Risk factors for Clostridium difficile infection in intestinal transplant recipients during the first year post-transplant.

BACKGROUND: Clostridium difficile is the most common cause of healthcare-associated infectious diarrhea. Risk factors for C. difficile infections (CDI) in intestinal transplant recipients (ITR) are not well-defined. The aim of our study was to assess specific risk factors for CDI in ITR. METHODS: This is a 1:3 case-control study that included 29 ITR who developed CDI (cases) and 87 ITR without CDI (controls) observed during the first year post-transplantation. Wilcoxon rank sum and Fisher's exact tests were used to compare variables. Univariate and multivariable conditional logistic regressions analysis were performed to identify risk factors for CDI. RESULTS: The multivariable conditional logistic regression analysis showed that proton pump inhibitors (PPI) administration (odds ratio [OR] = 0.06; 95% confidence interval [CI]: 0.007-0.52; P = .01) was the only factor associated with lower rates of CDI. Outcomes for cases vs controls: rejection episodes 24.14% vs 20.69% (P = .7), graft loss 0% vs 2.3% (P = .99), and survival rate 1 year post-transplantation 79.3% (59.6-90.1%) vs 87.2% (78.1-92.7%) (P = .38). CONCLUSIONS: Proton pump inhibitor administration might be protective for CDI in ITR. Risks factors for CDI might be different in ITR compared to other populations; anatomical differences and medications administered in the post-transplantation period may affect intestinal microbiota.

Elevated ST2 Distinguishes Incidences of Pediatric Heart and Small Bowel Transplant Rejection.

Elevated serum soluble (s) suppressor of tumorigenicity-2 is observed during cardiovascular and inflammatory bowel diseases. To ascertain whether modulated ST2 levels signify heart (HTx) or small bowel transplant (SBTx) rejection, we quantified sST2 in serially obtained pediatric HTx (n = 41) and SBTx recipient (n = 18) sera. At times of biopsy-diagnosed HTx rejection (cellular and/or antibody-mediated), serum sST2 was elevated compared to rejection-free time points (1714 ± 329 vs. 546.5 ± 141.6 pg/mL; p = 0.0002). SBTx recipients also displayed increased serum sST2 during incidences of rejection (7536 ± 1561 vs. 2662 ± 543.8 pg/mL; p = 0.0347). Receiver operator characteristic (ROC) analysis showed that serum sST2 > 600 pg/mL could discriminate time points of HTx rejection and nonrejection (area under the curve [AUC] = 0.724 ± 0.053; p = 0.0003). ROC analysis of SBTx measures revealed a similar discriminative capacity (AUC = 0.6921 ± 0.0820; p = 0.0349). Quantitative evaluation of both HTx and SBTx biopsies revealed that rejection significantly increased allograft ST2 expression. Pathway and Network Analysis of biopsy data pinpointed ST2 in the dominant pathway modulated by rejection and predicted tumor necrosis factor-α and IL-1ß as upstream activators. In total, our data indicate that alloimmune-associated pro-inflammatory cytokines increase ST2 during rejection. They also demonstrate that routine serum sST2 quantification, potentially combined with other biomarkers, should be investigated further to aid in the noninvasive diagnosis of rejection.

Parvovirus associated fulminant hepatic failure and aplastic anemia treated successfully with liver and bone marrow transplantation. A report of two cases.

Aplastic anemia (AA) has been observed in nearly a third of patients undergoing liver transplantation (LT) for non-A-E fulminant hepatic failure (FHF). Few of these patients have been successfully managed with sequential LT and bone marrow transplantation (BMT). No causative agent has been identified for the FHF or AA in these reported cases. At our center, two patients, aged 15 years and 7 years, respectively, underwent sequential living-related LT and living-unrelated BMT. These patients are 10/9 years and 5/4 years post-LT/BMT. Human parvovirus B19 (HPV-B19) was established as the causative agent for FHF in both these patients by polymerase chain reaction. This report presents the first two cases associating HPV-B19 with FHF and AA who underwent sequential LT and BMT with excellent outcomes.

Infection, growth and maintenance of Wolbachia pipientis in clonal and non-clonal Aedes albopictus cell cultures.

