Effect of cisapride on intestinal bacterial and endotoxin translocation in cirrhosis

Preventing Bacterial Translocation in Patients with Leaky Gut Syndrome: Nutrition and Pharmacological Treatment Options

Leaky gut syndrome is a medical condition characterized by intestinal hyperpermeability. Since the intestinal barrier is one of the essential components maintaining homeostasis along the gastrointestinal tract, loss of its integrity due to changes in bacterial composition, decreased expression levels of tight junction proteins, and increased concentration of pro-inflammatory cytokines may lead to intestinal hyperpermeability followed by the development of gastrointestinal and non-gastrointestinal diseases. Translocation of microorganisms and their toxic metabolites beyond the gastrointestinal tract is one of the fallouts of the leaky gut syndrome. The presence of intestinal bacteria in sterile tissues and distant organs may cause damage due to chronic inflammation and progression of disorders, including inflammatory bowel diseases, liver cirrhosis, and acute pancreatitis. Currently, there are no medical guidelines for the treatment or prevention of bacterial translocation in patients with the leaky gut syndrome; however, several studies suggest that dietary intervention can improve barrier function and restrict bacteria invasion. This review contains current literature data concerning the influence of diet, dietary supplements, probiotics, and drugs on intestinal permeability and bacterial translocation.

Current Status and Prospects of Spontaneous Peritonitis in Patients with Cirrhosis

Spontaneous bacterial peritonitis (SBP) is a common cirrhotic ascites complication which exacerbates the patient's condition. SBP is caused by gram-negative bacilli and, to a lesser extent, gram-positive cocci. Hospital-acquired infections show higher levels of drug-resistant bacteria. Geographical location influences pathogenic bacteria distribution; therefore, different hospitals in the same country record different bacteria strains. Intestinal changes and a weak immune system in patients with liver cirrhosis lead to bacterial translocation thus causing SBP. Early diagnosis and timely treatment are important in SBP management. When the treatment effect is not effective, other rare pathogens should be explored.

Microbial Infections as a Trigger for Acute-on-Chronic Liver Failure: A Review

Microbial infection is an important cause of acute-on-chronic liver failure (ACLF), which is a syndrome that results in multiple organ dysfunction or failure and is accompanied by an increased short-term risk of mortality. Early detection and treatment of microbial infection can effectively reduce the mortality of patients with ACLF. However, antimicrobial resistance has recently increased due to the increased use of antimicrobial agents. Therefore, it is important to choose appropriate antibiotics and antifungal agents for early prevention or treatment of patients with microbial infection and ACLF to reduce the occurrence of drug resistance and to reduce patient mortality. This review summarizes the current status in the understanding of the epidemiology, pathogenesis, early diagnosis, treatment, and strategies for prevention of microbial infection in patients with ACLF.

Mosapride Stabilizes Intestinal Microbiota to Reduce Bacterial Translocation and Endotoxemia in CCl4-Induced Cirrhotic Rats

BACKGROUND

Impaired intestinal motility may lead to the disruption of gut microbiota equilibrium, which in turn facilitates bacterial translocation (BT) and endotoxemia in cirrhosis. We evaluated the influence of mosapride, a prokinetic agent, on BT and DNA fingerprints of gut microbiota in cirrhotic rats.

METHODS

A rat model of cirrhosis was set up via subcutaneous injection of carbon tetrachloride (CCl₄). The portal pressure, liver and intestinal damage, plasma endotoxin, BT, and intestinal transit rate (ITR) of cirrhotic rats were determined. Fecal DNA fingerprints were obtained by ERIC-PCR. The expressions of tight junction proteins were evaluated by western blotting.

RESULTS

Mosapride treatment to cirrhotic rats significantly reduced the plasma endotoxin level and incidence of BT, accompanied by increased ITR. Cirrhotic rats (including those treated with mosapride) suffered from BT exhibited significantly lower ITR than those who are free of BT. Pearson coefficient indicated a significant and negative correlation between the plasma endotoxin level and ITR. The genomic fingerprints of intestinal microbiota from the three groups fell into three distinctive clusters. In the mosapride-treated group, Shannon's index was remarkably increased compared to the model group. Significantly positive correlation was detected between Shannon's index and ITR. Mosapride did not improve hepatic and intestinal damages and ileal expressions of occludin and ZO-1.

