Comparison of translocation of different types of microorganisms from the intestinal tract of burned mice

Persistent Systemic Microbial Translocation, Inflammation, and Intestinal Damage During Clostridioides difficile Infection

BACKGROUND

Clostridioides difficile infection (CDI) might be complicated by the development of nosocomial bloodstream infection (n-BSI). Based on the hypothesis that alteration of the normal gut integrity is present during CDI, we evaluated markers of microbial translocation, inflammation, and intestinal damage in patients with CDI.

METHODS

Patients with documented CDI were enrolled in the study. For each subject, plasma samples were collected at T0 and T1 (before and after CDI therapy, respectively), and the following markers were evaluated: lipopolysaccharide-binding protein (LPB), EndoCab IgM, interleukin-6, intestinal fatty acid binding protein (I-FABP). Samples from nonhospitalized healthy controls were also included. The study population was divided into BSI+/BSI- and fecal microbiota transplantation (FMT) +/FMT- groups, according to the development of n-BSI and the receipt of FMT, respectively.

RESULTS

Overall, 45 subjects were included; 8 (17.7%) developed primary n-BSI. Markers of microbial translocation and intestinal damage significantly decreased between T0 and T1, however, without reaching values similar to controls (P < .0001). Compared with BSI-, a persistent high level of microbial translocation in the BSI+ group was observed. In the FMT+ group, markers of microbial translocation and inflammation at T1 tended to reach control values.

CONCLUSIONS

CDI is associated with high levels of microbial translocation, inflammation, and intestinal damage, which are still present at clinical resolution of CDI. The role of residual mucosal perturbation and persistence of intestinal cell damage in the development of n-BSI following CDI, as well as the possible effect of FMT in the restoration of mucosal integrity, should be further investigated.

Late-Onset Bloodstream Infection and Perturbed Maturation of the Gastrointestinal Microbiota in Premature Infants

Background

Late-onset bloodstream infection (LO-BSI) is a common complication of prematurity, and lack of timely diagnosis and treatment can have life-threatening consequences. We sought to identify clinical characteristics and microbial signatures in the gastrointestinal microbiota preceding diagnosis of LO-BSI in premature infants.

Method

Daily faecal samples and clinical data were collected over two years from 369 premature neonates (<32 weeks gestation). We analysed samples from 22 neonates who developed LO-BSI and 44 matched control infants. Next-generation sequencing of 16S rRNA gene regions amplified by PCR from total faecal DNA was used to characterise the microbiota of faecal samples preceding diagnosis from infants with LO-BSI and controls. Culture of selected samples was undertaken, and bacterial isolates identified using MALDI-TOF. Antibiograms from bloodstream and faecal isolates were compared to explore strain similarity.

Results

From the week prior to diagnosis, infants with LO-BSI had higher proportions of faecal aerobes/facultative anaerobes compared to controls. Risk factors for LO-BSI were identified by multivariate analysis. Enterobacteriaceal sepsis was associated with antecedent multiple lines, low birth weight and a faecal microbiota with prominent Enterobacteriaceae. Staphylococcal sepsis was associated with Staphylococcus OTU faecal over-abundance, and the number of days prior to diagnosis of mechanical ventilation and of the presence of centrally-placed lines. In 12 cases, the antibiogram of the bloodstream isolate matched that of a component of the faecal microbiota in the sample collected closest to diagnosis.

Conclusions

The gastrointestinal tract is an important reservoir for LO-BSI organisms, pathogens translocating across the epithelial barrier. LO-BSI is associated with an aberrant microbiota, with abundant staphylococci and Enterobacteriaceae and a failure to mature towards predominance of obligate anaerobes.

Has the Epidemiology of Nosocomial Candidemia Changed?

Objective:

To assess changes in the epidemiology of nosocomial candidemia in the post-fluconazole era among hospitalized patients using a case–control study design.

