Nosocomial infections within the first month of solid organ transplantation

Assessing the quality of antimicrobial prescribing in solid organ transplant recipients: a new frontier in antimicrobial stewardship

Background

Post-transplant infections remain a leading cause of morbidity and mortality in solid organ transplant recipients (SOTRs) and local standardized antimicrobial treatment guidelines may contribute to improved clinical outcomes. Our study assessed the rate of therapeutic compliance with local standard guidelines in the treatment of common infections in SOTR, and their associated outcomes.

Methods

Consecutive adult SOTRs admitted to the transplant floor from January-September 2020 and were treated for an infectious syndrome were followed until discharge or for 30 days following the date of diagnosis, whichever was shorter. Data was extracted from electronic medical records. Guideline compliance was characterized as either appropriate, effective but unnecessary, undertreatment, or inappropriate.

Results

Nine hundred and thirty-six SOTR were admitted to the transplant ward, of which 328 patients (35%) received treatment for infectious syndromes. Guidelines were applicable to 252 patients, constituting 275 syndromes: 86 pneumonias; 82 urinary tract infections; 40 intra-abdominal infections; 38 bloodstream infections; and 29 C. difficile infections. 200/246 (81%) of infectious syndromes received appropriate or effective but unnecessary empiric treatment. In addition, appropriate tailoring of antimicrobials resulted in a significant difference in 30-day all-cause mortality (adjusted OR of 0.07, 95% CI 0.01-0.38; P = .002). Lastly, we found that guideline-compliant empiric therapy was found to prevent the development of multi-drug resistance in a time-dependent analysis (adjusted HR of 0.21, 95% CI 0.08-0.52; P = .001).

Conclusion

Our data show that adherence to locally developed guidelines was associated with reduced mortality and resistant-organism development in our cohort of SOTR.

Substantial decline of organ preservation fluid contamination following adoption of ischemia-free liver transplantation: a post-hoc analysis

INTRODUCTION

Preservation fluid (PF) contaminations are common in conventional liver transplantation (CLT) and presumably originate from organ or PF exposures to the external environment in a non-strict sterile manner. Such exposures and PF contamination may be avoided in ischaemia-free liver transplantation (IFLT) because of the strict sterile surgical procedures. In this study, the authors evaluated the impact of IFLT on organ PF contamination.

METHODS

A post-hoc analysis using data from the first randomized controlled trial of IFLT was performed to compare the incidence, pathogenic spectrum of PF contamination, and incidence of early recipient infection between IFLT and CLT. Multivariable logistic regression was used to explore risk factors for PF contamination.

RESULTS

Of the 68 cases recruited in the trial, 64 were included in this post-hoc analysis. The incidence of culture-positive PF was 9.4% (3/32) in the IFLT group versus 78.1% (25/32) in the CLT group ( P <0.001). Three microorganisms were isolated from PF in the IFLT group, while 43 were isolated in the CLT group. The recipient infection rate within postoperative day 14 was 3.1% (1/32) in the IFLT group vs 15.6% (5/32) in the CLT group, although this difference did not reach statistical significance ( P =0.196). Multivariate analysis revealed that adopting IFLT is an independent protective factor for culture-positive PF.

CONCLUSION

PF contamination is substantially decreased in IFLT, and IFLT application is an independent protective factor for PF contamination. Using rigorous sterile measures and effective antibiotic therapy during IFLT may decrease PF contamination.

Development of a Risk Prediction Model for Infection After Kidney Transplantation Transmitted from Bacterial Contaminated Preservation Solution

Background

The risk of transplant recipient infection is unknown when the preservation solution culture is positive.

Methods

We developed a prediction model to evaluate the infection in kidney transplant recipients within microbial contaminated preservation solution. Univariate logistic regression was utilized to identify risk factors for infection. Both stepwise selection with Akaike information criterion (AIC) was used to identify variables for multivariate logistic regression. Selected variables were incorporated in the nomograms to predict the probability of infection for kidney transplant recipients with microbial contaminated preservation solution.

Results

Age, preoperative creatinine, ESKAPE, PCT, hemofiltration, and sirolimus had a strongest association with infection risk, and a nomogram was established with an AUC value of 0.72 (95% confidence interval, 0.64-0.80) and Brier index 0.20 (95% confidence interval, 0.18-0.23). Finally, we found that when the infection probability was between 20% and 80%, the model oriented antibiotic strategy should have higher net benefits than the default strategy using decision curve analysis.

Conclusion

Our study developed and validated a risk prediction model for evaluating the infection of microbial contaminated preservation solutions in kidney transplant recipients and demonstrated good net benefits when the total infection probability was between 20% and 80%.

Postoperative Bloodstream Infection Is Associated with Early Vascular Complications in Pediatric Liver Transplant Recipients with Biliary Atresia

Bloodstream infection (BSI) after pediatric liver transplantation (PLT) is a common and severe complication that affects patient survival. Children with biliary atresia (BA) are at an increased risk for clinically significant infections. This study evaluated the impact of post-PLT BSI on clinical outcomes in children with BA. A total of 67 patients with BA aged <18 years who underwent PLT between April 2006 and September 2020 were analyzed and divided into two groups according to the occurrence of post-PLT BSI within 1 month (BSI vs. no BSI = 13 [19.4%] vs. 54 [80.6%]). The BSI group was significantly younger at the time of PLT and had a higher frequency of BSI at the time of PLT than the no BSI group. Early vascular complications within 3 months and reoperations were significantly more frequent in the BSI group. Univariate and multivariate analyses revealed that bacteremia within 1 month of PLT and graft-to-recipient weight ratio >4% were significantly associated with vascular complications. In conclusion, BSI after PLT is associated with increased vascular complications and reoperations. Proper control of bacterial infections and early liver transplantation before uncontrolled BSI may reduce vascular complications and unexpected reoperations in children with BA.

Pediatric Lung Transplant Outcomes Based on Immunosuppressive Regimen at Discharge: Retrospective Cohort Study Using Real-World Evidence From the US Scientific Registry of Transplant Recipients

BACKGROUND

This retrospective analysis of the US Scientific Registry of Transplant Recipients was undertaken to obtain real-world evidence concerning the efficacy and safety of tacrolimus-based immunosuppression in pediatric lung transplant recipients to support a supplemental New Drug Application.

