Assessment of antivirulence activity of several d-amino acids against Acinetobacter baumannii and Pseudomonas aeruginosa.

OBJECTIVES: Biofilm formation and bacterial adherence are important requirements for persistence, multidrug resistance and infection. The d-amino acids play a role as modulators of bacterial growth and persistence, though their ability to inhibit biofilms is much debated. In this study, we analysed the effects of 18 different d-amino acids on the pathogens Acinetobacter baumannii and Pseudomonas aeruginosa. METHODS: In vitro assays were carried out to analyse the effect of d-amino acids on bacterial growth, biofilm formation/disassembly, capacity to attach to eukaryotic cells and cellular death. In addition, in vivo assays were performed in mice, using experimental models of sepsis and pneumonia. RESULTS: Biofilm formation was inhibited in A. baumannii by d-His, d-Cys and d-Trp (35%-86%) at 2 mM and in P. aeruginosa by d-Cys, d-Trp and d-Tyr (10%-30%) at 4 mM. Attachment to the A549 human alveolar cells was reduced in A. baumannii by d-Cys, d-His, d-Met, d-Val and d-Ser, and in P. aeruginosa by d-Arg and d-Trp. Growth was inhibited in A. baumannii by d-Cys and d-Trp, and in P. aeruginosa by d-Trp. In virulence assays, incubation of alveolar cells infected with P. aeruginosa with d-Cys, d-Trp and d-Arg reduced cell death (56%-45%). However, no significant effect of d-amino acids was observed in vivo. CONCLUSIONS: Some d-amino acids can inhibit bacterial growth, biofilm formation and adherence to eukaryotic cells in A. baumannii and P. aeruginosa, and showed a protective effect against infection of alveolar cells with P. aeruginosa. Despite the fact that some considerable protection was observed in mice, survival differences between treated and control groups were not statistically significant.

Contribution of efflux pumps, porins, and ß-lactamases to multidrug resistance in clinical isolates of Acinetobacter baumannii.

We investigated the mechanisms of resistance to carbapenems, aminoglycosides, glycylcyclines, tetracyclines, and quinolones in 90 multiresistant clinical strains of Acinetobacter baumannii isolated from two genetically unrelated A. baumannii clones: clone PFGE-ROC-1 (53 strains producing the OXA-58 ß-lactamase enzyme and 18 strains with the OXA-24 ß-lactamase) and clone PFGE-HUI-1 (19 strains susceptible to carbapenems). We used real-time reverse transcriptase PCR to correlate antimicrobial resistance (MICs) with expression of genes encoding chromosomal ß-lactamases (AmpC and OXA-51), porins (OmpA, CarO, Omp33, Dcap-like, OprB, Omp25, OprC, OprD, and OmpW), and proteins integral to six efflux systems (AdeABC, AdeIJK, AdeFGH, CraA, AbeM, and AmvA). Overexpression of the AdeABC system (level of expression relative to that by A. baumannii ATCC 17978, 30- to 45-fold) was significantly associated with resistance to tigecycline, minocycline, and gentamicin and other biological functions. However, hyperexpression of the AdeIJK efflux pump (level of expression relative to that by A. baumannii ATCC 17978, 8- to 10-fold) was significantly associated only with resistance to tigecycline and minocycline (to which the TetB efflux system also contributed). TetB and TetA(39) efflux pumps were detected in clinical strains and were associated with resistance to tetracyclines and doxycycline. The absence of the AdeABC system and the lack of expression of other mechanisms suggest that tigecycline-resistant strains of the PFGE-HUI-1 clone may be associated with a novel resistance-nodulation-cell efflux pump (decreased MICs in the presence of the inhibitor Phe-Arg ß-naphthylamide dihydrochloride) and the TetA(39) system.

What is the normal small bowel length in humans? first donor-based cohort analysis.