Design:

Candidemia case-patients were matched 1:1 on diagnosis, age, and length of stay with control-patients. Conditional logistic regression was used to determine predictors and outcomes of candidemia. Treatment regimens and compliance with national practice guidelines were compared among case-patients.

Setting:

Barnes-Jewish Hospital, a 1,278-bed, tertiary-care center affiliated with Washington University School of Medicine, St. Louis, Missouri.

Participants:

Patients admitted from January 1 to December 31, 2000. Case-patients were identified through the hospital microbiological surveillance system and matched with control-patients.

Results:

Predictors of candidemia included Hickman catheters (odds ratio [OR], 9.53; 95% confidence interval [CI95], 1.34 to 68.01), gastric acid suppressants (OR, 6.38; CI95, 2.33 to 17.43), nasogastric tubes (OR, 3.69; CI95, 1.27 to 10.78), antibiotics (OR, 1.46; CI95,1.15 to 1.86), and admission to the intensive care unit (OR, 6.40; CI95, 2.12 to 19.31). The crude case-fatality rate was 40%. Seventeen (15%) of the case-patients received the recommended treatment regimen according to recently published practice guidelines.

Conclusions:

The epidemiology of candidemia has changed little at our hospital during the past decade and remains a significant cause of mortality. Further studies on the benefits of preventive therapy will be essential to improve the outcome of this infection.

Severe community onset healthcare-associated Clostridium difficile infection complicated by carbapenemase producing Klebsiella pneumoniae bloodstream infection

BACKGROUND

Clostridium difficile infection (CDI) and Klebsiella pneumoniae carbapenemase producing-Klebsiella pneumoniae (KPC-Kp) bloodstream infection (BSI) are emerging health-care associated (HCA) diseases of public health concern, in terms of morbidity, mortality, and insufficient response to antibiotic therapy. Both agents can be acquired in the hospital but clinical disease can develop in a community setting, after discharge. We report here a putative link between the above-mentioned healthcare associated infections that appeared as a dramatic community onset disease with a fulminant fatal outcome.

CASE PRESENTATION

We describe the case of a 63 year old man affected by severe CDI. Even though the patient underwent 72 hours of standard CDI antibiotic treatment, the clinical course was complicated by toxic megacolon and KPC-Kp BSI. The patient died 24 hours after total colectomy.

CONCLUSION

The impact of HCA-BSIs in complicating CDI is still unknown. Intestinal inflammatory injury and disruption of intestinal flora by standard antibiotic treatment could be responsible for promoting difficult-to-treat infections in CDI. By preserving intestinal flora, Fidaxomicin could have a crucial role in preventing BSIs complicating severe CDI.

Laboratory diagnostics of spontaneous bacterial peritonitis

The term peritonitis indicates an inflammatory process involving the peritoneum that is most frequently infectious in nature. Primary or spontaneous bacterial peritonitis (SBP) typically occurs when a bacterial infection spreads to the peritoneum across the gut wall or mesenteric lymphatics or, less frequently, from hematogenous transmission in combination with impaired immune system and in absence of an identified intra-abdominal source of infection or malignancy. The clinical presentation of SBP is variable. The condition may manifest as a relatively insidious colonization, without signs and symptoms, or may suddenly occur as a septic syndrome. Laboratory diagnostics play a pivotal role for timely and appropriate management of patients with bacterial peritonitis. It is now clearly established that polymorphonuclear leukocyte (PMN) in peritoneal fluid is the mainstay for the diagnosis, whereas the role of additional biochemical tests is rather controversial. Recent evidence also suggests that automatic cell counting in peritoneal fluid may be a reliable approach for early screening of patients. According to available clinical and laboratory data, we have developed a tentative algorithm for efficient diagnosis of SBP, which is based on a reasonable integration between optimization of human/economical resources and gradually increasing use of invasive and expensive testing. The proposed strategy entails, in sequential steps, serum procalcitonin testing, automated cell count in peritoneal fluid, manual cell count in peritoneal fluid, peritoneal fluid culture and bacterial DNA testing in peritoneal fluid.