METHODS

Overall, 725 pediatric recipients of a primary deceased-donor lung transplant between January 1, 1999, and December 31, 2017, were followed for up to 3 years post-transplant based on an immunosuppressive regimen at hospital discharge: immediate-release tacrolimus (TAC)+mycophenolate mofetil (MMF), TAC+azathioprine (AZA), cyclosporine (CsA)+MMF, or CsA+AZA. The primary outcome was the composite endpoint of graft failure or death (all-cause) at 1 year post-transplant, calculated by Kaplan-Meier analysis.

RESULTS

The use of TAC+MMF increased over time. During 2010 to 2017, 91.7% of pediatric lung transplant recipients were receiving TAC+MMF at the time of discharge. The proportion of recipients continuing their discharge regimen at 1 year post-transplant was 83.7% with TAC+MMF and 40.4% to 59.7% with the other regimens. Cumulative incidence of the composite endpoint of graft failure or death at 1 year post-transplant was 7.7% with TAC+MMF, 13.9% with TAC+AZA, 8.9% with CsA+MMF, and 9.1% with CsA+AZA. There was no significant difference in the risk of graft failure or death at 1 year post-transplant between groups from 1999 to 2005 (the only era when adequate numbers on each regimen allowed statistical comparison). No increase in hospitalization for infection or malignancy was seen with TAC+MMF.

CONCLUSION

The real-world evidence from the US database of transplant recipients supported the Food and Drug Administration's approval of tacrolimus-based maintenance immunosuppression in pediatric lung transplant recipients.

A randomized-controlled trial of ischemia-free liver transplantation for end-stage liver disease

BACKGROUND & AIMS

Ischemia-reperfusion injury (IRI) has thus far been considered as an inevitable component of organ transplantation, compromising outcomes, and limiting organ availability. Ischemia-free organ transplantation is a novel approach designed to avoid IRI, with the potential to improve outcomes.

METHODS

In this randomized, controlled clinical trial, recipients of livers from donors after brain death were randomly assigned to receive either an ischemia-free or a 'conventional' transplant. Primary end point was the incidence of early allograft dysfunction. Secondary end points included complications related to graft IRI.

RESULTS

65 out of 68 randomized patients underwent transplants and were included in the analysis. 32 patients received ischemia-free liver transplantation (IFLT), and 33 received conventional liver transplantation (CLT). Early allograft dysfunction occurred in 2 (6%) randomized to IFLT and in 8 (24%) randomized to CLT (difference, -18%; 95% CI, -35% to -1%; P=.044). Post-reperfusion syndrome occurred in 3 (9%) randomized to IFLT and in 21 (64%) randomized to CLT (difference, -54%; 95% CI, -74% to -35%; P < .001). Non-anastomotic biliary strictures diagnosed with protocol magnetic resonance cholangiopancreatography at 12 months were observed in 2 recipients (8%) randomized to IFLT and in 9 recipients (36%) randomized to CLT (difference, -28%; 95% CI, -50% to -7%; P = .014). The comprehensive complication index at one year after transplantation was 30.48 (95% CI, 23.25-37.71) in the IFLT group vs 42.14 (95% CI, 35.01-49.26) in the CLT group (difference, -11.66; 95% CI, -21.81 to -1.51; P = .025).

CONCLUSIONS

Among patients with end-stage liver disease, IFLT, compared with conventional approach, significantly reduced complications related to ischemia reperfusion injury.

CLINICAL TRIAL REGISTRATION

Chictr.org. ChiCTR1900021158 IMPACT AND IMPLICATIONS: Ischemia reperfusion injury has thus far been considered as an inevitable event in organ transplantation, compromising outcomes and limiting organ availability. Ischemia-free liver transplantation is a novel approach of transplanting donor livers without interruption of blood supply. We showed that in patients with end-stage liver disease, ischemia-free liver transplantation, compared with conventional approach led to reduced complications related to ischemia reperfusion injury in this randomized trial. This new approach is expected to change the current practice in organ transplantation improving transplant outcomes, increasing organ utilization, while providing a clinical model to delineate the impact of organ injury on alloimmunity.

Infections after organ transplantation and immune response

Organ transplantation has provided another chance of survival for end-stage organ failure patients. Yet, transplant rejection is still a main challenging factor. Immunosuppressive drugs have been used to avoid rejection and suppress the immune response against allografts. Thus, immunosuppressants increase the risk of infection in immunocompromised organ transplant recipients. The infection risk reflects the relationship between the nature and severity of immunosuppression and infectious diseases. Furthermore, immunosuppressants show an immunological impact on the genetics of innate and adaptive immune responses. This effect usually reactivates the post-transplant infection in the donor and recipient tissues since T-cell activation has a substantial role in allograft rejection. Meanwhile, different infections have been found to activate the T-cells into CD₄⁺ helper T-cell subset and CD₈⁺ cytotoxic T-lymphocyte that affect the infection and the allograft. Therefore, the best management and preventive strategies of immunosuppression, antimicrobial prophylaxis, and intensive medical care are required for successful organ transplantation. This review addresses the activation of immune responses against different infections in immunocompromised individuals after organ transplantation.

Risk of Pneumocystis jirovecii Pneumonia among Solid Organ Transplant Recipients: A Population-Based Study

Few studies have comprehensively investigated the occurrence of Pneumocystis jirovecii pneumonia (PJP) among solid organ transplant (SOT) recipients. This study investigated the risk of PJP after organ transplantation. Each patient who underwent SOT was propensity-score-matched with four non-SOT individuals in terms of sex, age, insured salary, urbanization of residence, comorbidities, and year of enrollment. When considering the 3-year follow-up, the patients who had undergone SOT were at higher risk of PJP, with the adjusted odds ratio (aOR) being 17.18 (95% confidence interval (CI): 8.80-33.53). Furthermore, SOT recipients were also at higher PJP risk than the patients without SOT at 6 months, 1 year, and 2 years, with the aOR being 22.64 (95% CI: 7.53-68.11), 26.19 (95% CI: 9.89-69.37), and 23.06 (95% CI: 10.23-51.97), respectively. Patients comorbid with HIV infection, hematological malignancies, or vasculitis were at higher risk (aOR = 59.08, 95% CI = 20.30-171.92), (aOR = 11.94, 95% CI = 5.36-26.61), and (aOR = 21.72, 95% CI = 2.41-195.81), respectively. The recipients of SOT were at higher risk of PJP, and PJP can develop at any stage after transplantation. SOT recipients comorbid with HIV, hematologic malignancies, or vasculitis were at higher PJP risk.

