Antibiotic prophylaxis diminishes bacterial translocation but not mortality in experimental burn wound sepsis

Pseudomonas (PSA) burn wound sepsis results in prolonged bacterial translocation (BT) of enteric organisms such as E. coli to the mesenteric lymph nodes (MLN) and organs in rats. Intestinal decontamination with oral antibiotics may improve mortality after burn injury, perhaps due to decreased BT. To determine the effect of oral antibiotic prophylaxis effective against E. coli but not PSA on BT and subsequent mortality in a model of PSA burn wound sepsis, rats were given a 30% scald burn and wound inoculation with 10(8) PSA followed by randomization to either ampicillin (50 mg/kg/d) or saline gavage. Cultures of MLN, organs, blood, and cecal contents were obtained on days 1, 4, and 7 after injury, with additional animals observed for 14-day mortality. Although oral antibiotic prophylaxis resulted in increased cecal colony counts, the incidence of BT was unchanged. The number of organisms present in both the MLN and organs, however, was significantly reduced with prophylaxis, indicating cecal overgrowth by non-translocating bacteria. Reduction of the number of translocating organisms did not result in improved mean survival time after injury, suggesting that mortality from PSA burn wound sepsis occurs independently of bacterial translocation.     

Differential pathophysiology of bacterial translocation after thermal injury and sepsis.

Bacterial translocation (BT) occurs transiently after thermal injury and may result from an ischemic intestinal insult. To evaluate continued intestinal ischemia in the ongoing BT associated with sepsis after injury, rats were randomized to (1) 30% burn injury with Pseudomonas wound infection (BI), (2) BI + fluid resuscitation (BI + Fluid), (3) BI after allopurinol pretreatment to inhibit xanthine oxidase (BI + Allo), or (4) BI after azapropazone pretreatment to inhibit neutrophil degranulation (BI + Aza). On postburn days (PBD) 1, 4, and 7, animals were studied for evidence of BT and intestinal lipid peroxidation. BI + Fluid, BI + Allo, and BI + Aza significantly (p less than 0.05) reduced rates of BT and ileal lipid peroxidation acutely after thermal injury (PBD 1) compared to BI. All four groups had equally high rates of BT associated with the onset of sepsis (PBDs 4 and 7), without evidence of further intestinal lipid peroxidation. These data indicate that the chronic gut barrier failure associated with sepsis after injury occurs independently of continued intestinal ischemia.     

Additive effects of thermal injury and infection on the small bowel

Thermal injury is associated with functional alterations of multiple organ systems, including the gastrointestinal tract. To study the effects of ongoing infection after thermal injury on bowel mass, composition, and blood flow, male Wistar rats were randomized to receive either 30% scald burn, 30% scald burn with Pseudomonas aeruginosa wound inoculation, sham burn, or sham burn with pair feeding to burned and infected animals. On days 3 and 7 after injury, intestinal blood flow was measured with 51Cr-labeled microspheres, and intestinal mass and composition were analyzed. Burned and infected animals demonstrated a chronic loss of small bowel mass not seen in burned animals without infection by day 7 after injury. Compositional alterations of the small bowels of burned and infected animals included protein wasting similar to but occurring earlier than that seen with anorexia alone and significantly decreased deoxyribonucleic acid and ribonucleic acid content, whereas tissue water content remained unchanged. These chronic intestinal alterations in the burned and infected group could not be explained by ongoing ischemia because intestinal blood flow in these animals was not significantly altered at either time point, implying mediation by other pathophysiologic mechanisms.     

Effect of Probiotic Supplementation on Bacterial Translocation in Thermal Injury

Purpose To examine the effects of probiotic supplementation and enteral solutions containing glutamine and arginine on bacterial translocation (BT) and intestinal villous atrophy in thermal injury.Methods Forty male Sprague-Dawley rats weighing 200–250 g were divided into four groups of ten. Group 1 served as control group without thermal injury and was fed standard chow. Thermal injury was inflicted as a 30% scald burn in the other three groups. Group 2 was fed standard chow and group 3 was fed standard chow supplemented with a probiotic (Acidophilus plus) containing Bifidobacterium bifidum, Lactobacillus acidophilus, and Lactobacillus bulgaricus (2 × 10⁹ CFU/day) via an orogastric tube. Group 4 was fed only an enteral diet (Stresson multifiber) containing glutamine, arginine, and medium chain triglyceride, at 1 g/kg per day amino acid and 230 kcal/kg, for 7 days before thermal injury. All the animals were killed 24 h after thermal injury, and ileal segments were resected and examined histopathologically. To evaluate BT, samples from blood, mesenteric lymph nodes, and cecal content were cultured under aerobic and anaerobic conditions. Terminal ileum specimens were histologically examined to evaluate mucosal integrity.Results Significantly less BT was seen in groups 3 and 4 than in group 2 (P < 0.001). No significant difference was found between groups 3 and 4. Histological evaluation showed significant reduction in villous atrophy in groups 3 and 4.Conclusion Probiotic supplementation seems to reduce bacterial translocation and decrease intestinal mucosal atrophy in rats with thermal injury, as do enteral solutions with arginine and glutamine.     