CONCLUSIONS

Mosapride significantly increases intestinal motility in cirrhotic rats, thus to recover the disordered intestinal microbiota, finally resulting in decreased plasma endotoxin and BT.

Bacterial infections and hepatic encephalopathy in liver cirrhosis-prophylaxis and treatment

Infections are common among patients with liver cirrhosis. They occur more often in cirrhotic patient groups than in the general population and result in higher mortality. One reason for this phenomenon is bacterial translocation from the intestinal lumen that occurs as a consequence of intestinal bacterial overgrowth, increased permeability and decreased motility. The most common infections in cirrhotic patients are spontaneous bacterial peritonitis and urinary tract infections, followed by pneumonia, skin and soft tissue infections. Intestinal bacterial overgrowth is also responsible for hyperammonemia, which leads to hepatic encephalopathy. All of these complications make this group of patients at high risk for mortality. The role of antibiotics in liver cirrhosis is to treat and in some cases to prevent the development of infectious complications. Based on our current knowledge, antibiotic prophylaxis should be administered to patients with gastrointestinal hemorrhage, low ascitic fluid protein concentration combined with liver or renal failure, and spontaneous bacterial peritonitis as a secondary prophylaxis, as well as after hepatic encephalopathy episodes (also as a secondary prophylaxis). In some cases, the use of non-antibiotic prophylaxis can also be considered. Current knowledge of the treatment of infections allows the choice of a preferred antibiotic for empiric therapy depending on the infection location and whether the source of the disease is nosocomial or community-acquired.

The gut microbiome and liver cancer: mechanisms and clinical translation

Hepatocellular carcinoma (HCC) is the third leading cause of worldwide cancer mortality. HCC almost exclusively develops in patients with chronic liver disease, driven by a vicious cycle of liver injury, inflammation and regeneration that typically spans decades. Increasing evidence points towards a key role of the bacterial microbiome in promoting the progression of liver disease and the development of HCC. Here, we will review mechanisms by which the gut microbiota promotes hepatocarcinogenesis, focusing on the leaky gut, bacterial dysbiosis, microbe-associated molecular patterns and bacterial metabolites as key pathways that drive cancer-promoting liver inflammation, fibrosis and genotoxicity. On the basis of accumulating evidence from preclinical studies, we propose the intestinal-microbiota-liver axis as a promising target for the simultaneous prevention of chronic liver disease progression and HCC development in patients with advanced liver disease. We will review in detail therapeutic modalities and discuss clinical settings in which targeting the gut-microbiota-liver axis for the prevention of disease progression and HCC development seems promising.

Gastrointestinal Motility Disorders and Their Clinical Implications in Cirrhosis

Gastrointestinal motility is impaired in a substantial proportion of patients with cirrhosis. Cirrhosis-related autonomic neuropathy, increased nitric oxide production, and gut hormonal changes have been implicated. Oesophageal dysmotility has been associated with increased frequency of abnormal gastro-oesophageal reflux. Impaired gastric emptying and accommodation may result in early satiety and may have an impact on the nutritional status of these patients. Small intestinal dysmotility might be implicated in small intestinal bacterial overgrowth and increased bacterial translocation. The latter has been implicated in the pathophysiology of hepatic encephalopathy and spontaneous bacterial peritonitis. Enhanced colonic motility is usually associated with the use of lactulose. Pharmacological interventions aiming to alter gastrointestinal motility in cirrhosis could potentially have a beneficial effect reducing the risk of hepatic decompensation and improving prognosis.