Normal small bowel length (SBL) has been reported within a wide range, but never studied in a cohort of either pediatric or adult deceased donors. Between 5/2006 and 2/2011, SBL was measured in all grafts procured for intestinal transplantation at a single center and used for either isolated intestinal transplant (15) or multiorgan transplants (5) employing a standardized method. SBL was the only not significantly different variable among pediatric and adult donors divided by age 16. Furthermore, donors were classified in 3 groups: group 1: Height < 70 cm, group 2: 71-150 cm and group 3: ≥ 151 cm. Mean age was: 0.58, 5.6, 22.01 years, respectively. Mean height and weight were 65.8, 123.2, 166.1 cm (p = 0.001) and 6.9, 23.8, 65.2 kg (p = 0.001), for each group. The SBL by group was: 283.0, 324.7, 356.0 cm, remaining as the only nonsignificant variable (p = 0.06), in contrast to BMI, BSA (p = 0.001). The SBL/height ratio: 4.24, 2.7, 2.12 (p = 0.001; rho: -0.623) or SBL/BSA ratio was 8.36, 3.7, and 2.03, respectively (p : 0.0001; rho: -0.9). SBL does not increase with growth like other anthropometric variables. The SBL/height ratio significantly decreases with growth; however, bowel diameter increases, which needs further evaluation.

Analysis of immune cells draining from the abdominal cavity as a novel tool to study intestinal transplant immunobiology.

During intestinal transplant (ITx) operation, intestinal lymphatics are not reconstituted. Consequently, trafficking immune cells drain freely into the abdominal cavity. Our aim was to evaluate whether leucocytes migrating from a transplanted intestine could be recovered from the abdominal draining fluid collected by a peritoneal drainage system in the early post-ITx period, and to determine potential applications of the assessment of draining cellular populations. The cell composition of the abdominal draining fluid was analysed during the first 11 post-ITx days. Using flow cytometry, immune cells from blood and draining fluid samples obtained the same day showed an almost complete lymphopenia in peripheral blood, whereas CD3(+) CD4(+) CD8(-) , CD3(+) CD4(-) CD8(+) and human leucocyte antigen D-related (HLA-DR)(+) CD19(+) lymphocytes were the main populations in the draining fluid. Non-complicated recipients evolved from a mixed leucocyte pattern including granulocytes, monocytes and lymphocytes to an exclusively lymphocytic pattern along the first post-ITx week. At days 1-2 post-Itx, analysis by short tandem repeats fingerprinting of CD3(+) CD8(+) sorted T cells from draining fluid indicated that 50% of cells were from graft origin, whereas by day 11 post-ITx this proportion decreased to fewer than 1%. Our results show for the first time that the abdominal drainage fluid contains mainly immune cells trafficking from the implanted intestine, providing the opportunity to sample lymphocytes draining from the grafted organ along the post-ITx period. Therefore, this analysis may provide information useful for understanding ITx immunobiology and eventually could also be of interest for clinical management.

Use of Nonvascularized Abdominal Rectus Fascia After Liver, Small Bowel, and Multiorgan Transplantation: Long-Term Follow-up of a Single-Center Series.

BACKGROUND: The abdominal wall may be severely compromised in the vast majority of intestinal and multiorgan transplant candidates, and sometimes as a consequence of complex liver transplantation. Multiple options have been described to overcome this problem, varying from component separation to the extreme need of performing an abdominal wall transplantation. The aim of the present paper is to report the largest and longest-term results of patients that received an abdominal rectus fascia (ARF) after liver, intestinal, or multiorgan transplantation at a single transplant center. METHODS: This is a retrospective report of a prospectively collected dataset of all the patients that received ARF during liver, isolated intestine, combined, or multiorgan transplantation at Fundación Favaloro from May 2006 to June 2016. RESULTS: A total of 19 out of 528 patients (3.5%) that underwent abdominal organ transplant received an ARF graft: 17 patients after receiving an intestine-containing graft, and 2 after liver retransplantations. Three patients required changing the ARF, 2 with a synthetic mesh and 1 with another ARF. Five patients required late reoperations: A relaparotomy was performed by transecting the ARF without encountering adhesions on the inner ARF surface. None of the 2 patients who received liver retransplantations and ARF developed acute or chronic ventral defects. CONCLUSIONS: The use of ARF is a simple and reliable surgical option to close abdominal wall defects during transplantation, the fascia adequately incorporates to the abdominal wall, allowing it to be transected and resutured in the long term and preserving the integrity of the peritoneal layer.

Right Extended Split Liver Transplantation Compared With Whole Liver Transplantation: Lessons Learned at a Single Center in Latin America-Results From a Match Case-Control Study.