Lung Transplant Outcomes in Adults in the United States: Retrospective Cohort Study Using Real-world Evidence from the SRTR

BACKGROUND

The Scientific Registry of Transplant Recipients was retrospectively analyzed to provide real-world evidence of the efficacy and safety of tacrolimus-based immunosuppressive regimens in adult lung transplant recipients in the United States.

METHODS

Adult recipients (N = 25 355; ≥18 y) of a primary deceased-donor lung transplant between January 1, 1999, and December 31, 2017, were followed for 3 y posttransplant based on immunosuppressive regimen at discharge: immediate-release tacrolimus (TAC) + mycophenolate mofetil (MMF), TAC + azathioprine (AZA), cyclosporine (CsA) + MMF, or CsA + AZA. The primary outcome was the composite endpoint of graft failure or death (all-cause) at 1 y posttransplant (calculated via a modified Kaplan-Meier method).

RESULTS

Discharge immunosuppressive regimens in lung transplant recipients changed over time, with a substantial increase in the use of TAC + MMF. TAC + MMF was the most common immunosuppressive regimen (received by 61.0% of individuals at discharge). The cumulative incidence of graft failure or death at 1 y posttransplant in adult lung transplant patients receiving TAC + MMF was 8.6% (95% confidence interval 8.1-9.1). Risk of graft failure or death was significantly higher in adults receiving CsA + MMF or CsA + AZA compared with TAC + MMF, with no significant difference seen between TAC + MMF and TAC + AZA. TAC + MMF had the highest continued use at 1 y posttransplant (72.0% versus 35.4%-51.5% for the other regimens). There was no increase in the rate of infection or malignancy in the TAC + MMF group.

CONCLUSIONS

Real-world evidence from the most comprehensive database of transplant recipients in the United States supports the use of TAC in combination with MMF or AZA as maintenance immunosuppression in adult lung transplant recipients.

Surgical Antimicrobial Prophylaxis in Abdominal Surgery for Neonates and Paediatrics: A RAND/UCLA Appropriateness Method Consensus Study

Surgical site infections (SSIs), i.e., surgery-related infections that occur within 30 days after surgery without an implant and within one year if an implant is placed, complicate surgical procedures in up to 10% of cases, but an underestimation of the data is possible since about 50% of SSIs occur after the hospital discharge. Gastrointestinal surgical procedures are among the surgical procedures with the highest risk of SSIs, especially when colon surgery is considered. Data that were collected from children seem to indicate that the risk of SSIs can be higher than in adults. This consensus document describes the use of preoperative antibiotic prophylaxis in neonates and children that are undergoing abdominal surgery and has the purpose of providing guidance to healthcare professionals who take care of children to avoid unnecessary and dangerous use of antibiotics in these patients. The following surgical procedures were analyzed: (1) gastrointestinal endoscopy; (2) abdominal surgery with a laparoscopic or laparotomy approach; (3) small bowel surgery; (4) appendectomy; (5) abdominal wall defect correction interventions; (6) ileo-colic perforation; (7) colorectal procedures; (8) biliary tract procedures; and (9) surgery on the liver or pancreas. Thanks to the multidisciplinary contribution of experts belonging to the most important Italian scientific societies that take care of neonates and children, this document presents an invaluable reference tool for perioperative antibiotic prophylaxis in the paediatric and neonatal populations.

Emergency Department Management of Pediatric Heart Transplant Recipients: Unique Immunologic and Hemodynamic Challenges

BACKGROUND

Since the first heart transplant in 1967, there has been significant progress in this field of cardiac transplantation. Approximately 600 pediatric heart transplants are performed every year worldwide. With the increasing number of pediatric heart transplant patients, and given the few tertiary care pediatric transplant centers, adult and pediatric emergency department (ED) providers are increasingly engaged in the care of pediatric heart transplant recipients in the ED.

OBJECTIVE

The aim of this article is to review common ED scenarios pertinent to the pediatric heart transplant patients.

DISCUSSION

There are complications unique to this population, such as rejection, opportunistic infections, and medication side effects, that require special considerations, and it is helpful for the emergency medicine (EM) provider to have knowledge about them.

CONCLUSIONS

The unique immunological challenges in these patients, including rejection and medication side effects and opportunistic infections, make this population fragile, and the knowledge of these challenges is helpful for EM providers.

Long-Term Infectious Complications of Kidney Transplantation

Infections remain a common complication of solid-organ transplantation. Most infections in the first month after transplant are typically health care-associated infections, whereas late infections, beyond 6-12 months, are community-acquired infections. Opportunistic infections most frequently present in the first 12 months post-transplant and can be modulated on prior exposures and use of prophylaxis. In this review, we summarize the current epidemiology of postkidney transplant infections with a focus on key viral (BK polyomavirus, cytomegalovirus, Epstein-Barr virus, and norovirus), bacterial (urinary tract infections and Clostridioides difficile colitis), and fungal infections. Current guidelines for safe living post-transplant are also summarized. Literature supporting prophylaxis and vaccination is also provided.