Bacterial translocation in critical illness

Bacterial translocation involves the passage of intestinal bacteria to extraintestinal sites and has been shown to increase morbidity and mortality in critical illness. This review outlines the pathophysiology of bacterial translocation, host defence mechanisms, and reviews the evidence for the clinical management of critically ill patients in order to minimise the negative outcomes associated with bacterial translocation.

Intestinal permeability in a patient with liver cirrhosis

Liver cirrhosis is a worldwide public health problem, and patients with this disease are at high risk of developing complications, bacterial translocation from the intestinal lumen to the mesenteric nodes, and systemic circulation, resulting in the development of severe complications related to high mortality rate. The intestinal barrier is a structure with a physical and biochemical activity to maintain balance between the external environment, including bacteria and their products, and the internal environment. Patients with liver cirrhosis develop a series of alterations in different components of the intestinal barrier directly associated with the severity of liver disease that finally increased intestinal permeability. A "leaky gut" is an effect produced by damaged intestinal barrier; alterations in the function of tight junction proteins are related to bacterial translocation and their products. Instead, increasing serum proinflammatory cytokines and hemodynamics modification, which results in the appearance of complications of liver cirrhosis such as hepatic encephalopathy, variceal hemorrhage, bacterial spontaneous peritonitis, and hepatorenal syndrome. The intestinal microbiota plays a fundamental role in maintaining the proper function of the intestinal barrier; bacterial overgrowth and dysbiosis are two phenomena often present in people with liver cirrhosis favoring bacterial translocation. Increased intestinal permeability has an important role in the genesis of these complications, and treating it could be the base for prevention and partial treatment of these complications.

Novel prevention strategies for bacterial infections in cirrhosis

INTRODUCTION

Bacterial infections are a serious complication of cirrhosis, as they can lead to decompensation, multiple organ failure, and/or death. Preventing infections is therefore very relevant. Because gut bacterial translocation is their main pathogenic mechanism, prevention of infections is mostly based on the use of orally administered poorly absorbed antibiotics such as norfloxacin (selective intestinal decontamination). However, antibiotic prophylaxis leads to antibiotic resistance, limiting therapy and increasing morbidity and mortality. Prevention of bacterial infections in cirrhosis should therefore move away from antibiotics.

AREAS COVERED

This review focuses on various potentially novel methods to prevent infections in cirrhosis focusing on non-antibiotic strategies. The use of probiotics, nonselective intestinal decontamination with rifaximin, prokinetics and beta-blockers or fecal microbiota transplant as means of targeting altered gut microbiota, bile acids and FXR agonists are all potential alternatives to selective intestinal decontamination. Prokinetics and beta-blockers can improve intestinal motility, while bile acids and FXR agonists help by improving the intestinal barrier. Finally, granulocyte colony stimulating factor (G-CSF) and statins are emerging therapeutic strategies that may improve immune dysfunction in cirrhosis.

EXPERT OPINION

Evidence for these strategies has been restricted to animal studies and proof-of concept studies but we expect this to change in coming years.

The chronic use of beta-blockers and proton pump inhibitors may affect the rate of bacterial infections in cirrhosis

BACKGROUND & AIMS

Bacterial infections are among the most common and life-threatening complications in cirrhosis. Qualitative and quantitative modifications of the gut microbiota, dysfunction of the intestinal barrier and multiple immune defects are factors that contribute to a pathological 'bacterial translocation' (BT), leading to a higher susceptibility to infections in cirrhotic patients. Long-term therapies, commonly adopted in cirrhotic patients, may influence BT and modify the risk of infection in these patients. To investigate the influence of chronic therapies on the prevalence and microbiological characteristics of infections in cirrhosis.

METHODS

Consecutive cirrhotic patients hospitalised from 2008 to 2013 were enrolled. All previous treatments were carefully recorded. Infections were actively sought out, patients were actively monitored for infection, and possible risk factors were evaluated.

