Jennifer Defazio

The Shift of an Intestinal "Microbiome" to a "Pathobiome" Governs the Course and Outcome of Sepsis Following Surgical Injury.

ABSTRACT Sepsis following surgical injury remains a growing and worrisome problem following both emergent and elective surgery. Although early resuscitation efforts and prompt antibiotic therapy have improved outcomes in the first 24 to 48 h, late onset sepsis is now the most common cause of death in modern intensive care units. This time shift may be, in part, a result of prolonged exposure of the host to the stressors of critical illness which, over time, erode the health promoting intestinal microbiota and allow for virulent pathogens to predominate. Colonizing pathogens can then subvert the immune system and contribute to the deterioration of the host response. Here, we posit that novel approaches integrating the molecular, ecological, and evolutionary dynamics of the evolving gut microbiome/pathobiome during critical illness are needed to understand and prevent the late onset sepsis that develops following prolonged critical illness.

Phosphate-Containing Polyethylene Glycol Polymers Prevent Lethal Sepsis by Multidrug-Resistant Pathogens

ABSTRACT Antibiotic resistance among highly pathogenic strains of bacteria and fungi is a growing concern in the face of the ability to sustain life during critical illness with advancing medical interventions. The longer patients remain critically ill, the more likely they are to become colonized by multidrug-resistant (MDR) pathogens. The human gastrointestinal tract is the primary site of colonization of many MDR pathogens and is a major source of life-threatening infections due to these microorganisms. Eradication measures to sterilize the gut are difficult if not impossible and carry the risk of further antibiotic resistance. Here, we present a strategy to contain rather than eliminate MDR pathogens by using an agent that interferes with the ability of colonizing pathogens to express virulence in response to host-derived and local environmental factors. The antivirulence agent is a phosphorylated triblock high-molecular-weight polymer (here termed Pi-PEG 15–20) that exploits the known properties of phosphate (Pi) and polyethylene glycol 15-20 (PEG 15-20) to suppress microbial virulence and protect the integrity of the intestinal epithelium. The compound is nonmicrobiocidal and appears to be highly effective when tested both in vitro and in vivo. Structure functional analyses suggest that the hydrophobic bis-aromatic moiety at the polymer center is of particular importance to the biological function of Pi-PEG 15-20, beyond its phosphate content. Animal studies demonstrate that Pi-PEG prevents mortality in mice inoculated with multiple highly virulent pathogenic organisms from hospitalized patients in association with preservation of the core microbiome.

Bacterial colonization and succession in a newly opened hospital

Patients share their microbiota with their rooms and with nursing staff, and this shapes the microbial ecology of the hospital environment. A new hospital teems with life Lax et al. conducted a yearlong survey of the bacterial diversity associated with the patients, staff, and built surfaces in a newly opened hospital. They found that the bacterial communities on patient skin strongly resembled those found in their rooms. The authors demonstrated that the patient skin microbial communities were shaped by a diversity of clinical and environmental factors during hospitalization. They found little effect of intravenous or oral antibiotic treatment on the skin microbiota of patients. The microorganisms that inhabit hospitals may influence patient recovery and outcome, although the complexity and diversity of these bacterial communities can confound our ability to focus on potential pathogens in isolation. To develop a community-level understanding of how microorganisms colonize and move through the hospital environment, we characterized the bacterial dynamics among hospital surfaces, patients, and staff over the course of 1 year as a new hospital became operational. The bacteria in patient rooms, particularly on bedrails, consistently resembled the skin microbiota of the patient occupying the room. Bacterial communities on patients and room surfaces became increasingly similar over the course of a patient’s stay. Temporal correlations in community structure demonstrated that patients initially acquired room-associated taxa that predated their stay but that their own microbial signatures began to influence the room community structure over time. The α- and β-diversity of patient skin samples were only weakly or nonsignificantly associated with clinical factors such as chemotherapy, antibiotic usage, and surgical recovery, and no factor except for ambulatory status affected microbial similarity between the microbiotas of a patient and their room. Metagenomic analyses revealed that genes conferring antimicrobial resistance were consistently more abundant on room surfaces than on the skin of the patients inhabiting those rooms. In addition, persistent unique genotypes of Staphylococcus and Propionibacterium were identified. Dynamic Bayesian network analysis suggested that hospital staff were more likely to be a source of bacteria on the skin of patients than the reverse but that there were no universal patterns of transmission across patient rooms.

The Opposing Forces of the Intestinal Microbiome and the Emerging Pathobiome

This article summarizes emerging concepts on the role of the intestinal microbiome in surgical patients. Revolutionary research over the past decade has shown that human beings live in close and constant contact with boundless communities of microbes. Recent innovations in the study of the human microbiome are reviewed. To demonstrate the applicability of these studies to surgical disease, the authors discuss what is known about the role of microbes in the pathogenesis of perioperative complications. Enhanced awareness of the human microbiome will empower clinicians to adopt novel practices in the prevention and treatment of a variety of surgical conditions.