The role of antibiotic prophylaxis with sodium ceftriaxone to prevent bacterial translocation associated with hypovolemic shock: an experimental study in rats.

One of the measures adopted to reduce or prevent intestinal bacterial translocation (BT) in patients who are in hemorrhagic shock consists of prophylactic antibiotics. This study attempted to assess the effectiveness of administering systemic antibiotic to suppress BT in rats submitted to hemorrhagic shock. Sixty-eight male Wistar rats were divided into two experiments. In experiment 1 (n = 28), the animals were randomly divided into three groups: group I (n = 7), sham operation; group II (n = 11), constituted by animals that were submitted to hemorrhagic shock by removing 40% of the volemia, and were resuscitated after 40 min of sustained shock, replacing the previously removed blood; and group III (n = 10), animals that, besides hemorrhagic shock and volemic replacement, received 50 mg/kg of sodium ceftriaxone intravenous 1 min after blood readministration. Mesenteric lymph nodes (MLN) for culture tests and segments of the small bowel were removed for histopathological studies 1 day after the operation in the three groups. In experiment 2, the same procedures were performed, except the laparotomy for removing MLN and segments of jejunal and ileal bowel, but the animals were followed during 7 days, in order to evaluate the mortality rate. In the control group (group I), the bacteriological assessment of the MLN was negative in all cases. Only 40% of the animals treated with antibiotics after hypovolemic shock (group III) presented positive bacteriological exams of the MLN, and this rate was 90% in the group of animals that did not receive this substance (group II) (p < .05). Escherichia coli was the bacteria identified most frequently in culture tests (92.8%). The villosities atrophy and inflammatory infiltrate of the lamina propria were the most common histological changes in the bowel, although the intensity was similar in groups II and III (p > .05), but more intense that in group I (p < .05). The mortality rates in groups I, II, and III 7 days after hypovolemic shock were 0%, 20%, and 20%, respectively. Prophylactic antibiotics significantly reduced the presence of bacteria in the MLN in situations of hypovolemic shock, in rats. This was probably related to a lower BT. However, this aspect did not modify the mortality rate of the animals. Also, the possibility that BT may not have a significant influence in this outcome should be considered.     

Effects of granulocyte colony-stimulating factor on bacterial translocation due to burn wound sepsis

The presence of certain defects in both cellular and humoral immunity after thermal injury has been established. Likewise, the translocation of enteric bacteria to the mesenteric lymph nodes and to distant organs has also been observed following serious thermal injury. The effects of granulocyte colony-stimulating factor (G-CSF) on bacterial translocation, the small bowel mucosa, and cecal bacterial content were investigated in a rat model of burn wound sepsis in which albino Wistar rats were scalded over 30% of their bodies, after which the lesions were infected by 1×10⁸ colony-forming units (cfu)Pseudomonas aeruginosa. The control group was treated with 5% dextrose solution subcutaneously starting 2 days preburn, while the treatment group received 100μg/kg human G-CSF subcutaneously. On the 4th day post burn all animals were killed to examine the bowel and culture of the mesenteric lymph nodes (MLN), livers, and spleens. No significant differences were observed between the groups regarding the cecal bacterial content and small bowel; however, a difference was seen in the ratio of translocation in the MLN liver and spleen and quantitative MLN cultures. Based on these findings, G-CSF was thus found to be significantly effective in reducing bacterial translocation due to burn wound sepsis.     