RESULTS

Four hundred cirrhotic patients were included. The most frequent therapies were proton pump inhibitors (PPIs) (67%), non-absorbable-disaccharides (44%), beta-blockers (BBs) (39%) and non-absorbable-antibiotics (10%). Child-Pugh C (P < 0.001; OR 5; 95%CI: 2.6-9.9) and PPI therapy (P = 0.008; OR 2; 95% CI: 1.2-3.2) were found to be independent predictors of infection, and the use of BBs was a protective factor (P = 0.001; OR 0.46; 95%CI: 0.3-0.7). Cirrhotic patients with bacterial infection showed lower morbidity and mortality when taking BBs.

CONCLUSIONS

Proton pump inhibitors increase the risk of infection in cirrhosis and should not be prescribed in these patients without specific indications. In contrast, the use of BBs is associated with a lower rate of infection and attenuates the consequences of infections in cirrhotic patients.

Short-term probiotic therapy alleviates small intestinal bacterial overgrowth, but does not improve intestinal permeability in chronic liver disease

AIM

: Although numerous animal studies suggest that probiotic therapy has beneficial effects in various liver diseases, the evidence for beneficial effects in human liver disease is controversial. This study was carried out to investigate the efficacy of probiotic therapy in alleviating small intestinal bacterial overgrowth (SIBO) and permeability in chronic liver disease.

METHODS

Fifty-three patients with chronic liver disease were randomized to either probiotic therapy or placebo. Six bacterial species were used: Bifidobacterium bifidum, Bifidobacterium lactis, Bifidobacterium longum, Lactobacillus acidophilus, Lactobacillus rhamnosus, and Streptococcus thermophilus. After 4 weeks, changes in the composition of fecal bacteria, SIBO, intestinal permeability, and clinical symptoms were examined.

RESULTS

Three of the six probiotic species, B. lactis, L. rhamnosus, and L. acidophilus, increased in the feces of the probiotic therapy group (P<0.001), whereas there was no change in fecal microbiota in the placebo group. SIBO disappeared in many individuals of the probiotic therapy group, but none in the placebo (24 vs. 0%, P<0.05). General gastrointestinal symptoms also improved more in the probiotic group and improvement in intestinal permeability was slightly but not significantly more frequent in the probiotic arm than the placebo arm (50 vs. 31.3%, P=0.248). Numbers of lactobacilli in stool were correlated negatively with intestinal permeability (P for trend<0.05). Liver chemistry did not improve significantly in either group.

CONCLUSIONS

We conclude that short-term probiotic administration in chronic liver disease is effective in alleviating SIBO and clinical symptoms, but ineffective in improving intestinal permeability and liver function.

Drug therapies in liver disease

The likelihood of a general physician encountering a patient with compensated and decompensated liver disease is increasing. This article provides an overview of pharmaceutical agents currently used in the management of cirrhosis and is designed to allow a better understanding of the rationale for using certain drugs in patients with often complex pathology.

Gut bacterial translocation contributes to microinflammation in experimental uremia

BACKGROUND

Microinflammation frequently develops in chronic uremia with pathological intestinal changes. However, the relationship between gut bacterial translocation and microinflammation in uremia has not been widely investigated.

AIM

This study aimed to investigate whether gut microbiome dysbiosis and translocation occurred in experimental uremia, and whether they consequently contributed to microinflammation.

METHODS

Forty rats underwent surgical renal mass 5/6 ablation. The surviving (uremic group, n = 21) and healthy (sham group, n = 20) rats were used in the experiment. Postoperative blood, livers, spleens, and mesenteric lymph nodes (MLNs) were subjected to bacterial 16S ribosomal DNA amplification to determine if bacteria were present. Bacterial genomic DNA samples from the MLNs and colon were amplified with specific primers designed by the 16S rRNA sequence of the species obtained from blood, livers, and spleens. Pyrosequencing was used to analyze the colonic microbiome of each subject. Intestinal permeability to (99m)Tc-DTPA, plasma hs-CRP, and IL-6 were measured.