BACKGROUND: Despite the progressively increasing gap between patients waiting for liver transplant under the Model for End-stage Liver Disease MELD system and the availability of deceased donor organs, the use of right extended split liver grafts (RESLG) has not been accepted by all centers. In this study, we compared the results obtained using RESLG vs a group of matched whole liver graft (WLG) recipients at a single center in Latin America. METHODS: A single-center retrospective review performed between August 2009 and December 2015. RESULTS: Fifteen RESLGs were implanted to recipients between 13 and 70 years of age; 80% were performed ex situ. The "biological MELD" score for the RESLG group was 17.5 ± 5.6, and it was 12.8 ± 4.5 for the WLG group (P = .01). Cold ischemia times were significantly longer in RESLG recipients compared with WLG recipients (528 minutes vs 420 minutes; P < .01). No significant differences were found in biliary (leak or strictures P = .40) and arterial complications (hepatic artery thrombosis, P = .06). RESLG patients benefited from a considerable reduction on their waiting time in list. The 1-, 3-, and 5-year patient survival rates were 93%, 93%, and 93% respectively, for RESLG recipients vs 100%, 95.7%, and 86.1%, respectively, for WLG recipients. The 1-, 3-, and 5-year graft survival rates were 79.4%, 79.4%, and 79.4% for RESLG recipients and 89.7%, 89.7%, and 89.7% for WLG recipients, respectively. No statistical differences were observed. CONCLUSION: RESLG allows expeditious transplantation for low MELD recipients. Its use should be expanded in Latin America and worldwide as a valid alternative to increase the donor pool as it has been used in other regions.

Case Report: Multivisceral Transplantation for an Extensive Cystic Lymphangioma of the Mesenteric Root.

BACKGROUND: We report the case of a 7-year-old girl with intestinal failure owing to a cystic lymphangioma compromising the root of the mesentery, not amenable to resection, leading to intestinal failure. Oncologic treatment was attempted to reduce tumor size with no response; therefore, she was listed for multivisceral transplantation. PROCEDURE: Resection of the tumor required resection of all abdominal organs with vascular inflow and outflow. A multivisceral graft (liver, stomach, duodenum-pancreas and spleen complex, small bowel, and right colon) was implanted. For vascular reconstruction, donor's superior vena cava was sutured to the recipient's suprahepatic veins in a common patch. For arterial inflow, an arterial conduit was placed directly to the infrarenal aorta, and sutured to an aortic patch of the graft. Cold ischemia time was 8:45 hours; warm ischemia time was 35 minutes. A double-layer gastrogastric anastomosis and piloroplasty was made; and the distal reconstruction was performed with ileocolic side-to-end anastomosis that allowed to perform of a Bishop-Koop ileostomy for endoscopic monitoring. OUTCOME: The patient recovered well after the procedure and was discharged 36 days after transplantation with intestinal sufficiency. To the best of our knowledge, this is the first report describing cystic lymphangioma as an indication for multivisceral transplantation.

Case Report: Spleen-preserving Multivisceral Transplant for Peutz-Jeghers Syndrome.

CASE REPORT: A 24-year-old man diagnosed with Peutz-Jeghers syndrome as a child underwent multiple surgeries owing to intussusception. Pretransplant workup showed >150 polyps along the gastrointestinal (GI) tract, some of them with high-grade dysplasia. Despite having intestinal sufficiency, a modified multivisceral transplantation was offered. PROCEDURE: An 18-year-old donor was procured using University of Wisconsin solution. The recipient's surgery started with a midline incision. Mobilization of the right colon and the root of the mesentery was done to isolate the superior mesenteric artery. The same maneuver was done with the left and sigmoid colon. The common bile duct was then isolated and transected at the cystic duct level. The abdominal portion of the esophagus and the proximal stomach were isolated and divided at the gastroesophageal junction. After that, the pancreas was mobilized, preserving the spleen with the splenic vessels. The distal GI tract was transacted at the level of the proximal rectum. For engraftment, an arterial conduit was placed in the infrarenal aorta and anastomosed to the graft's aortic patch. End-to-side portal reconstruction was made at the level of the portal vein, allowing performing a duct-to-duct biliary reconstruction over a 5-Fr T-tube. A hand-sewn gastrogastric anastomosis and piloroplasty were performed; the distal anastomosis was done with circular staplers. A gastrojejunostomy and a loop ileostomy were the final steps of the procedure. RESULTS: The patient stayed in intensive care for 2 days and enteral feeds were started on day 7. Currently, 23 months after transplant he is alive with an excellent quality of life.