Bacterial translocation after cirrhotic liver resection: a clinical investigation of 181 patients

BACKGROUND: Cirrhotic patients are usually associated with a high susceptibility to infection. Although bacterial translocation from gut mucosa to mesenteric lymph node (MLN) and systemic circulation is a well-known phenomenon after hepatectomy, its role in cirrhotic patients remains unclear. MATERIALS AND METHODS: MLN was harvested for bacterial culture before and after liver resection in 181 cirrhotic patients. The characteristics and postoperative courses of patients with positive and negative bacterial culture for MLN after hepatectomy were compared. Postoperative systemic antibiotics were administered if infectious complications occurred. RESULTS: No bacteria were cultured in MLN before hepatectomy. Bacterial translocation (BT) to MLN after hepatectomy occurred in 36 patients (BT group). After multivariate analysis, intraoperative blood transfusion was the only independent factor that influenced bacterial translocation rates after cirrhotic liver resection. BT group patients also had higher infectious and overall complication rates, with a longer postoperative hospital stay. Among the cultured bacteriae from infected sites in BT group patients with infectious complications, only 2 patients (12.5%) had totally different bacterial species to those cultured from MLNs. CONCLUSIONS: Bacterial translocation more often occurred after liver resection in cirrhotic patients who received intraoperative blood transfusion. Such patients had higher postoperative infectious and overall complication rates. Thus, avoidance of intraoperative blood transfusion is mandatory for cirrhotic liver resection.     

Surgical manipulation of the large intestine increases bacterial translocation in patients undergoing elective colorectal surgery

OBJECTIVE: Several animal studies have suggested that surgical manipulation of the intestine alters the barrier function and promotes bacterial translocation (BT). Whether this occurs in humans has never been investigated. The aim of this study was to determine the effect of surgical manipulation of the intestine on the prevalence of BT in patients undergoing elective colorectal surgery. METHOD: This was a prospective observational study of 50 consecutive elective surgical patients in whom a sample of mesenteric lymph node (MLN) was harvested after mobilization of the colon, prior to ligation of the vascular pedicle. These results were compared with 472 historical controls, who had a sample of MLN taken before the mobilization of colon during laparotomy. A positive culture of MLN confirmed BT. RESULTS: BT was identified in 39/49 (79.6%) patients in the study group compared with 54/472 (11.4%) patients in the control group. This difference was statistically significant (P < 0.001, chi(2) test). CONCLUSION: Surgical manipulation of the bowel does increase the prevalence of BT and therefore is associated with changes in gut barrier function in elective surgical patients.     

The effects of ketamine and propofol on bacterial translocation in rats after burn injury

BACKGROUND: Bacterial translocation (BT) occurs after thermal injury and may result from an ischemic intestinal insult. The aim of the study was to investigate the effects of ketamine and propofol as anesthetic agents on BT in an animal model of burn injury. METHODS: Sixty male Wistar Albino rats were randomly assigned to six groups of 10 rats each. Anesthesia was induced and maintained with ketamine in groups 1, 2 and 3 and with propofol in groups 4, 5 and 6 during 6 h. Groups 2, 3, 5 and 6 received 30% total body surface area (TBSA) third-degree burns. Groups 1 and 4 had no burn injury. Then, they were allowed to recover from the anesthesia at the end of 6 h. Mean arterial pressure (MAP) was monitored continuously and maintained within 10% of baseline (before burn injury) levels in all animals. Animals in groups 3 and 6 had a laparotomy to obtain a tissue sample from the terminal ileum for determination of intestinal lipid peroxidation by-product malondialdehyde (MDA) before (baseline) and 6 and 24 h after burn injury (ABI). So these animals were not included in the BT studies. At postburn 24 h, animals in groups 1, 2 and 4, 5 were sacrified and samples were taken from the mesenteric lymph nodes (MLN), liver and spleen for bacteriologic cultures. RESULTS: The incidence of BT was found to be significantly higher in group 2 than in all the other groups. Bacterial translocation incidence of group 5 was not significantly different from that of groups 4 and 1. Group 5 was associated with a significantly reduced number of enteric organisms per gram of tissue compared to group 2. Baseline MDA contents of groups 3 and 6 were similar. Ileal MDA levels were increased in group 3, but there were no significant changes in group 6 at 6 and 24 h ABI compared to baseline. CONCLUSION: Our results suggest that propofol as an anesthetic agent may prevent BT by scavenging reactive oxygen species and inhibiting lipid peroxidation in an animal model of burn injury.     

