Postoperative selective bowel decontamination prevents gram-negative bacterial translocation in small-bowel graft recipients

Cold Storage Injury to Rat Small-bowel Transplants-Beneficial Effect of a Modified HTK Solution

BACKGROUND

The small bowel is prone to ischemic injury during transport before transplantation, an injury that endangers the recipient patient. The small-bowel mucosal microcirculation in particular appears to be highly sensitive to injury. Current preservation solutions such as histidine-tryptophan-ketoglutarate (HTK) solution provide some protection to the graft. However, these were developed decades ago and do not address several critical processes, such as hypoxia-induced membrane pores and free radical-mediated hypothermic injury.

METHODS

To protect the graft from cold ischemic injury, we implemented a modified HTK solution here, including glycine, alanine, and iron chelators in a heterotopic, syngeneic small-bowel transplantation model of the rat. The effects of the modified solution and its major components were compared against the conventional HTK solution using intravital microscopy in the early reperfusion period.

RESULTS

The amino acid glycine, added to HTK solution, slightly improved mucosal perfusion. Both, the modified base solution (without iron chelators) and iron chelators increased functional capillary density of the mucosa during the early reperfusion period. The complete modified solution (with glycine, alanine, and iron chelators) significantly increased the perfusion index, functional capillary density of the mucosa, and red blood cell velocity in the grafts after reperfusion in comparison with the grafts preserved with HTK.

CONCLUSIONS

The modified preservation solution improved the microcirculation of the transplants and needs detailed evaluation in further models of small-bowel transplantation.

Incidence of bloodstream infections in small bowel transplant recipients receiving selective decontamination of the digestive tract: A single-center experience

Pediatric patients undergoing small bowel transplantation are susceptible to postoperative CLABSI. SDD directed against enteric microbes is a strategy for reducing CLABSI. We hypothesized that SDD reduces the frequency of CLABSI, infections outside the bloodstream, and allograft rejection during the first 30 days following transplant. A retrospective chart review of 38 pediatric small bowel transplant recipients at CCHMC from 2003 to 2011 was conducted. SDD antimicrobials were oral colistin, tobramycin, and amphotericin B. The incidence of CLABSI, infections outside the bloodstream, and rejection episodes were compared between study periods. The incidence of CLABSI did not differ between study periods (6.9 CLABSI vs. 4.6 CLABSI per 1000 catheter days; p = 0.727), but gram positives and Candida predominated in the first 30 days. Incidence of bacterial infections outside the bloodstream did not differ (p = 0.227). Rejection occurred more frequently during the first month following transplant (p = 0.302). SDD does not alter the incidence of CLABSI, bacterial infections outside the bloodstream, or allograft rejection in the immediate 30 days post-transplantation. However, SDD does influence CLABSI organism types (favoring gram positives and Candida) and Candidal infections outside the bloodstream.

Organ Changes and Bacterial Translocation in a Rat Model of Chronic Rejection After Small Bowel Transplantation

Rejection after small bowel transplantation (SBTx) may allow bacterial translocation damaging the liver and lungs. This study investigated these issues in a rat model of chronic rejection.

MATERIALS AND METHODS

Orthotopic SBTx was performed in syngeneic (SYN) (ACI-ACI, n=8) and allogeneic (ALLO) (ACI-Lewis, n=8) rat strain combinations. Cyclosporine was given to ALLO rats for 28 days. Animals were sacrified between 55 and 65 days. Lymph nodes and venous samples were cultured; Escherichia coli DNA was assessed by polymerase chain reaction. We measured intestine, liver, spleen, and lung protein and DNA contents. Chronic rejection was histologically confirmed.

RESULTS

Two of eight and four of eight rats died in the first week after SYN and ALLO SBTx, respectively. There were no differences in organ weights or DNA and protein contents compared with the controls. Gram-negative enteric bacteria were found in two of four ALLO and two of six SYN rats (ns), and aerobic gram-positive were found in two of four and two of six (ns), respectively. Anaerobic growth occurred in mesenteric lymph nodes in only one ALLO rat. E. coli DNA was negative in all animals. Lungs were severely emphysematous in ALLO rats with no histologic changes observed in the other phagocytic organs. Mild rejection was found in the intestine of ALLO rats.

CONCLUSIONS

Bowel lesions in ALLO rats might be consistent with chronic rejection and lung lesions could be related to bacterial translocation after SBTx. However, contrary to our expectations, no significant bacterial translocation was demonstrated in either group at the end of the experiments.

Gut Decontamination Prevents Bronchoscopy-Induced Bacterial Translocation

BACKGROUND

Selective gut decontamination is suggested to suppress the gram-negative bacterial overgrowth in the intestine and consequently to reduce bacterial translocation.

OBJECTIVE

The purpose of the present study is to examine the effects of gut decontamination on bronchoscopy-induced bacterial translocation, and intestinal mucosal injury.

METHODS

Forty-five rats were assigned into three groups. Group 1 served as control (n=15). Group 2 (n=15) and group 3 (n=15) underwent bronchoscopy. In addition, group 3 underwent gut decontamination. Gut decontamination was performed two days prior to bronchoscopy with erythromycin and neomycin. Twenty-four hours after bronchoscopy, blood, mesenteric lymph nodes, spleen, liver, ileum and cecum were harvested for bacterial determination. The ileum was also assessed and graded histologically according to Chiu's injury scale.

RESULTS

In the bronchoscopy group, bacterial translocation to the mesenteric lymph nodes was found in 7/15 rats (46.7%), compared to none of the controls (p=0.01). These rats also showed significant evidence of intestinal injury, compared to the controls (mean ranks, 32.7 or 8.5, p<0.0001). On the other hand, gut decontamination prevented bacterial translocation, compared to the bronchoscopy group (p=0.011). However, gut decontamination provided no beneficial effect on the intestinal mucosal injury, compared to the bronchoscopy group. These animals also revealed significant intestinal injury, compared to the controls (mean ranks, 27.8 or 8.5, p<0.0001).

CONCLUSIONS

Our data shows that despite no amelioration in bronchoscopy-induced intestinal mucosal injury, gut decontamination has a preventive role for bronchoscopy-induced bacterial translocation.

Intensive Care of the Intra-Abdominal Organ Transplant Recipient

The postoperative care of a patient who receives an intra-abdominal organ transplant is in some ways simi lar to that of any major intra-abdominal procedure. However, certain features unique to organ transplanta tion, such as the variable functional status of the newly transplanted graft, complications that are specific to the organ transplanted, and the side effects from immuno suppressive drugs, suggest that transplantation inten sive care is a distinct subspecialty in critical care medicine. Today, the majority of patients receiving an intra-abdominal transplant will have a relatively uncom plicated postoperative course. However, preoperative disposition, intraoperative misadventure, or immediate postoperative difficulty will require the availability of an intensivist experienced in transplantation. The future of intra-abdominal transplantation will be highly depen dent on progress in immunotherapy. Newer, more spe cific immunomodulators with fewer nonimmune toxici ties should result in improved organ receptance, less graft dysfunction, and improved patient survival.