(+) and CD8(+)/TNF-α(+), CD8(+)/interleukin (IL)-2(+) and CD8(+)/TNF-α(+)/IL-2(+) T lymphocytes in the absence of T cells capable of producing TNF-α, IL-2 and IFN-γ after EBV stimulation simultaneously. Moreover, DLBCL patients displayed higher IL-10 levels both under baseline conditions and after EBV stimulation. These findings were also observed in patients with positive EBV viral loads. Prospective studies including a large number of patients are needed to confirm these findings.

Ceftriaxone plus once daily aminoglycoside with filgrastim for treatment of febrile neutropenia: early hospital discharge vs. Standard In-patient care.

BACKGROUND: In febrile neutropenic patients, ceftriaxone plus an aminoglycoside is effective for the treatment of infection, while filgrastim reduces the extent and duration of neutropenia. Because the once daily dosing regimen of this combination permits ambulatory treatment, there is a need to test criteria for early hospital discharge. METHODS: Hospitalized adult patients with febrile neutropenia (following chemotherapy) considered to be potentially treatable on a follow-up out-patient basis were entered into this open-label, multinational study. Patients received a once daily combination of ceftriaxone for > or =5 days, aminoglycoside for > or =2 days, and filgrastim until the absolute neutrophil count was > or =1.0x10(9)/l for 2 days. Those initially responding to therapy (reduction of fever by > or =1 degrees C within 72 h, and clinical improvement) were randomized into standard in-patient or follow-up out-patient treatment groups, the latter patients being discharged from hospital early, after meeting defined criteria. RESULTS: 105 patients were enrolled, of whom 21 initial non-responders were not randomized. Efficacy was evaluable in 80 patients. Success (resolution of fever and symptoms, maintained for 7 days after cessation of therapy, and eradication of infecting pathogens) was similar among in-patients (40/42, 95%) and out-patients (34/38, 89%). The duration of hospitalization was shorter for out-patients than in-patients (median of 4 vs. 6 days, respectively). No hospital readmissions were necessary in out-patients. All other efficacy parameters assessed were comparable in both groups, as was tolerability/safety. One potentially drug-related death was reported. CONCLUSIONS: Patients who satisfy prospectively defined criteria for early discharge can be treated safely on an out-patient basis with a regimen of once daily ceftriaxone plus an aminoglycoside with filgrastim. In addition to reducing healthcare costs, it may improve patients' quality of life.