Multiple Blood Culture Sampling, Proper Antimicrobial Choice, and Adequate Dose in Definitive Therapy Supported by the Antimicrobial Stewardship Team Could Decrease 30-Day Sepsis Mortality Rates.

Objective: This study aimed to identify factors that should be focused on by the antimicrobial stewardship team for treating patients with sepsis, by investigating the mortality of patients with sepsis within 30 days and the mortality-related factors in our hospital over a 10-year period from the perspective of appropriate antimicrobial use. Methods: Factors associated with 30-day mortality were investigated using hierarchical multiple logistic regression in 1406 patients with pathogen-identified sepsis in Hirosaki University Hospital. These factors were clinical data, microbiological data, antimicrobials used in empiric and definitive therapies, presence/absence of ineffective use, underdosing as evaluated using Monte Carlo simulation, and practice of de-escalation. Results: The ineffective use of antimicrobials in empiric therapy and the underdosing and ineffective use in definitive therapy were significantly associated with 30-day mortality (odds ratio [OR] = 2.70, 3.72, and 3.65, respectively). Multiple blood culture sampling was inversely associated with these inappropriate antimicrobial uses. Every year, the 30-day mortality rate has been decreasing, in line with the increase in multiple blood culture sampling and de-escalation; the inappropriate use of antimicrobials has also decreased. Conclusion: Multiple blood culture sampling, proper choice of antimicrobial, and using an adequate dose in definitive therapy could decrease the 30-day mortality rate in patients with sepsis and these factors could be supported by the antimicrobial stewardship team.

Arsenite suppresses IL-2-dependent tumoricidal activities of natural killer cells.

Chronic exposure to arsenic causes cancers in various organs including the skin, liver, lung, and bladder in humans, but the mechanisms of the multi-organ carcinogenicity of arsenic remain unknown. Natural killer (NK) cells play important roles in the immune surveillance and elimination of tumor cells. Although accumulating evidence has indicated that arsenic has immunosuppressive properties, little is known about the effects of arsenic on the tumoricidal functions of NK cells. We examined the effects of arsenite on the cytotoxic activities of human and mouse NK cells toward target tumor cells. Exposure of human NK-92 cells and primary mouse NK cells to sublethal doses of arsenite reduced the IL-2-activated cytotoxic activities toward human K562 cells and murine YAC-1 cells, respectively. NK cells recognize target cells via integrated signals from both activating and inhibitory receptors and induce apoptosis of target cells via a granzyme/perforin system. We found that exposure of NK-92 cells to arsenite diminished the IL-2-activated down-regulation of the inhibitory receptors, KIR2DL2 and KIR2DL3, and the up-regulation of granzyme B and lymphotoxin-α. The IL-2-activated increases in secretion of interferon-γ and IL-10 were also slightly reduced by arsenite. Thus, arsenite suppressed the IL-2-activated cytotoxic activity of NK cells by disrupting multiple pathways required for the recognition and killing of target tumor cells. Our findings provide new insights into the roles of NK cell-mediated tumor immunity in cancer development by arsenic.

Arsenite suppresses NO production evoked by lipopolysaccharide and poly(I:C) via the suppression of interferon-ß expression in RAW264.7 cells.

Immunological functions are disturbed in humans who have been chronically exposed to arsenic via contaminated groundwater. Little is known about the specific mechanisms underlying the impairment of immunological defense system caused by arsenic. The activation of macrophage cells upon infection with bacteria and viruses plays important roles in the defense against these pathogens. Here we show that exposure to arsenite (As(III)) suppresses nitric oxide (NO) production in murine RAW264.7 macrophage cells stimulated with lipopolysaccharide (LPS) and poly(I:C), the compounds mimicking bacterial and viral infection, respectively. As(III) suppressed the LPS- or poly(I:C)-evoked induction of inducible NO synthase (iNOS) without affecting the transactivation of NF-κB. As the interferon (IFN)-ß/STAT1 pathway is also involved in the induction of iNOS in addition to NF-κB, we examined the effects of As(III) on the expression and secretion of IFN-ß, the expression of the components of IFN-α/ß receptor, the phosphorylation of STAT1, and the levels of cytokines involved in STAT1 activation. The results showed that the expression and secretion of IFN-ß were specifically suppressed by As(III) treatment in RAW264.7 cells stimulated with LPS or poly(I:C). These results suggest that As(III) suppresses the expression and secretion of IFN-ß, leading to the reduced STAT1 activation and consequently the reduced iNOS induction in macrophage cells. Our data suggest an important role of the arsenic-induced suppression of IFN-ß on the disturbances in immunological defense against both bacteria and viruses.