Effect of growth hormone, epidermal growth factor, and insulin on bacterial translocation in experimental short bowel syndrome

BACKGROUND/PURPOSE: An adaptive process starts in the remaining intestine after massive resection, and several trophic factors including growth hormone (GH), epidermal growth factor (EGF), and insulin (INS) have been shown to have a positive effect on it. Bacterial translocation (BT) is frequent after extensive small bowel resection, but the effects of GH, EGF, or INS have not been investigated in experimental short bowel syndrome (SBS). This study tests the hypothesis that GH, EGF, or INS decrease BT in SBS in rats with parenteral nutrition (PN). METHODS: Thirty-eight adult Wistar rats underwent central venous cannulation and were assigned randomly to 1 of 4 groups receiving for 10 days 4 treatment regimes: (1) PN group (n = 10): fasting, all-in-one PN solution (300 mL/kg/24 h, 280 kcal/kg/24 h), 80% gut resection including ileo-cecal valve; (2) GH group (n = 9): fasting, same PN regime and resection, GH (1 mg/kg/d, subcutaneously); (3) EGF group (n = 9): fasting, PN, resection, EGF (150 microg/24 h intravenously); (4) INS group (n = 9): fasting, PN, resection, INS (1 UI/100 g/24 h subcutaneously). At the end of the experiment they were killed, and mesenteric lymph nodes (MLN) and peripheral and portal blood samples were recovered and cultured. Several fragments of intestine were taken to determine cell proliferation (PCNA index) and morphometric parameters (villous height, crypt depth). RESULTS: GH, EGF, and INS groups showed a 28%, 29%, and 30% increase in gut mucosal thickness, and PCNA index rose 21%, 20%, and 25%, respectively in comparison with PN controls. Bacterial translocation to peripheral blood was detected in 0% of PN animals and in 44%, 40%, and 28% of GH, EGF, or INS rats, respectively (P < .05). No differences were found in BT in MLN or portal blood among groups. CONCLUSION: Administration of GH, EGF, or INS improves gut mucosal structure in rats with SBS under PN, but, surprisingly, the incidence of BT detected in peripheral blood was increased rather than decreased in animals receiving these treatments.     

The effect of N-acetylcysteine on oxidative stress in intestine and bacterial translocation after thermal injury

Ischemia due to transient splanchnic vasoconstriction following major burns causes oxidative and/or nitrosative damage in intestinal tissue followed by reperfusion injury. Thus, burn injury leads to breakdown in the intestinal mucosal barrier which can induce bacterial translocation (BT). As an antioxidant and anti-inflammatory agent the protective effects of N-acetylcysteine (NAC) are documented in several studies. This study was designed to determine the effect of NAC treatment on the oxidative stress in the intestine and BT after burn injury. To evaluate this, 32 Wistar rats were randomly divided into four groups as sham (n = 8), burn (n = 8), pre-burn, NAC injection (150 mg kg⁻¹, intraperitoneally) 15 min before thermal injury (n = 8), post-burn, NAC injection (150 mg kg⁻¹, intraperitoneally) 2 h after thermal injury. Under anesthesia, the shaved dorsal skin of rats was exposed to boiling water for 12 s to induce burn injury in a standardized manner. Twenty-four hours later, tissue samples from mesenteric lymph nodes (MLN), spleen, and liver were obtained under sterile conditions for microbiological analysis and ileum samples were harvested for biochemical analysis. In the burn group, the incidence of isolating bacteria in MLN, spleen, and liver specimens was significantly higher than other groups. NAC treatment prevented burn-induced BT in both pre- and post-burn groups. Thermal injury caused a significant decrease in glutathione (GSH) level, significant increases in malondialdehyde (MDA) and myeloperoxidase (MPO) activity at post-burn 24th hour. Treatment of rats with NAC significantly elevated the reduced GSH levels while decreasing MDA levels and MPO activity. These data suggested that NAC has a crucial cytoprotective role in intestinal mucosal barrier and preventive effects against burn injury-induced BT.     

