Gut origin of sepsis: a prospective study investigating associations between bacterial translocation, gastric microflora, and septic morbidity

Polymicrobial interactions: impact on pathogenesis and human disease

Microorganisms coexist in a complex milieu of bacteria, fungi, archaea, and viruses on or within the human body, often as multifaceted polymicrobial biofilm communities at mucosal sites and on abiotic surfaces. Only recently have we begun to appreciate the complicated biofilm phenotype during infection; moreover, even less is known about the interactions that occur between microorganisms during polymicrobial growth and their implications in human disease. Therefore, this review focuses on polymicrobial biofilm-mediated infections and examines the contribution of bacterial-bacterial, bacterial-fungal, and bacterial-viral interactions during human infection and potential strategies for protection against such diseases.

Bacterial translocation in abdominal trauma and postoperative infections

BACKGROUND

Bacterial translocation (BT) describes the passage of bacteria residing into the gastrointestinal tract, through the intestinal mucosa barrier to sterile tissues such as mesenteric lymph nodes (MLN) and other organs. This phenomenon has not been thoroughly studied in patients with trauma to date, and an association between BT and postoperative infection has not been well established so far.

METHODS

MLNs from 36 patients with abdominal trauma were removed during laparotomy and cultured to detect BT. Postoperative infectious complications in these patients were registered, and both phenotypical and molecular typings (through multilocus sequencing) were carried out for microorganisms isolated from MLN and postoperative infection sites. Associations between clinical variables, BT presence, and postoperative infection development were established.

RESULTS

BT was detected in 33% of the patients (n = 12). Postoperative infections were present in 22.2% of the patients (n = 8). A significant statistical difference was found between postoperative infections in patients with BT evidence (41.6%), when compared with patients without BT (12.5%; p = 0.047). Bacteria isolated from infection sites were the same as those cultured in MLN in 40% of the cases (n = 2 of 5), allowing us to establish causality between BT and postoperative infection.

CONCLUSIONS

There is higher risk of BT in trauma patients, and it is associated with a significant increase of postoperative infections. An abdominal trauma index ≥10 was found to be associated with the development of BT. This is the first study describing BT among patients with abdominal trauma, where causality is confirmed at molecular level.

Intestinal barrier function in patients undergoing colectomy

AIM

The aim of this pilot study was to determine whether the type of approach (open or laparoscopic) and the order of devascularization during laparoscopic colectomy affect intestinal barrier function, local inflammatory response and clinical outcome.

METHOD

Twenty-two patients undergoing elective colectomy from April 2006 to July 2008 were randomized to two sequences of vascular ligation, starting with either the inferior mesenteric artery or the ileocolic artery. Eighteen patients scheduled for open surgery served as a prospective control group. To assess the intestinal barrier function, release of intestinal fatty-acid binding protein (I-FABP; a marker of mucosal injury and ischaemia) was measured pre- and postoperatively. Mesenteric lymph nodes were harvested to assess the expression of inflammatory mediator-related genes using multiplex ligation probe amplification. The study was registered under NTR1025.

RESULTS

Laparoscopic devascularization starting at the ileocolic artery resulted in a significantly increased excretion of I-FABP over time (P = 0.002). In this group, the I-FABP levels were significantly increased on postoperative days 1 and 3 compared with preoperative values (P = 0.011 and P = 0.001, respectively). There were no differences in expression of inflammatory mediator-related genes or postoperative morbidity among the groups.

CONCLUSIONS

In this pilot study, devascularization commencing at the ileocolic artery during laparoscopic colectomy was associated with prolonged intestinal mucosal ischaemia.

Lactobacillus plantarum prevents bacterial translocation in rats following ischemia and reperfusion injury

BACKGROUND

Bacterial translocation is considered a major cause of initiation and development of systemic sepsis and multiple organ dysfunction in clinic. The aim of this study was to determine the ability of a defined Lactobacillus plantarum to prevent ischemia/reperfusion (I/R) induced intestinal infection.

METHODS

Female Sprague-Dawley rats were randomly allocated into three groups: (1) controls (sham-operated, no treatment), (2) ischemia/reperfusion and (3) ischemia/reperfusion and Lactobacillus plantarum treatment. Lactobacillus plantarum L2 was administered daily intragastrically 14 days prior to induction of I/R. Rats were then sacrificed, and tissue and blood samples were cultured to determine bacterial translocation. Cytokines in plasma were detected by ELISA. Ileal segments were removed for morphological examination.

RESULTS

Intestinal I/R induced excess pro-inflammatory cytokine secretion and barrier dysfunction (increased epithelial cell apoptosis, cecal flora dysbiosis, disruption of mucosa and multiple erosions) in the intestine, associated with increased bacterial translocation to extraintestinal sites. Approximately 87.5% of rats exposed to I/R had bacterial translocation while there was no bacterial translocation in controls. However, pretreatment of animals with Lactobacillus plantarum completely prevented I/R induced bacterial translocation, reduced pro-inflammatory cytokine release, and intestinal epithelial cell apoptosis, resulting in recovered microflora and mucosal integrity.

CONCLUSIONS

These findings indicate that Lactobacillus plantarum L2 can prevent I/R-induced bacterial translocation and intestinal barrier dysfunction and, thereby, exert beneficial effects in the intestinal tract.

Early appropriate care: definitive stabilization of femoral fractures within 24 hours of injury is safe in most patients with multiple injuries

BACKGROUND

Type and timing of treatment of femur fractures is controversial. Although reported as safe and effective in many reports, others have suggested that early definitive stabilization may cause complications, particularly in patients with chest and head injuries. Damage control orthopedics was proposed as an alternative in unstable patients. This study examines the effects of timing of fixation and investigates risk factors for complications.

METHODS

Seven hundred fifty patients with femur fractures treated between 1999 and 2006 were reviewed. Skeletally mature patients with mean age 35.8 years and mean Injury Severity Score (ISS) 23.7 were included. Four hundred ninety-two patients had ISS ≥18. Early stabilization (n = 656) was defined as definitive treatment of the femur fracture within 24 hours of injury.

RESULTS

Early definitive stabilization in patients with multiple injuries was associated with fewer complications than delayed stabilization (18.9% vs. 42.9%, p < 0.037) after adjusting for patient age and ISS. Early treatment was also associated with shorter hospital stay, intensive care unit stay, and ventilator days (p < 0.001). Severe (Abbreviated Injury Scale score ≥3) abdominal injury was associated with more complications than severe head (Glasgow Coma Scale score ≤8) and chest (Abbreviated Injury Scale score ≥3) injuries (44.2% vs. 40.9%, p = 0.68, and 34.4%, p = 0.024, respectively) and was an independent risk factor for complications (p < 0.0001). Chest injury was an independent risk factor for pulmonary complications (p < 0.001), but surgical delay in patients with chest injury was also associated with pulmonary complications (p = 0.04). More sepsis was noted patients with severe head injury (22.7% vs. 4.5%, p = 0.037) or severe chest injury (10.2% vs. 2.5%, p = 0.044) when treated on a delayed basis. More patients transferred from other hospitals were treated on a delayed basis (48.9% vs. 37.5%, p = 0.04).