RESULTS

Bacterial DNA in extraintestinal sites and altered colonic microbiomes were detected in some rats in the uremic group. Bacterial genomic DNA in MLNs and colon were obtained by primers specific for bacterial species observed from blood, livers, and spleens of identical individuals. Intestinal permeability, plasma hs-CRP, and IL-6 levels were statistically higher in the uremic group compared with the sham group. Plasma hs-CRP and IL-6 were significantly higher in uremic rats with bacterial DNA in their blood than in those without.

CONCLUSIONS

Gut microbiome dysbiosis occurs and bacteria translocate to the systemic and lymph circulation, thereby contributing to microinflammation in experimental uremia.

Microbial translocation in chronic liver diseases

The intestinal microflora is not only involved in the digestion of nutrients, but also in local immunity, forming a barrier against pathogenic microorganisms. The derangement of the gut microflora may lead to microbial translocation, defined as the passage of viable microorganisms or bacterial products (i.e., LPS, lipopeptides) from the intestinal lumen to the mesenteric lymph nodes and other extraintestinal sites. The most recent evidence suggests that microbial translocation (MT) may occur not only in cirrhosis, but also in the early stage of several liver diseases, including alcoholic hepatopathy and nonalcoholic fatty liver disease. Different mechanisms, such as small intestinal bacterial overgrowth, increased permeability of intestinal mucosa, and impaired immunity, may favor MT. Furthermore, MT has been implicated in the pathogenesis of the complications of cirrhosis, which are a significant cause of morbidity and mortality in cirrhotic subjects. Therapeutic strategies aiming at modulating the gut microflora and reducing MT have focused on antibiotic-based options, such as selective intestinal decontamination, and nonantibiotic-based options, such as prokinetics and probiotics. In particular, probiotics may represent an attractive strategy, even though the promising results of experimental models and limited clinical studies need to be confirmed in larger randomized trials.

Glutamine prevents total parenteral nutrition-associated changes to intraepithelial lymphocyte phenotype and function: a potential mechanism for the preservation of epithelial barrier function

Total parenteral nutrition (TPN) results in a number of derangements to the intestinal epithelium, including a loss of epithelial barrier function (EBF). As TPN supplemented with glutamine has been thought to prevent this loss, this article further defined the impact of glutamine on EBF, and investigated potential mechanisms that contributed to the preservation of EBF. C57BL/6J male mice were randomized to enteral nutrition (control), TPN, or TPN supplemented with glutamine (TPN+GLN). Changes in intraepithelial lymphocyte (IEL)-derived cytokine expression were measured, and EBF was assessed with electrophysiologic methods and assessment of junctional protein expression. TPN resulted in a significant decline in EBF, and this loss of EBF was significantly prevented in the TPN+GLN group. Coincident with these changes was a loss of intraepithelial lymphocyte (IEL, mucosal lymphocyte)-derived IL-10 and increase in interferon-gamma (IFN-gamma) expression, and a decline in IEL numbers in the TPN group. A prevention in the increase in IFN-gamma and decline in IL-10 expression was seen in the TPN+GLN group. To determine the mechanism responsible for these glutamine-associated cytokine changes, we tested whether blockade of the IL-7 signaling pathway between epithelial cells (EC) and IEL would prevent these changes; however, blockade failed to influence IEL-derived cytokine changes. Glutamine-supplemented TPN leads to a specific IEL-derived cytokine profile, which may account for the preservation of EBF; and such action may be due to a direct action of glutamine on the IEL.

Role of bile in intestinal motility after massive liver resection in conscious rats

AIM

To investigate the effect of 90% partial hepatectomy (90% PHx) and the involvement of bile on ileal motility in conscious rats.

METHODS

Two strain gauge force transducers were chronically implanted in the ileum of each of 20 rats. The rats were divided into four groups, three of which underwent 90% PHx. The experiments were performed with the rats in a conscious, fasted state. After ileal motility was recorded, bile or saline was perfused into the duodenum of each rat in two of the 90% PHx groups. The effects of the perfusion on ileal motility were observed and recorded using the motility index (MI), defined as the area under the contraction cues after surgery and expressed as the ratio to the MI in the preoperational motility. The time of the first passage of stool after surgery was recorded.

