Selective bowel decontamination results in gram-positive translocation

Bloodstream infection caused by enteric organisms during the first 6 months after intestinal transplant

BACKGROUND

Data on bloodstream infection (BSI) due to enteric organisms are scarce.

METHODS

This retrospective study (1/2009-5/2017) was aimed to evaluate the incidence of BSI episodes due to enteric organisms during the first 6 months after intestinal transplant (ITx). Differences between the first (2009-2012) and second period (2013-2017) were evaluated as they differed from each other in the perioperative fungal prophylaxis and immunosuppressive regimen.

RESULTS

Fifty-five adult patients were analyzed. Twenty-eight (51%) patients developed a total of 51 episodes of BSI. Mean time from transplant to BSI was 85.5 ± 58.8 days. The most common organisms were Klebsiella pneumoniae (33%), Enterococcus spp (31%), and Candida spp (18%). Twenty-three (45%) were multidrug resistant. The most common sources were gut translocation (35%), central line infection (20%), and intra-abdominal abscess (14%). Biopsy-proven rejection was associated with 16 (31%) of the BSI episodes. Patients during the first period were more likely to develop BSI (79% vs 41%, P = 0.03). There were more episodes of rejection associated with BSI in the first period (45% vs 14%, P = 0.03). The rate of reoperation into the abdominal cavity within 2 weeks after ITx was higher and the transplant hospital stay was longer among those who developed BSI (P = 0.04 for both).

CONCLUSIONS

Half of our patients developed BSI (typically during the first 3 months). Gut translocation was the most common source of BSI. Patients with rejection and/or enteritis should be monitored closely for BSI.

The Biological Fight Against Pathogenic Bacteria and Protozoa

The animal gastrointestinal tract is a tube with two open ends; hence, from the microbial point of view it constitutes an open system, as opposed to the circulatory system that must be a tightly closed microbial-free environment. In particular, the human intestine spans ca. 200 m² and represents a massive absorptive surface composed of a layer of epithelial cells as well as a paracellular barrier. The permeability of this paracellular barrier is regulated by transmembrane proteins known as claudins that play a critical role in tight junctions.

Antibiotic regimens and intestinal colonization with antibiotic-resistant gram-negative bacilli

The intestinal tract provides an important reservoir for antibiotic-resistant gram-negative bacilli, including Enterobacteriaceae species, Pseudomonas aeruginosa, and Acinetobacter baumannii. Selective pressure exerted by antibiotics plays a crucial role in the emergence and dissemination of these pathogens. Many classes of antibiotics may promote intestinal colonization by health care-associated gram-negative bacilli, because the organisms are often multidrug resistant. Antibiotics may inhibit colonization by gram-negative pathogens that remain susceptible, but the benefits of this effect are often limited because of the emergence of resistance. Antibiotic formulary alterations and standard infection control measures have been effective in controlling outbreaks of colonization and infection with antibiotic-resistant gram-negative pathogens. Additional research is needed to clarify the role of strategies such as selective decontamination of the digestive tract and decontamination of environmental surfaces and of patients' skin and wounds.

Role of the gastrointestinal tract in burn sepsis

During the last 50 years, our understanding of the role of the gastrointestinal tract as a first-line defense against the development of postburn sepsis has increased dramatically. Starting with the concept of that gut-derived bacteria cause distant injury, investigators have delineated a complex series of physical changes in the barrier of the gastrointestinal tract. Along with an understanding of these physical changes has come an appreciation of the role of the immune system in modulating postburn organ failure. Importantly, recent investigations into the role of mesenteric lymph have fundamentally changed the paradigm of organ failure and have implicated the gut as a cytokine-secreting organ. This article traces the development of key concepts in the study of burn sepsis and their clinical implications.