Long-Term Outcomes of Intestinal and Multivisceral Transplantation at a Single Center in Argentina.

BACKGROUND: Intestinal failure (IF) patients received parenteral nutrition (PN) as the only available therapy until intestinal transplantation (ITx) evolved as an accepted treatment. The aim of this article is to report the long-term outcomes of a series of ITx performed in pediatric and adult patients at a single center 9 years after its creation. PATIENTS AND METHODS: This is a retrospective analysis of the ITx performed between May 2006 and January 2015. Diagnoses, pre-ITx mean time on PN, indications for ITx, time on the waiting list for types of ITx, mean total ischemia time, and warm ischemia time, time until PN discontinuation, incidence of acute and chronic rejection, and 5-year actuarial patient survival are reported. RESULTS: A total of 42 patients received ITx; 80% had short gut syndrome (SG); the mean time on PN was 1620 days. The main indication for ITx was lack of central venous access followed by intestinal failure-associated liver disease (IFALD) and catheter-related infectious complications. The mean time on the waiting list was 188 days (standard deviation, ±183 days). ITx were performed in 26 children and 14 adults. In all, 32 procedures were isolated ITx (IITX); 10 were multiorgan Tx (MOT; 3 combined, 7 multivisceral Tx (MVTx), 1 modified MVTx and 2 with kidney); 2 (4.7 %) were retransplantations: 1 IITx, 1 MVTx, and 5 including the right colon. Thirteen patients (31%) received abdominal rectus fascia. All procedures were performed by the same surgical team. Total ischemia time was 7:53 ± 2:04 hours, and warm ischemia time was 40.2 ± 10.5 minutes. The mean length of implanted intestine was 325 ± 63 cm. Bishop-Koop ileostomy was performed in 67% of cases. In all, 16 of 42 Tx required early reoperations. The overall mean follow-up time was 41 ± 35.6 months. The mean time to PN discontinuation after Tx was 68 days (P = .001). The total number of acute cellular rejection (ACR) episodes until the last follow-up was 83; the total number of grafts lost due to ACR was 4; and the total graft lost due to chronic rejection was 3. At the time of writing, the overall 5-year patient survival is 55% (65% for IITx vs 22% for MOT; P = .0001); 60% for pediatric recipients vs 47% for adults (P = NS); 64% when the indication for ITx was SG vs 25% for non-SG (P = .002). CONCLUSIONS: At this center, candidates with SG, in the absence of IFALD requiring IITx, showed the best long-term outcomes, independent of recipient age. A multidisciplinary approach is mandatory for the care of intestinal failure patients, to sustain a rehabilitation and transplantation program over time.

The value of plasma citrulline to predict mucosal injury in intestinal allografts.

Diagnosis of intestinal transplant rejection depends on clinical assessment, endoscopy and most importantly, histology of intestinal biopsies. Plasma citrulline levels (P-Cit) reflect functional enterocyte mass in nontransplant patients and have been evaluated in two small series after transplant. This study was designed to determine the sensitivity and specificity of P-Cit as diagnostic tool for allograft injury, especially to distinguish between viral enteritis and rejection. We prospectively collected 403 P-Cit samples within 24 h of intestinal biopsy in 49 patients. P-Cit levels were correlated with the mucosal damage and histopathological diagnoses. P-Cit levels in bowels with significant mucosal damage (i.e. moderate or severe rejection, viral enteritis, PTLD, ischemia reperfusion injury, allergic enteritis) were significantly lower than in intestines with no or mild injury (i.e. indeterminate or mild rejection, nonspecific enteritis): 22.9 +/- 15.4 versus 38 +/- 23.2 nmol/mL (p < 0.0001). Sensitivity and specificity of the test were 80% and 58.1% for rejection, and 56.5% and 66% for viral enteritis, thereby unable to distinguish between both entities. In conclusion, P-Cit reflects the extent of mucosal injury regardless of the etiology, but does not seem to be a predictive marker for rejection or viral enteritis, as its values may decline only when diffuse mucosal damage has occurred.