RESULTS

A typical migrating motor complex (MMC) pattern was observed in normal fasted rats. Increased MMC cycle lengths and a decreased MI at 1 day and 3 days after 90% PHx were observed. The MMC after 90% PHx was characterized by an increased duration of Phase 2-like activity. The MMC cycle length, the MI, and the time of the first passage of stool after 90% PHx were improved by perfusion of bile into the duodenum through the biliary cannula but were not influenced by perfusion of saline into the duodenum through the biliary cannula.

CONCLUSION

The MMC cycle length and the MI were inhibited after 90% PHx, with the involvement of decreased bile flow into the gastrointestinal tract by liver resection.

Glutamine and recombinant human growth hormone protect intestinal barrier function following portal hypertension surgery

AIM: To evaluate the effects of combined treatment of glutamine (Gln) and recombinant human growth hormone(rhGH) on intestinal barrier function following portal hypertension surgery.

METHODS: This study was designed as a prospective, randomized and controlled clinical trial. Forty two patients after portal hypertension surgery were randomly assigned into 2 groups: control group (n = 20) and supplemental group (adding Gln and rhGH, n = 22). Every patient received isocaloric and isonitrogenous standard total parenteral nutrition (TPN) starting 3 d after surgery for 7 d. Blood samples were obtained before surgery and at the 3rd and 10th day postoperatively. Host immunity was evaluated by measuring levels of CD4, CD8, CD4/CD8, IgG, IgM and IgA, and the inflammatory responses were determined by assessing IL-2, TNF-α and C-reactive protein (CRP) levels. Intestinal permeability and integrity was evaluated by L/M test and histological examination, respectively.

RESULTS: On postoperative d 10, CD4, CD4/CD8, IgG and IL-2 levels in supplemental group were significantly higher than those in control group (33.7 ± 5.5 vs 31.0± 5.4, P < 0.05, (1.17 ± 0.32 vs 1.05 ± 0.15, P < 0.05, 13.94 ± 1.09 vs 12.33 ± 1.33, P < 0.05, and 368.12± 59.25 vs 318.12 ± 45.65, P < 0.05, respectively), whereas the increase in serum TNF-α concentration was significantly reduced (41.02 ± 27.56 vs 160.09 ± 35.17, P < 0.05). The increase in L/M ratio was significantly lower in the supplemental group than in the control group (0.0166 ± 0.0017 vs 0.0339 ± 0.0028, P < 0.05). Moreover, mucosal integrity in the supplemental group was better than in the control group.

CONCLUSION: Postoperative administration of TPN supplemented with Gln and rhGH in patients after portal hypertension surgery improves immune function, modulates inflammatory response, prevents the intestinal mucous membrane from atrophy and preserves intestinal integrity.

Review article: bacterial translocation in the critically ill--evidence and methods of prevention

BACKGROUND

Delayed sepsis, systemic inflammatory response syndrome (SIRS) and multiorgan failure remain major causes of morbidity and mortality on intensive care units. One factor thought to be important in the aetiology of SIRS is failure of the intestinal barrier resulting in bacterial translocation and subsequent sepsis.

AIM

This review summarizes the current knowledge about bacterial translocation and methods to prevent it.

METHODS

Relevant studies during 1966-2006 were identified from a literature search. Factors, which detrimentally affect intestinal barrier function, are discussed, as are methods that may attenuate bacterial translocation in the critically ill patient.

RESULTS

Methodological problems in confirming bacterial translocation have restricted investigations to patients undergoing laparotomy. There are only limited data available relating to specific interventions that might preserve intestinal barrier function or limit bacterial translocation in the intensive care setting. These can be categorized broadly into pre-epithelial, epithelial and post-epithelial interventions.

CONCLUSIONS

A better understanding of factors that influence translocation could result in the implementation of interventions which contribute to improved patient outcomes. Glutamine supplementation, targeted nutritional intervention, maintaining splanchnic flow, the judicious use of antibiotics and directed selective gut decontamination regimens hold some promise of limiting bacterial translocation. Further research is required.