Increased circulating D-lactate levels predict risk of mortality after hemorrhage and surgical trauma in baboons

Patients with hemorrhagic shock and/or trauma are at risk of developing colonic ischemia associated with bacterial translocation that may lead to multiple organ failure and death. Intestinal ischemia is difficult to diagnose noninvasively. The present retrospective study was designed to determine whether circulating plasma D-lactate is associated with mortality in a clinically relevant two-hit model in baboons. Hemorrhagic shock was induced in anesthetized baboons (n = 24) by controlled bleeding (mean arterial pressure, 40 mmHg), base excess (maximum -5 mmol/L), and time (maximum 3 h). To mimic clinical setting more closely, all animals underwent a surgical trauma after resuscitation including midshaft osteotomy stabilized with reamed femoral interlocking nailing and were followed for 7 days. Hemorrhagic shock/surgical trauma resulted in 66% mortality by day 7. In nonsurvivor (n = 16) hemorrhagic shock/surgical trauma baboons, circulating D-lactate levels were significantly increased (2-fold) at 24 h compared with survivors (n = 8), whereas the early increase during hemorrhage and resuscitation declined during the early postresuscitation phase with no difference between survivors and nonsurvivors. Moreover, D-lactate levels remained elevated in the nonsurvival group until death, whereas it decreased to baseline in survivors. Prediction of death (receiver operating characteristic test) by D-lactate was accurate with an area under the curve (days 1-3 after trauma) of 0.85 (95% confidence interval, 0.72-0.93). The optimal D-lactate cutoff value of 25.34 μg/mL produced sensitivity of 73% to 99% and specificity of 50% to 83%. Our data suggest that elevation of plasma D-lactate after 24 h predicts an increased risk of mortality after hemorrhage and trauma.

Spontaneous bacterial peritonitis: from pathophysiology to prevention

Patients with cirrhosis present an increased susceptibility to bacterial infections, which are the cause of hospital admission in about 10% of patients and are present in about 40% of those admitted for ongoing complications. Lastly, about a third of patients develop nosocomial infections. Spontaneous bacterial peritonitis (SBP) is the most frequent infection in advanced cirrhosis; it is mostly caused by Gram-negative bacteria of intestinal origin, but Gram-positive cocci can be involved in nosocomial-acquired SBP. Its occurrence is associated with complications, such as renal and circulatory failure, cardiac dysfunction, coagulopathy, encephalopathy, and relative adrenal insufficiency, ultimately leading to multi-organ failure and death within a few days or weeks in about 30% of cases. The main mechanism underlying the development of SBP, as well as other bacterial infections in cirrhosis, is represented by bacterial translocation from the intestinal lumen to mesenteric lymph nodes or other extraintestinal organs and sites. This process is facilitated by several factors, including changes in intestinal flora, portal hypertension, and, mainly, impairment in local/systemic immune defense mechanisms. Bacterial infections in advanced cirrhosis evoke an enhanced systemic inflammatory response, which explains the ominous fate of PBS. Indeed, an exaggerated production of cytokines ensues, which ultimately activates vasodilating systems and generates reactive oxygen species. Primary antibiotic prophylaxis of PBS is warranted in those conditions implying an increased incidence of bacterial infections, such as gastro-intestinal bleeding and low protein content in ascites associated with severe liver and/or renal dysfunction. Fluoroquinolones are commonly employed, but the frequent occurrence of resistant bacterial strains make third generation cephalosporins preferable in specific settings. The high PBS recurrence indicates secondary antibiotic prophylaxis.