Proceedings of the 2014 A.S.P.E.N. Research Workshop The Interface Between Nutrition and the Gut Microbiome: Implications and Applications for Human Health

The human and earth microbiomes are among the most important biological agents in understanding and preventing disease. Technology is advancing at a fast pace and allowing for high-resolution analysis of the composition and function of our microbial partners across regions, space, and time. Bioinformaticists and biostatisticians are developing ever more elegant displays to understand the generated megadatasets. A virtual cyberinfrastructure of search engines to cross-reference the rapidly developing data is emerging in line with technologic advances. Nutrition science will reap the benefits of this new field, and its role in preserving the earth and the humans who inhabit it will become evidently clear. In this report we highlight some of the topics of an A.S.P.E.N.-sponsored symposium held during Clinical Nutrition Week in 2013 that address the importance of the human microbiome to human health and disease.

Morphine Promotes Colonization of Anastomotic Tissues with Collagenase - Producing Enterococcus faecalis and Causes Leak

BackgroundDespite ever more powerful antibiotics, newer surgical techniques, and enhanced recovery programs, anastomotic leaks remain a clear and present danger to patients. Previous work from our laboratory suggests that anastomotic leakage may be caused by Enterococcus faecalis strains that express a high collagenase phenotype (i.e., collagenolytic). Yet the mechanisms by which the practice of surgery shifts or selects for collagenolytic phenotypes to colonize anastomotic tissues remain unknown.MethodsHere, we hypothesized that morphine, an analgesic agent universally used in gastrointestinal surgery, promotes tissue colonization with collagenolytic E. faecalis and causes anastomotic leak. To test this, rats were administered morphine in a chronic release form as would occur during routine surgery or vehicle. Rats were observed for 6 days and then underwent exploratory laparotomy for anastomotic inspection and tissue harvest for microbial analysis. These results provide further rationale to enhanced recovery after surgery (i.e., ERAS) programs that suggest limiting or avoiding the use of opioids in gastrointestinal surgery.ResultsResults demonstrated that compared to placebo-treated rats, morphine-treated rats demonstrated markedly impaired anastomotic healing and gross leaks that correlated with the presence of high collagenase-producing E. faecalis adherent to anastomotic tissues. To determine the direct role of morphine on this response, various isolates of E. faecalis from the rats were exposed to morphine and their collagenase activity and adherence capacity determined in vitro. Morphine increased both the adhesiveness and collagenase production of four strains of E. faecalis harvested from anastomotic tissues, two that were low collagenase producers at baseline, and two that were high collagenase producers at baseline.ConclusionThese results provide further rationale to enhanced recovery after surgery (i.e., ERAS) programs that suggest limiting or avoiding the use of opioids in gastrointestinal surgery.

Critical role of microbiota within cecal crypts on the regenerative capacity of the intestinal epithelium following surgical stress

This study provides novel insight into the process by which surgical injury places the intestinal epithelium at risk for colonization by pathogenic microbes and impairment of its regenerative capacity via loss of its microbiota. We show that fecal transplant restores crypt homeostasis in association with repopulation of the microbiota within cecal crypts.

Modeling Acinetobacter baumannii wound infections: The critical role of iron

BACKGROUND Acinetobacter baumannii has emerged as an increasingly important and successful opportunistic human pathogen due to its ability to withstand harsh environmental conditions, its characteristic virulence factors, and quick adaptability to stress. METHODS We developed a clinically relevant murine model of A. baumannii traumatic wound infection to determine the effect of local wound environment on A. baumannii virulence. Mice underwent rectus muscle crush injury combined with ischemia created by epigastric vessel ligation, followed by A. baumannii inoculation. Reiterative experiments were performed using (1) a mutant deficient in the production of the siderophore acinetobactin, or (2) iron supplementation of the wound milieu. Mice were euthanized 7 days later, and rectus muscle analyzed for signs of clinical infection, HIF1&agr; accumulation, bacterial abundance, and colony morphotype. To determine the effect of wound milieu on bacterial virulence, Galleria mellonella infection model was used. RESULTS The combination of rectus muscle injury with ischemia and A. baumannii inoculation resulted in 100% incidence of clinical wound infection that was significantly higher compared with other groups (n = 15/group, p < 0.0001). The highest level of wound infection was accompanied by the highest level of A. baumannii colonization (p < 0.0001) and the highest degree of HIF1&agr; accumulation (p < 0.05). A. baumannii strains isolated from injured/ischemic muscle with clinical infection displayed a rough morphotype and a higher degree of virulence as judged by G. mellonella killing assay as compared with smooth morphotype colonies isolated from injured muscle without clinical infection (100% vs. 60%, n = 30 Log-Rank test, p = 0.0422). Iron supplementation prevented wound infection (n = 30, p < 0.0001) and decreased HIF1&agr; (p = 0.039643). Similar results of decrease in wound infection and HIF1&agr; were obtained when A. baumannii wild type was replaced with its derivative mutant [INCREMENT]BasD deficient in acinetobactin production. CONCLUSION The ability of A. baumannii to cause infections in traumatized wound relies on its ability to scavenge iron and can be prevented by iron supplementation to the wound milieu.