CONCLUSIONS

Early definitive stabilization is associated with acceptably low rates of complications and is safe in most patients with multiple injuries, including some with severe abdominal, chest, or head injuries with attention to resuscitation before surgery. More complications and longer hospital stay were noted with delayed fixation after adjusting for age and ISS. Chest injury was associated with pulmonary complications; however, the presence of severe abdominal injury was the greatest risk factor for complications. Expediting access to definitive care may reduce complications and expenses.

Conversion of commensal Escherichia coli K-12 to an invasive form via expression of a mutant histone-like protein

The HUα^{E38K, V42L} mutant of the bacterial histone-like protein HU causes a major change in the transcription profile of the commensal organism Escherichia coli K-12 (Kar S, Edgar R, Adhya S, Proc. Natl. Acad. Sci. U. S. A. 102:16397–16402, 2005). Among the upregulated genes are several related to pathogenic interactions with mammalian cells, as evidenced by the expression of curli fibers, Ivy, and hemolysin E. When E. coli K-12/ HUα^{E38K, V42L} was added to Int-407 cells, there was host cell invasion, phagosomal disruption, and intracellular replication. The invasive trait was also retained in a murine ileal loop model and intestinal explant assays. In addition to invasion, the internalized bacteria caused a novel subversion of host cell apoptosis through modification and regulation of the BH3-only proteins Bim_EL and Puma. Changes in the transcription profile were attributed to positive supercoiling of DNA leading to the altered availability of relevant promoters. Using the E. coli K-12/HUα^{E38K, V42L} variant as a model, we propose that traditional commensal E. coli can adopt an invasive lifestyle through reprogramming its cellular transcription, without gross genetic changes.

Escherichia coli K-12 is well established as a benign laboratory strain and a human intestinal commensal. Recent evidences, however, indicate that the typical noninvasive nature of resident E. coli can be reversed under specific circumstances even in the absence of any major genomic flux. We previously engineered an E. coli strain with a mutant histone-like protein, HU, which exhibited significant changes in nucleoid organization and global transcription. Here we showed that the changes induced by the mutant HU have critical functional consequences: from a strict extracellular existence, the mutant E. coli adopts an almost obligate intracellular lifestyle. The internalized E. coli exhibits many of the prototypical characteristics of traditional intracellular bacteria, like phagosomal escape, intracellular replication, and subversion of host cell apoptosis. We suggest that E. coli K-12 can switch between widely divergent lifestyles in relation to mammalian host cells by reprogramming its cellular transcription program and without gross changes in its genomic content.

Dramatic changes of the gut flora immediately after severe and sudden insults

BACKGROUND

The gut flora is crucially involved in host homeostasis. However, the changes in the gut flora during the early phase of a critical illness are unknown.

AIMS

We investigated the changes in the gut flora at an early phase of severe insult in critically ill patients.

METHODS

Fifteen patients who experienced a sudden and severe insult were studied, along with 12 healthy volunteers as the control group. Fecal samples were acquired from the subjects by swabs of the rectum within 6 h after admission to the emergency room (day 0). Samples were serially collected from patients until day 14. Samples were also collected from control subjects.

RESULTS

On day 0, total bacterial counts were decreased to one-thousandth the number of the control subjects, in particular, obligate anaerobes and Lactobacillus were significantly decreased. In addition, on day 0, the major short-chain fatty acids of the patients were significantly lower than those of the control subjects. The gut flora and the concentrations of major short-chain fatty acids did not recover to normal levels. In contrast, Enterococcus and Pseudomonas increased during the study period.

CONCLUSIONS

The gut flora in critically ill patients changed immediately after a severe insult. The concentrations of the three major short-chain fatty acids were immediately decreased in tandem with the destruction of the gut flora. The gut flora and the concentration of major short-chain fatty acids did not improve during the first 2 weeks after hospital admission. At the same time, the number of harmful bacteria gradually increased.

Vasoactive intestinal peptide promotes gut barrier function against severe acute pancreatitis

To explore the influence of vasoactive intestinal peptide (VIP) on the gut barrier function in severe acute pancreatitis (SAP). Fifty four SD rats were randomly divided into three groups: sham operated (SO) group, SAP group and VIP intervention group. Each group was further divided into three time points: 1, 6 and 12 h after operation with 6 rats for each treatment point. SAP models were induced by retrograde injection of 4% sodium taurocholate into the bili-pancreatic duct. VIP intervention group was made by 5 nmol VIP intraperitoneal injection within 5 min after SAP model successfully obtained. The VIP in plasma and intestinal homogenate were detected with ELISA. The endotoxin in plasma of all groups was also tested. The expression levels of TLR4, TNF-α, IL-6, and IL-10 in gut mucosa were measured by RT-PCR. Meanwhile intestinal samples were harvested for pathological examination. Compared to SO group, the VIP in plasma and intestinal homogenate of SAP group were significantly decreased at 1 h after induction, and then gradually increased to beyond the level of SO group at 12 h. The endotoxin of SAP group was continually increased. The mRNA levels of TLR4, TNF-α, IL-6, and IL-10 were also increased with obvious pathological injuries in the intestine. In the VIP group, endotoxin in plasma was obviously decreased compared to SAP group. The expressions of TNF-α, IL-6 mRNA were suppressed while IL-10mRNA was increased. The intestinal pathological injuries were also markedly alleviated. These results suggested that VIP had protective effects on SAP gut barrier function through inhibiting intestinal mucosal inflammatory responses.

Bacterial translocation is reduced by a specific nutritional combination in mice with chemotherapy-induced neutropenia

Immune function is compromised in many cancer patients, leading to an increased risk of (infectious) complications. Chemotherapy-induced neutropenia is a common cause of treatment-induced immune suppression. In the present study, the effect of a specific nutritional combination (SNC) on bacterial translocation was studied in a model of chemotherapy-induced neutropenia in C3H/HeN mice colonized with Pseudomonas aeruginosa PAO-1. Dietary intervention started after stable colonization with P. aeruginosa to compare the SNC containing high protein, l-leucine, fish oil, and specific oligosaccharides to an isoenergetic control diet. After 3 wk, the mice were treated with cyclophosphamide to induce neutropenia. This rendered the mice susceptible to Pseudomonas translocation, which was quantified 5 d later. Intervention with the SNC resulted in a reduced incidence and intensity of bacterial translocation to the liver (P < 0.05) and a similar trend in the lungs (P ≤ 0.057). In addition, the SNC reduced the fecal pH (P < 0.05) and decreased P. aeruginosa counts in fecal samples (P < 0.05). Moreover, plasma concentrations of proinflammatory cytokines were correlated with the reduced bacterial translocation to the liver (ρ > 0.78; P < 0.001). In conclusion, dietary intervention with the SNC significantly reduced the incidence and severity of P. aeruginosa translocation in a mouse model of chemotherapy-induced immune suppression. Several mechanisms might have played a role, including the modulation of the intestinal microbiota, an improved gut barrier function, immune function, and a reduced inflammatory state. These results suggest an opportunity to develop new applications in cancer patients, with the aim to reduce infectious and other complications.