Antimicrobial photodynamic inactivation and photodynamic therapy for infections

Photodynamic therapy (PDT) was initially discovered over 100 years ago by its ability to kill microorganisms, but its use to treat infections clinically has not been much developed. However, the present relentless increase in antibiotic resistance worldwide and the emergence of strains that are resistant to all known antibiotics has stimulated research into novel antimicrobial strategies such as PDT that are thought to be unlikely to lead to the development of resistance. In this chapter we will cover the use of PDT to kill pathogenic microbial cells in vitro and describe a mouse model of localized infection and its treatment by PDT without causing excessive damage to the host tissue.

Photodynamic therapy for Acinetobacter baumannii burn infections in mice

Multidrug-resistant Acinetobacter baumannii infections represent a growing problem, especially in traumatic wounds and burns suffered by military personnel injured in Middle Eastern conflicts. Effective treatment with traditional antibiotics can be extremely difficult, and new antimicrobial approaches are being investigated. One of these alternatives to antimicrobials could be the combination of nontoxic photosensitizers (PSs) and visible light, known as photodynamic therapy (PDT). We report on the establishment of a new mouse model of full-thickness thermal burns infected with a bioluminescent derivative of a clinical Iraqi isolate of A. baumannii and its PDT treatment by topical application of a PS produced by the covalent conjugation of chlorin(e6) to polyethylenimine, followed by illumination of the burn surface with red light. Application of 10(8) A. baumannii cells to the surface of 10-s burns made on the dorsal surface of shaved female BALB/c mice led to chronic infections that lasted, on average, 22 days and that were characterized by a remarkably stable bacterial bioluminescence. PDT carried out on day 0 soon after application of the bacteria gave over 3 log units of loss of bacterial luminescence in a light exposure-dependent manner, while PDT carried out on day 1 and day 2 gave an approximately 1.7-log reduction. The application of PS dissolved in 10% or 20% dimethyl sulfoxide without light gave only a modest reduction in the bacterial luminescence from mouse burns. Some bacterial regrowth in the treated burn was observed but was generally modest. It was also found that PDT did not lead to the inhibition of wound healing. The data suggest that PDT may be an effective new treatment for multidrug-resistant localized A. baumannii infections.

Diagnostic accuracy of sigmoidoscopy compared with histology for ischemic colitis after aortic aneurysm repair

Clinically relevant rates of ischemic colitis (IC) causing diarrhea, systemic involvement, colon necrosis, and, ultimately, death by multiple organ failure affect only a small proportion of patients after aortic reconstructions, with reported incidences of 2.7 to 3.3%. The key to treating and saving patients with this complication remains early detection and consequent treatment. The aim of this retrospective analysis of prospectively collected data was to compare the diagnostic accuracy of colonoscopy for detecting postoperative IC compared with histology and to evaluate the interobserver difference of two experienced surgeons. One hundred patients with infrarenal aortic aneurysms, operated on electively from March 2001 to December 2003, who had on postoperative days 3 to 6 a sigmoidoscopy by two independent surgeons and a histologic sample of the sigmoid mucosa, were included in the study. Patients with previous colon resection or inflammatory bowel disease were excluded from the study. All patients gave written informed consent. The study was approved by the Institutional Review Board. Histologic examination of the sigmoid mucosa revealed IC in 13 patients. The combined sensitivity of both investigators for detecting IC by sigmoidoscopy compared with histology was 84%, the specificity was 92.0%, the positive predictive value was 61.1%, the negative predictive value was 97.6%, and the diagnostic accuracy was 91.0%. There was no statistically significant difference between investigator 1 and investigator 2 (p=1.0) and between both investigators and histology (p=.380). Histology remains the gold standard for detecting IC after aortic surgery. Sigmoidoscopy, however, is a valid diagnostic tool allowing immediate clinical decision making with a negative predictive value of more than 94% and a diagnostic accuracy of 92%.