Insect cell lines provide useful in vitro models for studying biological systems, including interactions between mosquitoes and obligate intracellular endosymbionts such as Wolbachia pipientis. The Aedes albopictus Aa23 cell line was the first cell line developed to allow examination of Wolbachia infections. However, Wolbachia studies using Aa23 can be complicated by the presence of different cell types in the cell line and the substantial temporal variation in infection level. Two approaches were examined to ameliorate infection variability. In the first approach, multiple Aa23 passaging regimes were tested for an effect on infection variability. Fluorescence in situ hybridization (FISH) staining was used to characterize Wolbachia infection level over time. The results demonstrate an impact of passaging method on Wolbachia infection level, with some methods resulting in loss of infection. None of the passaging methods succeeded in effectively mitigating infection level variation. In a second approach, the clonal C7-10 A. albopictus cell line was infected with Wolbachia from Aa23 cells and Drosophila simulans (Riverside), resulting in cell lines designated C7-10B and C7-10R, respectively. Characterization via FISH staining showed greater stability and uniformity of Wolbachia infection in C7-10R relative to the infection in C7-10B. Characterization of the Aa23, C7-10B and C7-10R lines is discussed as a tool for the study of Wolbachia-host cell interactions.

Characterization of the ileal microbiota in rejecting and nonrejecting recipients of small bowel transplants.

Small bowel transplantation can be a life-preserving procedure for patients with irreversible intestinal failure. Allograft rejection remains a major source of morbidity and mortality and its accurate diagnosis and treatment are critical. In this study, we used pyrosequencing of 16S ribosomal RNA gene tags to compare the composition of the ileal microbiota present during nonrejection, prerejection and active rejection states in small bowel transplant patients. During episodes of rejection, the proportions of phylum Firmicutes (p < 0.001) and the order Lactobacillales (p < 0.01) were significantly decreased, while those of the phylum Proteobacteria, especially the family Enterobacteriaceae, were significantly increased (p < 0.005). Receiver-operating characteristic analysis revealed that relative proportions of several bacterial taxa in ileal effluents and especially Firmicutes, could be used to discriminate between nonrejection and active rejection. In conclusion, the findings obtained during this study suggest that small bowel transplant rejection is associated with changes in the microbial populations in ileal effluents and support microbiota profiling as a potential diagnostic biomarker of rejection. Future studies should investigate if the dysbiosis that we observed is a cause or a consequence of the rejection process.

Staphylococcus aureus infections after liver transplantation.

BACKGROUND: More data on the risk factors and outcomes after Staphylococcus aureus infections in liver transplantation are needed. METHODS: Liver recipients with S. aureus infections (cases) were retrospectively identified and compared to gender-, age-, and transplant type-matched (1:2) non-S. aureus-infected controls. Risk factors associated with S. aureus infections were identified by conditional logistic regression analysis. RESULTS: We evaluated 51 patients (median age 52 years). First S. aureus infections developed at a median time of 29 days after transplantation, with 52.94% of them in the first month; 88.24% were nosocomial, 41.18% were polymicrobial, and 47.06% were caused by methicillin-resistant S. aureus (MRSA). Surgical site infections represented 58.82% and bacteremia 23.53%. By univariate analysis, patients with S. aureus infections were intubated more frequently (odds ratio [OR] 26.92, 95% confidence interval [CI] 3.23-3,504.15, p = 0.0006), had a central line (OR 11.69, 95% CI 1.42-95.9, p = 0.02), or recent surgery (OR 26.92, 95% CI 3.23-3,504.15, p = 0.0006) compared with controls. By multivariate analysis, subjects who underwent surgery within 2 weeks prior to infection had a 26.9 times higher risk of developing S. aureus infection (95% CI 3.23-3,504.15, p = 0.0006); these results were adjusted for matched criteria. S. aureus infections did not affect graft or patient survival, but the study was not powered for such outcomes. CONCLUSION: Only recent surgical procedure was found to be a significant independent risk factor for S. aureus infections after liver transplantation.

Incidence, risk factors, and outcomes associated with cytomegalovirus disease in small bowel transplant recipients.

Despite improved prophylaxis, monitoring, and more efficient immunosuppression, CMV infection remains a common opportunistic infection in transplant recipients. We assessed the incidence of CMV disease in pediatric SBT recipients, the timing of CMV disease after transplantation, and its impact on patient outcome. The medical records of 98 SBT recipients were reviewed. We performed descriptive analysis, regression analysis, and Kaplan-Meier curves to determine the time-to-event after transplantation. Fifty-three percent patients were male and 47% female, with a mean age of 38.3 months. Thirty-five percent of patients received prophylactic VGC, 55% GCV, 10% a combination of GCV/VGC, and 99% CMV immunoglobulins. A total of 24.5% recipients were CMV D+/R- (CMV serostatus donor positive/recipient negative). Seven (c. 7%) patients developed CMV disease. CMV disease was associated with 2.5 times (0.52-12.1; p = 0.25) higher rate of CMV mismatch and 11.1 times (1.3-95.9; p = 0.03) higher risk of death. CMV prophylaxis increased time-to-death (p = 0.074). Time-to-CMV disease was shorter in patients with enteritis (p < 0.0001), and CMV disease was associated with shorter time-to-death after transplantation (p = 0.001). CMV disease in SBT recipients was associated with an 11-fold mortality increase and a fourfold faster time-to-death. Time-to-death was significantly shorter with CMV enteritis.