Colonization of the gut with Gram-negative bacilli, its association with neonatal sepsis and its clinical relevance in a developing country

This study examined the pattern of colonization of the neonatal gut by aerobic Gram-negative bacilli (GNB) and evaluated the association between gut colonization and sepsis in the developing world. This deserves attention because of the high incidence of sepsis and the differences in hygienic environments in developing countries compared with the developed world. The study was carried out on neonates in a tertiary-care government hospital. Serial gut samples were analysed (gastric aspirates and stool samples) for GNB. Blood samples of cases showing clinical signs of sepsis were also analysed for septic screening and culture positivity. Antibiograms, serotyping and PFGE were carried out to evaluate the relatedness of the gut and blood isolates. A diverse array of GNB was isolated from the gut of the neonates, Klebsiella pneumoniae being most common, followed by Escherichia coli. The rate of isolation of GNB was consistently higher in stool samples compared with gastric aspirate samples. Colonization was influenced by a stay in the neonatal intensive care unit and by the prolonged use of a feeding tube. GNB were the cause of sepsis in the majority of cases, with K. pneumoniae being the most frequently isolated GNB from the blood. Acinetobacter baumannii, Escherichia coli, Enterobacter cloacae and Burkholderia cepacia were the other GNB recovered from the blood of the neonates. Neonates with GNB in the gut had a higher incidence of clinical sepsis than those without. In 50 % of cases, the genotypes of the organisms found in the blood were indistinguishable from their gut counterpart. These results show that the neonatal gut is colonized with a diverse array of GNB, and an association between gut colonization and neonatal sepsis was observed.

Reactivity of (1→3)-β-d-glucan assay in bacterial bloodstream infections

To diagnose invasive fungal infections, the detection of (1 → 3)-β-d-glucan in serum has shown variable specificity, depending on the targeted population. Several circumstances for false-positive results of beta-glucan tests have been identified, among which are severe bacterial infections. In this study, we measured (1 → 3)-β-d-glucan by the Fungitell test in the serum of 62 patients (one serum sample tested per patient) for whom invasive fungal infection was not suspected: 19 control subjects and 43 patients with bacteraemia. The test was interpretable for 58 sera: all 19 control subjects had negative beta-glucan test; among the 39 bacteraemic patients, we report 16 false-positive results. For the 22 patients undergoing bacteraemia due to Gram-negative bacilli, we observed 13 false-positive results (59%). Among the 17 patients with bloodstream infection involving Gram-positive cocci, three false-positive tests were recorded, but none in the eight cases of Streptococcus pneumoniae bacteraemia. Statistical analysis showed that beta-glucan levels were significantly higher in patients with Gram-negative bacilli bloodstream infection in comparison to those with bacteraemia due to Gram-positive cocci. These results were independent from other previously described causes for false-positive beta-glucan tests. These data might help physicians to interpret positive beta-glucan detection when an invasive fungal infection is suspected, especially for patients with bacterial infections.

Intestinal mast cells in gut inflammation and motility disturbances

Mast cells may be regarded as prototypes of innate immune cells that can be controlled by neuronal mediators. Their activation has been implicated in many types of neuro-inflammatory responses, and related disturbances of gut motility, via direct or indirect mechanisms that involve several mechanisms relevant to disease pathogenesis such as changes in epithelial barrier function or activation of adaptive or innate immune responses. Here we review the evidence for the involvement of mast cells in the inflammation of the bowel wall caused by bowel manipulation that leads to motility disturbances such as postoperative gastroparesis and ileus. Also in IBD there is substantial evidence for the involvement of mast cells and a mast cell-mediated neuroimmune interaction showing an increased number and an increased degranulation of mast cells. We discuss the potential of mast cell inhibition as a bona fide drug target to relief postoperative ileus. Further research on mast cell-related therapy either by stabilizing the mast cells or by blocking specific mast cell mediators as adjunctive therapy in IBD is encouraged, bearing in mind that several drugs currently used in the treatment of IBD possess properties affecting mast cell activities. This article is part of a Special Issue entitled: Mast cells in inflammation.

Gastrointestinal dysmotility is associated with altered gut flora and septic mortality in patients with severe systemic inflammatory response syndrome: a preliminary study

BACKGROUND

The gut is an important target organ for injury after severe insult, and resolution of feeding intolerance is crucial for critically ill patients. We investigated gut flora and motility to evaluate the impact of gastrointestinal dysmotility on septic complications in patients with severe systemic inflammatory response syndrome (SIRS).

METHODS

Sixty-three ICU patients with severe SIRS were divided into two groups depending on their intestinal condition. Patients with feeding intolerance comprised patients who had feeding intolerance, defined as ≥ 300 mL reflux from nasal gastric feeding tube in 24 h, and patients without feeding intolerance comprised patients with no feeding intolerance. We compared fecal microflora, incidences of bacteremia, and mortality between these groups.

KEY RESULTS

Analysis of feces showed that patients with feeding intolerance had significantly lower numbers of total obligate anaerobes including Bacteroidaceae and Bifidobacterium, higher numbers of Staphylococcus, lower concentrations of acetic acid and propionic acid, and higher concentrations of succinic acid and lactic acid than those in patients without feeding intolerance (P ≤ 0.05). Patients with feeding intolerance had higher incidences of bacteremia (86%vs 18%) and mortality (64%vs 20%) than did patients without feeding intolerance (P ≤ 0.05).

CONCLUSIONS & INFERENCES

Gut flora and organic acids were significantly altered in patients with severe SIRS complicated by gastrointestinal dysmotility, which was associated with higher septic mortality in SIRS patients.

Altered host-microbe interaction in HIV: a target for intervention with pro- and prebiotics

The intestinal immune system is severely affected by HIV and circulating microbial products from the intestinal tract that provide an ongoing source of systemic inflammation and concomitant viral replication. In addition, HIV-infected individuals can have a deregulated immune response that may hamper the anti-viral capacity of the host. Various probiotic organisms and prebiotic agents have been shown to enhance intestinal epithelial barrier functions, reduce inflammation, and support effective Th-1 responses. As these characteristics may benefit HIV patients, this review aims to provide a theoretical framework for the development of probiotic and prebiotic interventions specifically for this population.

Microbiological and immunological effects of enteral feeding on the upper gastrointestinal tract

Enteral feeding via a percutaneous endoscopic gastrostomy tube is required for nutritional support in patients with dysphagia. Enteral tube feeding bypasses the innate defence mechanisms in the upper gastrointestinal tract. This study examined the surface-associated microbial populations and immune response in the gastric and duodenal mucosae of eight enteral nutrition (EN) patients and ten controls. Real-time PCR and fluorescence in situ hybridization were employed to assess microbiota composition and mucosal pro-inflammatory cytokine expression. The results showed that EN patients had significantly higher levels of bacterial DNA in mucosal biopsies from the stomach and duodenum (P<0.05) than the controls, and that enterobacteria were the predominant colonizing species on mucosal surfaces in these individuals. Expression of the pro-inflammatory cytokines interleukin (IL)-1α, IL-6 and tumour necrosis factor-α was significantly higher in gastric and small intestinal mucosae from patients fed normal diets in comparison with those receiving EN (P<0.05). These results indicate that EN can lead to significant bacterial overgrowth on upper gastrointestinal tract mucosae and a significantly diminished pro-inflammatory cytokine response.

