Bacterial translocation in multiple organ failure: Cause or epiphenomenon still unproven

Impact of bacterial translocation in calves with atresia coli

OBJECTIVE

To identify whether enteric bacteria pass into the mesenteric lymph nodes (MLNs) and peritoneal cavity in calves with atresia coli and to evaluate whether the presence of bacterial translocation (BT) has an impact on the success of surgical treatment.

DESIGN

Prospective clinical study.

ANIMALS

Twenty-six client-owned calves.

INTERVENTIONS

During laparotomy, swab samples were collected from the peritoneal cavity and MLNs using a sterile swab stick and were submitted for microbiological analysis.

MEASUREMENTS AND MAIN RESULTS

Bacterial cultures of swab samples revealed that 65% (n = 17) of the calves experienced BT. Of these, 14 calves experienced BT to the MLNs, 9 to the peritoneal cavity, and 5 to both regions. Of the bacteria isolated from the MLNs, 72% (n = 10) were Escherichia coli. Of the samples isolated from the peritoneal fluid, 33% (n = 3) contained E. coli and 33% (n = 3) contained E. coli + coagulase-negative Staphylococcus (CNS). In calves with BT that were discharged (n = 13) and without BT that were discharged (n = 7), the median survival was 30 days; these data were found to be similar in the 2 groups.

CONCLUSIONS

This study revealed that BT is observed in the majority of atresia coli cases. E. coli is more common in BT, and translocation occurs primarily through the lymphatic route. These results suggest that the presence of BT is closely related to the success of the operation for correction of atresia coli.

Sepsis caused by Listeria monocytogenes during chemotherapy for small cell carcinoma of the thymus

BACKGROUND

Listeria monocytogenes is a facultative intracellular parasitic bacterium that is Gram positive, catalase positive, oxidase negative, and a facultative anaerobe. It is known to infect humans through food. It is a bacillus with low virulence, but can cause meningitis and sepsis in infants and immunocompromised patients.

CASE PRESENTATION

A case of 75-year-old Japanese female with small cell carcinoma of the thymus and pleural dissemination is described. She was treated with carboplatin and etoposide and showed a partial response. However, the tumor recurred 6 months later. Therefore, we again administered carboplatin and etoposide. Though peritoneal dissemination was suspected based on abdominal computed tomography findings after two courses, the assessment was stable disease. She was occasionally treated for constipation. She developed chills, rigor, and diarrhea, necessitating admission on the 7th day of the third course of chemotherapy. We suspected intestinal infection, and cefepime was thus administered. However, her blood pressure dropped and neutropenia manifested on the 4th day of admission. We therefore switched the antibiotic from cefepime to meropenem and also administered granulocyte-colony stimulating factor. Listeria monocytogenes was detected by two blood cultures, and the antimicrobial medication was thus switched to ampicillin, in consideration of sensitivity. Her general condition improved and she was able to leave the hospital on the 19th day after admission.

CONCLUSIONS

During chemotherapy, factors such as impaired bowel movements, malnutrition, and myeloablation can contribute to the development of severe infections. It is necessary to comprehensively assess a patient's state and treat all aspects of illness.

The impact of bacterial DNA translocation on early postoperative outcomes in Crohn's patients undergoing abdominal surgery

BACKGROUND AND AIMS

Bacterial DNA (bactDNA) translocation occurs frequently in patients with Crohn's disease and can be present in patients with a negative blood microbiological culture. We aimed to determine the effects of bactDNA translocation on postoperative outcomes in Crohn's disease patients undergoing abdominal surgery.

METHODS

Patients with Crohn's disease who underwent abdominal surgery between January 2012 and March 2014 were identified. General and postoperative outcome-related information was retrieved from a database, and the data were compared between patients with and without bactDNA translocation. Multivariate analysis was used to determine the independent effect of bactDNA translocation on postoperative morbidity.

RESULTS

One hundred and seven patients who underwent abdominal surgery were included in our study. The presence of bactDNA in blood samples was identified in 29 patients (27.1%). There was a total of 55 complications in 28 patients (26.2%). Patients with bactDNA in their blood had a mean postoperative hospital stay of 12.7±4.2 days and patients without DNA translocation had a mean postoperative hospital stay of 10.1±4.8 days (p = 0.009). The readmission rate was increased in patients with bactDNA translocation (p = 0.032). A low preoperative level of serum albumin (p = 0.024), preoperative immunosuppressive agent use (p = 0.046), and the presence of bactDNA in blood (p = 0.005) were independently associated with increased postoperative adverse outcomes.

CONCLUSIONS

Preoperative bactDNA translocation into the blood increases the incidence of postoperative adverse outcomes in patients with Crohn's disease who undergo abdominal surgery.

The common prophylactic therapy for bowel surgery is ineffective for clearing Bacteroidetes, the primary inducers of systemic inflammation, and causes faster death in response to intestinal barrier damage in mice

Introduction and objective

The role of secreted gut microbial components in the initiation of systemic inflammation and consequences of antibiotic therapies on this inflammatory process are poorly elucidated. We investigate whether peripheral innate cells mount an inflammatory response to gut microbial components, the immune cells that are the primary drivers of systemic inflammation, the bacterial populations that are predominantly responsible, and whether perioperative antibiotics affect these processes.

Method and experimental design

Conditioned supernatants from gut microbes were used to stimulate murine innate cell types in vitro and in vivo, and proinflammatory responses were characterised. Effects of antibiotic therapies on these responses were investigated using a model of experimental intestinal barrier damage induced by dextran sodium sulfate.

Results

Proinflammatory responses in the periphery are generated by components of anaerobes from the Bacteroidetes phylotype and these responses are primarily produced by myeloid dendritic cells. We found that the common prophylactic therapy for sepsis (oral neomycin and metronidazole administered to patients the day prior to surgery) is ineffective for clearing Bacteroidetes from the murine intestine. A point of critical consequence of this result is the increased systemic inflammation and premature death observed in treated mice, and these outcomes appear to be independent of gut bacterial spread in the initial phase of intestinal barrier damage. Importantly, spillage of gut microbial products, rather than dissemination of gut microbes, may underlay the initiation of systemic inflammation leading to death.

Conclusions

Our data further affirm the importance of a balanced gut microflora biodiversity in host immune homeostasis and reinforce the notion that inadequate antibiotic therapy can have detrimental effects on overall immune system.

Complement C5A antagonist treatment improves the acute circulatory and inflammatory consequences of experimental cardiac tamponade

OBJECTIVE

Cardiogenic shock often leads to splanchnic macro- and microcirculatory complications, and these events are linked to local and systemic inflammatory activation. Our aim was to investigate the consequences of complement C5a antagonist treatment on the early circulatory and inflammatory changes in a clinically relevant large animal model of cardiac tamponade.

DESIGN AND SETTING

A randomized, controlled in vivo animal study in a university research laboratory.

SUBJECTS

Anesthetized, ventilated, and thoracotomized Vietnamese mini pigs (24 ± 3 kg).

INTERVENTIONS

Group 1 (n = 6) served as sham-operated control. In group 2 (n = 7), cardiac tamponade was induced for 60 minutes by the administration of intrapericardial fluid, while the mean arterial pressure was kept in the interval 40 to 45 mm Hg. Group 3 (n = 6) was treated with a complement C5a antagonist compound (the peptide acetyl-peptide-A, 4 mg/kg) after 45 minutes of tamponade.

MEASUREMENTS AND MAIN RESULTS

The macrohemodynamics, including the superior mesenteric artery flow, was monitored; the average red blood cell velocity in the small intestinal mucosa was determined by an intravital orthogonal polarization imaging technique. The whole blood superoxide production, the plasma level of high-mobility group box protein-1 and big-endothelin and the small intestinal myeloperoxidase activity were measured. One hundred eighty minutes after the relief of tamponade, the mean arterial pressure was decreased, while the plasma levels of superoxide, high-mobility group box protein-1, and big-endothelin, and the intestinal myeloperoxidase activity were increased. The administration of acetyl-peptide-A normalized the mean arterial pressure and preserved the cardiac output, while the superior mesenteric artery flow and mucosal average red blood cell velocity were increased significantly, and the plasma superoxide, high-mobility group box protein-1, big-endothelin, and intestinal myeloperoxidase levels were reduced.