Bacterial infections in lung transplantation

Lung transplantation has lower survival rates compared to other than other solid organ transplants (SOT) due to higher rates of infection and rejection-related complications, and bacterial infections (BI) are the most frequent infectious complications. Excess morbidity and mortality are not only a direct consequence of these BI, but so are subsequent loss of allograft tolerance, rejection, and chronic lung allograft dysfunction due to bronchiolitis obliterans syndrome (BOS). A wide variety of pathogens can cause infections in lung transplant recipients (LTRs), including a number of nosocomial pathogens and other multidrug-resistant (MDR) pathogens. Although pneumonia and intrathoracic infections predominate, LTRs are at risk of a number of types of infections. Risk factors include altered anatomy and function of airways, impaired immunity, the microbial flora of the donor and recipient, underlying medical conditions, and genetic factors. Further work on immune monitoring has the potential to improve outcomes. The infecting agents can be derived from the donor lung, pre-existing recipient flora, or acquired from the environment over time. Certain infections may preclude lung transplantation, but this varies from center to center, and more recent studies suggest fewer patients should be disqualified. New molecular methods allow microbiome studies of the lung, gut, and other sites that may further our knowledge of how airway colonization can result in infection and allograft loss. Surveillance, early diagnosis, and aggressive antimicrobial therapy of BI is critical in LTRs. Antibiotic resistance is a major barrier to successful management of these infections. The availability of new agents for MDR Gram-negatives may improve outcomes. Other new therapies, such as bacteriophage therapy, show promise for the future. Finally, it is important to prevent infections through peri-transplant prophylaxis, vaccination, and infection control measures.

Posttransplant Pneumonia Among Solid Organ Transplant Recipients Followed in Intensive Care Unit

OBJECTIVES

Pneumonia is a significant cause of morbidity and mortality in solid-organ transplant recipients. We studied the demographic characteristics, respiratory management, and outcomes of solid-organ transplant recipients with pneumonia in an intensive care unit.

MATERIALS AND METHODS

There have been 2857 kidney, 687 liver, and 142 heart transplants performed between October 16, 1985, and February 28, 2021, at our center. We retrospectively analyzed records for 51 of 193 recipients with pneumonia during the posttransplant period between January 1, 2016, and December 31, 2018.

RESULTS

Fifty-one of 193 recipients were followed in the intensive care unit. Mean age was 45.4 ± 16.6 years among 42 male (82.4%) and 9 female (17.6%) recipients. Twenty-six patients (51%) underwent kidney transplant, 14 (27.5%) liver transplant, 7 (13.7%) heart transplant, and 4 (7.8%) combined kidney and liver transplant. Most pneumonia episodes occurred 6 months after transplant (70.6%) with acute hypoxemic respiratory failure. Mean Acute Physiology and Chronic Health Evaluation System II score was 18.9 ± 7.7, and the Sequential Organ Failure Assessment score was 8.5 ± 3.9 at intensive care unit admission. Whereas 66.7% of pneumonia cases were nosocomial acquired, 33.3% were community acquired. The intensive care unit and 28-day mortality rates were 39.2% and 64.7%, respectively.

CONCLUSIONS

Solid-organ transplant recipients with pneumonia have been associated with poor prognosis. Our cohort followed in the intensive care unit comprised mostly patients with nosocomial pneumonia with acute hypoxemic respiratory failure, hospitalized 6 months after transplant with high Acute Physiology and Chronic Health Evaluation System II scores predictive of mortality. In this high-risk patient group, careful follow-up, early discovery of warning signs, and rapid treatment initiation could improve the outcomes in the intensive care unit.

Oral nutritional supplements for preventing surgical site infections: protocol for a systematic review and meta-analysis

BACKGROUND

Surgical site infections (SSIs) are among the most common healthcare-associated infections. Under-nutrition is an important risk factor for SSIs and can lead to delayed wound healing and longer hospital stays. Oral nutritional supplements are prescribed to reduce the risk of infection and improve health status, but data from randomised controlled trials (RCTs) have shown mixed results. Thus, the objective of our planned systematic review is to evaluate oral nutritional supplements on preventing SSIs in adult surgical patients METHODS: RCTs conducted in adult surgical patients who receive oral nutritional support will be included. The primary outcome will be the incidence of SSIs (within 30 days of surgery or within 90 days for joint replacement surgery). Secondary outcomes will be changes in nutritional status, mortality, health-related quality of life and costs. Literature searches will be conducted in several electronic databases (from inception onwards): MEDLINE, Embase, CINAHL and The Cochrane Central Register of Controlled Trials (CENTRAL). Grey literature will be identified through searching clinical trial registers and dissertation databases. Two reviewers will independently screen all citations, full-text articles and abstract data. The study methodological quality (or bias) will be appraised using the Cochrane risk of bias tool. If feasible, we will conduct random effects meta-analysis where appropriate.

DISCUSSION

This systematic review will evaluate the evidence for pre- and post-surgical intervention with oral nutritional supplements in adults. Findings from this planned review may inform subsequent nutritional interventions for hospitalised patients who undergo surgery.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020140954.

Pre- and post-transplant bacterial infections in liver transplant recipients

BACKGROUND

Early (<1 month) bacterial infection after liver transplant is a major cause of morbidity and mortality among liver transplant recipients. We investigated the impact of pre-transplant bacterial infection on early post-transplant bacterial infection incidence and outcomes.

METHODS

A retrospective cohort study identified all patients who underwent liver transplantation between January 1, 2011, and December 31, 2012, at a single tertiary center in the United States. Infections occurring within the 30 days prior to transplant and within the 30 following transplant were identified. Information regarding pre-transplant morbidity and post-transplant outcomes was collected.

RESULTS

One-hundred seventy-four patients were included in the study. Forty patients (23%) experienced a total of 50 pre-transplant infections. Fifty-two (30%) developed a total of 62 post-transplant infections. Patients with a pre-transplant infection were more likely to develop a post-transplant infection compared to patients without a pre-transplant infection (48% [19 of 40] vs. 25% [33 of 134], respectively, P = .006). Patients with a pre-transplant infection had a longer mean post-transplant length of stay compared to those without a pre-transplant infection (16.3 days vs. 10.4 days, respectively, P < .001), but survival at 30 days was similar in both groups (95% [38 of 40] vs. 97% [130 of 134, respectively, P = .56).

CONCLUSIONS

Among liver transplant recipients, pre-transplant infection is an important risk factor for early post-transplant bacterial infections. Pre-transplant infection is associated with increased early morbidity but not mortality after transplant.