[Gut translocation septicemia in infant]

Intestinal microbiotype necessary for life is a source of complications in childhood. Bacterial translocation is responsible of endogenous septicaemia and invasive complications. We report five cases of severe invasive infections associated with diarrhoea, digestive bleeding or sepsis. Biological parameters for inflammation are highly positive, and blood cultures reveal bacterial identification: salmonella enteridis, enterobacter cloacae, campylobacter jejuni, escherichia coli or clostridium difficile. We describe the predisposing factors and susceptibility status to develop translocation: invasive diarrhoea, asplenia, gasto-intestinal disease… All invasive infections in children require etiological approach with the possibility of an endogenous septicaemia (bacterial translocation). This approach minimises the nosocomial features undercurrent in these invasive infections, and leads also to other alternative preventive measures: antibiotic association, maintaining an enteral nutrition, pre or probiotic use, specific digestive decontamination.

Randomised clinical trial: the effects of perioperative probiotic treatment on barrier function and post-operative infectious complications in colorectal cancer surgery - a double-blind study

BACKGROUND

Infection following abdominal operation remains a major factor affecting the morbidity of patients after surgery.

AIM

To determine the effects of perioperative administration of probiotics on the gut barrier function and the surgical outcome in patients undergoing elective colorectal surgery.

METHODS

One hundred patients with colorectal carcinoma were randomly divided into the control group (n = 50) and the probiotics group (n = 50). The probiotics were given orally for 6 days preoperatively and 10 days post-operatively. Outcomes were measured by bacterial translocation, gut permeability, the effect on the faecal microbiota, and the clinical outcomes such as infectious-related complications and gut defecation function.

RESULTS

Compared with the control group, probiotics group had increased transepithelial resistance (P < 0.05), reduced transmucosal permeation of horseradish peroxidase and lactulose/mannitol ratio, reduced bacterial translocation (P < 0.05), decreased ileal-bile acid binding protein (P < 0.05) and positive rate of blood bacterial DNA (P < 0.05) and an enhanced mucosal tight junction protein expression. They had decreased blood enteropathogenic bacteria and increased faecal bacterial variety. The post-operative recovery of peristalsis, incidence of diarrhoea, and infectious-related complications were also improved.

CONCLUSION

Probiotics can improve the integrity of gut mucosal barrier by benefiting the faecal microbiota, and decreasing infectious complications in patients with colorectal cancer undergoing colorectomy.

Candida tropicalis in human disease

Candida tropicalis is one of the more common Candida causing human disease in tropical countries; the frequency of invasive disease varies by geography causing 3--66% of candidaemia. C. tropicalis is taxonomically close to C. albicans and shares many pathogenic traits. C. tropicalis is particularly virulent in neutropenic hosts commonly with hematogenous seeding to peripheral organs. For candidaemia and invasive candidiasis amphotericin B or an echinocandin are recommended as first-line treatment, with extended-spectrum triazoles acceptable alternatives. Primary fluconazole resistance is uncommon but may be induced on exposure. Physicians in regions where C. tropicalis is common need to be mindful of this lesser-described pathogen.

Sepsis as a cause and consequence of acute kidney injury: Program to Improve Care in Acute Renal Disease

Purpose

Sepsis commonly contributes to acute kidney injury (AKI); however, the frequency with which sepsis develops as a complication of AKI and the clinical consequences of this sepsis are unknown. This study examined the incidence of, and outcomes associated with, sepsis developing after AKI.

Methods

We analyzed data from 618 critically ill patients enrolled in a multicenter observational study of AKI (PICARD). Patients were stratified according to their sepsis status and timing of incident sepsis relative to AKI diagnosis.

Results

We determined the associations among sepsis, clinical characteristics, provision of dialysis, in-hospital mortality, and length of stay (LOS), comparing outcomes among patients according to their sepsis status. Among the 611 patients with data on sepsis status, 174 (28%) had sepsis before AKI, 194 (32%) remained sepsis-free, and 243 (40%) developed sepsis a median of 5 days after AKI. Mortality rates for patients with sepsis developing after AKI were higher than in sepsis-free patients (44 vs. 21%; p < 0.0001) and similar to patients with sepsis preceding AKI (48 vs. 44%; p = 0.41). Compared with sepsis-free patients, those with sepsis developing after AKI were also more likely to be dialyzed (70 vs. 50%; p < 0.001) and had longer LOS (37 vs. 27 days; p < 0.001). Oliguria, higher fluid accumulation and severity of illness scores, non-surgical procedures after AKI, and provision of dialysis were predictors of sepsis after AKI.

Conclusions

Sepsis frequently develops after AKI and portends a poor prognosis, with high mortality rates and relatively long LOS. Future studies should evaluate techniques to monitor for and manage this complication to improve overall prognosis.

Immunonutrition in patients undergoing major upper gastrointestinal surgery: a prospective double-blind randomised controlled study

INTRODUCTION

current studies suggest immunonutrition decreases the inflammatory process, infection rates and reduces length of hospital stay in surgical patients, however studies are often conducted on heterogeneous groups of patients with varying composition of the immuno-nutrition. We aim to investigate the effect of immunonutrition on patients undergoing major upper gastrointestinal surgery by assessment of (i) the inflammatory and immune response and (ii) changes in clinical outcome when compared to a randomised control receiving conventional feeding.

METHOD

a prospective double-blind randomised controlled study was undertaken to compare a feed supplemented with glutamine, arginine, -3 fatty acids and tributyrin, vitamin C, E and B-carotene and micronutrients (zinc, selenium and chromium) to an isonitrogenous, isocaloric control feed in patients undergoing major upper GI surgery. The primary end-points were defined as C-reactive protein (CRP), prealbumin and retinol binding protein (RBP) levels. Secondary end-points included performance scoring systems, length of hospital stay, adverse events and protein and nutrient assays. Variables were measured pre-operatively and routinely up to the 4th post-operative day.

RESULTS

there was no statistically significant change in primary end-points between the immunonutrition group and the control group. There was no difference in length of hospital stay between the groups. The vitamin C level in the study group was significantly higher at the end of the study period. Both groups tolerated the feeds well with adequate target feeding rate. There were no other significant changes in clinical outcomes between the two groups.

CONCLUSION

this study has not shown a benefit of immunonutrition through changes in inflammatory or nutritional markers, a decrease in length of hospital stay, or other morbidity. This may be because of inadequate numbers recruited to the study. Further, multi-centre, randomised trials on homogeneous patient groups are necessary to investigate the role of immunonutrition in major upper GI surgery.

Interplay between inflammation, immune system and neuronal pathways: Effect on gastrointestinal motility

Sepsis is a systemic inflammatory response representing the leading cause of death in critically ill patients, mostly due to multiple organ failure. The gastrointestinal tract plays a pivotal role in the pathogenesis of sepsis-induced multiple organ failure through intestinal barrier dysfunction, bacterial translocation and ileus. In this review we address the role of the gastrointestinal tract, the mediators, cell types and transduction pathways involved, based on experimental data obtained from models of inflammation-induced ileus and (preliminary) clinical data. The complex interplay within the gastrointestinal wall between mast cells, residential macrophages and glial cells on the one hand, and neurons and smooth muscle cells on the other hand, involves intracellular signaling pathways, Toll-like receptors and a plethora of neuroactive substances such as nitric oxide, prostaglandins, cytokines, chemokines, growth factors, tryptases and hormones. Multidirectional signaling between the different components in the gastrointestinal wall, the spinal cord and central nervous system impacts inflammation and its consequences. We propose that novel therapeutic strategies should target inflammation on the one hand and gastrointestinal motility, gastrointestinal sensitivity and even pain signaling on the other hand, for instance by impeding afferent neuronal signaling, by activation of the vagal anti-inflammatory pathway or by the use of pharmacological agents such as ghrelin and ghrelin agonists or drugs interfering with the endocannabinoid system.