Hepatitis C virus replication in mice with chimeric human livers.

Lack of a small animal model of the human hepatitis C virus (HCV) has impeded development of antiviral therapies against this epidemic infection. By transplanting normal human hepatocytes into SCID mice carrying a plasminogen activator transgene (Alb-uPA), we generated mice with chimeric human livers. Homozygosity of Alb-uPA was associated with significantly higher levels of human hepatocyte engraftment, and these mice developed prolonged HCV infections with high viral titers after inoculation with infected human serum. Initial increases in total viral load were up to 1950-fold, with replication confirmed by detection of negative-strand viral RNA in transplanted livers. HCV viral proteins were localized to human hepatocyte nodules, and infection was serially passaged through three generations of mice confirming both synthesis and release of infectious viral particles. These chimeric mice represent the first murine model suitable for studying the human hepatitis C virus in vivo.

Measurement of 227Ac impurity in 225Ac using decay energy spectroscopy.

225Ac is a valuable medical radionuclide for targeted α therapy, but 227Ac is an undesirable byproduct of an accelerator-based synthesis method under investigation. Sufficient detector sensitivity is critical for quantifying the trace impurity of 227Ac, with the 227Ac/225Ac activity ratio predicted to be approximately 0.15% by end-of-bombardment (EOB). Superconducting transition edge sensor (TES) microcalorimeters offer high resolution energy spectroscopy using the normal-to-superconducting phase transition to measure small changes in temperature. By embedding 225Ac production samples in a gold foil thermally coupled to a TES microcalorimeter we can measure the decay energies of the radionuclides embedded with high resolution and 100% detection efficiency. This technique, known as decay energy spectroscopy (DES), collapses several peaks from α decays into single Q-value peaks. In practice there are more complex factors in the interpretation of data using DES, which we will discuss herein. Using this technique we measured the EOB 227Ac impurity to be (0.142 ± 0.005)% for a single production sample. This demonstration has shown that DES is a useful tool for quantitative measurements of complicated spectra.

Incidence and outcome of fungal infections in pediatric small bowel transplant recipients.

BACKGROUND: Data on the incidence, timing, and outcome of fungal infections in pediatric small bowel transplantation (SBT) are lacking. METHODS: Cases of pediatric SBT from January 2003 through December 2007 were collected. Standard induction was with thymoglobulin and/or basiliximab and maintenance immunosuppression was a tacrolimus-based regimen. Chi-square was used for categorical variables and Kaplan-Meier for survival analyses. RESULTS: A total 98 recipients were included; 25 patients developed 59 episodes of Candida infections and 4 episodes of invasive aspergillosis (incidence 25.5%, 95% confidence interval [CI] 17%, 34%). Of the Candida species, 37.3% were Candida albicans and 62.7% non-albicans Candida. Of all yeast infections, 66.1% were fungemia, 28.8% intra-abdominal infections, 1.7% empyema, and 3.4% urinary tract infection. Of the Candida intra-abdominal infections, 41.2% developed in the first month post transplantation, while 79.5% of candidemia developed after >6 months. Median time from transplantation to fungal infection was significantly shorter for abdominal infections compared with fungemia (9 versus 163 days; P=0.004). All-cause mortality was not significantly different between patients with and without fungal infections (32.3% versus 29.8%; odds ratio=1.12, 95% CI 0.45, 2.8). CONCLUSION: Fungal infections occurred in 25% of SBT recipients and C. albicans was the most common species. Intra-abdominal fungal infections occurred earlier (<1 month) than fungemia (>6 months) post transplantation.

Regulatory role of parasites: impact on host population shifts with resource availability.