Effect of Lactobacillus-fermented diets on bacterial translocation and intestinal flora in experimental prehepatic portal hypertension

Spontaneous bacterial infections in cirrhosis and portal hypertension have been attributed to translocation of gut-derived bacteria, a process promoted by intestinal bacterial overgrowth and disruption of the gut mucosal barrier. Bacteriotherapy with Lactobacillus has been reported to correct bacterial overgrowth, stabilize mucosal barrier function, and decrease bacterial translocation in rat models of acute liver injury and failure. In this study we investigated the effect of Lactobacillus-supplemented diets on intestinal flora and on bacterial translocation rate in portal vein ligated rats. Lactobacillus-fermented milk (yogurt) containing at least 2 x 10(9) colony forming units/ml or placebo (water) was adminstrated by gavage twice daily (2 ml) for 9 days. Portal vein ligation was performed on day 7 of treatment. Bacterial translocation to mesenteric lymph nodes and quantification of intestinal flora was assessed by standard bacteriological cultures. Bacterial translocation was not significantly different between animals that received yogurt (82%) and those that received placebo (75%). Yogurt did not induce any significant changes in intestinal flora, whether it was produced with Lactobacillus acidophilus or Lactobacillus GG. In conclusion, in acute prehepatic portal hypertension, bacteriotherapy with Lactobacillus was unable to induce changes in bacterial translocation probably because it was unable to induce changes in bacterial flora.

Reduced incidence of necrotizing enterocolitis associated with enteral administration of Lactobacillus acidophilus and Bifidobacterium infantis to neonates in an intensive care unit

OBJECTIVES

Necrotizing enterocolitis (NEC) has been associated with a wide variety of bacteria and their cytotoxins. The content and the nature of gut bacterial colonization in newborns that require intensive care hospitalization has been demonstrated to be abnormal. In the 25-bed neonatal intensive care unit in Hospital Simon Bolivar, in Bogotá, Colombia, cases of NEC are common causes of morbidity and mortality. This article examines the hypothesis that oral administration of prophylactic Lactobacillus acidophilus and Bifidobacterium infantis to all neonates in an intensive care unit, would decrease the incidence of NEC.

METHODS

Daily doses of 250 million live L. acidophilus and 250 million B. infantis were given to all 1237 newborns (both inpatients and transfer patients) admitted to the unit during 1 year, until they were discharged from the hospital. In this study, 1282 patients hospitalized during the previous year were used as controls.

RESULTS

There were no complications attributed to the daily administration of L. acidophilus and B. infantis. The study groups were compared for place of origin, clinical, and demographic variables, and there was no statistically significant difference in those variables. In the historic control group, there were 85 NEC cases compared to 34 cases in the group that received probiotic prophylaxis (P < 0.0002). In the historic control group, there were 35 NEC-associated fatalities compared to 14 fatalities in the group that received probiotic prophylaxis (P < 0.005).

CONCLUSIONS

The positive results in this study support the need for further investigation of bacterial colonization and its role in NEC.

Pathogenesis and prevention of early pancreatic infection in experimental acute necrotizing pancreatitis

OBJECTIVE

The authors test antibiotic strategies aimed at either mitigating bacterial translocation from the gut or delivering antibiotics specifically concentrated by the pancreas for prevention of early secondary infection after acute necrotizing pancreatitis.

BACKGROUND

Infection currently is the principal cause of death after severe pancreatitis. The authors have shown that the risk of bacterial infection correlates directly with the degree of tissue injury in a rodent model of pancreatitis. Bacteria most likely arrive by translocation from the colon.

METHODS

Severe acute necrotizing pancreatitis was induced in rats by a combination of low-dose controlled intraductal infusion of glycodeoxycholic acid superimposed on intravenous cerulein hyperstimulation. At 6 hours, animals were randomly allocated to five treatment groups: controls, selective gut decontamination (oral antibiotics and cefotaxime), oral antibiotics alone, cefotaxime alone, or imipenem. At 96 hours, surviving animals were killed for quantitative bacterial study of the cecum, pancreas, and kidney.

RESULTS

The 96-hour mortality (35%) was unaffected by any treatment regimen. Cecal gram-negative bacteria were significantly reduced only by the oral antibiotics. Pancreatic infection was significantly reduced by full-gut decontamination and by imipenem, but not by oral antibiotics or by cefotaxime alone. Renal infection was reduced by both intravenous antibiotics.