Virulence characteristics of translocating Escherichia coli and the interleukin-8 response to infection

Four efficiently translocating Escherichia coli (TEC) strains isolated from the blood of humans (HMLN-1), pigs (PC-1) and rats (KIC-1 and KIC-2) were tested for their ability to adhere and translocate across human gut epithelial Caco-2 and HT-29 cells, to elicit a proinflammatory response and for the presence of 47 pathogenic E. coli virulence genes. HMLN-1 and PC-1 were more efficient in adhesion and translocation than rat strains, had identical biochemical phenotype (BPT) and serotype (O77:H18) and phylogenetic group (D). KIC-2 adhered more than KIC-1, belonged to different BPT and serotype but the same phylogenetic group as KIC-1. TEC strains elicited significantly higher IL-8 response in both cell lines (P < 0.05) and monocytic THP-1 (P < 0.0001) cells than non-TEC strains. KIC-2 induced the highest IL-8 response which may be associated with its immunostimulatory flagellin. Apart from adhesin genes fimH and bmaE that were carried by all strains, HMLN-1 and PC-1 carried capsule synthesis gene kpsMT III and KIC-2 carried the EAST1 toxin gene. The lack of known virulence genes and the ability of TEC to efficiently adhere and translocate whilst causing proinflammatory response suggests that these strains may carry as yet unidentified genes that enable their translocating ability.

The interaction between a non-pathogenic and a pathogenic strain synergistically enhances extra-intestinal virulence in Escherichia coli

Finding two or more genotypes of a single species within an infected sample is a not infrequent event. In this work, three Escherichia coli strains of decreasing extra-intestinal virulence (pathogenic B2S and B1S strains, and the avirulent K-12 MG1655 strain) were tested in septicaemia and urinary tract infection (UTI) mouse models, either separately or in pairs. Survival was monitored and bacteria were counted in various organs. Serum interleukin (IL)-6, tumour necrosis factor alpha (TNFα) and IL-10 were measured. We show that a mix of high amounts of B1S or of MG1655 with low amounts of B2S killed more rapidly (B1S), or killed more mice (MG1655), than either high amounts of B1S, high amounts of MG1655 or low amounts of B2S separately in the mouse septicaemia model. This bacterial synergy persisted when high amounts of dead or abnormal-LPS K-12 cells were injected together with a low amount of B2S. In both septicaemia and UTI models, significantly more bacteria were recovered from the organs of mice injected with the MG1655/B2S mix than from those of mice injected with the inocula separately. Consistently, in the septicaemia model, more IL-6 was secreted before death by the mice that were injected with the mix of bacteria than by the mice that were injected with the inocula separately. The synergistically enhanced mortality in the case of co-infection in the septicaemia model persisted in RFcγ(-/-), Myd88(-/-) and IL-6(-/-) knockout mice. This synergistically increased virulence resulting from the interaction between an avirulent and a pathogenic strain of the same bacterial species raises questions about the role of avirulent bacteria in the development of some extra-intestinal infections.

Population structure of gut Escherichia coli and its role in development of extra-intestinal infections

Extra-intestinal pathogenic Escherichia coli (ExPEC) strains are divided into uropathogenic E. coli (UPEC), strains causing neonatal meningitis and septicaemic E. coli. The most common pathotype of ExPEC is found among patients with urinary tract infection (UTI), defined as UPEC. These bacteria are responsible for >90% of cases of UTI and are often found amongst the faecal flora of the same host. E.coli strains are classified into four phylogenetic groups, A, B1, B2, and D. Groups A and B1 are commensal strains and carry few virulence-associated genes (VGs) while pathogenic group B2 and D usually possess VGs which enhance colonic persistence and adhesion in the urinary tract (UT). The gastrointestinal (GI) tract is widely accepted as a reservoir for UPEC and is believed that healthy humans have a reservoir of UPEC strains, belonging to phylogenetic group B2, and to a lesser extent, group D. These strains have superior ability to survive and persist in the gut of humans and can spread to cause extra-intestinal infections. ExPEC trains possess a range of VGs which are involved in their pathogenesis. These include adhesins, toxins, iron-acquisition systems (e.g. siderophores), and capsules. Evolutionary influences on the acquisition and main role of VGs amongst E. coli are widely debated, with some research holding that the prevalence of strains with VGs increases the likelihood of infections, whereas others believe that VGs provide a selective advantage for infection of extra-intestinal sites. This review is intended to present our existing knowledge and gaps in this area.

Effects of gut microflora on hepatic damage after acute liver injury in rats

BACKGROUND

Liver injury often causes disruption of the gut microflora. The aim of this work was to evaluate the effects of microflora variations on acute liver injury.

METHODS

Sprague-Dawley rats received saline, probiotics, Escherichia coli, Salmonella enteritidis, or gentamicin via daily gavage for 7 days. Acute liver injury was induced on the eighth day by intraperitoneal injection of d-galactosamine except for the normal group. Samples were collected 24 hours later. Bacterial translocation (BT) was evaluated from the liver, spleen, kidney, and mesenteric lymph nodes. Liver enzymes, histologic analysis, endotoxin, serum tumor necrosis factor-alpha, interleukin (IL)-6, IL-10, IL-12, CD3 and CD4 T cells in peripheral blood and Peyer's patches, intestinal bacteria, and intestinal mucosal ultrastructure were studied.

RESULTS

Orally administered probiotics, nonpathogenic E. coli, and gentamicin, respectively, markedly attenuated liver damage, decreased BT, and decreased the levels of serum tumor necrosis factor-alpha, IL-6, IL-10, and IL-12. Treatment with S. enteritidis had opposite results. Only orally supplemented S. enteritidis significantly affected the CD3 and CD4 T cells counts in peripheral blood and Peyer's patches.

CONCLUSIONS

We demonstrated that modifications in gut microflora had different effects on the prevention or exacerbation of acute liver injury. Moreover, alterations in gut microflora affected liver damage through three major factors: BT and the release of local gut cytokine and endotoxin.

The value of serum procalcitonin level for differentiation of infectious from noninfectious causes of fever after orthopaedic surgery

BACKGROUND

Early diagnosis of postoperative orthopaedic infections is important in order to rapidly initiate adequate antimicrobial therapy. There are currently no reliable diagnostic markers to differentiate infectious from noninfectious causes of postoperative fever. We investigated the value of the serum procalcitonin level in febrile patients after orthopaedic surgery.

METHODS

We prospectively evaluated 103 consecutive patients with new onset of fever within ten days after orthopaedic surgery. Fever episodes were classified by two independent investigators who were blinded to procalcitonin results as infectious or noninfectious origin. White blood-cell count, C-reactive protein level, and procalcitonin level were assessed on days 0, 1, and 3 of the postoperative fever.