CONCLUSIONS

These results provide evidence that blockade of the C5a effects significantly influences the acute splanchnic macro- and microhemodynamic complications and decreases the potentially harmful inflammatory consequences of experimental cardiogenic shock.

Therapeutic effect of Tripterygium wilfordii Hook F multiglycosides on gut barrier dysfunction in rats with acute necrotizing pancreatitis

The aim of the current study was to investigate the therapeutic effect of Tripterygium wilfordii Hook F multiglycosides (TWG) on gut barrier dysfunction in rats with acute necrotizing pancreatitis (ANP). ANP was induced in rats using 3.5% sodium taurocholate. The rats were divided into 3 groups: the sham operation (SO), ANP and ANP+TWG groups. Biochemical and pathological change of pancreatic tissue and ileal mucosa, bacterial cultures and the survival rate were measured following surgery and treatment. TWG treatment significantly decreased amylase and lipase activities and plasma endotoxin and D-lactate levels. Edema and inflammation in the pancreas and ileal mucosa were alleviated. Positive bacterial cultures were significantly reduced. The survival rate of the rats in the ANP+TWG group was higher than that of the rats in the ANP group. TWG treatment showed beneficial effects by protecting the pancreas from bacterial infection caused by gut barrier dysfunction and improving the outcomes of the rats with ANP.

Escherichia coli translocation in experimental short bowel syndrome: probiotic supplementation and detection by polymerase chain reaction

BACKGROUND

After massive bowel resection, bacterial overgrowth is frequent and favors the occurrence of Gram-negative intestinal bacterial translocation (BT). Probiotics have been recommended in several diseases and may also have beneficial effects on BT. Conversely, polymerase chain reaction (PCR) technique has shown better sensitivity than conventional methods in bacterial detection and has not been investigated in experimental models of short bowel syndrome and BT.

OBJECTIVE

To test the hypothesis that Bifidobacterium lactis (BL) administration decreases Escherichia coli bacterial translocation (ECBT) in experimental short bowel syndrome and to confirm the better sensitivity of PCR technique to detect ECBT.

METHODS

Forty-eight adult Wistar rats, orally fed with standard rat chow and tap water ad libitum, were maintained in individual metabolic cages for 10 days and divided into three groups: Control group (n = 15): non-manipulated animals. RES group (n = 15): 80% gut resection. 1 ml of sterile water was administered daily after orogastric intubation. RES-PRO group (n = 18): same resection as RES group and daily administration of 7.8 × 10(9) BL (CFU). At the end of the study, portal blood, peripheral blood and mesenteric lymph node (MLN) samples were recovered and cultured. Also, genomic DNA from E. coli was detected by PCR technique.

RESULTS

In conventional culture there was no ECBT in control animals whereas 73% of RES and 33% of RES-PRO animals showed it. PCR detected ECBT in 47, 87 and 33%, respectively, showing higher sensitivity.

Kinetics of proinflammatory cytokines after intraperitoneal injection of tribromoethanol and a tribromoethanol/xylazine combination in ICR mice

Tribromoethanol (2,2,2-tribromoethanol, TBE) is a popular injectable anesthetic agent used in mice in Korea. Our goal was to assess the risks associated with side effects (lesions) in the abdominal cavity, especially at high doses. To understand the underlying pathophysiological changes, we examined levels of cytokines through ELISA of abdominal lavage fluid and spleen collected from mice treated with low and high-dose TBE. ICR mice were anesthetized using one of the following protocols: a combination of TBE 200 mg/kg (1.25%) and xylazine 10 mg/kg; TBE 400 mg/kg (1.25%); and TBE 400 mg/kg (2.5%). Administration of high-dose TBE (400 mg/kg) increased the interleukin-1β and interleukin-6 levels in the peritoneal cavity over the short term (<1 day) compared with sham controls and low-dose TBE (200 mg/kg) groups. Cytokine expression in the low-dose TBE group was similar to the control group, whereas in the high-dose TBE group cytokine levels were higher in abdominal lavage fluid and spleen over the long term (10 days post-injection). We conclude that a combination of TBE 200 mg/kg (1.25%) and xylazine (10 mg/kg) is a safe and effective anesthetic for use in animals.

Refined identification of Vibrio bacterial flora from Acanthasther planci based on biochemical profiling and analysis of housekeeping genes

We used a polyphasic approach for precise identification of bacterial flora (Vibrionaceae) isolated from crown-of-thorns starfish (COTS) from Lizard Island (Great Barrier Reef, Australia) and Guam (U.S.A., Western Pacific Ocean). Previous 16S rRNA gene phylogenetic analysis was useful to allocate and identify isolates within the Photobacterium, Splendidus and Harveyi clades but failed in the identification of Vibrio harveyi-like isolates. Species of the V harveyi group have almost indistinguishable phenotypes and genotypes, and thus, identification by standard biochemical tests and 16S rRNA gene analysis is commonly inaccurate. Biochemical profiling and sequence analysis of additional topA and mreB housekeeping genes were carried out for definitive identification of 19 bacterial isolates recovered from sick and wild COTS. For 8 isolates, biochemical profiles and topA and mreB gene sequence alignments with the closest relatives (GenBank) confirmed previous 16S rRNA-based identification: V. fortis and Photobacterium eurosenbergii species (from wild COTS), and V natriegens (from diseased COTS). Further phylogenetic analysis based on topA and mreB concatenated sequences served to identify the remaining 11 V harveyi-like isolates: V. owensii and V. rotiferianus (from wild COTS), and V. owensii, V. rotiferianus, and V. harveyi (from diseased COTS). This study further confirms the reliability of topA-mreB gene sequence analysis for identification of these close species, and it reveals a wider distribution range of the potentially pathogenic V. harveyi group.

Phylogenetic analysis of 16S rRNA gene sequences reveals distal gut bacterial diversity in wild wolves (Canis lupus)

The aim of this study was to describe the microbial communities in the distal gut of wild wolves (Canis lupus). Fecal samples were collected from three healthy unrelated adult wolves captured at the nearby of Dalai Lake Nature Reserve in Inner Mongolia of China. The diversity of fecal bacteria was investigated by constructing PCR-amplified 16S rRNA gene clone libraries using the universal bacterial primers 27 F and 1493 R. A total of 307 non-chimeric near-full-length 16S rRNA gene sequences were analyzed and 65 non-redundant bacteria phylotypes (operational taxonomical units, OTUs) were identified. Seventeen OTUs (26%) showed less than 98% sequence similarity to 16S rRNA gene sequences were reported previously. Five different bacterial phyla were identified, with the majority of OTUs being classified within the phylum Firmicutes (60%), followed by Bacteroidetes (16.9%), Proteobacteria (9.2%), Fusobacteria (9.2%) and Actinobacteria (4.6%). The majority of clones fell within the order Clostridiales (53.8% of OTUs). It was predominantly affiliated with five families: Lachnospiraceae was the most diverse bacterial family in this order, followed by Ruminococcaceae, Clostridiaceae, Peptococcaceae and Peptostreptococcaceae.

Combining enteral with parenteral nutrition to improve postoperative glucose control

The provision of parenteral nutrition (PN) to ‘stressed’ patients often results in hyperglycaemia, which may be detrimental. In animal models limited amounts of enteral nutrition (EN) improve intestinal integrity and stimulate intestinal incretin production, which may lead to improved glucose control. We set out to assess if combining EN with PN results in improved glucose homeostasis rather than PN given alone. We conducted a randomised trial in a university teaching hospital of patients undergoing a ‘curative’ oesophagectomy for adenocarcinoma. Differences between the two intervention groups were assessed for continuous glucose measurement, insulin sensitivity using insulin tolerance tests (ITT) and homeostasis model analysis (HOMA), the incretin glucose-dependent insulinotropic polypeptide (GIP) and intestinal permeability. The combination of PN with EN resulted in lower interstitial glucose concentrations (P = 0·002), reduced insulin resistance, improved insulin sensitivity (HOMA-insulin resistance (IR)P = 0·045; HOMA βP = 0·037; ITTP = 0·006), improved intestinal permeability (P < 0·001) and increased GIP (P = 0·01) when compared with PN alone. The combination of EN with PN, when compared with PN alone, results in reduced glucose concentrations, reduced insulin resistance, increased incretins and improvements in intestinal permeability.