Effects of infections by the ciliate Lambornella clarki on larval populations of its mosquito host Aedes sierrensis were examined in laboratory and field studies. When host populations developed with sufficient food, mortality from parasites was additive and reduced the number of emerging mosquitoes. For food-limited populations, mortality was compensatory or depensatory; emerging adults were as or more abundant with higher average fitness than those from uninfected control populations. When nutrients were scarce, parasitic infections relaxed larval competition and increased per capita food by reducing host abundance. Food limitation altered larval feeding behavior, reducing horizontal transmission and subsequent mortality from parasitism.

Predator-induced trophic shift of a free-living ciliate: parasitism of mosquito larvae by their prey.

Larvae of the treehole mosquito, Aedes sierrensis, release a waterborne factor that induces morphogenesis of one of their prey, the tetrahymenid ciliate Lambornella clarki. Induced free-living trophonts of L. clarki undergo a synchronous response in which cells divide and transform into parasitic cells (theronts) that encyst on larval predators. Parasitic ciliates penetrate the cuticle, enter the hemocoel, and ultimately kill their predator-host. In nature, this trophic shift can lead to predator extinction and dramatic changes in microbial populations. Facultative parasitism by this polymorphic ciliate may have evolved as an antipredator strategy. The experimentally inducible parasitic response of L. clarki provides a novel model for studying cellular morphogenesis of ciliated protozoa.

A reliable and safe gastrotomy closure technique assessed in a porcine survival model pilot study: success of the Queen's closure.

BACKGROUND AND STUDY AIMS: The evolution of NOTES to clinical implementation has been hampered by lack of a reliable, safe, and easy-to-implement technique for closure of the opening created in accessing the peritoneum. The Queen's closure uses a combination of endoscopic clips and loop devices to seal such defects in the stomach wall. This study aimed to assess the Queen's closure in a porcine survival model. METHODS: Five 30-kg pigs underwent endoscopic transgastric surgery with exploration of the peritoneum. The endoscope was then withdrawn back into the stomach and the closure performed. The animals were recovered, monitored closely, and underwent endoscopy 1 week after surgery. They were then euthanized at 2 (n = 2) and 3 (n = 3) weeks after surgery with subsequent necropsy. RESULTS: The mean procedure time (from intubation of the esophagus to withdrawal of the endoscope) was 79 minutes (range 45-105 minutes) with a mean time of exploration of the peritoneum of 14 minutes (range 8-25 minutes). All animals recovered well with no apparent pain, distress, or signs of infection. Endoscopic examination 1 week after surgery revealed all the closures to be intact and only identifiable by a small ulcer. At necropsy, the gastrotomy site was identifiable only by minor serosal adhesions. Histological study demonstrated full-thickness closure with minimal inflammation. CONCLUSIONS: The Queen's closure is a reliable and safe technique that provides full-thickness gastrotomy closure without any observed complications. The technique has proven to be transferable knowledge that holds promise for clinical implementation.

The Queen's closure: a novel technique for closure of endoscopic gastrotomy for natural-orifice transluminal endoscopic surgery.

BACKGROUND AND AIMS: Finding a reliable, safe, adaptable method of closing gastrotomies for natural-orifice transluminal endoscopic surgery (NOTES) procedures has been a major challenge facing this new clinical area. The Queen's NOTES Group has designed a novel endoscopic method of closing gastrotomies which involved using PolyLoop polyp ligature devices and endoscopic clips. The current study describes the technique and a pilot study of leak testing it versus hand-sewn suture closure. METHODS: Ten fresh pig stomachs were used, five for each technique. A 16-mm endoscopic gastrotomy was performed on the anterior wall of each. Five stomachs were then closed using the Queen's closure technique, and five with a hand-sewn double-layer suture technique. The stomachs were then connected to a water infusion device with sensitive pressure monitoring and were filled until leakage was detected at the closure site. RESULTS: The closures were all technically successful. The mean time for each gastrotomy and closure using the Queen's closure technique was 1.2 hours. The mean leak pressure for the Queen's closure was 51.8 mmHg and for the hand-sewn suture technique it was 80.8 mmHg ( P < 0.001). CONCLUSIONS: The Queen's closure technique holds promise as a reliable transferable technique for closing gastrotomies. Further study is necessary to evaluate its effects in live models.

Measuring colposcopy quality in Canada: development of population-based indicators.