RESULTS

Infection was diagnosed in forty-five (44%) of 103 patients and involved the respiratory tract (eighteen patients), urinary tract (eighteen), joints (four), surgical site (two), bloodstream (two), and soft tissues (one). Unlike C-reactive protein levels and white blood-cell counts, procalcitonin values were significantly higher in patients with infection compared with patients without infection on the day of fever onset (p = 0.04), day 1 (p = 0.07), and day 3 (p = 0.003). Receiver-operating characteristics demonstrated that procalcitonin had the highest diagnostic accuracy, with a value of 0.62, 0.62, and 0.71 on days 0, 1, and 3, respectively. In a multivariate logistic regression analysis, procalcitonin was a significant predictor for postoperative infection on days 0, 1, and 3 of fever with an odds ratio of 2.3 (95% confidence interval, 1.1 to 4.4), 2.3 (95% confidence interval, 1.1 to 5.2), and 3.3 (95% confidence interval, 1.2 to 9.0), respectively.

CONCLUSIONS

Serum procalcitonin is a helpful diagnostic marker supporting clinical and microbiological findings for more reliable differentiation of infectious from noninfectious causes of fever after orthopaedic surgery.

Changes in intestinal mucosal immune barrier in rats with endotoxemia

AIM: To investigate the dysfunction of the immunological barrier of the intestinal mucosa during endotoxemia and to elucidate the potential mechanism of this dysfunction.

METHODS: Male Wistar rats were randomly distributed into two groups: control group and lipopolysaccharide (LPS) group. Endotoxemia was induced by a single caudal venous injection of LPS. Animals were sacrificed in batches 2, 6, 12 and 24 h after LPS infusion. The number of microfold (M)-cells, dendritic cells (DCs), CD4⁺ T cells, CD8⁺ T cells, regulatory T (Tr) cells and IgA⁺ B cells in the intestinal mucosa were counted after immunohistochemical staining. Apoptotic lymphocytes were counted after TUNEL staining. The levels of interleukin (IL)-4, interferon (IFN)-γ and forkhead box P3 (Foxp3) in mucosal homogenates were measured by ELISA. The secretory IgA (sIgA) content in the total protein of one milligram of small intestinal mucus was detected using a radioimmunological assay.

RESULTS: This research demonstrated that LPS-induced endotoxemia results in small intestinal mucosa injury. The number of M-cells, DCs, CD8⁺ T cells, and IgA⁺ B cells were decreased while Tr cell and apoptotic lymphocyte numbers were increased significantly. The number of CD4⁺ T cells increased in the early stages and then slightly decreased by 24 h. The level of IL-4 significantly increased in the early stages and then reversed by the end of the study period. The level of IFN-γ increased slightly in the early stages and then decreased markedly by the 24 h time point. Level of Foxp3 increased whereas sIgA level decreased.

CONCLUSION: Mucosal immune dysfunction forms part of the intestinal barrier injury during endotoxemia. The increased number and function of Tr cells as well as lymphocyte apoptosis result in mucosal immunodeficiency.

Bacterial translocation in an experimental intestinal obstruction model. C-reactive protein reliability?

BACKGROUND

Bacterial translocation occurs in preseptic conditions such as intestinal obstruction through unclear mechanism. The C-reactive protein is an acute phase reactant and a marker of ischemia.

METHODS

45 albino male rats were divided into 3 groups each 15 rats. GI control, GII simple intestinal-obstruction and GIII strangulated obstruction. Outcome measures were: (1) Bacteriologic count and typing for intestinal contents, intestinal wall, liver, mesenteric lymph nodes and blood (cardiac and portal) (2) Histopathologic: mucosal injury score, inflammatory cell infiltrate in the wall, MLN, liver, (3) Biochemical: serum CRP, IL-10, mucosal stress pattern (glutathione peroxidase-malonyldialdhyde tissue levels).

RESULTS

(1) Intestinal obstruction associates with BT precursors (Bact-overgrowth, mucosal-acidosis, immuno-incomptence), (2) Bacterial translocation (frequency and density) was found higher in strangulated I.O, that was mainly enteric (aerobic and anaerobic) and mostly E.coli, (3) The pathogen commonality supports the gut origin hypothesis but the systemic inflammatory response goes with the cytokine generating one. (4) The CRP median values for GI, II, III were 0.5, 6.9, 8.5 mg/L, for BT +ve 8 mg/L and 0.75 mg/L for BT -ve rats.

CONCLUSION

Bacterial translocation occurs bi-directional (systemic-portal) in intestinal obstruction and the resultant inflammatory response pathogenesis is mostly 3 hit model. The CRP is a non selective marker of suspected I.O cases. However, it is a reliable marker of BT, BT density and vascular compromise during I.O.

Genetic relatedness and virulence gene profiles of Escherichia coli strains isolated from septicaemic and uroseptic patients

We investigated the relationship between clonality and virulence factors (VFs) of a collection of Escherichia coli strains isolated from septicaemic and uroseptic patients with respect to their origin of translocation. Forty septicaemic and 30 uroseptic strains of E. coli were tested for their phylogenetic groupings, genetic relatedness using randomly amplified polymorphic DNA (RAPD), biochemical fingerprinting method (biochemical phenotypes [BPTs]), adherence to HT-29 cells and the presence of 56 E. coli VF genes. Strains belonging to phylogenetic groups B2 and D constituted 93% of all strains. Fifty-four (77%) strains belonged to two major BPT/RAPD clusters (A and B), with cluster A carrying significantly (P = 0.0099) more uroseptic strains. The degree of adhesion to HT-29 cells of uroseptic strains was significantly (P = 0.0012) greater than that of septicaemic strains. Of the 56 VF genes tested, pap genes was the only group that were found significantly (P < 0.0001) more often among uroseptic isolates. Phylogenetic group B2 contained a significantly higher number of strains carrying pap genes than those in group D. We conclude that uroseptic E. coli are clonally different from septicaemic strains, carry more pap genes and predominantly adhere more to the HT-29 cell model of the gut.

Pathogenic natural antibodies recognizing annexin IV are required to develop intestinal ischemia-reperfusion injury

Intestinal ischemia-reperfusion (IR) injury is initiated when natural IgM Abs recognize neo-epitopes that are revealed on ischemic cells. The target molecules and mechanisms whereby these neo-epitopes become accessible to recognition are not well understood. Proposing that isolated intestinal epithelial cells (IEC) may carry IR-related neo-epitopes, we used in vitro IEC binding assays to screen hybridomas created from B cells of unmanipulated wild-type C57BL/6 mice. We identified a novel IgM mAb (mAb B4) that reacted with the surface of IEC by flow cytometric analysis and was alone capable of causing complement activation, neutrophil recruitment and intestinal injury in otherwise IR-resistant Rag1(-/-) mice. mAb B4 was found to specifically recognize mouse annexin IV. Preinjection of recombinant annexin IV blocked IR injury in wild-type C57BL/6 mice, demonstrating the requirement for recognition of this protein to develop IR injury in the context of a complex natural Ab repertoire. Humans were also found to exhibit IgM natural Abs that recognize annexin IV. These data in toto identify annexin IV as a key ischemia-related target Ag that is recognized by natural Abs in a pathologic process required in vivo to develop intestinal IR injury.

