Evolution of a Vegetarian Vibrio: Metabolic Specialization of Vibrio breoganii to Macroalgal Substrates.

While most Vibrionaceae are considered generalists that thrive on diverse substrates, including animal-derived material, we show that Vibrio breoganii has specialized for the consumption of marine macroalga-derived substrates. Genomic and physiological comparisons of V. breoganii with other Vibrionaceae isolates revealed the ability to degrade alginate, laminarin, and additional glycans present in algal cell walls. Moreover, the widely conserved ability to hydrolyze animal-derived polymers, including chitin and glycogen, was lost, along with the ability to efficiently grow on a variety of amino acids. Ecological data showing associations with particulate algal material but not zooplankton further support this shift in niche preference, and the loss of motility appears to reflect a sessile macroalga-associated lifestyle. Together, these findings indicate that algal polysaccharides have become a major source of carbon and energy in V. breoganii, and these ecophysiological adaptations may facilitate transient commensal associations with marine invertebrates that feed on algae.IMPORTANCE Vibrios are often considered animal specialists or generalists. Here, we show that Vibrio breoganii has undergone massive genomic changes to become specialized on algal carbohydrates. Accompanying genomic changes include massive gene import and loss. These vibrios may help us better understand how algal biomass is degraded in the environment and may serve as a blueprint on how to optimize the conversion of algae to biofuels.

Environmental factors determining ammonia-oxidizing organism distribution and diversity in marine environments.

Ammonia-oxidizing bacteria (AOB) and archaea (AOA) play a vital role in bridging the input of fixed nitrogen, through N-fixation and remineralization, to its loss by denitrification and anammox. Yet the major environmental factors determining AOB and AOA population dynamics are little understood, despite both groups having a wide environmental distribution. This study examined the relative abundance of both groups of ammonia-oxidizing organisms (AOO) and the diversity of AOA across large-scale gradients in temperature, salinity and substrate concentration and dissolved oxygen. The relative abundance of AOB and AOA varied across environments, with AOB dominating in the freshwater region of the Chesapeake Bay and AOA more abundant in the water column of the coastal and open ocean. The highest abundance of the AOA amoA gene was recorded in the oxygen minimum zones (OMZs) of the Eastern Tropical South Pacific (ETSP) and the Arabian Sea (AS). The ratio of AOA : AOB varied from 0.7 in the Chesapeake Bay to 1600 in the Sargasso Sea. Relative abundance of both groups strongly correlated with ammonium concentrations. AOA diversity, as determined by phylogenetic analysis of clone library sequences and archetype analysis from a functional gene DNA microarray, detected broad phylogenetic differences across the study sites. However, phylogenetic diversity within physicochemically congruent stations was more similar than would be expected by chance. This suggests that the prevailing geochemistry, rather than localized dispersal, is the major driving factor determining OTU distribution.

A Multifunctional, Low-Volume Resuscitation Cocktail Improves Vital Organ Blood Flow and Hemostasis in a Pig Model of Polytrauma with Traumatic Brain Injury.

The resuscitation of polytrauma with hemorrhagic shock and traumatic brain injury (TBI) is a balance between permissive hypotension and maintaining vital organ perfusion. There is no current optimal solution. This study tested whether a multifunctional resuscitation cocktail supporting hemostasis and perfusion could mitigate blood loss while improving vital organ blood flow during prolonged limited resuscitation. Anesthetized Yorkshire swine were subjected to fluid percussion TBI, femur fracture, catheter hemorrhage, and aortic tear. Fluid resuscitation was started when lactate concentration reached 3-4 mmol/L. Animals were randomized to one of five groups. All groups received hydroxyethyl starch solution and vasopressin. Low- and high-dose fibrinogen (FBG) groups additionally received 100 and 200 mg/kg FBG, respectively. A third group received TXA and low-dose FBG. Two control groups received albumin, with one also including TXA. Animals were monitored for up to 6 h. Blood loss was decreased and vital organ blood flow was improved with low- and high-dose fibrinogen compared to albumin controls, but survival was not improved. There was no additional benefit of high- vs. low-dose FBG on blood loss or survival. TXA alone decreased blood loss but had no effect on survival, and combining TXA with FBG provided no additional benefit. Pooled analysis of all groups containing fibrinogen vs. albumin controls found improved survival, decreased blood loss, and improved vital organ blood flow with fibrinogen delivery. In conclusion, a low-volume resuscitation cocktail consisting of hydroxyethyl starch, vasopressin, and fibrinogen concentrate improved outcomes compare to controls during limited resuscitation of polytrauma.

Effect of emergency department fibrinogen testing on survival of trauma patients receiving blood transfusions.