Endotoxin detection--from limulus amebocyte lysate to recombinant factor C

Gram negative bacterial endotoxin is a biological pyrogen that causes fever when introduced intravenously. The endotoxin, also known as lipopolysaccharide (LPS), is found in the outer membrane of Gram-negative bacteria. During Gram-negative sepsis, endotoxin stimulates host macrophages to release inflammatory cytokines. However, excessive inflammation causes multiple organ failure and death. Endotoxins, which are ubiquitous pathogenic molecules, are a bane to the pharmaceutical industry and healthcare community. Thus early and sensitive detection of endotoxin is crucial to prevent endotoxaemia. The limulus amebocyte lysate (LAL) has been widely used for ~30 years for the detection of endotoxin in the quality assurance of injectable drugs and medical devices. The LAL constitutes a cascade of serine proteases which are triggered by trace levels of endotoxin, culminating in a gel clot at the end of the reaction. The Factor C, which normally exists as a zymogen, is the primer of this coagulation cascade. In vivo, Factor C is the perfect biosensor, which alerts the horseshoe crab of the presence of a Gram-negative invader. The hemostatic end-point entraps the invader, killing it and limiting further infection. However, as an in vitro endotoxin detection tool, variations in the sensitivity and specificity of LAL to endotoxin, and the dwindling supply of horseshoe crabs are posing increasing challenges to the biotechnology industry. This has necessitated the innovation of an alternative test for endotoxin. Thus, Factor C became the obvious, albeit tricky target for the recombinant technology effort. This chapter documents the backwater of mining the natural blood lysate of the endangered species to the monumental effort of genetic engineering, to produce recombinant Factor C (rFC). The rFC is a 132 kDa molecule, which was produced as a proenzyme inducible by the presence of trace levels of endotoxin. The rFC forms the basis of the "PyroGene" kit, which is a novel micro-enzymatic endotoxin diagnostic assay for high-throughput screens of endotoxin. Using the rFC, Lonza Inc. has spawned the "PyroSense" which serves as checkpoints of the biotechnology production line. Thus, from cloning to commercial applications, the rFC has initiated a new era in endotoxin-testing for the quality assurance of biomedical products and for the healthcare industry, whilst sparing the endangered horseshoe crabs.

Effect of probiotics on intestinal regrowth and bacterial translocation after massive small bowel resection in a rat

BACKGROUND/PURPOSE

Because of their ability to inhibit intestinal bacterial overgrowth, probiotics (PROs) have been advocated for the treatment of patients with short bowel syndrome (SBS). This study was conducted to determine the effect of PROs on bacterial translocation and intestinal regrowth after massive small bowel resection in a rat.

METHODS

Male Sprague-Dawley rats were divided into 3 experimental groups: sham rats underwent bowel transection and reanastomosis, SBS rats underwent 75% small bowel resection, and SBS-PRO rats underwent bowel resection and were treated with a PRO given in drinking water from day 4 through 14. Intestinal structural changes (bowel circumference, overall bowel and mucosal weight, mucosal DNA and protein, villus height and crypt depth, enterocyte proliferation and enterocyte apoptosis) and bacterial translocation (BT) to mesenteric lymph nodes, liver, portal blood, and peripheral blood were determined on day 15 after operation.

RESULTS

Sham rats exhibited a 20% BT to the mesenteric lymph nodes (level I), liver (level II), and blood (level III). Short bowel syndrome rats demonstrated a 100% BT to lymph nodes (level I) and liver (level II) and 40% translocation to peripheral blood (level III). Treatment with PROs resulted in a significant decrease in BT to all 3 target organs and decreased enterocyte apoptosis compared with SBS-untreated animals. Short bowel syndrome rats showed a significant increase (vs sham) in jejunal and ileal bowel and mucosal weight, mucosal DNA and protein, villus height, and crypt depth. Short bowel syndrome rats also had a greater proliferation index and apoptotic index in both jejunum and ileum compared with sham animals. SBS-PRO rats showed a significant increase (vs SBS rats) in crypt depth in ileum and a mild decrease in apoptotic index in jejunum and ileum, compared with SBS-untreated animals.

CONCLUSIONS

In a rat model of SBS, PROs decrease BT through mechanisms which maybe dependent on intestinal mucosal integrity.

Bacterial translocation as a source of Dacron-graft contamination in experimental aortic operation: the importance of controlling SIRS

BACKGROUND

Several experimental studies have shown the beneficial effects of nitric oxide (NO) in the modulation of the systemic inflammatory response syndrome (SIRS). Nitric oxide is involved in and affects almost all stages in the development of inflammation. We have attempted to ascertain whether the nitric oxide donor molsidomine prevents aortic graft contamination through control of the SIRS and a decrease in bacterial translocation (BT).

METHODS

Twenty-four mini-pigs were divided into 4 groups. The animals were subjected to suprarenal aortic/iliac cross-clamping (for 30 minutes) and by-pass with a Dacron-collagen prosthetic graft impregnated in rifampicin. Groups: 1) sham (aortic dissection alone); 2) cross-clamping and bypass; 3) hemorrhage of 40% of total blood volume before cross-clamping and by-pass; and 4) the same as in group 3 but also including the administration of the NO donor molsidomine (4 mg/kg) 5 minutes before cross-clamping.

VARIABLES

1) bacteriology of mesenteric lymph nodes (MLN), kidney, blood, and prosthesis; 2) serum TNF-alpha (ELISA); and 3) iNOS expression in kidney and liver (Western blot).

RESULTS

Aortic cross-clamping with or without hemorrhage was associated with BT in 80% and 100% of the animals, respectively. About 86% of the bacteria isolated in the graft were also present in MLN. This contamination coincided with an increase in TNF-alpha and with a greater expression of iNOS. Molsidomine administration decreased TNF-alpha and iNOS, decreased BT (from 100% to 20% of the animals), and decreased graft contamination (from 83% to 20%).

CONCLUSIONS

The present model induces high levels of BT and SIRS, both acted as sources of contamination for the implanted Dacron graft. Molsidomine administration decreased the presence of bacteria in the graft by controlling BT and modulating SIRS.

Prevention of bacterial translocation using glutamine: a new strategy of investigation

OBJECTIVE

This study investigated the role of glutamine (Gln) on bacterial translocation in an intestinal obstruction model by using Escherichia coli labeled with technetium 99m (99mTc-E. coli).

METHODS

Intestinal obstruction was performed by a single ligature of the terminal ileum in rats. Animals in the control group (group 1) were sham operated (not obstructed). Experimental group 2 had intestinal obstruction. Groups 1 and 2 were not treated with Gln. Groups 3 and 4 were treated with Gln for 7 d before surgery with 250 and 500 mg x kg(-1) x d(-1), respectively. A suspension containing 100 million colony-forming units/mL of (99m)Tc-E. coli was injected into the lumen of the ileum. Twenty-four hours after surgery, blood, mesenteric lymph nodes, livers, spleens, and lungs were collected for determination of radioactivity. The Mann-Whitney U test was performed for statistical analysis. P <or= 0.05 was considered statistically significant.

RESULTS

Rats that had an intestinal obstruction showed a significant increase in 99mTc-E. coli translocation from the lumen to all organs investigated compared with the sham-operated group (P <or= 0.01). There was a significant difference between the intestinally obstructed group and Group 4 treated with Gln at 500 mg x kg(-1) x d(-1) (P <or= 0.05), which did not occur in Group 3 treated with Gln at 250 mg x kg(-1) x d(-1).

CONCLUSIONS

The new method using 99mTc-E. coli was found to be suitable for studies of bacterial translocation. Gln did not prevent bacterial translocation but did significantly decrease the spread of 99mTc-E. coli among organs such as the liver, lung, and spleen. The effect of Gln in cases of intestinal obstruction was found to be dose dependent.