Perioperative prophylaxis with ertapenem reduced infections caused by extended-spectrum betalactamase-producting Enterobacteriaceae after kidney transplantation

Backgound

In recent years we have witnessed an increase in infections due to multidrug-resistant organisms in kidney transplant recipients (KTR). In our setting, we have observed a dramatic increase in infections caused by extended-spectrum betalactamase-producing (ESBL) Enterobacteriaceae in KTR. In 2014 we changed surgical prophylaxis from Cefazolin 2 g to Ertapenem 1 g.

Methods

We compared bacterial infections and their resistance phenotype during the first post-transplant month with an historical cohort collected during 2013 that had received Cefazolin.

Results

During the study period 110 patients received prophylaxis with Cefazolin and 113 with Ertapenem. In the Ertapenem cohort we observed a non-statistically significant decrease in the percentage of early bacterial infection from 57 to 47%, with urine being the most frequent source in both. The frequency of infections caused by Enterobacteriaceae spp. decreased from 64% in the Cefazolin cohort to 36% in the Ertapenem cohort (p = 0.005). In addition, percentage of ESBL-producing strains decreased from 21 to 8% of all Enterobacteriaceae isolated (p = 0.015). After adjusted in multivariate Cox regression analysis, male sex (HR 0.16, 95%CI: 0.03–0.75), cefazolin prophylaxis (HR 4.7, 95% CI: 1.1–22.6) and acute rejection (HR 14.5, 95% CI: 1.3–162) were associated to ESBL- producing Enterobacteriaceae infection.

Conclusions

Perioperative antimicrobial prophylaxis with a single dose of Ertapenem in kidney transplant recipients reduced the incidence of early infections due to ESBL-producing Enterobacteriaceae without increasing the incidence of other multidrug-resistant microorganisms or C. difficile.

The Impact of Culturing the Organ Preservation Fluid on Solid Organ Transplantation: A Prospective Multicenter Cohort Study

Background

We analyzed the prevalence, etiology, and risk factors of culture-positive preservation fluid and their impact on the management of solid organ transplant recipients.

Methods

From July 2015 to March 2017, 622 episodes of adult solid organ transplants at 7 university hospitals in Spain were prospectively included in the study.

Results

The prevalence of culture-positive preservation fluid was 62.5% (389/622). Nevertheless, in only 25.2% (98/389) of the cases were the isolates considered "high risk" for pathogenicity. After applying a multivariate regression analysis, advanced donor age was the main associated factor for having culture-positive preservation fluid for high-risk microorganisms. Preemptive antibiotic therapy was given to 19.8% (77/389) of the cases. The incidence rate of preservation fluid-related infection was 1.3% (5 recipients); none of these patients had received preemptive therapy. Solid organ transplant (SOT) recipients with high-risk culture-positive preservation fluid receiving preemptive antibiotic therapy presented both a lower cumulative incidence of infection and a lower rate of acute rejection and graft loss compared with those who did not have high-risk culture-positive preservation fluid. After adjusting for age, sex, type of transplant, and prior graft rejection, preemptive antibiotic therapy remained a significant protective factor for 90-day infection.

Conclusions

The routine culture of preservation fluid may be considered a tool that provides information about the contamination of the transplanted organ. Preemptive therapy for SOT recipients with high-risk culture-positive preservation fluid may be useful to avoid preservation fluid-related infections and improve the outcomes of infection, graft loss, and graft rejection in transplant patients.

Pneumonia in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These guidelines from the AST Infectious Diseases Community of Practice review the diagnosis and management of pneumonia in the post-transplant period. Clinical presentations and differential diagnosis for pneumonia in the solid organ transplant recipient are reviewed. A two-tier approach is proposed based on the net state of immunosuppression and the severity of presentation. With a lower risk of opportunistic, hospital-acquired, or exposure-specific pathogens and a non-severe presentation, empirical therapy may be initiated under close clinical observation. In all other patients, or those not responding to the initial therapy, a more aggressive diagnostic approach including sampling of tissue for microbiological and pathological testing is warranted. Given the broad range of potential pathogens, a microbiological diagnosis is often key for optimal care. Given the limited literature comparatively evaluating diagnostic approaches to pneumonia in the solid organ transplant recipient, much of the proposed diagnostic algorithm reflects clinical experience rather than evidence-based data. It should serve as a template which may be modified according to local needs. The same holds true for the suggested empiric therapies, which need to be adapted to the local resistance patterns. Further study is needed to comparatively evaluate diagnostic and empiric treatment strategies in SOT recipients.

A simple score can identify kidney transplant recipients at high risk of severe infection over the following 2 years

BACKGROUND

The aim of this study was to determine whether a composite score of simple immune biomarkers and clinical characteristics could predict severe infections in kidney transplant recipients.

METHODS

We conducted a prospective study of 168 stable kidney transplant recipients who underwent measurement of lymphocyte subsets, immunoglobulins, and renal function at baseline and were followed up for 2 years for the development of any severe infections, defined as infection requiring hospitalization. A point score was developed to predict severe infection based on logistic regression analysis of factors in baseline testing.

RESULTS

Fifty-nine (35%) patients developed severe infection, 36 (21%) had two or more severe infections, and 3 (2%) died of infection. A group of 19 (11%) patients had the highest predicted infectious risk (>60%), as predicted by the score. Predictive variables were mycophenolate use, graft function, CD4+, and natural killer cell number. The level of immunosuppression score had an area under the receiver operating curve of 0.75 (95% CI: 0.67-0.83).

CONCLUSION

Our level of immunosuppression score for predicting the development of severe infection over 2 years has sufficient prognostic accuracy for identification of high-risk patients. This data can inform research that examines strategies to reduce the risks of infection.

Is hospital-acquired pneumonia different in transplant recipients?

