Inflammatory consequences of the translocation of bacteria and endotoxin to mesenteric lymph nodes

Procalcitonin as an Early Marker of Colorectal Anastomotic Leakage in Postoperative Colorectal Cancer Patients: A Systematic Review and Meta-Analysis

Background The timely identification of colorectal anastomotic leakage (CAL) is still a significant challenge, and identifying reliable markers is essential to minimize patient morbidity and mortality. While procalcitonin (PCT) has shown promise as a biomarker for CAL, its effectiveness must be specifically evaluated in colorectal cancer patients. This systematic review and meta-analysis sought to assess the mean differences in PCT levels between individuals with and without CAL who underwent colorectal surgery for colorectal cancer. Methodology A comprehensive search of the "PubMed," "Scopus," and "Web of Science" databases was carried out, covering studies published through April 2024. The objective was to identify studies examining PCT levels in colorectal cancer patients who underwent colorectal surgery, with a particular focus on the occurrence of CAL. Data on the mean of PCT levels in CAL and non-CAL patients were extracted from the selected studies. The mean differences in PCT levels were subsequently analyzed for each postoperative day (POD). Results Seventeen articles were selected for inclusion in this systematic review. The statistical analysis included five eligible articles that assessed PCT levels in groups exclusively involving patients with colorectal cancer. The findings showed no significant increase in PCT levels in CAL patients compared to non-CAL patients on any POD when a leave-one-out sensitivity analysis was performed to validate the results. Conclusions To date, PCT levels should not be regarded as early indicators of CAL after colorectal surgery in patients with colorectal cancer. Additional research is necessary to evaluate if PCT could be a dependable marker for CAL in this particular setting.

Pneumatosis intestinalis and hepatic portal venous gas associated with gas-forming bacterial translocation due to postoperative paralytic ileus: A case report

RATIONALE

Pneumatosis intestinalis (PI) and hepatic portal venous gas (HPVG) are rare but potentially lethal conditions in which gas pathologically accumulates in the portal vein and intestinal wall, respectively. Proposed mechanisms include flatus escaping through an injured intestinal mucosa into the submucosa and thence into the portal venous system, or bacterial translocation (BT) of gas-forming enteric microorganisms from the gut into and through the intestinal wall to other organs. However, there has been no clear histopathological evidence to support these hypotheses.

PATIENT CONCERNS

A 61-year-old man underwent sigmoidectomy for colonic adenocarcinoma. Postoperatively, he developed paralytic ileus and then had a sudden cardiopulmonary arrest.

DIAGNOSES

PI and HPVG were found at autopsy, presumably caused by the postoperative paralytic ileus and associated with BT of gas-forming organisms.

INTERVENTIONS

Cardiopulmonary resuscitation was unsuccessful.

OUTCOMES

Postmortem imaging indicated the presence of massive PI and HPVG. At autopsy, there was marked intestinal emphysema with diffuse ischemic mucosal necrosis and severe pneumatosis in the stomach and intestine and marked gaseous dilation of the intrahepatic portal veins. Postmortem bacterial cultures revealed enteric bacteria in the peripheral blood and liver tissue.

LESSONS

Postoperative ileus leading to intestinal mucosal damage may be associated with BT of gas-forming enteric bacteria and the rapid onset of PI and HPVG with a lethal outcome.

Role of Procalcitonin in the Management of Infected Patients in the Intensive Care Unit

The combination of molecular pathogen diagnostics and the biomarker procalcitonin (PCT) are changing the use of antimicrobials in patients admitted to critical care units with severe community-acquired pneumonia, possible septic shock, or other clinical syndromes. An elevated serum PCT level is good supportive evidence of a bacterial pneumonia, whereas a low serum PCT level virtually eliminates an etiologic role for bacteria even if the culture for a potential bacterial pathogen is positive. Serum PCT levels can be increased in any shocklike state; a low PCT level eliminates invasive bacterial infection as an etiology in more than 90% of patients.