Effect of oral glutamine administration on bacterial tanslocation, endotoxemia, liver and ileal morphology, and apoptosis in rats with obstructive jaundice

Postoperative complications in patients with obstructive jaundice remain increased when associated with endotoxemia and the inflammatory response due to gut barrier failure. Administration of glutamine has been proposed to maintain the integrity of the gut mucosa and thus reduce bacterial translocation (BT), but the effects of this pretreatment on apoptosis and histologic morphology of various organs affected by BT in obstructive jaundice have not been studied. We therefore studied the effects of oral glutamine supplementation on endotoxemia, BT, liver and terminal ileal morphology, and apoptosis in an experimental model of obstructive jaundice. A total of 60 male Wistar rats were randomly divided into four groups of 15 each: I, controls; II, sham-operated; III, bile duct ligation (BDL); IV, BDL + glutamine (4.5 g/kg/day in drinking water). Ileal samples for histology, DNA and protein content, liver biopsies, mesenteric lymph nodes (MLNs) for culture, and portal and systemic blood samples for endotoxin measurements were obtained 10 days later. Compared to the controls, a significant increase in contaminated MLN and liver samples and increased endotoxemia were noted in group III (p < 0.01) but were significantly reduced in group IV (p < 0.05). Group IV also had a significantly higher number of mitoses per crypt (M/c) (p < 0.05), less apoptotic body counts (ABCs) (p < 0.05), and a higher DNA content than did group III (p < 0.05). Liver biopsies from group III displayed typical changes of large duct obstruction that significantly improved after glutamine treatment, with decreased ductular proliferation. We concluded that supplementation of oral glutamine in the presence of obstructive jaundice ameliorates BT, endotoxemia, and apoptosis and improves the ileal and liver histology.

Comparison of bacterial diversity along the human intestinal tract by direct cloning and sequencing of 16S rRNA genes

Bacterial diversity of the mucosal biopsies from human jejunum, distal ileum, ascending colon and rectum were compared by analysis of PCR-amplified 16S rDNA clone libraries. A total of 347 clones from the mucosal biopsies were partially sequenced and assigned to six phylogenetic phyla of the domain Bacteria: Firmicutes, Bacteroidetes, Proteobacteria, Fusobacteria, Verrucomicrobia, and Actinobacteria. The jejunum sample had least microbial diversity compared to the other samples and a trend towards highest diversity in ascending colon was observed. The clone libraries of distal ileum, ascending colon and rectum were not significantly different from each other (P>0.0043), but they differed significantly from the jejunum library (P=0.001). The population of sequences retrieved from jejunal biopsies was dominated by sequences closely related to Streptococcus (67%), while the population of sequences derived from distal ileum, ascending colon and rectum were dominated by sequences affiliated with Bacteroidetes (27-49%), and Clostridium clusters XIVa (20-34%) and IV (7-13%). The results indicate that the microbial community in jejunum is different from those in distal ileum, ascending colon and rectum, and that the major phylogenetic groups are similar from distal ileum to rectum.

Variability of bacterial translocation in the absence of intestinal mucosal damage following injury and the influence of interleukin-6

Bacterial translocation and intestinal mucosal damage have been reported as potentially clinically important sequelae of injury. Evidence that endogenous interleukin-6 (IL-6) is able to protect against infection, and that orally administered IL-6 could prevent bacterial translocation and mucosal damage following haemorrhage, led us to evaluate the impact of injury on the intestinal mucosa and the role of endogenous IL-6. Normal and IL-6-deficient (IL-6-/-) mice were subjected to haemorrhage of increasing severity, hind limb ischaemia, or both. Mucosal integrity and bacterial translocation to the liver, spleen and mesenteric lymph nodes (MLN) were examined after 16 h. Bacterial translocation to each of these tissues was observed in unoperated animals. The more severe haemorrhage procedures, and hind limb ischaemia, increased bacterial translocation to the liver significantly in most experiments with normal mice. The IL-6-/- mice survived the most severe haemorrhage procedure less well (p = 0.0015), although increased bacterial translocation was not seen. There was no clear evidence of mucosal damage, or bacterial translocation to spleen and mesenteric lymph nodes, in either normal or IL-6-/- mice. Intestinal IgA concentrations were the same in IL-6-/- mice and controls. These data demonstrate that increased bacterial translocation can be observed following severe injury, but that neither bacterial translocation nor severe injury are inevitably associated with morphological damage to the intestinal mucosa, and endogenous IL-6 is more likely to promote bacterial translocation than protect the gut.

Intestinal permeability and systemic infections in critically ill patients: effect of glutamine

OBJECTIVE

This article provides a critical review of the evidence indicating that an increase in intestinal permeability is associated with the installation of bacteremia, sepsis, and the multiple organ failure syndrome and that glutamine in pharmacologic doses reduces the acute increase of intestinal permeability and the infection frequency in critically ill patients.

DATA SOURCE

All studies published until December 2004 about intestinal permeability, bacterial translocation, and glutamine were located by search of PubMed and Web of Science. The reference lists of review articles and primary publications were also examined to identify references not detected in the computer search.

STUDY SELECTION

Clinical and experimental studies investigating the correlation between intestinal permeability, bacterial translocation, and frequency of infections, associated or not with the effect of glutamine administration.

DATA EXTRACTION

Information regarding patient population, experimental design, glutamine doses and routes of administration, nutritional therapy prescribed, methods used to assess intestinal permeability, metabolic variables, and the frequency of infections were obtained from the primary literature.

DATA SYNTHESIS

Intestinal permeability is increased in critically ill patients. The results have not always been consistent, but the studies whose results support the association between intestinal permeability and systemic infections have had better design and more appropriate controls. The administration of glutamine by the intravenous or oral route and at the doses recommended before or immediately after surgery, burns, or the administration of parenteral nutrition has a protective effect that prevents or reduces the intensity of the increase in intestinal permeability. Glutamine reduces the frequency of systemic infections and may also reduce the translocation of intestinal bacteria and toxins, but this has not been demonstrated.

CONCLUSIONS

Glutamine administration improves the prognosis of critically ill patients presumably by maintaining the physiologic intestinal barrier and by reducing the frequency of infections.

Infection prophylaxis of gunshot wounds using probiotics

OBJECTIVE

To report a new method of surgical infection prophylaxis for postoperative gunshot wounds to the extremities.

METHOD

Gunshot wounded animals were divided into three groups: treatment (probiotic Sporobacterin), antibiotic (cephalosporin cefamezin) and control (no treatment). Histological studies of wound-bed tissue were taken on days 1, 3, 5 and 10 of the study.

RESULTS

The probiotic administered per os was more effective than antibiotics for prophylaxis of surgical infection.

CONCLUSION

The probiotic's effect is based on the natural defence mechanism activated after injury--the bacterial translocation of saprophytic bacteria from the gut to the wound.

DECLARATION OF INTEREST

None.

Oral arginine reduces gut mucosal injury caused by lipopolysaccharide endotoxemia in rat

BACKGROUND

The objective of this study was to evaluate the effects of lipopolysaccharide (LPS) endotoxemia and enteral arginine (ARG) supplementation on intestinal structural changes, enterocyte proliferation, and apoptosis in rat.

METHODS

Male Sprague-Dawley rats, weighing 250-280 g, were divided into three experimental groups: control rats, LPS rats treated with lipopolysaccharide given ip at a dose of 10 mg/kg every 24 h (two injections), and LPS-ARG rats treated with enteral arginine given in drinking water (2%) 72 h before and following injection of LPS. Intestinal structural changes, enterocyte proliferation, and enterocyte apoptosis were determined on day 3 following the first LPS injection.

RESULTS

LPS rats demonstrated a significant decrease in bowel weight in duodenum, mucosal weight in duodenum, jejunum, and ileum, mucosal DNA and protein in jejunum and ileum, and villus height in jejunum and ileum compared to control animals. LPS rats also had a significantly lower cell proliferation index in jejunum and ileum and a higher apoptotic index in jejunum and ileum compared to control rats. LPS-ARG animals demonstrated greater duodenal bowel weight, duodenal and ileal mucosal weight, ileal mucosal DNA and protein, ileal villus height, and jejunal and ileal cell proliferation index compared to LPS animals.

CONCLUSIONS

LPS endotoxemia impairs the integrity of the gastrointestinal mucosa in rat. Decreased cell proliferation and increased apoptosis may be considered the main mechanisms responsible for the decreased cell mass. Enteral arginine administration decreases the mucosal injury caused by lipopolysaccharide.

Exogenous Nitric Oxide Donor and Related Compounds Protect Against Lung Inflammatory Response After Hemorrhagic Shock and Resuscitation

BACKGROUND

Resuscitation from hemorrhagic shock triggers an inflammatory response characterized by upregulation of cytokine and adhesion molecule expression, increased leukocyte activity, and accumulation of polymorphonuclear neutrophils in a variety of tissues. This study investigated the capability of an exogenous nitric oxide (NO) donor, sodium nitroprusside (NP); a NO substrate, L-arginine; and an inducible NO synthase inhibitor, L-N6-(1-iminoethyl)lysine (L-NIL) to reduce lung injury in an animal model of mixed controlled and uncontrolled hemorrhagic shock.