Intestinal permeability and bacterial translocation following small bowel transplantation in the rat

In addition to its role in absorbing nutrients, the intestinal mucosa provides an important barrier against toxins and bacteria in the bowel lumen. The present study evaluated gut barrier function following orthotopic (in continuity) intestinal grafting in rats. Graft histology, intestinal permeability, and bacterial translocation to the grafted mesenteric lymph nodes, the host's liver, and the host's spleen were assessed on the 3rd, 5th, and 7th postoperative days. The study group received no immunosuppression after allotransplantation. The two control groups included rats with isografts and rats with cyclosporine-treated allografts. On the 7th POD, the study animals had moderate transmural inflammation due to rejection, with normal histology in the isografts and CsA-treated allografts; increased intestinal permeability, measured by urinary excretion of oral 51Cr-EDTA (P less than 0.01); and increased number of bacteria in the MLN and spleen (P less than 0.05). The number of bacteria in the MLN and spleen of the study group positively correlated with the changes in intestinal permeability (P less than 0.05). Rejection of the orthotopic intestinal graft leads to increased intestinal permeability and bacterial translocation from the lumen of the graft to the host's reticuloendothelial system. Measures to improve gut barrier function and antibiotic therapy during rejection episodes may help reduce the incidence of septic complications after intestinal grafting.     

Probiotic supplementation reduces the risk of bacterial translocation in experimental short bowel syndrome

Background/Purpose: Probiotics are live organisms that survive passage through the gastrointestinal tract and have beneficial effects on the host. Lactobacillus and Bifidobacterium have been recommended for cholesterol lowering, acute diarrhea, prevention of cancer, or inflammatory bowel disease. On the other hand, after massive bowel resection, bacterial overgrowth is frequent and favors bacterial translocation (BT). The possible beneficial effects of Bifidobacterium lactis (BL) administration on BT in experimental short bowel syndrome (SBS), have not been investigated. The aim of this study was to test the hypothesis that BL administration decreases BT in SBS in animals fed orally. Methods: One hundred twenty-eight adult Wistar rats fed orally with standard rat chow and tap water [ldquo ]ad libitum[rdquo ] were maintained in individual metabolic cages for 10 days and divided into 3 groups: control group (n = 71): nonmanipulated animals; RES group (n = 39): 80% gut resection from 10 cm beyond the angle of Treitz to 10 cm above the cecum; RES-PRO group (n = 18): same resection and daily 7.8 [times ] 10⁸ CFU B Lactis administration, after orogastric intubation. At the end of the experiment they were killed, and mesenteric lymph nodes (MLN) and peripheral and portal blood specimens were recovered and cultured. Bacterial identification in blood was made by conventional methods, and MLN culture was considered positive with a growth over 100 CFU/g. Results: Bacterial translocation was detected in 6% of control group rats. The incidence of BT in the RES group was 87% (34 of 39), whereas only 50% (9 of 18) of RES-PRO animals had BT (P [lt ] .05). The relative risk reduction (RRR) was 0.43 (95% Cl 0.14 to 0.72), and the number needed to treat (NNT) was 3 (95% Cl 2 to 8). In other words, animals that received BL had the risk of BT reduced by 43% (RRR of 0.43), and of every 3 animals treated, 1 is expected to be free of BT (NNT of 3). Conclusion: Administration of B Lactis reduces the incidence of BT in adult Wistar rats after 80% gut resection.     

Prostaglandin E1 maintains structural integrity of intestinal mucosa and prevents bacterial translocation during experimental obstructive jaundice.

The absence of bile in the gut lumen induces mucosal injury and promotes bacterial translocation (BT). Prostaglandin E (PGE) has a protective effect on the mucosal layer of the alimentary tract. We hypothesize that PGE1 may prevent BT by its beneficial action on the mucosa of the small bowel. Thirty Wistar albino rats were divided equally into 3 groups; Group 1 (control) underwent sham laparotomy, group 2 obstructive jaundice (OJ) and group 3 (OJ + PGE1) underwent common bile duct (CBD) ligation and transection. Groups 1 and 2 received; 1 mL normal saline and group 3 received 40 mg of the PGE1 analogue misoprostol dissolved in 1 mL normal saline administered by orogastric tube once daily. After 7 days, laparotomy and collection of samples for laboratory analyses were performed, including bacteriological analysis of intestine, mesenteric lymph nodes (MLNs), and blood, and histopathologic examination of intestinal mucosa to determine mucosal thickness and structural damage. Serum bilirubin and alkaline phosphatase levels confirmed OJ in all animals with CBD transection. The mucosal damage score was significantly reduced in jaundiced animals receiving PGE1 compared to jaundiced controls (2.15 +/- 0.74 vs 5.3 +/- 0.59; p < .00001) and mucosal thickness was greater (607 +/- 59.1 microm vs. 393 +/- 40.3 microm; p < .00001). The incidence of BT to MLNs decreased from 90% to 30% (p < .02) when jaundiced rats received PGE1. PGE1 treatment reduced the detection rate of viable enteric bacteria in the blood from 60% to 10% (p < .057). We conclude that administration of PGE1 provides protection against OJ-induced atrophy and damage of intestinal mucosa, and thereby prevents translocation of enteric bacteria to underlying tissues.     