Host species-specific translocation of Escherichia coli

The purpose of this paper is to investigate the rate of translocation of Escherichia coli strains in different experimental/animal models. Four proficient translocating E. coli strains isolated from mesenteric lymph nodes (MLNs) and/or the blood of rats (strains KIC-1 and KIC-2), from a fatal case of pancreatitis (HMLN-1) and from pigs (PC-1 isolated in this study) were tested for their ability to translocate across two host species and the Caco-2 cell line as a model of the human gut epithelium. HMLN-1 was found in the MLNs of all 15 pigs tested. This strain, however, did not translocate in any rats and only colonised the caecum of four rats in small numbers. HMLN-1 and PC-1 were the dominant translocating strains in Caco-2 cells compared to KIC-1 and KIC-2, which were found to translocate at a lower rate in pigs and in Caco-2 cells. The rate of translocation of PC-1 in rats was also very low compared to KIC-1 and KIC-2. We suggest that, in studies aiming to investigate the mechanism of translocation of E. coli strains isolated from humans, rats may not be an appropriate animal model and that the Caco-2 cells or pigs are more suitable in vitro and in vivo models, respectively.

Synbiotics decrease the incidence of septic complications in patients with severe SIRS: a preliminary report

The purpose of this study was to evaluate if synbiotic therapy can correct the deteriorated gut flora and environment in patients with severe systemic inflammatory response syndrome (SIRS). Twenty-nine SIRS patients, who fulfilled a serum C-reactive protein (CRP) level >10 mg/dl, received synbiotics (Bifidobacterium breve, Lactobacillus casei, and galactooligosaccharides) (S group) and were compared with previous observations in 26 patients without synbiotics (NS group). Analysis of fecal flora confirmed that patients in the S group had significantly greater levels of beneficial Bifidobacterium, Lactobacillus, and total organic acids (particularly short-chain fatty acids) than those in the NS group. The incidence of infectious complications such as enteritis, pneumonia, and bacteremia was significantly lower in the S group than in the NS group. Synbiotics maintain the gut flora and environment and decrease the incidence of septic complications in patients with severe SIRS. Further randomized controlled study is necessary to determine the effects of synbiotics.

Does the use of probiotics/synbiotics prevent postoperative infections in patients undergoing abdominal surgery? A meta-analysis of randomized controlled trials

BACKGROUND

Advances in surgery have considerably lowered postoperative morbidity. However, infection remains a considerable morbidity factor. The aim of this review is to identify the potential benefit(s) of the perioperative administration of probiotics/synbiotics to patients undergoing abdominal surgery.

METHODS

We searched PubMed, Scopus, Web of Science, and Cochrane library to identify randomized controlled trials (RCTs) that studied the perioperative administration of probiotics/synbiotics to patients undergoing abdominal surgery.

RESULTS

Nine RCTs studying 733 patients were included in our review. The incidence of postoperative pneumonia, cholangitis, and any infections as well as the duration of postoperative hospital stay and length of antibiotic therapy were lower among patients receiving probiotics than in the control group [six RCTs, 355 patients, odds ratio (OR) 0.24, 95% confidence interval (CI) 0.09-0.68; three RCTs, 209 patients, OR 0.18, 95% CI 0.05-0.57; seven RCTs, 514 patients, OR 0.26, 95% CI 0.12-0.55; five RCTs, 313 patients, OR -2.70, 95% CI -5.15 to -0.25; four RCTs, 250 patients, OR -4.01, 95% CI -5.11 to -2.92, respectively], while the incidence of postoperative wound infection, urinary tract infection, intra-abdominal abscess, and mortality was not different between patients of the compared groups (six RCTs, 355 patients, OR 0.52, 95% CI 0.23-1.18; five RCTs, 313 patients, OR 0.44, 95% CI 0.04-5.54; four RCTs, 226 patients, OR 0.44, 95% CI 0.12-1.59; nine RCTs, 685 patients, OR 0.98, 95% CI 0.29-3.29, respectively).

CONCLUSION

The use of probiotics/synbiotics may reduce postoperative infections after abdominal surgery. This is a promising infection-preventive measure that may decrease morbidity, length of antibiotic therapy, duration of hospital stay, and pressure for emergence of antimicrobial resistance. However, the results of this meta-analysis should be interpreted with caution due to the significant heterogeneity of the studies included.

Effects of gut barrier dysfunction and NF-kappaB activation on aggravating mechanism of severe acute pancreatitis

OBJECTIVE

To study the effects of gut-derived endotoxin translocation and NF-kappaB activation on the aggravating mechanism of severe acute pancreatitis (SAP) and of treatment with pyrrolidine dithiocarbamate (PDTC) on rats with SAP.

METHODS

SD rats were randomly divided into sham operation group (SO), SAP group, SAP + lipopolysaccharide(LPS) group, pyrrolidine dithiocarbamate (PDTC) treatment group and LPS group. Biochemical parameters and cytokines were examined in the serum. Multiple organs pathological slices were examined. Expression of NF-kappaB mRNA in the liver tissue was detected by RT-PCR. Activation of NF-kappaB by the method of streptomycin avidin-peroxidase (SP) and expression of NF-kappaB p65 protein and its binding activity were analyzed by Western blot and electrophoretic mobidity shift assay (EMSA).

RESULTS

Compared with sham operation group, the concentration of TNF-alpha, alanine aminotransferase (ALT), and diamine oxidase (DAO) in serum significantly increased in SAP + LPS group (P < 0.05). Pathological changes were markedly observed in tissues and the expression of NF-kappaB mRNA in the liver significantly increased (P < 0.05) also, the activation of NF-kappaB and binding activity of NF-kappaB p65 protein in the liver markedly increased (P < 0.01) in SAP + LPS group. Treatment with PDTC markedly reduced concentration of ALT, DAO and TNF-alpha, and the expression of NF-kappaB, and the pathologic scores, as well as significantly decreased the expression of NF-kappaB p65 protein.

CONCLUSION

The activation and overexpression of NF-kappaB may participate in the aggravating mechanism of SAP. Treatment with PDTC has a protective effect on multiple organs damage in SAP.

Liver dysfunction and sepsis determine operative mortality after liver resection

BACKGROUND

Liver failure is the principal cause of death after hepatectomy. Its progression towards death and its relationship with sepsis are unclear. This study analysed predictors of mortality in patients with liver dysfunction and the role of sepsis in the death of these patients.

METHODS

The study focused on patients with liver dysfunction, excluding those with vascular thrombosis, after liver resection at one of two centres between 1998 and 2006.

RESULTS

Liver dysfunction occurred after 57 (4.5 per cent) of 1271 hepatectomies. Fifty-three patients without vascular thrombosis were included in the analysis, with a mortality rate of 23 per cent. Independent predictors of death were age (odds ratio (OR) 1.18 per year increase; P = 0.017), cirrhosis (OR 54.09; P = 0.004) and postoperative sepsis (OR 37.58; P = 0.005). Sepsis occurred in 15 patients (28 per cent), seven of whom died. Intestinal pathogens were isolated in 12 patients with sepsis. The risk of sepsis was significantly increased in those with surgical complications (11 of 16 versus four of 37; P < 0.001).

CONCLUSION

Sepsis plays a key role in the death of patients with liver dysfunction after hepatectomy. Early recognition and aggressive treatment of sepsis may reduce mortality.