Bacterial translocation and in vivo assessment of intestinal barrier permeability in rainbow trout (Oncorhynchus mykiss) with and without soyabean meal-induced inflammation

The primary aim of this experiment was to evaluate the intestinal barrier permeability in vivo in rainbow trout (Oncorhynchus mykiss) fed increasing levels of soyabean meal (SBM). The relationship between SBM-induced enteritis (SBMIE) and the permeability markers was also investigated. Our results showed that the mean score of morphological parameters was significantly higher as a result of 37·5 % SBM inclusion in the diet, while the scores of fish fed 25 % SBM or lower were not different from those of the fish meal-fed controls (P < 0·05). SBMIE was found in the distal intestine (DI) in 18 % of the fish (eleven of sixty): ten in the 37·5 % SBM-fed group and one in the 25 % SBM-fed group. Sugar markers in plasma showed large variation among individuals probably due to variation in feed intake. We found, however, a significant linear increase in the level of plasma d-lactate with increasing SBM inclusion level (P < 0·0001). Plasma concentration of endotoxin was not significantly different in groups with or without SBMIE. Some individual fish showed high values of endotoxin in blood, but the same individuals did not show any bacterial translocation. Plasma bacterial DNA was detected in 28 % of the fish with SBMIE, and 8 % of non-SBMIE fish (P = 0·07). Plasma concentration of d-lactate was significantly higher in fish with SBMIE (P < 0·0001). To conclude, SBMIE in the DI of rainbow trout was associated with an increase in bacterial translocation and plasma d-lactate concentration, suggesting that these permeability markers can be used to evaluate intestinal permeability in vivo.

Influence of prophylactic probiotics and selective decontamination on bacterial translocation in patients undergoing pancreatic surgery: a randomized controlled trial

Bacterial translocation (BT) is suspected to play a major role in the development of infections in surgical patients. However, the clinical association between intestinal barrier dysfunction, BT, and septic morbidity has remained unconfirmed. The objective of this study was to study BT in patients undergoing major abdominal surgery and the effects of probiotics, selective decontamination of the digestive tract (SDD), and standard treatment on intestinal barrier function. In a randomized controlled setting, 30 consecutive patients planned for elective pylorus-preserving pancreaticoduodenectomy (PPPD) were allocated to receive perioperatively probiotics, SDD, or standard treatment. To assess intestinal barrier function, intestinal fatty acid-binding protein (mucosal damage) and polyethylene glycol recovery (intestinal permeability) in urine were measured perioperatively. BT was assessed by real-time polymerase chain reaction and multiplex ligation-dependent probe amplification (MLPA) in mesenteric lymph nodes (MLNs) harvested early (baseline control) and at the end of surgery ("end-of-surgery" MLNs, after 3h in PPPD patients). Polymerase chain reaction detected bacterial DNA in 18 of 27 end-of-surgery MLNs and in 13 of 23 control MLNs (P = 0.378). Probiotics and SDD had no significant effect on the number of positive MLNs or the change in bacterial DNA during operation. Multiplex ligation-dependent probe amplification analysis showed significantly increased expression of only 4 of 30 inflammatory mediator-related genes in end-of-surgery compared with early sampled MLN (P < 0.05). Polyethylene glycol recovery was unaffected by operation, probiotics and SDD as compared with standard treatment. Intestinal fatty acid-binding protein levels were increased shortly postoperatively only in patients treated with SDD (P = 0.02). Probiotics and SDD did not influence BT, intestinal permeability, or inflammatory mediator expression. Bacterial translocation after abdominal surgery may be part of normal antigen-sampling processes of the gut.

Hypoxia-inducible factor 1 alpha expression increases during colorectal carcinogenesis and tumor progression

BACKGROUND

Hypoxia-inducible factor 1 alpha (HIF-1alpha) is involved in processes promoting carcinogenesis of many tumors. However, its role in the development of colorectal cancer is unknown. To investigate the significance of HIF-1alpha during colorectal carcinogenesis and progression we examined its expression in precursor lesions constituting the conventional and serrated pathways, as well as in non-metastatic and metastatic adenocarcinomas.

METHODS

Immunohistochemistry and Western blot is used to analyse HIF-1alpha expression in normal colonic mucosa, hyperplastic polyps (HPP), sessile serrated adenomas (SSA), low-grade (TA-LGD) and high-grade (TA-HGD) traditional adenomas as well as in non-metastatic and metastatic colorectal adenocarcinomas. Eight colorectal carcinoma cell lines are tested for their HIF-1alpha inducibility after lipopolysaccharide (LPS) stimulation using western blot and immunocytochemistry.