CONCLUSIONS

Early pancreatic infection after acute necrotizing pancreatitis can be reduced with a full-gut decontamination regimen or with an antibiotic concentrated by the pancreas (imipenem) but not by unconcentrated antibiotics of similar spectrum (cefotaxime) or by oral antibiotics alone. These findings suggest that 1) both direct bacterial translocation from the gut and hematogenous seeding interplay in pancreatic infection while hematogenous seeding is dominant at extrapancreatic sites and 2) imipenem may be useful in clinical pancreatitis.

Controlled clinical trial of selective decontamination for the treatment of severe acute pancreatitis

OBJECTIVE

A randomized, controlled, multicenter trial was undertaken in 102 patients with objective evidence of severe acute pancreatitis to evaluate whether selective decontamination reduces mortality.

SUMMARY BACKGROUND DATA

Secondary pancreatic infection is the major cause of death in patients with acute necrotizing pancreatitis. Controlled clinical trials to study the effect of selective decontamination in such patients are not available.

METHODS

Between April 22, 1990 and April 19, 1993, 102 patients with severe acute pancreatitis were admitted to 16 participating hospitals. Patients were entered into the study if severe acute pancreatitis was indicated, on admission, by multiple laboratory criteria (Imrie score > or = 3) and/or computed tomography criteria (Balthazar grade D or E). Patients were randomly assigned to receive standard treatment (control group) or standard treatment plus selective decontamination (norfloxacin, colistin, amphotericin; selective decontamination group). All patients received full supportive treatment, and surveillance cultures were taken in both groups.

RESULTS

Fifty patients were assigned to the selective decontamination group and 52 were assigned to the control group. There were 18 deaths in the control group (35%), compared with 11 deaths (22%) in the selective decontamination group (adjusted for Imrie score and Balthazar grade: p = 0.048). This difference was mainly caused by a reduction of late mortality (> 2 weeks) due to significant reduction of gram-negative pancreatic infection (p = 0.003). The average number of laparotomies per patient was reduced in patients treated with selective decontamination (p < 0.05). Failure of selective decontamination to prevent secondary gram-negative pancreatic infection with subsequent death was seen in only three patients (6%) and transient gram-negative pancreatic infection was seen in one (2%). In both groups of patients, all gram-negative aerobic pancreatic infection was preceded by colonization of the digestive tract by the same bacteria.

CONCLUSION

Reduction of gram-negative colonization of the digestive tract, preventing subsequent pancreatic infection by means of selective decontamination, significantly reduces morbidity and mortality in patients with severe acute necrotizing pancreatitis.

Pathogenesis of pancreatic sepsis

Although pancreatic sepsis is the most common cause of major morbidity and mortality associated with acute pancreatitis, the pathogenesis of such infections is unknown. Since intraperitoneal foci of inflammation are known to promote bacterial translocation, we hypothesized that acute pancreatitis promotes bacterial translocation that leads to infection of the inflamed pancreas and peripancreatic tissues. Non-lethal acute pancreatitis was induced in rats, and the translocation of live bacteria to the pancreas, mesenteric lymph nodes, liver, and spleen was determined. The presence of orally fed fluorescent beads, sensitive inert markers of translocation, was also determined in the pancreas and mesenteric lymph nodes. Live bacteria were recovered from 33% of the pancreata of rats with acute pancreatitis but from none of the control rats. Beads were visualized in 91% of the pancreata of rats with acute pancreatitis but in none of the pancreata from control rats. Beads were not visualized in the mesenteric lymph nodes of rats with acute pancreatitis, suggesting a transperitoneal route of migration. We conclude that acute pancreatitis promotes bacterial translocation leading to transperitoneal infection of the pancreas. These results support the use of selective decontamination of the gut and peritoneal lavage for the prevention of pancreatic infections in acute pancreatitis.