Mesenteric microcirculatory dysfunctions and translocation of indigenous bacteria in a rat model of strangulated small bowel obstruction

PURPOSE

Bacterial translocation has been shown to occur in critically ill patients after extensive trauma, shock, sepsis, or thermal injury. The present study investigates mesenteric microcirculatory dysfunctions, the bacterial translocation phenomenon, and hemodynamic/metabolic disturbances in a rat model of intestinal obstruction and ischemia.

METHODS

Anesthetized (pentobarbital 50 mg/kg, i.p.) male Wistar rats (250-350 g) were submitted to intestinal obstruction or laparotomy without intestinal obstruction (Sham) and were evaluated 24 hours later. Bacterial translocation was assessed by bacterial culture of the mesenteric lymph nodes (MLN), liver, spleen, and blood. Leukocyte-endothelial interactions in the mesenteric microcirculation were assessed by intravital microscopy, and P-selectin and intercellular adhesion molecule (ICAM)-1 expressions were quantified by immunohistochemistry. Hematocrit, blood gases, lactate, glucose, white blood cells, serum urea, creatinine, bilirubin, and hepatic enzymes were measured.

RESULTS

About 86% of intestinal obstruction rats presented positive cultures for E. coli in samples of the mesenteric lymph nodes, liver, and spleen, and 57% had positive hemocultures. In comparison to the Sham rats, intestinal obstruction induced neutrophilia and increased the number of rolling (approximately 2-fold), adherent (approximately 5-fold), and migrated leukocytes (approximately 11-fold); this increase was accompanied by an increased expression of P-selectin (approximately 2-fold) and intercellular adhesion molecule-1 (approximately 2-fold) in the mesenteric microcirculation. Intestinal obstruction rats exhibited decreased PaCO2, alkalosis, hyperlactatemia, and hyperglycemia, and increased blood potassium, hepatic enzyme activity, serum urea, creatinine, and bilirubin. A high mortality rate was observed after intestinal obstruction (83% at 72 h vs. 0% in Sham rats).

CONCLUSION

Intestinal obstruction and ischemia in rats is a relevant model for the in vivo study of mesenteric microcirculatory dysfunction and the occurrence of bacterial translocation. This model parallels the events implicated in multiple organ dysfunction (MOD) and death.

Food fight! Parenteral nutrition, enteral stimulation and gut-derived mucosal immunity

INTRODUCTION

Nutrition support is an integral component of modern patient care. Type and route of nutritional support impacts clinical infectious outcomes in critically injured patients.

DISCUSSION

This article reviews the relationships between type and route of nutrition and gut-derived mucosal immunity in both the clinical and laboratory settings.

Magnolol attenuates sepsis-induced gastrointestinal dysmotility in rats by modulating inflammatory mediators

AIM: To investigate the protective effects of magnolol on sepsis-induced inflammation and intestinal dysmotility.

METHODS: Sepsis was induced by a single intraperitoneal injection of lipopolysaccharide (LPS). Male Wistar rats were randomly assigned to one of three treatment groups: magnolol prior to LPS injection (LPS/Mag group); vehicle prior to LPS injection (LPS/Veh group); vehicle prior to injection of saline (Control/Veh). Intestinal transit and circular muscle mechanical activity were assessed 12 h after LPS injection. Tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), monocyte chemoattractant protein-1 (MCP-1) and inducible nitric oxide synthase (iNOS) mRNA in rat ileum were studied by RT-PCR 2 h after LPS injection. Nuclear factor-κB (NF-κB) activity in the intestine was also investigated at this time using electrophoretic mobility shift assay. In addition, antioxidant activity was determined by measuring malondialdehyde (MDA) concentration and superoxide dismutase (SOD) activity in the intestine 2 h after LPS injection.

RESULTS: Magnolol significantly increased intestinal transit and circular muscle mechanical activity in LPS-treated animals. TNF-α, MCP-1 and iNOS mRNA expression in the small intestine were significantly reduced after magnolol treatment in LPS-induced septic animals, compared with untreated septic animals. Additionally, magnolol significantly increased IL-10 mRNA expression in septic rat ileum. Magnolol also significantly suppressed NF-κB activity in septic rat intestine. In addition, magnolol significantly decreased MDA concentration and increased SOD activity in rat ileum.

CONCLUSION: Magnolol prevents sepsis-induced suppression of intestinal motility in rats. The potential mechanism of this benefit of magnolol appears to be modulation of self-amplified inflammatory events and block of oxidative stress in the intestine.

Bioflora probiotic in immunomodulation and prophylaxis of intestinal bacterial translocation in rats

The immunomodulator effect of Bioflora probiotic on T (CD4+) and B (CD20) lymphocytes in gastrointestinal mucosa and intestinal bacterial translocation was studied using Wistar rats (n = 10 per group). Two experiments were used: (I) stress with immobilization and water immersion at 22 degrees C for 7 h plus the application of indomethacin (Indo) 10 mg/kg SC every 24 h for 3 days (comparator group), and (II) stress experiment I with the addition of 1 mL of Bioflora applied through a orogastric tube every 12 h for 3 days. At the 4th day, in asepsis, a dissection laparotomy of liver, spleen, mesenteric lymphatic nodes, and cecum was performed for microbiological culture, and stomach, ileum, and colon were also dissected for immunohistochemical and quantification of CD4+ and CD20. Findings in experiment I revealed cecum bacterial overdevelopment of 6 x 10(10) +/- 2.3 x 10(9) colony-forming units (CFU) (P < 0.01) and positive cultures in liver, spleen, and all mesenteric lymphatic nodes. On the other hand, in the group treated with Probiotic Bioflora, cecum without overdevelopment (3 x 10(6) +/- 1.3 x 10(5) CFU), negative cultures in liver and spleen, and in lymphatic nodes two positive and eight negative cultures for E. coli and P. vulgaris (P < 0.01) were observed. Immunohistochemistry revealed a relevant increase of T lymphocytes (CD4+) in ileum and colon.

CONCLUSIONS

Bioflora probiotic was shown to be an intestinal immunomodulator that induced increased T (CD4+) lymphocytes that also offer prophylaxis of intestinal bacterial translocation in a stressed rat model.

Distribution of secretory inhibitor of platelet microbicidal protein among anaerobic bacteria isolated from stool of children with diarrhea

AIM: To study the secretory inhibitor of platelet microbicidal protein (SIPMP) phenotypes of faecal anaerobic isolates from patients with diarrhea.

METHODS: Faecal isolates of anaerobic bacteria (B. fragilis, n = 42; B. longum, n = 70; A. israelii, n = 21; E. lentum, n = 12) from children with diarrhea were tested. SIPMP production was tested by inhibition of platelet microbicidal protein (PMP) bioactivity against B. subtilis and was expressed as percentage of inhibition of PMP bactericidal activity.

RESULTS: Among anaerobic isolates 80% of B. longum strains, 85.7% of A. israelii strains, 50% of E. lentum strains and 92.86% of B. fragilis strains were SIPMP-positive. The isolated anaerobic organisms demonstrated SIPMP production at a mean level of 13.8% ± 0.7%, 14.7% ± 1.8%, 3.9% ± 0.9% (P < 0.05) and 26.8% ± 7.5% (P < 0.05) for bifidobacteria, A. israelii, E. lentum and B. fragilis, respectively.

CONCLUSION: Data from the present study may have significant implications in understanding the pathogenesis of microecological disorders in the intestine, as well as for future improvement in the prevention and therapy of anaerobe-associated infections.