RESULTS

In normal mucosa, HPP and TA-LGD HIF-1alpha was not expressed. In contast, perinuclear protein accumulation and nuclear expression of HIF-1alpha were shown in half of the examined SSA and TA-HGD. In all investigated colorectal carcinomas a significant nuclear HIF-1alpha overexpression compared to the premalignant lesions was observed but a significant correlation with the metastatic status was not found. Nuclear HIF-1alpha expression was strongly accumulated in perinecrotic regions. In these cases HIF-1alpha activation was seen in viable cohesive tumor epithelia surrounding necrosis and in dissociated tumor cells, which subsequently die. Enhanced distribution of HIF-1alpha was also seen in periinflammatory regions. In additional in vitro studies, treatment of diverse colorectal carcinoma cell lines with the potent pro-inflammatory factor lipopolysaccharide (LPS) led to HIF-1alpha expression and nuclear translocation.

CONCLUSION

We conclude that HIF-1alpha expression occurs in early stages of colorectal carcinogenesis and achieves a maximum in the invasive stage independent of the metastatic status. Perinecrotic activation of HIF-1alpha in invasive tumors underlines a dual role of HIF-1alpha by regulating both pro-survival and pro-death processes. HIF-1alpha up-regulation in response to LPS-mediated stimulation and periinflammatory expression in invasive carcinomas suggest its involvement in inflammatory events. These patterns of HIF-1alpha inducibility could contribute indirectly to the acquisition of a metastatic phenotype.

Bacterial translocation during liver transplantation: a randomized trial comparing conventional with venovenous bypass vs. piggyback methods

The aim of this study was to evaluate the bacterial translocation in liver transplantation (LT), comparing the conventional and the piggyback methods. A total of 32 patients were randomized into the 2 groups. Samples of blood were collected from the radial artery, portal vein (PV) and hepatic vein (HV), in up to 120 minutes postreperfusion. The samples were sent for endotoxin level, as well as samples up to 2 minutes post-perfusion were sent to culture. Hepatic artery and PV blood flows were measured at postreperfusion collection times. The results analyzed were: endotoxin concentration, its quantity, and hepatic clearance. The statistical treatment consisted of analyzing each group's mean profile. The analysis for endotoxin concentration in the radial artery was the deviation related to presurgery measure, and in the PV the deviation related to preclamping (PC) measure. The overall mean level of endotoxin concentration was 0.99 EU/mL in the artery, 1.30 EU/mL in the PV, and 1.22 EU/mL in the HV. The deviation was significant in the portal (P = 0.0031), but not in the artery samples (P = 0.2092). We detected a significant quantity of endotoxin in the artery and in the portal and the HVs (P < 0.001). There was no difference between the 2 groups and no hepatic clearance of endotoxin was detected either (P = 0.1515). All the cultures were negative. In conclusion, the study detected a significant translocation of endotoxin, but not of bacteria. The study also detected the absence of endotoxin hepatic clearance in both the piggyback and the conventional methods without any difference between them.

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.

Inflammatory response in patients with malignant obstructive jaundice

OBJECTIVE

Surgery in patients with malignant obstructive jaundice is associated with increased risks for postoperative septic complications. The aim of this study was to investigate the inflammatory and the local cellular immune response in patients accepted for surgery because of tumours in the hepatic-pancreatic-biliary (HPB) tract.

MATERIAL AND METHODS

Patients with obstructive jaundice (group HPB(+)) were compared with those without (HPB(-)). Patients undergoing surgery for benign abdominal disorders served as controls. Obstructive jaundice was present in 18 out of 33 HPB patients. Preoperatively, blood was analysed for bacteria, endotoxins and cytokines (TNF-alpha, IL-6 and IL-10). At operation, mesenteric lymph nodes (MLNs) were excised for bacterial cultures using standard microbiological techniques, and immunohistochemistry, using antibodies CD4 and CD8 (mainly staining T lymphocytes), CD68 (macrophages), and anti-caspase-3 (to determine the rate of apoptosis).

RESULTS

Bacterial translocation was not demonstrated in any of the patients. Increased preoperative concentrations of endotoxins were found in group HPB(+). The number of macrophages and the rate of apoptosis in MLNs were increased in jaundiced patients, while the number of T lymphocytes was decreased.

CONCLUSIONS

Malignant obstructive jaundice causes increased blood concentrations of endotoxins and cytokines, an increased number of macrophages in MLNs, a higher rate of apoptosis in MLNs, but a decreased number of T lymphocytes in MLNs. The lymphocyte depletion is probably due to the increased rate of apoptosis, and might reduce the ability of jaundiced patients to eradicate infection.