Chitosan acetate bandage as a topical antimicrobial dressing for infected burns

An engineered chitosan acetate bandage preparation (HemCon) is used as a hemostatic dressing, and its chemical structure suggests that it should also be antimicrobial. We previously showed that when a chitosan acetate bandage was applied to full-thickness excisional wounds in mice that had been infected with pathogenic bioluminescent bacteria (Pseudomonas aeruginosa, Proteus mirabilis, and Staphylococcus aureus), it was able to rapidly kill the bacteria and save the mice from developing fatal infections. Wound healing was also stimulated. In the present study, we asked whether a chitosan acetate bandage could act as a topical antimicrobial dressing when it was applied to third-degree burns in mice contaminated with two of these bacterial species (P. aeruginosa and P. mirabilis). Preliminary experiments established the length of burn time and the number of bacteria needed to produce fatal infections in untreated mice and established that the chitosan acetate bandage could adhere to the infected burn for up to 21 days. In the case of P. aeruginosa infections, the survival rate of mice treated with the chitosan acetate bandage was 73.3% (whereas the survival rate of mice treated with a nanocrystalline silver dressing was 27.3% [P = 0.0055] and that of untreated mice was 13.3% [P < 0.0002]). For P. mirabilis infections, the comparable survival rates were 66.7%, 62.5%, and 23.1% respectively. Quantitative bioluminescent signals showed that the chitosan acetate bandage effectively controlled the growth of bacteria in the burn and prevented the development of systemic sepsis, as shown by blood culture. These data suggest that chitosan acetate bandage is efficacious in preventing fatal burn infections.

Dengue hemorrhagic shock and disseminated candidiasis

Dengue fever, one of the common endemic viral fevers, often presents with fever, rash, and mild liver dysfunction. However, plasma leakage induced by dengue virus infection can lead to dengue hemorrhagic fever and dengue shock syndrome, and it can cause severe complications including liver failure and encephalopathy. Infection of dengue virus with other pathogens is an unusual but serious complication. We report a case of dengue shock syndrome with liver failure and impaired consciousness. The patient developed a disseminated Candida tropicalis infection, which may have been due to translocation of the fungus from the intestine damaged by the dengue virus.

Listeria monocytogenes translocates throughout the digestive tract in asymptomatic sheep

Ruminants are fed forage which is often contaminated with Listeria, and frequently shed Listeria monocytogenes with their faeces. The present study was designed to localize the sites of infection in the digestive tract concomitant with Listeria faecal excretion in a sheep model. Ten Listeria-free sheep were inoculated per os with a dose of 10(10) c.f.u. of a pathogenic L. monocytogenes strain. Listeria received by two of the ten animals were radiolabelled with (111)indium oxine. The dissemination of the Listeria was assessed by in vivo imaging, by culture of bacteria in the faeces, organs and digesta samples taken at slaughter on days 1, 2, 6, 10 and 14 post-inoculation, and by measuring gamma radioactivity of samples on day 6. It was shown that Listeria spread through the entire volume of the forestomachs within 4 h, and through the whole gastrointestinal tract (GIT) within 24 h. Faecal shedding of Listeria lasted 10 days. Rumen, duodenum, jejunum, ileum, caecum and colon walls and digesta, mesenteric lymph nodes, liver and spleen were temporarily infected. However, Listeria persisted for at least 14 days in rumen digesta and retropharyngeal lymph nodes, and at a relatively high level (1 x 10(4) c.f.u. g(-1)) in palatine tonsils. These findings suggest that L. monocytogenes can translocate from all parts of the GIT, with the rumen digesta, but not the gallbladder, serving as a reservoir. The results indicate that brief and low-level faecal excretion of L. monocytogenes is concomitant with a transitory asymptomatic infection in sheep.

The role of bifidobacteria in gut barrier function after thermal injury in rats

BACKGROUND

Early multiple organ dysfunction syndrome appears to be facilitated with bacterial translocation in severe burn injury, yet the mechanisms of bacterial translocation remain in dispute. The aim of this study was to characterize the potential role of intestinal bifidobacteria in the pathogenesis of gut-derived bacterial translocation after burns and to analyze the effects of bifidobacterial supplement on gut barrier function.