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are serious complications in transplant patients. The aim of this review is to summarize the evidence regarding nosocomial pneumonia in transplant recipients, including HAP in non-ventilated patients and VAP, and to identify future directions for improvement.A comprehensive literature search in the PubMed/MEDLINE database was performed. Articles written in English and published between 1990 and November 2018 were included. HAP/VAP in transplant patients usually occurs early post-transplant, particularly during neutropenia in haematopoietic stem cell transplant recipients. Bacteria are the leading cause of nosocomial pneumonia for both immunocompetent and transplant recipients, being Gram negative organisms, and especially Pseudomonas aeruginosa, highly prevalent. Multidrug-resistant bacteria are of special concern. Pneumonia in the transplant setting may be caused by opportunistic pathogens, and the differential diagnosis needs to be extended to other non-infectious complications. The most relevant opportunistic pathogens are Aspergillus fumigatus, Pneumocystis jirovecii and cytomegalovirus. Nevertheless, they are an exceptional cause of nosocomial pneumonia, and usually occur in severely immunosuppressed patients not receiving antimicrobial prophylaxis. Performing bronchoalveolar lavage may improve the rate of aetiological diagnosis, leading to a change in therapeutic management and improved outcomes. The optimal length of antibiotic therapy for bacterial HAP/VAP has not been well defined, but it should perhaps be longer than in the general population. Mortality associated with HAP/VAP is high. HAP/VAP in transplant patients is frequent and is associated with increased mortality. There is room for improvement in gaining knowledge about the management of HAP/VAP in this population.

Is It Safe to Remove Teeth in Liver Transplant Patients Without Antibiotics? A Retrospective Study of 346 Patients

PURPOSE

Eradication of oral infectious foci is essential for liver transplant candidates. The main issue is whether antibiotic prophylaxis is necessary for all dental extractions despite the possible fostering of resistant bacteria. To overcome the scarcity of evidence-based data, our study analyzed the background and outcomes of a large number of routine extractions performed in our institution without antibiotic prophylaxis in patients with different liver pathologies.

MATERIALS AND METHODS

In this retrospective cohort study, the outcome of interest was the occurrence of local infections and minor complications during the 7-day follow-up period after extraction; the predictors were the demographic and clinical variables of the patients (age, gender, liver pathology, Model for End-Stage Liver Disease score, international normalized ratio) and the extraction variables (single vs multiple extractions, isolated vs contiguous teeth, single-rooted vs multirooted teeth). The statistical analysis used univariate nonparametric tests and binary multivariate logistic regressions.

RESULTS

The 346 liver transplant candidates (mean age, 53 ± 8 years; 24% women) underwent 662 routine extraction sessions involving 1,329 teeth. The 7-day dental follow-up detected no signs of postoperative wound infection (rate = 0% [95% confidence interval (CI), 0 to 0.9%]). Accordingly, the 2-week post-extraction clinical monitoring excluded symptoms of systemic infection attributable to the dental procedure. Minor complications (mild bleeding, slow healing, inflamed socket) occurred in 50 patients (rate = 14% [95% CI, 11 to 18%]) in the 3 days after extraction. Significant risk factors for minor complications were refractory ascites (P < .0001; OR = 8 [95% CI, 3 to 20]), extraction of multirooted contiguous teeth (P < 0.0001; OR = 5 [95% CI, 2.5 to 9]), and a Model for End-Stage Liver Disease score greater than 18 (P = 0.01; OR = 2.4 [95% CI, 1.2 to 5]).

CONCLUSIONS

Our study showed that routine extractions without antibiotic prophylaxis can be performed safely in liver transplant candidates, even in the presence of 1 or more non-controllable risk factors. Using atraumatic techniques, we achieved satisfactory healing of the gingiva and socket in all patients in a week, without any signs of local infection. The few minor complications were readily managed and resolved within 3 days after extraction.

Diagnostic and therapeutic approach to infectious diseases in solid organ transplant recipients

Purpose

Prognosis of solid organ transplant (SOT) recipients has improved, mainly because of better prevention of rejection by immunosuppressive therapies. However, SOT recipients are highly susceptible to conventional and opportunistic infections, which represent a major cause of morbidity, graft dysfunction and mortality.

Methods

Narrative review.

Results

We cover the current epidemiology and main aspects of infections in SOT recipients including risk factors such as postoperative risks and specific risks for different transplant recipients, key points on anti-infective prophylaxis as well as diagnostic and therapeutic approaches. We provide an up-to-date guide for management of the main syndromes that can be encountered in SOT recipients including acute respiratory failure, sepsis or septic shock, and central nervous system infections as well as bacterial infections with multidrug-resistant strains, invasive fungal diseases, viral infections and less common pathogens that may impact this patient population.

Conclusion

We provide state-of the art review of available knowledge of critically ill SOT patients with infections.

Incidence of Hospitalization for Vaccine-Preventable Infections in Children Following Solid Organ Transplant and Associated Morbidity, Mortality, and Costs

IMPORTANCE

Pediatric transplant recipients are at risk for vaccine-preventable infections owing to immunosuppression, suboptimal response to vaccines before and after transplant, and potential underimmunization if transplant occurred early in life. However, the incidence and burden of illness from vaccine-preventable infections in this population is unknown.

OBJECTIVES

To evaluate in pediatric solid organ transplant recipients the number of hospitalizations for vaccine-preventable infections in the first 5 years after transplant and to determine the associated morbidity, mortality, and costs.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study from January 1, 2004, to December 31, 2011, with 5 years of follow-up per participant (unless they died during the study period). The participants of this multicenter study through the Pediatric Health Information System were solid organ transplant recipients who were younger than 18 years at the time of transplant. Analysis began in July 2017.

EXPOSURES

Transplant.

MAIN OUTCOMES AND MEASURES

Hospitalizations for a vaccine-preventable infection during the first 5 years after transplant were ascertained using International Classification of Diseases, Ninth Revision, and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, clinical modification diagnosis codes. Data were collected on clinical care, outcomes, and costs during these hospitalizations.

RESULTS

Of 6980 transplant recipients identified, there were 3819 boys (54.7%), and the mean (SD) age at transplant was 8 (6.2) years. Overall, 1092 patients (15.6%) had a total of 1471 cases of vaccine-preventable infections. There were 187 of 1471 cases (12.7%) that occurred during transplant hospitalization. The case fatality rate was 1.7% for all infections. Excluding infections that occurred during transplant hospitalization (when all patients go to the intensive care unit), 213 of 1257 patients (17.0%) were hospitalized with a vaccine-preventable infection requiring intensive care. In multivariable analysis, age younger than 2 years at time of transplant and receipt of a lung, heart, intestine, or multivisceral organ were positively associated with increased risk of a hospitalization from a vaccine-preventable infection.Transplant hospitalizations complicated by vaccine-preventable infections were $120 498 more expensive (median cost) than transplant hospitalizations not complicated by vaccine-preventable infections.