Bacteriophage translocation

The occurrence of phages in the human body, especially in the gastrointestinal tract, raises the question of their potential role in the physiology and pathology of this system. Especially important is the issue of whether phages can pass the intestinal wall and migrate to lymph, peripheral blood, and internal organs and, if so, the effects such a phenomenon could have (such passage by bacteria, known as bacterial translocation, has been shown to cause various disturbances in humans, from immune defects to sepsis). Available data from the literature support the assumption that phage translocation can take place and may have some immunomodulatory effects. In addition, phages of the gut may play a protective role by inhibiting local immune reactions to antigens derived from gut flora.

Differential cytokine response from dendritic cells to commensal and pathogenic bacteria in different lymphoid compartments in humans

Resident host microflora condition and prime the immune system. However, systemic and mucosal immune responses to bacteria may be divergent. Our aim was to compare, in vitro, cytokine production by human mononuclear and dendritic cells (DCs) from mesenteric lymph nodes (MLNs) and peripheral blood mononuclear cells (PBMCs) to defined microbial stimuli. Mononuclear cells and DCs isolated from the MLN (n = 10) and peripheral blood (n = 12) of patients with active colitis were incubated in vitro with the probiotic bacteria Lactobacillus salivarius UCC118 or Bifidobacterium infantis 35624 or the pathogenic organism Salmonella typhimurium UK1. Interleukin (IL)-12, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, and IL-10 cytokine levels were quantified by ELISA. PBMCs and PBMC-derived DCs secreted TNF-alpha in response to the Lactobacillus, Bifidobacteria, and Salmonella strains, whereas MLN cells and MLN-derived DCs secreted TNF-alpha only in response to Salmonella challenge. Cells from the systemic compartment secreted IL-12 after coincubation with Salmonella or Lactobacilli, whereas MLN-derived cells produced IL-12 only in response to Salmonella. PBMCs secreted IL-10 in response to the Bifidobacterium strain but not in response to the Lactobacillus or Salmonella strain. However, MLN cells secreted IL-10 in response to Bifidobacteria and Lactobacilli but not in response to Salmonella. In conclusion, commensal bacteria induced regulatory cytokine production by MLN cells, whereas pathogenic bacteria induce T cell helper 1-polarizing cytokines. Commensal-pathogen divergence in cytokine responses is more marked in cells isolated from the mucosal immune system compared with PBMCs.

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.

Bacterial Translocation: Not a Clinically Relevant Phenomenon in Colorectal Cancer

The aim of this study was to identify the risk factors for bacterial translocation and to determine the clinical significance of bacterial translocation in patients with colorectal cancer. Mesenteric lymph node sampling was performed to identify the presence of bacterial translocation in 75 patients with colorectal cancer undergoing laparotomy. Bacterial translocation was identified in 29 patients (39%), with the most common organism being Escherichia coli (31%). Three factors for bacterial translocation were identified, including a preoperative low peripheral lymphocyte count, metastasis to lymph nodes, and invasion depth (= T3). Stepwise regression analysis, however, selected only = T3 [odds ratio (OR) 4.0, 95% confidence interval (CI) 1.2-13.5]. Altogether, 35% of patients with bacterial translocation developed septic complications, compared with 20% in patients without bacterial translocation. In the multivariate analysis, bacterial translocation was not an independent risk factor for infection, with an OR of 1.8 (95% CI 0.56-5.96). Systemic inflammatory response syndrome developed on the first day in 62% of patients with bacterial translocation, compared with 50% of patients without bacterial translocation. Adjusting for the other factors, bacterial translocation was not a significant risk factor in the occurrence of systemic inflammatory response syndrome after surgery (OR 1.1, 95% CI 0.37-3.29). We concluded that in patients with colorectal cancers bacterial translocation does occur and is increased in patients with deep invasion. However, it appears to be of no clinical significance.

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.

Searching for links between endotoxin exposure and pregnancy loss: CD14 polymorphism in idiopathic recurrent miscarriage

PROBLEM

Lipopolysaccharide (LPS) (endotoxin) is a well-known inducer of abortions in mice. In addition it has been proposed that gut-derived LPS of gram-negative bacteria may play a role in triggering idiopathic recurrent miscarriage (IRM) in humans. CD14 is one of the key molecules that mediates the effects of LPS. Promoter region polymorphism (-159C/T) in the CD14 gene is functionally important by regulating CD14 levels. High-producing CD14 genotype (TT) associates with deleterious effects of gut-derived LPS in hepatic cirrhosis in humans. It is not known whether women with IRM are genetically more prone to suffer from toxic effects of LPS.