METHODS

Wistar rats were randomly divided into burn group (Burn, n = 60), sham burn group (SB, n = 10) in experiment 1, and burn + saline group (BS, n = 30), burn + bifidobacteria group (BB, n = 30), and sham-burn + saline group (SS, n = 30) in experiment 2. Animals in BB group were fed bifidobacterial preparation (5 x 10(9) CFU/mL) after burns, 1.5 mL, twice daily. Animals in BS and SS were fed saline. Samples were taken on postburn days 1, 3, and 5. The incidence of bacterial translocation and counts of Bifidobacterium, fungi and Escherichia coli in gut mucosa, as well as the sIgA levels in mucus of the small intestine were determined. The positive sIgA expression in lamina propria and ileum mucosal injury were evaluated light microscopically by blinded examiners.

RESULTS

The incidence of bacterial translocation was increased after burns, which was accompanied by significant decrease in number of bifidobacteria but significant increase in E. coli and fungi in gut mucosa, and elevation of levels of plasma endotoxin and IL-6 (p < 0.001). The incidence of bacterial translocation was markedly reduced after 3- and 5-day supplementation of bifidobacteria compared with control group (p < 0.05). The counts of mucosal bifidobacteria were increased by 4- to 40-fold, whereas E. coli and fungi were decreased by 2- to 30-fold and 10- to 150-fold, respectively, after bifidobacterial supplementation. The damage of mucosa tended to be less pronounced after 3-day bifidobacteria-supplemented formula compared with control group (grade 2 [0-6] versus grade 4 [3-6], p < 0.05). Moreover, the expression and release of sIgA was markedly augmented after 3-days of bifidobacteria-supplementation formula and it returned to normal range on postburn day 5.

CONCLUSIONS

The decrease in counts and proportion of bifidobacteria to other flora in gut may play an important role in the development of bacterial translocation after thermal injury. Supplementation of exogenous bifidobacteria could improve gut barrier function, and attenuate bacterial/endotoxin translocation secondary to major burns.

Deficiency of mannose-binding lectin greatly increases susceptibility to postburn infection with Pseudomonas aeruginosa

Burn injury disrupts the mechanical and biological barrier that the skin presents against infection by symbionts like the Pseudomonas aeruginosa, a Gram-negative bacteria. A combination of local factors, antimicrobial peptides, and resident effector cells form the initial response to mechanical injury of the skin. This activity is followed by an inflammatory response that includes influx of phagocytes and serum factors, such as complement and mannose-binding lectin (MBL), which is a broad-spectrum pattern recognition molecule that plays a key role in innate immunity. A growing consensus from studies in humans and mice suggests that lack of MBL together with other comorbid factors predisposes the host to infection. In this study we examined whether MBL deficiency increases the risk of P. aeruginosa infection in a burned host. We found that both wild-type and MBL null mice were resistant to a 5% total body surface area burn alone or s.c. infection with P. aeruginosa alone. However, when mice were burned then inoculated s.c. with P. aeruginosa at the burn site, all MBL null mice died by 42 h from septicemia, whereas only one-third of wild-type mice succumbed (p = 0.0005). This result indicates that MBL plays a key role in containing and preventing a systemic spread of P. aeruginosa infection following burn injury and suggests that MBL deficiency in humans maybe a premorbid variable in the predisposition to infection in burn victims.

Plasma D-lactate as a potential early marker for colon ischaemia after open aortic reconstruction

BACKGROUND AND AIM

The breakdown of mucosal barrier function due to intestinal hypo-perfusion is the earliest dysfunction of ischaemic colitis. Severe colon ischaemia after aortic reconstruction is associated with mortality rates up to 90%. Therefore, early detection and treatment of patients with extensive ischaemic colitis is of crucial importance. In experimental studies, both D-lactate and bacterial endotoxin have been reported as markers of intestinal mucosal barrier impairment. However, evidence of their value in clinical practice is lacking. The aim of this pilot prospective cohort study was to assess the association between ischaemia of the colon (assessed histologically) and plasma levels of D-lactate and endotoxin in patients undergoing open aortic reconstruction.