CONCLUSIONS AND RELEVANCE

Hospitalization for vaccine-preventable infections occurred in more than 15% of solid organ transplant recipients in the first 5 years after transplant at a rate of up to 87 times higher than in the general population. There was significant morbidity, mortality, and costs from these infections, demonstrating the importance of immunizing all transplant candidates and recipients. Further research on improving immunization delivery, preventing nosocomial infections, and monitoring response to vaccines in the transplant population is needed.

Can immune biomarkers predict infections in solid organ transplant recipients? A review of current evidence

Despite improvements in graft survival, solid organ transplantation is still associated with considerable infection induced morbidity and mortality. If we were able to show that serious infection risk was associated with excessive suppression of immune capacity, we would be justified in "personalizing" the extent of immunosuppression by carefully monitored reduction to see if we can improve immune compromize without increasing the risk of rejection. Reliable biomarkers are needed to identify this patients at an increased risk of infection. This review focuses on the currently available evidence in solid organ transplant recipients for immune non-pathogen specific biomarkers to predict severe infections with the susceptibility to particular pathogens according to the component of the immune system that is suppressed. This review is categorized into immune biomarkers representative of the humoral, cellular, phagocytic, natural killer cell and complement system. Biomarkers humoral and cellular systems of the that have demonstrated an association with infections include immunoglobulins, lymphocyte number, lymphocyte subsets, intracellular concentrations of adenosine triphosphate in stimulated CD4⁺ cells and soluble CD30. Biomarkers of the innate immune system that have demonstrated an association with infections include natural killer cell numbers, complement and mannose binding lectin. Emerging evidence shows that quantification of viral nucleic acid (such as Epstein Barr Virus) can act as a biomarker to predict all-cause infections. Studies that show the most promise are those in which several immune biomarkers are assessed in combination. Ongoing research is required to validate non-pathogen specific immune biomarkers in multi-centre studies using standardized study designs.

Regulated Cell Death as a Therapeutic Target for Novel Antifungal Peptides and Biologics

The rise of microbial pathogens refractory to conventional antibiotics represents one of the most urgent and global public health concerns for the 21st century. Emergence of Candida auris isolates and the persistence of invasive mold infections that resist existing treatment and cause severe illness has underscored the threat of drug-resistant fungal infections. To meet these growing challenges, mechanistically novel agents and strategies are needed that surpass the conventional fungistatic or fungicidal drug actions. Host defense peptides have long been misunderstood as indiscriminant membrane detergents. However, evidence gathered over the past decade clearly points to their sophisticated and selective mechanisms of action, including exploiting regulated cell death pathways of their target pathogens. Such peptides perturb transmembrane potential and mitochondrial energetics, inducing phosphatidylserine accessibility and metacaspase activation in fungi. These mechanisms are often multimodal, affording target pathogens fewer resistance options as compared to traditional small molecule drugs. Here, recent advances in the field are examined regarding regulated cell death subroutines as potential therapeutic targets for innovative anti-infective peptides against pathogenic fungi. Furthering knowledge of protective host defense peptide interactions with target pathogens is key to advancing and applying novel prophylactic and therapeutic countermeasures to fungal resistance and pathogenesis.

The challenge of urinary tract infections in renal transplant recipients

Urinary tract infections (UTI) are an important cause of morbidity and mortality in renal transplant patients. These infections are quite common, and the goal of care is to identify and reduce risk factors while providing effective prophylaxis and treatment. Better understanding of long-term outcomes from these infections has led to the distinctions among UTI, recurrent UTI, and asymptomatic bacteriuria (ASB), and that each requires a different therapeutic approach. Specifically, new research has supported the perspective that asymptomatic bacteriuria should not be treated. Symptomatic UTI, on the other hand, requires intervention and remains an ongoing challenge for infectious disease clinicians. Many bacteria species are responsible for UTI in renal transplant patients, and in recent years there has been a global rise in infection caused by bacteria with newly acquired antibacterial resistance genes. Many renal transplant patients who experience UTI will also have multiple recurring episodes, which likely has a distinct pathophysiological mechanism leading to chronic colonization of the urinary tract. In these cases, long-term management includes bacterial suppression, which aims to reduce rather than eliminate bacteria to levels below the threshold for symptomatic infection. This review will address the current understanding of UTI epidemiology, pathogenesis, and risk factors in the renal transplant community, and also focus on current prevention and treatment strategies for patients who face an environment of increasingly antibiotic-resistant bacteria.

Clinical impact of culture-positive preservation fluid on solid organ transplantation: A systematic review and meta-analysis

Contamination of the preservation fluid (PF) used for donated organs is a potential source of post-transplant infection. However, the information on this issue is scarce. We therefore conducted a systematic review and meta-analysis to assess the incidence of culture-positive PF and its impact on solid organ transplant (SOT) recipients. Seventeen studies were identified and included. The overall incidence of culture-positive PF was 37% (95% CI: 27% to 49%), and the incidence of PF-related infections among SOT recipients with PF cultures that grew pathogenic microorganisms was 10% (95% CI: 7% to 15%). There were differences in the rates of infections due to pathogenic microorganisms between SOT recipients who received pre-emptive treatment and those who did not, but without statistical significance. The mortality rate among SOT recipients with PF-related infection was 35% (95% CI: 21% to 53%). In conclusion, although contamination of the PF of donated organs is frequent, the incidence of PF-related infection is relatively low. A closely clinical and microbiologic monitoring of the SOT recipient in case of culture-positive PF, regardless of the type of microorganism isolated might be do in order to establish a prompt diagnosis of PF-related infection.