METHODS

For this study, 72 Sprague-Dawley rats weighing 250 to 300 g were subjected to a model of uncontrolled hemorrhagic shock for 150 minutes. Six groups of animals were included in this study (12 per group): sham-saline, sham-NP, shock-saline, shock-NP, shock-L-arginine, and shock-L-N6-(1-iminoethyl)lysine. After the period of hemorrhagic shock, resuscitation of the groups was accomplished using normal saline (groups 1 and 3), NP (0.5 mg/kg) (groups 2 and 4), L-arginine (300 mg/kg) (group 5), or L-NIL (50 mg/kg) (group 6). The following indices were evaluated: fluid requirements for resuscitation, mean arterial pressure (MAP), arterial po2, pco2, and pH, lung wet-to-dry weight ratio, lung histology and cytokine (interleukin [IL]-1 alpha, IL-beta 1, tumor necrosis factor-beta [TNF beta], IL-3, IL-4, IL-5, IL-6, IL-10, TNF alpha, IL-2, interferon-gamma [IFN gamma]), and mRNA expression in the lung by a ribonuclease protection assay (RPA).

RESULTS

Sodium nitroprusside significantly increased MAP and reduced fluid requirements during resuscitation after hemorrhage. There also was a significant improvement in lung function, as expressed by improvements in po2, pco2, and pH, and reduction of the wet-to-dry weight ratio. In addition, a significant reduction in acute lung injury was observed in the histologic studies. Furthermore, the expression of cytokines was reduced by NP treatment. The use of L-arginine and L-NIL offered similar protective results for the injured lung.

CONCLUSIONS

These data suggest that limiting inducible NO synthase-generated NO availability with the exogenous NO donor, sodium nitroprusside, may reduce lung injury after severe hemorrhage, possibly, among other effects, by downregulating the expression of inflammatory cytokines. L-arginine and L-NIL also had a beneficial effect on lung function and structure.

Atrofia mucosa/translocação bacteriana na sepse experimental em ratos Wistar

OBJETIVO: Avalizar a relação entre lesão mucosa e translocação bacteriana. MÉTODO: Utilizou-se 50 ratos distribuídos em 5 grupos: 1.Controle: injeção de inóculo padrão de Pseudomonas aeruginosa, 2.Dreno: injeção do inóculo padrão e drenagem da cavidade abdominal, após 6 horas, 3.Lavado: injeção do inóculo padrão e lavagem da cavidade abdominal, após 6 horas, 4.Lavado + dreno: injeção do inóculo padrão e após 6 horas, drenagem e lavagem da cavidade, 5.Normal: avaliação histológica da parede intestinal normal. Após o óbito, realizou-se hemocultura e cultura peritoneal. Realizou-se medida da espessura total da parede do jejuno e da camada mucosa em vilosidades seccionadas de forma longitudinal. RESULTADOS: Na hemocultura, houve crescimento de Pseudomonas aeruginosa e Escherichia coli em 90% e 52,5% dos animais. Na cultura peritoneal, houve crescimento de P. aeruginosa, E. coli e Klebsiella sp em 87,5%, 85% e 5% dos animais. Quanto a altura da camada mucosa e da parede intestinal, não houve alteração estatisticamente significativa entre os 5 grupos. CONCLUSÃO: A sepse aguda não causou alteração na camada mucosa do intestino delgado e a translocação ocorrida não pode ser considerada como decorrente de uma lesão da mucosa intestinal.

Intestinal translocation of Streptococcus suis type 2 EF+ in pigs

Sepsis with subsequent multisystem organ failure after translocation of bacteria from the gut is a serious risk associated with stress situations. We showed that intestinal bacterial translocation could be one of the pathways for pathogenic Streptococcus suis infections in the pig. In 24 piglets weighing 10-14 kg, free of the extracellular factor (EF+) producing phenotype of S. suis serotype 2, a silicon canula was placed in the proximal jejunum to enable intestinal inoculation and bypassing the upper alimentary tract. The pigs were individually housed. After stress induction in 18 pigs by means of a truck drive in individual cages for 1h, pigs were inoculated through the intestinal canula either with S. suis type 2 EF+ or with growth medium only, and put back in their original housing. The six not transported pigs were also inoculated with the same strain. To prevent oral self-infection, faeces were collected in a bag that was glued around the anus. Clinical and behavioral symptoms were recorded for 72 h post inoculation, and then the animals were sacrificed for pathological and bacteriological examination. In three animals, the inoculation strain was re-isolated from mesenterial lymph nodes and typically affected organs. No S. suis type 2 EF+ was detected by specific polymerase chain reaction (PCR) in any of the tonsil-swabs and -homogenates. We concluded that infection of the organs had taken place after bacterial translocation out of the gut and that the intestinal tract can be a porte d'entree for S. suis type 2 EF+.

Microbial translocation and inflammatory response in patients with acute peritonitis

BACKGROUND

In peritonitis, increased production of cytokines and changes in the splanchnic cellular immune system may cause translocation of bacteria and endotoxins. The aims of this study were to assess the frequency of translocation and relate translocation to the immune response in patients with acute peritonitis.

METHODS

Patients with local (LP, n=20) or general peritonitis (GP, n=15) were compared with controls (C, n=12). Blood was obtained preoperatively for cultures, and analyses of endotoxin and cytokines (tumour necrosis factor-alpha, interleukins 6 and 10). Mesenteric lymph nodes (MLNs) were excised for culturing and immunohistochemistry using antibodies CD4, CD8 and CD68.

RESULTS

Positive blood and MLN cultures were not obtained in controls. DNA typing proved bacterial translocation in one patient with local and one patient with general peritonitis. Thus translocation was proven to occur in 6% of patients with peritonitis. Endotoxaemia was predominantly found in the GP group. Cytokines increased during peritonitis and more so in patients with GP than in those with LP. More CD8 and CD68 cells were found in MLNs from LP patients than in C patients and more CD4 and CD8 cells in LP patients than in GP patients. There was no significant difference in this regard between the GP and C groups.

CONCLUSIONS

Bacterial translocation occurs during acute peritonitis but seems to be fairly infrequent. Peritonitis causes significant inflammatory cellular reactions.

The 2003 Carl A Moyer Award: real-time metabolic monitors, ischemia-reperfusion, titration endpoints, and ultraprecise burn resuscitation

Real-time metabolic monitoring of varied vascular beds provides the raw data necessary to conduct ultraprecise burn shock resuscitation based on second-by-second assessment of regional tissue perfusion. It also illustrates shortcomings of current clinical practices. Arterial base deficit was continuously monitored during 11 clinical resuscitations of patients suffering burn shock using a Paratrend monitor. Separately, in a 30% TBSA rat burn model (N = 70), three Paratrend monitors simultaneously recorded arterial blood gas and tissue pCO2 of the burn wound and colonic mucosa during resuscitation at 0, 2, 4, 6, and 8 ml/kg/%TBSA. Paratrend data were analyzed in conjunction with previously reported laser Doppler images of actual burn wound capillary perfusion. With current clinical therapy, continuous monitoring of arterial base deficit revealed repetitive cycles of resolution/worsening/resolution during burn shock resuscitation. In the rat model, tissue pCO2 in both burn wounds and splanchnic circulation differed depending on the rate of fluid resuscitation (P <.01 between sham and 0 ml/kg/%TBSA and between 2 ml/kg/%TBSA and 4 ml/kg/%TBSA). Burn wound pCO2 values correlated well with laser Doppler determination of actual capillary perfusion (rho = -.48, P <.01). The following conclusions were reached: 1). Gratuitous and repetitive ischemia-reperfusion-ischemia cycles plague current clinical therapy as demonstrated by numerous "false starts" in the resolution of arterial base deficit; 2). in a rat model, real-time monitoring of burn wound and splanchnic pCO2 demonstrate a dose-response relationship with rate of fluid administration; and 3). burn wound and splanchnic pCO2 are highly correlated with direct measurement of burn wound capillary perfusion by laser Doppler imager. Either technique can serve as a resuscitation endpoint for real-time feedback-controlled ultraprecise resuscitation.