PATIENTS AND METHODS

Twelve consecutive patients underwent surgery between February and April 2003. Six patients underwent emergency surgery and six patients elective aortic surgery. D-Lactate and endotoxin levels were measured in blood samples collected according to a standardised protocol. For histological examination biopsies were obtained by sigmoidoscopy on days 4-6 after surgery, or earlier if indicated clinically.

RESULTS

As early as 2 h postoperatively, elevated plasma levels of d-lactate were measured in patients with histologically proven ischaemic colitis. The peak of D-lactate elevation was on postoperative days 1 and 2. Concentration of plasma endotoxin was not significantly different in patients with or without ischaemic colitis.

CONCLUSION

Our data suggest that plasma D-lactate levels are a useful marker for early detection of ischaemic colitis secondary to aortic surgery.

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.

Role of p38 mitogen-activated protein kinase pathway on renal failure in the infant rat after burn injury

The p38 mitogen-activated protein kinase (MAPK) pathway is a proinflammatory signal transduction pathway for the production of cytokines and cellular response to stress, such as bacterial LPS or ischemia. We examined the effects of FR167653, a specific inhibitor of p38 MAPK, to explore the relationship between intestinal barrier damage and remote renal dysfunction. Immunohistochemical data showed the accumulation of neutrophils in the intestine after burn, and a horseradish peroxidase (HRP) tracer experiment showed burn-induced intestinal barrier damage. Our quantitative bacterial culture data demonstrated that viable bacteria reached the remote organs after burn and prevented the invading viable bacteria from using FR167653. Western blotting identified increased phosphorylation of p38 MAPK in the kidney after burn, and it may also have shown the possibility that endotoxin associated with the bacterial translocation enhances the activation of the p38 MAPK pathway. We blocked the intestinal barrier damage using FR167653, which resulted in reduced neutrophils in the intestine. FR167653 also prevented the increased phosphorylation of p38 MAPK in the kidney, which resulted in reduced neutrophils in the glomerulus and the reduction of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta mRNA in the kidneys, and, finally, prevented burn-induced renal failure. This study provides evidence for the hypothesis that the p38 MAPK pathway controls inflammatory mediators and not only improves intestinal function but also reduces remote renal failure after burn. We identified the pathophysiologic role of the p38 MAPK pathway in the development of renal failure after burn.

Risk factors of development of gut-derived bacterial translocation in thermally injured rats

AIM: Studies have demonstrated that gut-derived bacterial translocation (BT) might play a role in the occurrence of sepsis and multiple organ dysfunction syndrome (MODS). Yet, no convincing overall analysis of risk factors for BT has been reported. The purpose of this study was to evaluate the related factors for the development of BT in burned rats.

METHODS: Wistar rats were subjected to 30% third-degree burns. Then samples were taken on postburn d 1, 3, and 5. Incidence of BT and counts of mucosal bifidobacteria, fungi and E. coli, mucus sIgA, degree of injury to ileal mucosa, and plasma interleukin-6 were observed. Univariate analysis and multivariate logistic regression analysis were performed.

RESULTS: The overall BT rate was 53.9% (69 in 128). The result of univariate analysis showed that the levels of plasma endotoxin and interleukin-6, the counts of mucosal fungi and E. coli, and the scores of ileum lesion were markedly increased in animals with BT compared with those without (P = 0.000-0.005), while the levels of mucus sIgA and the counts of mucosal bifidobacteria were significantly reduced in animals with translocation compared with those without (P = 0.000). There was a significant positive correlation between mucus sIgA and the counts of mucosal bifidobacteria (r = 0.74, P = 0.001). Moreover, there were strong negative correlations between scores of ileum-lesion and counts of bifidobacteria (r = -0.67, P = 0.001). Multivariate logistic regression revealed that ileum lesion score (odds ratio [OR] 45.52, 95% confidence interval [CI] 5.25-394.80), and counts of mucosal bifidobacteria (OR 0.039, 95% CI 0.0032-0.48) were independent predictors of BT secondary to severe burns.