: Fibrinogen is the first clotting factor to reach critically low levels during blood loss and its depletion is associated with coagulopathy, increased blood loss, transfusion requirements and mortality after trauma. However, direct measurements of fibrinogen concentration or function are not included in many Emergency Department (ED) trauma laboratory testing protocols. We hypothesized that including a test of fibrinogen concentration in the ED would be associated with increased survival for trauma patients requiring blood transfusions.To test this hypothesis, we performed a single-centre retrospective study of the effect of a resulted fibrinogen concentration measurement performed in the ED on survival of trauma patients receiving blood transfusions within the first 4 h of their hospital arrival. Multivariate logistic regression was used test the effect of a fibrinogen test on hospital survival after adjusting for the influence of INR, injury severity, lowest recorded blood pressure and blood transfusion intensity defined as the number of red blood cell units transfused in the first 4 h or care.Of 11 404 trauma registry individuals from 2016 to 2017, 843 (7.4%) received any blood transfusions within the first 4 h of ED care, of whom 635 (75.3%) had a documented fibrinogen concentration ordered and resulted. Multivariate logistic regression for hospital survival demonstrated a significant interaction effect between the presence of a fibrinogen test and transfusion intensity (Whole Model P < 0.0001, Interaction P = 0.035). Repeat analysis after stratifying for those individuals receiving more than 4 units of red blood cell units within 4 h of care found that the presence of a fibrinogen test was independently associated with survival only for those receiving more than 4 units [FIB test odds ratio for survival = 3.5 (1.0, 10.8), P = 0.03].Fibrinogen testing in the ED may be a valuable addition to resuscitation of the trauma patient receiving significant blood transfusions.

How can microbial population genomics inform community ecology?

Populations are fundamental units of ecology and evolution, but can we define them for bacteria and archaea in a biologically meaningful way? Here, we review why population structure is difficult to recognize in microbes and how recent advances in measuring contemporary gene flow allow us to identify clearly delineated populations among collections of closely related genomes. Such structure can arise from preferential gene flow caused by coexistence and genetic similarity, defining populations based on biological mechanisms. We show that such gene flow units are sufficiently genetically isolated for specific adaptations to spread, making them also ecological units that are differentially adapted compared to their closest relatives. We discuss the implications of these observations for measuring bacterial and archaeal diversity in the environment. We show that operational taxonomic units defined by 16S rRNA gene sequencing have woefully poor resolution for ecologically defined populations and propose monophyletic clusters of nearly identical ribosomal protein genes as an alternative measure for population mapping in community ecological studies employing metagenomics. These population-based approaches have the potential to provide much-needed clarity in interpreting the vast microbial diversity in human and environmental microbiomes. This article is part of the theme issue 'Conceptual challenges in microbial community ecology'.

Self-Propelled Dressings Containing Thrombin and Tranexamic Acid Improve Short-Term Survival in a Swine Model of Lethal Junctional Hemorrhage.

Hemorrhage is the leading cause of preventable death in trauma, and hemorrhage from noncompressible junctional anatomic sites is particularly difficult to control. The current standard is QuikClot Combat Gauze packing, which requires 3 min of compression. We have created a novel dressing with calcium carbonate microparticles that can disperse and self-propel upstream against flowing blood. We loaded these microparticles with thrombin and tranexamic acid and tested their efficacy in a swine arterial bleeding model without wound compression. Anesthetized immature female swine received 5 mm femoral arteriotomies to induce severe junctional hemorrhage. Wounds were packed with kaolin-based QuikClot Combat Gauze (KG), propelled thrombin-microparticles with protonated tranexamic acid (PTG), or a non-propelling formulation of the same thrombin-microparticles with non-protonated tranexamic acid (NPTG). Wounds were not compressed after packing. Each animal then received one 15 mL/kg bolus of hydroxyethyl starch solution followed by Lactated Ringer as needed for hypotension (maximum: 100 mL/kg) for up to 3 h. Survival was improved with PTG (3-h survival: 8/8, 100%) compared with KG (3/8, 37.5%) and NPTG (2/8, 25%) (P <0.01). PTG animals maintained lower serum lactate and higher hemoglobin concentrations than NPTG (P <0.05) suggesting PTG decreased severity of subsequent hemorrhagic shock. However, total blood loss, Lactated Ringer infusion volumes, and mean arterial pressures of surviving animals were not different between groups (P >0.05). Thus, in this swine model of junctional arterial hemorrhage, gauze with self-propelled, prothrombotic microparticles improved survival and 2 indicators of hemorrhagic shock when applied without compression, suggesting this capability may enable better treatment of non-compressible junctional wounds.

Effects of rapid wound sealing on survival and blood loss in a swine model of lethal junctional arterial hemorrhage.