Alterações da mucosa intestinal em ratos: estudo morfométrico em três diferentes tratamentos após indução experimental de sepse abdominal aguda

OBJETIVO: Verificar as possíveis alterações morfológicas da parede intestinal provocadas pela contaminação de uma monocultura bacteriana na cavidade abdominal de ratos, após tratamento por drenagem, lavagem e a combinação destes dois processos. MÉTODOS: Foram utilizados 50 ratos fêmeas da linhagem Wistar, foram distribuídos em 5 subgrupos: grupo Controle (C) - recebeu um inóculo padrão com 1,2.10(9) de Pseudomonas aeruginosa, intraperitonial, sem nenhum tipo de tratamento; grupo Dreno (D) - inóculo padrão e realizada a drenagem da cavidade abdominal; grupo Lavado (L) - inóculo e realizada a lavagem da cavidade abdominal com solução salina; grupo L+D - inóculo e submetido aos dois tipos de tratamentos; grupo Normal (N) sem nenhum tipo de inoculação ou tratamento. Realizou-se a análise morfométrica das lâminas coradas por H.E da mucosa intestinal e hemocultura. RESULTADOS: Não houve diferenças estatisticamente significantes na espessura da mucosa intestinal entre os 5 subgrupos de ratos analisados no período de 24 horas após a injeção do inóculo. 37 animais que receberam o inóculo evoluíram para o óbtito entre 5,83 e 28 horas, com 2 animais do grupo L sobrevivendo por um período de 28 horas. CONCLUSÃO: A sepse aguda não causou alterações morfológicas mensuráveis através desta metodologia na parede intestinal.

Administration of nitric oxide with caspase inhibitors minimizes bacterial translocation in experimental intestinal transplantation

BACKGROUND

Bacterial translocation (BT) has been suggested to be responsible for the high incidence of infections occurring after small-bowel transplantation (Trp). Nitric oxide (NO) and apoptosis could affect cell demise. The aim of this study was to asses whether supplementation of University of Wisconsin (UW) solution with NO donors and apoptosis inhibitors can abolish BT in Trp.

METHODS

The following experimental groups were studied: sham, Trp, intestinal transplantation, Trp+spermine NONOate (NONOs), and Trp+NONOs+caspase inhibitor Z-Val-Ala-Asp(Ome)-fluoromethylketone(Z-VAD-fmk). Histologic analysis, caspase-3 activity, DNA fragmentation, and BT from graft to mesenteric lymph nodes, liver, and spleen were measured in tissue samples after transplantation.

RESULTS

During intestinal transplantation, apoptosis and necrosis were increased, showing graft injury and high levels of BT. The rats treated with NONOs showed a histologic protection of transplanted graft and a decrease in BT despite caspase-3 and DNA fragmentation-inducing effects. Administration of caspase inhibitor Z-VAD to NONOs-treated rats reversed the NO apoptosis-inducing effects and showed the lowest levels of BT in all tissues.

CONCLUSIONS

Exogenous administration of NO associated with the inhibition of apoptosis maintains the graft in optimal conditions in terms of BT and improves the histology of the graft after intestinal transplantation in rats.

Bacterial translocation: what it is and what it is not

The reasons our critically ill patients die have been a matter of great interest for many decades, with the hope that if we can identify the mechanisms responsible for death, we might be able to intervene and improve outcome. Over the last 1 to 2 decades, the concept of bacterial translocation-the movement of gut origin microbes across the intact gastrointestinal tract into normally sterile tissues where the organisms may then directly cause infection or incite an inflammatory response that causes tissue injury, organ failure, and death-has grown to the point where it is virtually impossible to make rounds in any intensive care setting without a resident or student blaming some complication or another on bacterial translocation. We will attempt to review the clinically relevant information that supports and refutes the concept of bacterial translocation as a cause of our critically ill patients to exhibit the symptoms and signs of sepsis, develop organ failure, and ultimately die.

Exercise-induced endotoxemia: the effect of ascorbic acid supplementation

Strenuous, long-duration aerobic exercise results in endotoxemia due to increased plasma levels of lipopolysaccharide (LPS) leading to cytokine release, oxidative stress, and altered gastrointestinal function. However, the effect of short-term strenuous aerobic exercise either with or without antioxidant supplementation on exercise-induced endotoxemia is unknown. A significant increase in the concentration of bacterial LPS (endotoxin) was noted in the venous circulation of healthy volunteers following maximal acute aerobic exercise (0.14(-1) pre-exercise vs. 0.24(-1) postexercise, p <0.01). Plasma nitrite concentration also increased with exercise (0.09 +/- 0.05 nM x ml(-1) vs. 0.14 +/- 0.01 nM x ml(-1), p <0.05) as did ascorbate free radical levels (0.02 +/- 0.001 vs. 0.03 +/- 0.002 arbitrary units, p <0.05). Oral ascorbic acid supplementation (1000 mg) significantly increased plasma ascorbic acid concentration (29.45 mM x l(-1) to 121.22 mM x l(-1), p <0.05), and was associated with a decrease in plasma LPS and nitrite concentration before and after exercise (LPS: 0.01(-1); nitrite: 0.02 +/- 0.02 nM x ml(-1) vs. 0.02 +/- 0.03 nM x ml(-1)). Ascorbic acid supplementation led to a significant increase in ascorbate free radical levels both before (0.04 +/- 0.01 arbitrary units) and after exercise (0.06 +/- 0.02 arbitrary units, p <0.05). In conclusion, strenuous short-term aerobic exercise results in significant increases in plasma LPS levels (endotoxemia) together with increases in markers of oxidative stress. Supplementation with ascorbic acid, however, abolished the increase in LPS and nitrite but led to a significant increase in the ascorbate radical in plasma. The amelioration of exercise-induced endotoxemia by antioxidant pretreatment implies that it is a free radical-mediated process while the use of the ascorbate radical as a marker of oxidative stress in supplemented systems is limited.

Gastric Tonometry and Enteral Nutrition: a Possible Conflict in Critical Care Nursing Practice

• Background Gastric tonometry is used to assess gastrointestinal mucosal perfusion in critically ill patients. However, enteral feeding is withheld during monitoring with gastric tonometry because enteral feeding is thought to influence tonometric measurements.

• Objectives To examine the effect of enteral feeding on the tonometric measurement of gastric mucosal carbon dioxide.

• Methods Gastric tonometers were placed in 20 critically ill patients, and the Pco2 of the gastric mucosa was measured in both the full and the empty stomach during a 48-hour period.

• Results The Pco2 measured by the tonometer increased after enteral feeding, and a significant difference in the Pco2 of the full versus the empty stomach was evident at 24 and 48 hours. Pco2 at 4, 24, and 48 hours differed significantly in the full stomach and in the empty stomach. However, the data did not reveal a significant difference in either the full stomach or the empty stomach between Pco2 at 24 hours and Pco2 at 48 hours.

• Conclusion After 24 hours of feeding, the initial increase in Pco2 observed at 4 hours was not evident, suggesting stabilization of the intragastric environment. However, a higher Pco2 was evident in the empty stomach, indicating that the presence of the feeding solution may reduce the diffusion of carbon dioxide into the tonometer balloon. Consequently, measurements of intragastric Pco2 obtained after 24 hours of feeding may be reliable if the stomach is emptied by aspiration via the tonometer immediately before measurement.

Macrophages and post-burn immune dysfunction

The activation of a pro-inflammatory cascade after burn injury appears to be important in the development of subsequent immune dysfunction, susceptibility to sepsis and multiple organ failure. Macrophages are major producers of pro-inflammatory mediators and their productive capacity for these mediators is markedly enhanced following thermal injury. Thus, macrophage hyperactivity (as defined by increased productive capacity for pro-inflammatory mediators) appears to be of critical importance in the development of post-burn immune dysfunction. This review will focus on the current state of knowledge with regards to the role of macrophages in the development of post-burn immune dysfunction. Particular areas of discussion include: nitric oxide synthase (NOS) and cyclooxygenase (COX) enzyme systems, macrophages and the T-helper (Th)-1/Th-2 cytokine responses, alterations in macrophages signal transduction and a potential role for gamma/delta T-cells in the development of macrophage hyperactivity following thermal injury. A more comprehensive understanding of the relationship between macrophage activity and post-burn immune dysfunction will hopefully provide the basis for improved therapeutic regimes in the treatment of burn patients.