CONCLUSION: Ileal lesion score and counts of mucosal bifidobacteria can be chosen as independent prognosis factors of the development of BT. Specific interventions targeting these high-risk factors might be implemented to attenuate BT, including strategies for repair of damaged intestinal mucosae and restoration of the balance of gastrointestinal flora.

Mucosa or skin as source of coagulase-negative staphylococcal bacteraemia?

Nosocomial bacteraemia is associated with significant morbidity, mortality, and cost worldwide, and is most commonly caused by coagulase-negative staphylococci (CONS). Establishing the source of CONS bacteraemia is therefore important in the prevention and management of this infection. CONS infections are presumed to originate at the cutaneous sites of central venous catheters (CVCs), a belief that has led to prevention strategies that focus almost exclusively on the skin. However, mucosal colonisation by CONS is well established, suggesting that mucosal sites might be an important source of CONS bacteraemia. We review the published material that evaluates the source(s) of CONS. We included only studies that used a strict definition of CONS bacteraemia, evaluated skin and other potential sources of CONS, and studied the molecular association between CONS blood isolates and their potential sources. Three published reports fulfilled our criteria. In cancer patients with CONS or CONS bacteraemia, most of the colonising strains that had a molecular match with the strain recovered from the blood of the same patient were mucosal isolates; by contrast, no association was seen between CONS blood and skin isolates. Furthermore, in several patient populations evidence was reported of mucosal colonisation by CONS and in several reports experimental and clinical mucosal translocation of CONS with subsequent bacteraemia was documented. Together these data indicate that mucosal sites are an important source of CONS bacteraemia. Clinical strategies for the treatment of patients with a positive blood culture for CONS, the widespread use of antimicrobial-coated CVCs, and maximum barrier protection for CVC insertion should be reassessed, and strategies to decrease mucosal colonisation by CONS should be developed.

Increased plasma D-lactate is associated with the severity of hemorrhagic/traumatic shock in rats

D-lactate is produced by indigenous bacteria in the gastrointestinal tract. Mammals do not have the enzyme systems to metabolize D-lactate rapidly. The present study was designed to determine the kinetics of circulating D-lactate levels and to examine whether the severity of shock affects circulating D-lactate levels in rats subjected to hemorrhagic/traumatic shock. Anesthetized rats underwent midline laparotomy (duration 30 min) and were bled to 30-35 mmHg mean arterial pressure (MAP). After the onset of decompensation, MAP was either increased to 40-45 mmHg immediately by administration of Ringer's solution (moderate shock) or after 40% of shed blood volume had been re-infused as Ringer's solution (severe shock). MAP was then maintained at 40-45 mmHg for 40 min by further administration of Ringer's solution (inadequate resuscitation). Subsequently, adequate resuscitation was performed for 60 min with shed blood and additional Ringer's solution. Metabolic acidosis was significantly more pronounced in severe than in moderate hemorrhagic/traumatic shock. Plasma D-lactate levels were already significantly increased at the end of severe hemorrhagic/traumatic shock and remained high during inadequate resuscitation. D-lactate levels were significantly higher after severe than after moderate shock. Endotoxin levels did not correlate with shock severity. Damage to the intestinal mucosa was more profound in severe shock than in moderate shock. Our data suggest that hemorrhagic/traumatic shock is associated with mucosal damage and increased plasma D-lactate levels. The severity of shock affects D-lactate concentrations in plasma. Plasma D-lactate may be a useful marker of intestinal injury after hemorrhagic/traumatic shock.