BACKGROUND: Hemostatic gauzes, which must be packed into wounds and compressed for several minutes, may be of limited use for noncompressible wounds in junctional anatomic locations. Rapid mechanical wound sealing is an alternative approach that seals the wound at the skin, allowing internal clot formation. We evaluate wound sealing for junctional hemorrhage control using a hemostatic clamp (iTClamp). METHODS: Severe junctional hemorrhage was induced in anesthetized immature female swine using a 5-mm femoral arteriotomy. After 30 seconds of free bleeding, animals were randomized to one of seven hemostatic interventions: no intervention (control), direct compression for 3 minutes (compression), plain gauze packing (packing), mechanical wound seal (seal), plain gauze packing + wound seal (packing + seal), plain gauze packing + compression (packing + compression), or hemostatic gauze packing (Combat Gauze) + compression (HS-packing + compression). All animals then received one 15-mL/kg bolus of Hextend, followed by lactated Ringer's solution for hypotension up to 100 mL/kg. Animals were monitored for 3 hours. RESULTS: Survival was similar between control (3-hour survival, 0%) and compression (0%, Kaplan-Meier survival analysis and log-rank test [KM-LR], p = 1.0) but marginally improved with packing (12.5%, KM-LR, p < 0.001). Survival improved with seal (62.5%) versus control (KM-LR, p < 0.001) and with packing + seal (100%) versus packing alone (KM-LR, p < 0.001). Survival was similar between packing + compression (87.5%), HS-packing + compression (62.5%), and packing + seal (100%) (KM-LR, p ≥ 0.05). Total hemorrhage volume was decreased for seal versus control (p < 0.001) and for packing + seal versus packing (p < 0.001). Hemorrhage was similar among packing + compression, HS-packing + compression, seal, and packing + seal (analysis of variance p ≥ 0.05). Application times (mean [SD]) were significantly faster with packing + seal (125.8 [56.2] seconds) than packing + compression (236.6 [7.2] seconds) and HS-packing + compression (223.0 [6.8] seconds) (analysis of variance, all p < 0.001). CONCLUSION: In this preclinical junctional hemorrhage model, rapid wound sealing improved survival and decreased hemorrhage in both packed and unpacked wounds and performed comparably with standard-of-care hemostatic bandages. Rapidly sealing junctional wounds may be a viable alternative to wound compression.

Self-propelled particles that transport cargo through flowing blood and halt hemorrhage.

Delivering therapeutics deep into damaged tissue during bleeding is challenging because of the outward flow of blood. When coagulants cannot reach and clot blood at its source, uncontrolled bleeding can occur and increase surgical complications and fatalities. Self-propelling particles have been proposed as a strategy for transporting agents upstream through blood. Many nanoparticle and microparticle systems exhibiting autonomous or collective movement have been developed, but propulsion has not been used successfully in blood or used in vivo to transport therapeutics. We show that simple gas-generating microparticles consisting of carbonate and tranexamic acid traveled through aqueous solutions at velocities of up to 1.5 cm/s and delivered therapeutics millimeters into the vasculature of wounds. The particles transported themselves through a combination of lateral propulsion, buoyant rise, and convection. When loaded with active thrombin, these particles worked effectively as a hemostatic agent and halted severe hemorrhage in multiple animal models of intraoperative and traumatic bleeding. Many medical applications have been suggested for self-propelling particles, and the findings of this study show that the active self-fueled transport of particles can function in vivo to enhance drug delivery.

Associations and dynamics of Vibrionaceae in the environment, from the genus to the population level.

The Vibrionaceae, which encompasses several potential pathogens, including V. cholerae, the causative agent of cholera, and V. vulnificus, the deadliest seafood-borne pathogen, are a well-studied family of marine bacteria that thrive in a diverse habitats. To elucidate the environmental conditions under which vibrios proliferate, numerous studies have examined correlations with bulk environmental variables-e.g., temperature, salinity, nitrogen, and phosphate-and association with potential host organisms. However, how meaningful these environmental associations are remains unclear because data are fragmented across studies with variable sampling and analysis methods. Here, we synthesize findings about Vibrio correlations and physical associations using a framework of increasingly fine environmental and taxonomic scales, to better understand their dynamics in the wild. We first conduct a meta-analysis to determine trends with respect to bulk water environmental variables, and find that while temperature and salinity are generally strongly predictive correlates, other parameters are inconsistent and overall patterns depend on taxonomic resolution. Based on the hypothesis that dynamics may better correlate with more narrowly defined niches, we review evidence for specific association with plants, algae, zooplankton, and animals. We find that Vibrio are attached to many organisms, though evidence for enrichment compared to the water column is often lacking. Additionally, contrary to the notion that they flourish predominantly while attached, Vibrio can have, at least temporarily, a free-living lifestyle and even engage in massive blooms. Fine-scale sampling from the water column has enabled identification of such lifestyle preferences for ecologically cohesive populations, and future efforts will benefit from similar analysis at fine genetic and environmental sampling scales to describe the conditions, habitats, and resources shaping Vibrio dynamics.