The effect of caffeic acid phenethyl ester on bacterial translocation and intestinal damage in cholestatic rats

We investigated the effect of caffeic acid phenethyl ester in rat ileum injury induced by chronic biliary obstruction. Swiss albino rats were divided into three groups: Group 1, sham (n = 7); Group 2, common bile duct ligation (n = 7); and Group 3, common bile duct ligation plus caffeic acid phenethyl ester (n = 7). In the caffeic acid phenethyl ester-treated rats, ileum tissue levels of malondialdehyde and myeloperoxidase were significantly lower than those of the bile duct-ligated rats (P < 0.001). The levels of tumor necrosis factor-alpha, interleukin-6, and interleukin-1alpha in the caffeic acid phenethyl ester group were significantly lower than those in the bile duct ligation group (P < 0.03, P < 0.01, and P < 0.02 respectively). The present study demonstrates that intraperitoneal administration of caffeic acid phenethyl ester in bile duct-ligated rats reduces intestinal oxidative stress. This effect may be useful in the preservation of intestinal damage in cholestasis.

Gut flora and bacterial translocation in chronic liver disease

Increasing evidence suggests that derangement of gut flora is of substantial clinical relevance to patients with cirrhosis. Intestinal bacterial overgrowth and increased bacterial translocation of gut flora from the intestinal lumen, in particular, predispose to an increased potential for bacterial infection in this group. Recent studies suggest that, in addition to their role in the pathogenesis of overt infective episodes and the clinical consequences of sepsis, gut flora contributes to the pro-inflammatory state of cirrhosis even in the absence of overt infection. Furthermore, manipulation of gut flora to augment the intestinal content of lactic acid-type bacteria at the expense of other gut flora species with more pathogenic potential may favourably influence liver function in cirrhotic patients. Here we review current concepts of the various inter-relationships between gut flora, bacterial translocation, bacterial infection, pro-inflammatory cytokine production and liver function in this group.

Small intestinal bacterial overgrowth: roles of antibiotics, prebiotics, and probiotics

Small intestinal bacterial overgrowth is common in intestinal failure. Its occurrence relates to alterations in intestinal anatomy, motility, and gastric acid secretion. Its presence may contribute to symptoms, mucosal injury, and malnutrition. Relationships between bacterial overgrowth and systemic sepsis are of potential importance in the intestinal failure patient because the direct translocation of bacteria across the intestinal epithelium may contribute to systemic sepsis: a phenomenon that has been well established in experimental animal models. The accurate diagnosis of bacterial overgrowth continues to present a number of challenges in clinical practice and especially so among patients with intestinal failure. The management of patients with bacterial overgrowth remains, for the most part, primarily empiric and comprises antibiotic therapy and correction of any associated nutritional deficiencies. Although evidence from experimental animal studies consistently indicates that probiotics exert barrier-enhancing, antibacterial, immune-modulating, and anti-inflammatory effects, which all could be benefits in small intestinal bacterial overgrowth and intestinal failure, their role in human beings remains to be evaluated adequately.

Bacterial translocation (BT) in cirrhosis

Gut flora and bacterial translocation (BT) play an important role in the pathogenesis of the complications of cirrhosis. Research on the pathogenesis of BT and its clinical significance transcends established boundaries between microbiology, cell biology, intestinal pathophysiology, and immunology. This review delineates multiple mechanisms involved in the process of BT, with an emphasis on alterations in intestinal flora and mucosal barrier function, particularly immunological defense mechanisms. Current knowledge on the innate and adaptive immune response that allows a "friendly" communication between bacteria and host is summarized, and alterations occurring in cirrhosis that may facilitate BT are discussed. In addition, definition of a "pathological" BT is proposed together with an analysis of the anatomical site and route of BT. Finally, therapeutic approaches for the prevention of BT in experimental and human cirrhosis are reviewed. Future research in the field of BT in cirrhosis will allow the development of new therapeutic targets in the prevention of infections and other complications of cirrhosis.

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