Selective intestinal decontamination and parenteral nutrition related liver disease. Experimental study

Selective intestinal decontamination (SID) has been useful restraining Bacterial translocation (BT) in both animal models and human clinics. The not well known parenteral nutrition-related liver disease is a serious problem associated to short bowel and long-term parenteral nutrition (PN) use, and BT is also frequent in those patients. Germs reach liver through portal vein and activate Kupffer cells, which release cytokines as IL-1 or TNF-alpha. The aim of this study was to test the use of SID restraining BT in a PN undergoing experimental short bowel model, and its possible favourable consequences on hepatic injury determined by IL-1 and TNF-alpha levels. Twenty-five 240-280 g Wistar rats were divided into two groups and maintained in individual metabolic cages for ten days: Resection-PN group (n=15): animals with a bowel resection of the 80% and a continuous PN infusion. Resection-PN-SID (n=10) group: similar to previous group and a daily oral administration of Tobramycine (20mg/kg/day) and Polymyxine-E (25mg/kg/day). Animals were sacrificed and mesenteric lymph nodes (MLN), and both peripheral and portal blood samples were recovered for TB determination in bacterial culture. Determination of both IL-l and TNF-alpha seric levels were carried out by ELISA. Bacterial translocation incidence was higher in RES-NPT group (66.6%) than RES-NPT-SID group (30%) (P>0,05). The relative risk was 2.22 (IC 95% 0,81-6,11) and the number needed to treat was 3 (IC 95% 2-235). Seric levels of IL-1 and TNF-alpha were also higher in RES-NPT group (7,537 and 5,399 pg/ml, respectively) than in RES-NPT-SID group (6,397 and 5,032 pg/ml respectively) (p<0,001). 1. SID reduces TB in a PN undergoing experimental short bowel resection murine model. 2. Parenteral nutrition-related liver disease decreases in DIS receiving animals.     

Effect of stress and trauma on bacterial translocation from the gut

Previously, we established that bacteria contained within the gut can cross the GI mucosal barrier and spread systemically, a process termed bacterial translocation. Three models were used to extend this work: cold exposure (up to 16 hr at 4 degrees C), a nontissue injury stress model; femoral fracture-amputation, a trauma model; and thermal injury (30% third-degree burn), a trauma model with retained necrotic tissue. CD-1 mice either with a normal GI microflora or who were monoassociated with Escherichia coli C-25 were subjected to sham or actual stress or trauma. The animals were sacrificed at various times postinsult and the ceca, mesenteric lymph nodes (MLN), spleens, and livers were quantitatively cultured. Neither the incidence nor the magnitude of bacterial translocation was increased in the cold-exposed animals compared to control mice. The incidence of bacterial translocation to the systemic organs was higher in the animals with a normal flora receiving femoral fracture amputation (11%) (P less than 0.02) than in animals receiving a thermal injury (1%) or sham-injured control mice (0%). In contrast, the incidence of translocation to the liver or spleen was higher in burned mice monoassociated with E. coli C-25 (60%) (P less than 0.01) than in E. coli monoassociated mice sustaining femoral fracture amputation (17%). Stress alone (cold exposure) does not promote bacterial translocation; however, trauma, especially in combination with retained necrotic tissue, promotes bacterial translocation. Thus bacteria colonizing the gut can invade systemic organs after trauma, especially when the normal ecology of the gut flora has been disrupted.     

