Pathogenic and Commensal Gut Bacteria Harboring Glycerol/Diol Dehydratase Metabolize Glycerol and Produce DNA-Reactive Acrolein.

Bacteria harboring glycerol/diol dehydratase (GDH) encoded by the genes pduCDE metabolize glycerol and release acrolein during growth. Acrolein has antimicrobial activity, and exposure of human cells to acrolein gives rise to toxic and mutagenic responses. These biological responses are related to acrolein's high reactivity as a chemical electrophile that can covalently bind to cellular nucleophiles including DNA and proteins. Various food microbes and gut commensals transform glycerol to acrolein, but there is no direct evidence available for bacterial glycerol metabolism giving rise to DNA adducts. Moreover, it is unknown whether pathogens, such as Salmonella Typhymurium, catalyze this transformation. We assessed, therefore, acrolein formation by four GDH-competent strains of S. Typhymurium grown under either aerobic or anaerobic conditions in the presence of 50 mM glycerol. On the basis of analytical derivatization with a heterocyclic amine, all wild-type strains were observed to produce acrolein, but to different extents, and acrolein production was not detected in fermentations of a pduC-deficient mutant strain. Furthermore, we found that, in the presence of calf thymus DNA, acrolein-DNA adducts were formed as a result of bacterial glycerol metabolism by two strains of Limosilactobacillus reuteri, but not a pduCDE mutant strain. The quantification of the resulting adducts with increasing levels of glycerol up to 600 mM led to the production of up to 1.5 mM acrolein and 3600 acrolein-DNA adducts per 108 nucleosides in a model system. These results suggest that GDH-competent food microbes, gut commensals, and pathogens alike have the capacity to produce acrolein from glycerol. Further, the acrolein production can lead to DNA adduct formation, but requires high glycerol concentrations that are not available in the human gut.

Antithrombin deficiency is associated with mortality and impaired organ function in septic pediatric patients: a retrospective study.

BACKGROUND: Sepsis remains a major problem in intensive care medicine. It is often accompanied by coagulopathies, leading to thrombotic occlusion of small vessels with subsequent organ damage and even fatal multi-organ failure. Prediction of the clinical course and outcome-especially in the heterogeneous group of pediatric patients-is difficult. Antithrombin, as an endogenous anticoagulant enzyme with anti-inflammatory properties, plays a central role in controling coagulation and infections. We investigated the relationship between antithrombin levels and organ failure as well as mortality in pediatric patients with sepsis. METHODS: Data from 164 patients under the age of 18, diagnosed with sepsis, were retrospectively reviewed. Antithrombin levels were recorded three days before to three days after peak C-reactive protein to correlate antithrombin levels with inflammatory activity. Using the concept of developmental haemostasis, patients were divided into groups <1 yr and ≥1 yr of age. RESULTS: In both age groups, survivors had significantly higher levels of antithrombin than did deceased patients. An optimal threshold level for antithrombin was calculated by ROC analysis for survival: 41.5% (<1 yr) and 67.5% (≥1 yr). The mortality rate above this level was 3.3% (<1 yr) and 9.5% (≥1 yr), and below this level 41.7% (<1 yr) and 32.2% (≥1 yr); OR 18.8 (1.74 to 1005.02), p = 0.0047, and OR 4.46 (1.54 to 14.89), p = 0.003. In children <1 yr with antithrombin levels <41.5% the rate of respiratory failure (66.7%) was significantly higher than in patients with antithrombin levels above this threshold level (23.3%), OR 6.23 (1.23 to 37.81), p = 0.0132. In children ≥1 yr, both liver failure (20.3% vs 1.6%, OR 15.55 (2.16 to 685.01), p = 0.0008) and a dysfunctional intestinal tract (16.9% vs 4.8%, OR 4.04 (0.97 to 24.08), p = 0.0395) occurred more frequently above the antithrombin threshold level of 67.5%. CONCLUSION: In pediatric septic patients, significantly increased mortality and levels of organ failure were found below an age-dependent antithrombin threshold level. Antithrombin could be useful as a prognostic marker for survival and occurrence of organ failure in pediatric sepsis.