The role of the intestine in the pathophysiology and management of severe acute pancreatitis

BACKGROUND

The outcome of severe acute pancreatitis has scarcely improved in 10 years. Further impact will require new paradigms in pathophysiology and treatment. There is accumulating evidence to support the concept that the intestine has a key role in the pathophysiology of severe acute pancreatitis which goes beyond the notion of secondary pancreatic infection. Intestinal ischaemia and reperfusion and barrier failure are implicated in the development of multiple organ failure.

DISCUSSION

Conventional management of severe acute pancreatitis has tended to ignore the intestine. More recent attempts to rectify this problem have included 1) resuscitation aimed at restoring intestinal blood flow through the use of appropriate fluids and splanchnic-sparing vasoconstrictors or inotropes; 2) enteral nutrition to help maintain the integrity of the intestinal barrier; 3) selective gut decontamination and prophylactic antibiotics to reduce bacterial translocation and secondary infection. Novel therapies are being developed to limit intestinal injury, and these include antioxidants and anti-cytokine agents. This paper focuses on the role of the intestine in the pathogenesis of severe acute pancreatitis and reviews the implications for management.

Bacterial translocation: clinical implications and prevention

The occurrence of BT has been well documented in experimental animal models of hemorrhagic shock, trauma, severe burns, cirrhosis, pancreatitis, and bacterial overgrowth. Translocation of viable bacteria and endotoxins into mesenteric lymph nodes and other gut-associated lymphatic tissue is thought to activate a complex interplay of mediators that initiates the SIRS. Multiple humoral and cellular systems cause synthesis, expression, and release of inflammatory mediators, such as toxic oxygen radicals, proteolytic enzymes, adherence molecules, and various cytokines. A massive sustained proinflammatory response can ultimately result in irreversible multiple organ dysfunction. Because BT is associated with splanchnic hypoperfusion, the cornerstone of therapy involves rapid resuscitation and restoration of tissue perfusion. If a septic focus can be identified, it should be removed. Gut protectants, promotility agents, antioxidants, and immune-enhancing diets have shown promise in improving length of survival in these critically ill patients.

Microscopy of bacterial translocation during small bowel obstruction and ischemia in vivo--a new animal model

BACKGROUND

Existing animal models provide only indirect information about the pathogenesis of infections caused by indigenous gastrointestinal microflora and the kinetics of bacterial translocation. The aim of this study was to develop a novel animal model to assess bacterial translocation and intestinal barrier function in vivo.

METHODS

In anaesthetized male Wistar rats, 0.5 ml of a suspension of green fluorescent protein-transfected E. coli was administered by intraluminal injection in a model of small bowel obstruction. Animals were randomly subjected to non-ischemic or ischemic bowel obstruction. Ischemia was induced by selective clamping of the terminal mesenteric vessels feeding the obstructed bowel loop. Time intervals necessary for translocation of E. coli into the submucosal stroma and the muscularis propria was assessed using intravital microscopy.

RESULTS

Bacterial translocation into the submucosa and muscularis propria took a mean of 36 +/- 8 min and 80 +/- 10 min, respectively, in small bowel obstruction. Intestinal ischemia significantly accelerated bacterial translocation into the submucosa (11 +/- 5 min, p < 0.0001) and muscularis (66 +/- 7 min; p = 0.004). Green fluorescent protein-transfected E. coli were visible in frozen sections of small bowel, mesentery, liver and spleen taken two hours after E. coli administration.

CONCLUSIONS

Intravital microscopy of fluorescent bacteria is a novel approach to study bacterial translocation in vivo. We have applied this technique to define minimal bacterial transit time as a functional parameter of intestinal barrier function.

Organ damage in zymosan-induced multiple organ dysfunction syndrome in mice is not mediated by inducible nitric oxide synthase

OBJECTIVE

To examine the role of inducible nitric oxide synthase (iNOS) in the development of the multiple organ dysfunction syndrome (MODS) in a murine model by using either a selective iNOS inhibitor or iNOS knockout mice.

DESIGN

Prospective randomized laboratory study.

SETTING

Central animal laboratory and experimental laboratory.

SUBJECTS

Fifty inbred C57BL/6 mice, 39 iNOS knockout (-/-) mice, and 30 wild-type (+/+) mice, 7-9 wks old, weighing 20-25 g.

INTERVENTIONS

Mice received an aseptic intraperitoneal injection of 40 microg of lipopolysaccharide followed by zymosan at a dose of 1 mg/g of body weight 6 days later (day 0). In experiment 1, C57BL/6 mice additionally received intraperitoneal injections with 5 mg of aminoguanidine or saline every 12 hrs, from 4 days after the injection of zymosan onward. In experiment 2, both iNOS-/- mice and corresponding wild-type (iNOS+/+) mice were treated with lipopolysaccharide and zymosan.

MEASUREMENTS AND MAIN RESULTS

In all animals, the injection of zymosan induced an acute peritonitis, followed by an apparent recovery. From approximately day 6 onward, animals entered the third-MODS-like-phase, indicated by weight loss, a decrease in body temperature, and significant mortality rates. Quantitative reverse transcriptase polymerase chain reaction and immunochemistry revealed a strongly increased expression of iNOS messenger RNA and iNOS protein in livers of mice in the last phase. However, neither the in vivo administration of aminoguanidine to C57BL/6 mice nor the complete absence of iNOS enzyme (iNOS-/- mice) had a beneficial effect on survival rate, body temperature, or body weight. In addition, relative lung, liver, and spleen weights and lung scores were not different between experimental groups.

CONCLUSIONS

The current results strongly argue against an essential and causative role of iNOS in the development of organ damage in our murine model of MODS.

Intestinal permeation and gastrointestinal disease

The gastrointestinal tract constitutes one of the largest sites of exposure to the outside environment. The function of the gastrointestinal tract in monitoring and sealing the host interior from intruders is called the gut barrier. A variety of specific and nonspecific mechanisms are in operation to establish the host barrier; these include luminal mechanisms and digestive enzymes, the epithelial cells together with tight junctions in between them, and the gut immune system. Disruptions in the gut barrier follow injury from various causes including nonsteroidal anti-inflammatory drugs and oxidant stress, and involve mechanisms such as adenosine triphosphate depletion and damage to epithelial cell cytoskeletons that regulate tight junctions. Ample evidence links gut barrier dysfunction to multiorgan system failure in sepsis and immune dysregulation. Additionally, contribution of gut barrier dysfunction to gastrointestinal disease is an evolving concept and is the focus of this review. An overview of the evidence for the role of gut barrier dysfunction in disorders such as Crohn's disease, celiac disease, food allergy, acute pancreatitis, non-alcoholic fatty liver disease, and alcoholic liver disease is provided, together with critical insight into the implications of this evidence as a primary disease mechanism.

Oral glutamine does not prevent bacterial translocation in rats subjected to intestinal obstruction and Escherichia coli challenge but reduces systemic bacteria spread

OBJECTIVE

We investigated whether oral glutamine prevents bacterial translocation.

METHODS

Male Wistar rats were fed with isocaloric and isoproteic standard rat chow and randomly assigned to receive glutamine (GLN) or glycine administered through an orogastric tube at 1.5 g.kg(-1).d(-1) for 7 d. On day 8 of the study, the animals were anesthetized and intestinal obstruction was produced by ligature of the terminal ileum. A suspension containing 10(9) colony-forming units per milliliter of Escherichia coli ATCC 25992 was injected into the lumen of the ileum. Twenty-four hours later, blood was withdrawn, and mesenteric lymph nodes and fragments of spleen, liver, and lung were sent for microbiological analysis. Cultures were done on blood agar and MacConkey agar. Student's t test and analysis of variance between two proportions were used. P < 0.05 was considered significant.

RESULTS

Rats in both groups lost body weight during the experiment (not significant). Mesenteric lymph node cultures were positive in both groups. The GLN group had a smaller percentage of E. coli in blood and organ cultures (65.45% versus 82.67% in the glycine group; P = 0.027). Positive cultures of blood, spleen, liver and lung also were higher on glycine group, although not significantly.

CONCLUSIONS

Oral GLN does not prevent bacterial translocation in rats after intestinal obstruction and E. coli challenge. No specific organ was protected by GLN. Nevertheless, its use was associated with a reduced number of positive E. coli cultures in blood and remote organs, and thus diminished bacteria spread. This association suggests a role for GLN in gut barrier protection, possibly by immune system enhancement.