Background: Colposcopy is a key part of cervical cancer control. As cervical cancer screening and prevention strategies evolve, monitoring colposcopy performance will become even more critical. In the present paper, we describe population-based colposcopy quality indicators that are recommended for ongoing measurement by cervical cancer screening programs in Canada. Methods: The Pan-Canadian Cervical Cancer Screening Network established a multidisciplinary expert working group to identify population-based colposcopy quality indicators. A systematic literature review was conducted to ascertain existing population and program-level colposcopy quality indicators. A systems-level cervical cancer screening pathway describing each step from an abnormal screening test, to colposcopy, and back to screening was developed. Indicators from the literature were assigned a place on the pathway to ensure that all steps were measured. A prioritization matrix scoring system was used to score each indicator based on predetermined criteria. Proposed colposcopy quality indicators were shared with provincial and territorial screening programs and subsequently revised. Results: The 10 population-based colposcopy quality indicators identified as priorities were colposcopy uptake, histologic investigation (biopsy) rate, colposcopy referral rate, failure to attend colposcopy, treatment frequency in women 18-24 years of age, re-treatment proportion, colposcopy exit-test proportion, histologic investigation (biopsy) frequency after low-grade Pap test results, length of colposcopy episode of care, and operating room treatment rate. Two descriptive indicators were also identified: colposcopist volume and number of colposcopists per capita. Summary: High-quality colposcopy services are an essential component of provincial cervical cancer screening programs. The proposed quality and descriptive indicators will permit colposcopy outcomes to be compared between provinces and across Canada so as to identify opportunities for improving colposcopy services.

Self-implanted artificial nodules: a computed tomography mimic of penile pathology.

Self-introduction of foreign bodies along the penile shaft has been reported in several ethnic and social groups, mainly in Asia, and recently has been described in Europe. We present the case of a 34-year-old homeless Russian immigrant who had an abdominal CT performed during an emergency department visit. On the CT scan, several hyperdense, well-demarcated subcutaneous nodules along the penile shaft were noted. Following a focused history and physical examination, the nodules were found to represent artificial foreign bodies made of glass, which were self-introduced by the patient in order to allegedly increase the pleasure of sexual partners. Penile nodules may be a manifestation of diverse pathological entities including infectious, inflammatory, and neoplastic processes. It is important for the radiologist to be familiar with this social phenomenon and its radiological appearance in order to avoid erroneous diagnosis.

The gut in systemic inflammatory response syndrome and sepsis. Enzyme systems fighting multiple organ failure.

The prognosis and care of critically ill ICU patients has improved over recent years, but the development of multiple organ failure (MOF) continues to cause significant morbidity and mortality. Shock, with resultant organ ischemia, appears to play a critical role in the development of MOF. It is our global hypothesis that MOF is a gut-derived phenomenon and that novel interventions can improve outcome in shock-induced gut inflammation and dysfunction in critically ill patients. We have found that the anesthetic agent ketamine has a profound impact on the response to endotoxic shock. This review summarizes our findings on the mechanisms of action by which ketamine is able to modulate the nitric oxide, cyclo-oxygenase and heme-oxygenase enzyme systems to attenuate endotoxin-induced organ dysfunction.

Protein digestion in human intestine as reflected in luminal, mucosal, and plasma amino acid concentrations after meals.

Normal human volunteers were intubated with either aspiration tubes or a biopsy capsule placed in the small intestine. The subjects were then fed a test meal containing 50 g of purified bovine serum albumin which served as the model dietary protein. Electrophoretic analysis of intestinal fluids showed that for at least 4 h the fed albumin was detectable in jejunal and ileal fluids. On separate occasions, subjects were fed the same meal without the protein. No protein was detected in intestinal fluids when the protein-free meal was fed. After the protein-rich meal, total concentrations of measured free and peptide amino acids rose from 3.21 to 29.29, and 15.94 to 117.97 mumol/ml, respectively, (P values < 0.02) in the jejunum. Similarly, total concentrations of measured free and peptide amino acids rose from 5.45 to 19.74, and 13.59 to 65.39, respectively, (P values < 0.05) in the ileum. In contrast, concentrations of free and peptide amino acids in intestinal fluids did not increase after the protein-free meal. While intracellular concentrations of amino acids in the jejunal mucosa did not show significant changes, plasma concentrations of each individual free amino acid were increased after the protein-rich meal and were either decreased or unaltered after the protein-free meal. The amino acid composition of the fed protein was reflected in the increases in intraluminal and plasma concentrations of individual amino acids after the protein-rich meal. It is concluded that after the ingestion of a test meal containing a substantial amount of protein which is within the usual range of dietary intake; (a) the exogenous protein is the principal source of the increased free and peptide amino acids in the intraluminal contents and in the plasma; (b) there are greater amounts of amino acids present as small peptides than in the free form in the gut lumen; (c) the ingested protein can be recovered as late as 4 h both in the jejunum and in the ileum.