Bacterial translocation associated with short bowel: role of ileocecal valve and cecum

Sepsis in short bowel syndrome (SBS) is due in part to bacterial translocation (BT). Parenteral nutrition (PN) is often necessary in SBS and promotes BT. The presence of ileocecal valve (ICV) has been considered as a good prognostic factor in the outcome of this children. The aim of this study was to asses the effect of the presence or absence of ICV and cecum in five different models of gut resection in the rat. Fifty-five adult Wistar rats were randomly assigned to one of five groups: Group 1 (N = 14): standard rat chow + 80% small bowel resection. Group 2 (N = 10): standard rat chow + 80% small bowel resection including cecum. Group 3 (N = 10): standard rat chow + 80% small bowel resection including ICV. Group 4 (N = 11): NP + 80% small bowel resection. Group 5 (N = 10): NP + 80% small bowel resection including ICV and cecum. Ten days after surgery they were sacrificed and mesenteric lymph nodes (MLN), spleen and peripheral (PBL) and portal blood (POBL) specimens were recovered and cultured. Groups 3 (without ICV, with cecum) and 5 (without ICV, without cecum) showed 60% BT in MLN and POBL, and groups 1 and 4 (with ICV, without cecum) 93% and 91% respectively (p < 0.05). In PBL, group 3 (without ICV, with cecum) showed also less BT than groups 1 and 4 (10% vs 43% and 55% respectively, p < 0.05) and group 5 (without ICV and cecum) had less BT than groups 1, 2 and 4 (0% vs 43%, 30% and 55%, p < 0.01). In conclusion, these results suggest that the absence of ICV decreases BT and that the cecum does not seems to play a role on his.     

头孢噻甲羧肟对烧伤后肠源性感染的预防作用

采用３０％ＴＢＳＡⅢ度烫伤大鼠模型，分不同时相（伤后３、６和１２ｈ）腹腔注射头孢噻甲羧肟，并通过血液、内脏和肠系膜淋巴结中细菌的定性和定量分析，评价头孢噻甲羧肟对预防烫伤大鼠绿脓杆菌肠源性感染的效果。结果表明，伤后３ｈ和６ｈ开始用药组，肠源性感染的发生率明显下降（分别为Ｐ＜０．００１和Ｐ＜０．０５），而伤后１２ｈ开始用药组则无明显降低（Ｐ＞０．０５），但其肝、肾组织中的菌量也明显减少（Ｐ＜０．０１）。同时我们还动态观察了烫伤大鼠血液和内脏组织中药物的浓度，结果表明，用药后血、肝和小肠粘膜中能迅速达到有效药浓度，并维持４ｈ以上，但肠系膜淋巴结中未检测到药物。提示：大面积烧伤病人早期，短程使用有针对性的抗生素，对预防肠源性感染可能是有益的。     

Promotion by burn stress of the translocation of bacteria from the gastrointestinal tracts of mice

A mouse burn model was established to test the effect of nonlethal thermal injury on the translocation of indigenous bacteria from the gastrointestinal (GI) tract to other organs. Specific pathogen-free (SPF) mice were given 15% or 30% total body surface area burns, and the mesenteric lymph nodes (MLNs), spleens, livers, blood, and peritoneal cavities were cultured for translocated bacteria at various time intervals. No viable aerobic, facultatively anaerobic, or strictly anaerobic bacteria of the indigenous flora grew in cultures from the MLNs of these mice. Consequently, SPF mice were antibiotic decontaminated and then colonized with Escherichia coli to develop a model in which E coli maintains abnormally high cecal population levels and translocates continuously to the MLN. These mice received 15% or 30% thermal burns four days after colonization with E coli. The incidence of bacterial translocation and the numbers of E coli translocating to the MLN, spleen, liver, blood, and peritoneal cavity increased with increasing burn area compared with controls. Mice receiving 15% burns could not clear intravenously challenged E coli from their bloodstream, MLN, or liver. Thus, burn stress promotes the translocation of bacteria from the GI tract to other organs to cause bacteremia.     

78例肝硬化患者肠道细菌易位及其相关性研究

目的了解肝硬化患者肠道细菌易位（BT）的发生率及其相关危险因素,分析BT与术后感染的关系。方法对77例肝移植和1例未行肝移植的肝硬化患者进行术中采样,取外周血、门脉血及肠系膜淋巴结（MLN）,分别进行需氧及厌氧培养,了解BT的发生率。结合术前、术后各种临床资料分析发生BT的危险因素及BT的临床意义。结果78例肝硬化患者中BT的发生率为10．3％（8／78）;细菌易位的部位以MLN为主,占5／8,发生BT的细菌主要是肠道G-兼性厌氧杆菌（55．6％）,其次为G^＋兼性厌氧球菌（22．2％）。BT组患者术前胆红素总量显著高于无BT组（P=0．022）;发生BT的患者其术后感染的风险是无BT患者的1．3倍。结论高胆红素血症是促发BT的独立危险因素,发生BT的肝移植患者术后感染的风险明显升高。