Cytokines and inflammatory pathways in the pathogenesis of multiple organ failure following abdominal aortic aneurysm repair

Multiple organ failure is a common mode of death following abdominal aortic aneurysm repair, particularly after rupture. Cytokines are the principal mediators of the inflammatory response to injury and high levels of circulating cytokines have been associated with poor outcome in major trauma and sepsis. Abdominal aortic aneurysm repair results in an ischaemia-reperfusion injury to the tissues distal to the site of aortic clamping. The inflammatory response in these tissues causes the release of cytokines, principally Interleukins 1-beta, 6, and 8, and Tumour Necrosis Factor alpha. If released in large enough concentrations, these cytokines may enter the circulation and gain access to organs distant to the site of initial injury. Circulating cytokines cause dysfunction of the renal, cardiovascular, respiratory, nervous and musculo-skeletal systems. The combination of these individual changes in organ function is the multiple-organ dysfunction syndrome, which may progress to multiple organ failure.

Bacterial translocation in a non-lethal rat model of peritonitis

BACKGROUND

Bacterial translocation from the gut may occur under a variety of different clinical circumstances and has been implicated in the development of multiple organ failure. The aim of this study was to determine the distribution of bacterial translocation occurring in a model of chemically induced peritonitis. We also sought to document the degree of the associated immune and inflammatory response.

METHODS

Though a midline laparotomy, rats were injected with 5 mg of zymosan (in 0.2 ml of saline) into the subomental space. After 4, 18, 24, 48 and 96 h, a number of endpoints evaluated: intraperitoneal cellular influx, TNF-alpha and interleukin-6 concentrations and myeloperoxidase activity. Bacterial cultures were initiated from the free peritoneal fluid, mesenteric lymph nodes, liver, lung, and kidney. Imprints were also made of the peritoneal mesothelial surface to determine its integrity.

RESULTS

When comparing rats injected with zymosan with the controls, there was evidence of a peritoneal inflammatory response within 4 hours. Facultative gram negative bacteria were found to be growing in the mesenteric lymph nodes and in the peritoneal fluid at 48 h. Anaerobic organisms were also cultured from the peritoneal fluid at 48 h. No organisms were cultured from the liver, lung or kidneys. In addition there was a significant increase in intraperitoneal cell numbers (predominantly neutrophils, P < 0.05), myeloperoxidase activity (P < 0.05) and TNF-alpha and IL-6 concentrations (P < 0.05). There was extensive loss of the peritoneal mesothelial cells. The peritoneal inflammatory changes and bacterial translocation had resolved by 96 h.

CONCLUSION

Bacterial translocation can be induced by the presence of an acute inflammatory focus in the peritoneal cavity. The translocation and inflammatory changes were associated with extensive loss of mesothelial cells. Nonetheless, these changes all resolved, indicating that the peritoneal cavity has a significant capacity to deal with such insults. A clearer understanding of the cellular and molecular events involved in the resolution phase could lead to improvements in the treatment of peritonitis.

Bacterial [correction of baterial] translocation in humans

Bacterial translocation is a phenomenon in which live bacteria cross the intestinal barrier. The definition may be broadened to include transmural passage of bacterial cell wall components such as lipopolysaccharide and peptidoglycan polysaccharide. After translocation, bacteria or their products reach the mesenteric lymph nodes. From there, it is possible that enteric bacteria, their cell wall components, or both may disseminate throughout the body, causing sepsis, shock, multisystem organ dysfunction, or death of the host. Bacterial translocation and its complications have been shown clearly to occur in animal models, but its existence and importance in humans has been difficult to ascertain. The purpose of this review is to evaluate the data from studies in humans on the occurrence of bacterial translocation and, more importantly, to evaluate its role as a cause of death in humans. Studies from trauma and intensive care centers often imply that bacterial translocation is a major contributor to sepsis, shock, and multisystem organ failure in humans. However, the data reviewed herein do not support that view clearly. Carefully designed studies are needed to determine the relevance of bacterial translocation in human disease.

Acadesine and intestinal barrier function after hemorrhagic shock and resuscitation

OBJECTIVE

To determine actions of the prototype adenosine-regulating agent, acadesine (5-amino-1-[beta-D-ribofuranosyl]imidazole-4-carboxamideriboside; AICAR), on intestinal barrier function after hemorrhagic shock and fluid resuscitation, three series of experiments were performed to measure functional (series 1: intestinal permeability and intramural blood flow), structural (series 2: histology), and biochemical (series 3: tissue concentrations of adenine nucleotides and metabolites) changes.

DESIGN

Prospective, controlled animal study.

SETTING/SUBJECTS

University laboratory; juvenile crossbred pigs of either gender.

INTERVENTIONS

Either AICAR or its saline vehicle were intravenously administered 30 mins before 40% hemorrhage. After 1 hr shock, shed blood plus crystalloid was administered for resuscitation. Data were collected for 1 hr thereafter.

MEASUREMENTS AND MAIN RESULTS

In series 1, permeability of the ileum was measured by assaying the portal venous concentration of fluorescein-labeled dextran after placement of this tracer in the lumen. In addition, serosal and mucosal blood flow were monitored with laser-Doppler probes. With vehicle, hemorrhage and resuscitation increased the dextran concentration three-fold and decreased blood flow 50% of the baseline values (both p < .05). AICAR attenuated the permeability increase (p < .05) and attenuated mucosa, but not serosal, ischemia (p < .05). Similar effects were observed with a structurally dissimilar compound-- 4-amino-1-(5-amino-5-deoxy-1-beta-D-ribofuranosyl)-3-bromo-pyrazolo [3,4-d] pyrimidine, a specific adenosine kinase inhibitor-as well as continuous intra-arterial infusion of adenosine. In series 2, AICAR ameliorated the mucosal damage caused by shock/resuscitation (p < .05). In series 3, AICAR increased ileal tissue adenine nucleotides and metabolites during the shock period (p < .05).

CONCLUSIONS

AICAR attenuated gut permeability changes, increased mucosal perfusion, and increased tissue adenine nucleotides, which is consistent with preserved intestinal barrier function after hemorrhage and fluid resuscitation. In context with previous studies from this laboratory, these results provide further evidence for a role for adenosine as an endogenous anti-inflammatory autacoid after shock and trauma. Further study is needed to determine the therapeutic potential of adenosine-regulating agents in resuscitation fluids.

Surgical stress and the gastrointestinal tract

Surgery on any part of the body results in a wide spectrum of alterations in normal body homeostasis. The gastrointestinal tract is extremely sensitive to surgical stress, even at remote locations. It is now evident that the G.I. tract also plays an important role in development of postoperative complications, such as the systemic immune response syndrome and multiple organ failure syndrome. The amount of information available on the cellular and subcellular changes occurring in the gastrointestinal tract after surgical stress is scant. These changes are important since they would act as initiators of tissue damage seen at a later stage, which in turn lead to postoperative complications. This review looks at the information available on the effect of surgical stress on the small intestine, the role of oxygen free radicals in this process, and the changes occurring at the cellular level.

Significant changes in the serum levels of IL-6, h-HGF, and type IV collagen 7S during the perioperative period of a hepatectomy: relevance to SIRS

We analyzed the changes in the serum levels of both interleukin-6 (IL-6), human hepatocyte growth factor (h-HGF), and type IV collagen 7S (7S) during the perioperative period of a hepatectomy and evaluated their relationship with systemic inflammatory response syndrome (SIRS). The study subjects consisted of 40 patients who underwent a hepatectomy. In 14 out of 40 patients, postoperative SIRS(+) was observed. Between the SIRS(+) and SIRS(-) cases, there were significant differences in the preoperative values of prothrombin time, hepaplastin test, cholinesterase, and indocyanine green retention at 15 min (P < 0.01). Compared with the SIRS(-) cases, the IL-6, h-HGF, and 7S of the SIRS(+) cases fluctuated in a higher range and remained significantly higher after postoperative day 1 (P < 0.05). Eight out of 14 SIRS(+) patients had postoperative complications. In the 8 SIRS(+) patients with postoperative complications and in the 4 patients in which the SIRS(+) state lasted 3 days or longer, the 7S levels were significantly higher during the perioperative period (P < 0.05). In the SIRS(+) cases, the postoperative levels of IL-6 and h-HGF, as well as pre- and postoperative levels of 7S, were elevated. We therefore consider these levels to be risk factors for complications during the perioperative period of a hepatectomy.