METHOD OF STUDY

By using polymerase chain reaction we analyzed the CD14 promoter region polymorphism in 38 women with IRM and in 127 normal controls of Finnish origin.

RESULTS

There were no significant differences in the CD14 (-159C/T) allele or the genotype frequencies between the IRM women and the controls. However, there was a trend associating the presence of the T allele with increased odds of miscarriage.

CONCLUSIONS

Although we were not able to find a statistically significant association between CD14 genotypes and IRM in our relatively small study population, a further study with a larger sample size is warranted to explore the role of high-producing CD14 genotypes in IRM. Also studies highlighting environmental LPS triggers and other intrinsic mediators of LPS signalling are needed to solve the enigmatic role of LPS in IRM in humans.

Glutamine: clinical applications and mechanisms of action

Supplementation of the conditionally essential amino acid glutamine may be beneficial for individuals who are highly stressed and have minimal energy and protein reserves. This includes elderly individuals, postoperative patients, individuals with cancer and very low birthweight infants. Individuals who are undergoing treatment with catabolic glucocorticoids may also benefit. Unfortunately, confusion exists as to situations in which glutamine may be beneficial because a clearly defined "glutamine deficiency syndrome" has not been described as for some other nutrients. In this review, we will discuss how glutamine affects protein metabolism under certain stressful conditions, how it affects intestinal mucosal integrity and how this might relate to sepsis and systemic inflammation. We will also discuss nutrients that are closely related to glutamine such as glutamate, nucleotides, arginine, glucosamines, and ornithine alpha-ketoglutarate and how and why they might be used as substitutes for glutamine.

Antibiotic induced endotoxin release and clinical sepsis: a review

Sepsis and peritonitis have not lost much of their danger for patients. The mortality rate in peritonitis has only marginally decreased during the last 30 years despite aggressive surgical and sophisticated intensive care treatment. In intra-abdominal infection and peritonitis source control remains the mainstay of treatment, although general principles and denominators of successful source control need to be established. Endotoxin has been recognized as a major player in the pathogenesis of sepsis and its significance in clinical disease has been investigated in clinical studies for more than 20 years. Since the Sixties there is a growing interest in the effect of antibiotics and other compounds on the release of endotoxin. The effect of antibiotics on the release of endotoxin and inflammatory parameters, e.g., cytokines, remains to be clarified despite a growing body of in-vitro studies, animal studies and a few clinical studies. The purpose of this review is to evaluate the evidence of endotoxin release in clinical studies and the effect that antibiotic treatment may have in-vitro, in-vivo and in clinical studies on endotoxin and cytokine release. In-vitro antibiotic-induced endotoxin release may depend on antibiotic class, presence of serum, type of organism, site of antibiotic action and Gram-stain. Endotoxin release may be different in late or early lysis, proportional to the number of killed pathogens. Morphology of bacteria may have an impact on endotoxin release and phagocytosis. Antibiotic-treated animals may show higher endotoxin levels with a higher survival rate than untreated animals. Plasma endotoxin may increase despite decreasing bacteremia. There may be a similar killing rate by different antibiotics but a difference in endotoxin release. Intestinal endotoxin does not necessarily correlate to the level of gram-negative bacteria. However, the alteration of the gut content by pretreatment may be associated with reduced endotoxemia and increased survival. Antibiotic-induced endotoxin release may be different depending on the type of infection, the location of infection, the virulence of strains, Gram-stain, mode of application and dosage of antibiotic. Different antibiotics may induce the release of different forms of endotoxin which may be lethal for sensitized animals. The combination of antibiotics with inhibitors of endotoxin or the pro-inflammatory response may be responsible for increased survival by decrease of endotoxin release. The clinical significance of antibiotic-induced endotoxin release is documented only in a few clinical disorders, e.g., meningitis, urosepsis. The difference in endotoxin release by PBP 2-specific antibiotics, e.g., imipenem, and PBP 3-specific antibiotics, e.g., ceftazidime, may not be visible in each study. Patients with increased multi-organ failure (MOF) scores may profit from treatment with antibiotics known to decrease endotoxin. In conclusion, the clinical significance of antibiotic-induced endotoxin release remains to be clarified. Type of pathogen and its virulence may be more important than recently suggested. gram-positive pathogens were just recently recognized as an important factor for the development of the host response. In case of fever of unknown origin in intensive care patients either failure of treatment, e.g., failure of source control in intra-abdominal infection, or a side effect of antibiotic treatment, e.g., endotoxin release, should be considered as a cause of the fever.