Innovative Approaches to Improve Anti-Infective Vaccine Efficacy

Safe and efficacious vaccines are arguably the most successful medical interventions of all time. Yet the ongoing discovery of new pathogens, along with emergence of antibiotic-resistant pathogens and a burgeoning population at risk of such infections, imposes unprecedented public health challenges. To meet these challenges, innovative strategies to discover and develop new or improved anti-infective vaccines are necessary. These approaches must intersect the most meaningful insights into protective immunity and advanced technologies with capabilities to deliver immunogens for optimal immune protection. This goal is considered through several recent advances in host-pathogen relationships, conceptual strides in vaccinology, and emerging technologies. Given a clear and growing risk of pandemic disease should the threat of infection go unmet, developing vaccines that optimize protective immunity against high-priority and antibiotic-resistant pathogens represents an urgent and unifying imperative.

Review of Infectious Disease Prophylaxis in Solid Organ Transplantation

As immunosuppressive therapy has evolved over the years, rejection rates in solid organ transplant have declined, but infections remain a significant cause of morbidity and mortality in this population. Prophylaxis against bacterial, viral, and fungal infections is often used to prevent infection from common pathogens during high-risk periods. As an integral part of the multidisciplinary medical team, it is important that nurses caring for transplant recipients be familiar with methods to detect and prevent infectious diseases in this population. This article presents a review of risk factors for and prevalence of common infectious pathogens, as well as important considerations regarding prophylactic medications in solid organ transplant recipients.

Infections in pediatric solid-organ transplant recipients

Solid-organ transplantation in pediatrics can be a life-saving procedure, but it cannot be accomplished without risk of infection-related morbidity and mortality. Evaluation of the recipient during candidacy and donor during evaluation can assist with identification of risk. Further, risk of infection from the surgical procedure can be mitigated through careful planning and attention to infection prevention processes. Finally, early recognition of infection posttransplant can limit the impact of these events.

Bloodstream Infections

Bacteremia and sepsis are conditions associated with high mortality and are of great impact to health care operations. Among the top causes of mortality in the United States, these conditions cause over 600 fatalities each day. Empiric, broad-spectrum treatment is a common but often a costly approach that may fail to effectively target the correct microbe, may inadvertently harm patients via antimicrobial toxicity or downstream antimicrobial resistance. To meet the diagnostic challenges of bacteremia and sepsis, laboratories must understand the complexity of diagnosing and treating septic patients, in order to focus on creating algorithms that can help direct a more targeted approach to antimicrobial therapy and synergize with existing clinical practices defined in new Surviving Sepsis Guidelines. Significant advances have been made in improving blood culture media; as yet no molecular or antigen-based method has proven superior for the detection of bacteremia in terms of limit of detection. Several methods for rapid molecular identification of pathogens from blood cultures bottles are available and many more are on the diagnostic horizon. Ultimately, early intervention by molecular detection of bacteria and fungi directly from whole blood could provide the most patient benefit and contribute to tailored antibiotic coverage of the patient early on in the course of the disease. Although blood cultures remain as the best means of diagnosing bacteremia and candidemia, complementary testing with antigen tests, microbiologic investigations from other body sites, and histopathology can often aid in the diagnosis of disseminated disease, and application of emerging nucleic acid test methods and other new technology may greatly impact our ability to bacteremic and septic patients, particularly those who are immunocompromised.

Hospital-Associated Infections

Hospital-associated infection (HAI) in immunocompromised patients can result in high rates of morbidity and mortality. Infections caused by multidrug-resistant organisms (MDROs) are especially worrisome because of the limited choice of remaining antibiotics available when a patient becomes colonized or infected with an MDRO. It is therefore important that immunocompromised patients be cared for in an environment that limits the risk for acquiring infections. However, with healthcare being increasingly delivered in settings other than the traditional inpatient hospital wards, a bigger effort will need to be set forth to prevent or rapidly diagnose HAI. The last few years have seen a significant increase in the number of singleplex and multiplex molecular assays for the detection of many of the organisms responsible for HAI, but more is needed as infections caused by organisms like Legionella pneumophila and Aspergillus species are still diagnosed with methods that have relatively low yield and are slow to provide actionable results. Finally, the use of novel techniques for outbreak investigations will provide new information on transmission of infectious agents in healthcare settings and allow stronger, evidence-based recommendations to be developed for prevention of HAIs in the immunocompromised host.

Surgical Site Infections After Liver Transplantation: Emergence of Multidrug-Resistant Bacteria and Implications for Prophylaxis and Treatment Strategies. Transplantation. 2016;100:2107-2114. [PMID: 27479167 DOI: 10.1097/tp.0000000000001356]

BACKGROUND

Perioperative antimicrobial prophylaxis is administered to liver transplant (LTx) recipients to prevent surgical site infections (SSIs), but regimens are not standardized, and there are limited effectiveness data. Prevention and treatment of SSIs have been complicated by the emergence of multidrug-resistant (MDR) pathogens.

METHODS

We retrospectively reviewed SSIs among 331 LTx recipients at our center in 2010 to 2014.

RESULTS

Culture-proven superficial and deep SSIs occurred in 3% and 15% of patients, respectively, at median 12.5 and 13.5 days post-LTx. Recipients with superficial SSIs and those without SSIs were similar in demographics, clinical characteristics, length of hospital stay, and mortality. Deep SSIs included abscesses (58%), peritonitis (28%), deep incisional infections (8%), and cholangitis (6%). Rates of deep SSIs were comparable among patients receiving prophylaxis with ampicillin-sulbactam, aztreonam and vancomycin, or tigecycline (P = 0.61). Independent risk factors for deep SSIs were bile leak (P < 0.001) and operative time (P < 0.001). Enterobacteriaceae (42%), Enterococcus spp. (24%), and Candida spp. (15%) were predominant pathogens. Fifty-three percent of bacteria were MDR, including 95% of Enterococcus faecium and 55% of Enterobacteriaceae; 82% of deep SSIs were caused by bacteria resistant to antimicrobials used for prophylaxis, and 58% of patients were treated with an inactive empiric regimen. Deep SSIs were associated with longer lengths of stay (P < 0.001), and higher 90-day and long-term mortality rates (P < 0.001).

CONCLUSIONS

Deep SSIs, including those caused by MDR bacteria, were common after LTx despite prophylaxis with broad-spectrum antimicrobials. Rather than altering prophylaxis regimens, programs should devise empiric treatment regimens that are directed against the most common local pathogens.

Infection in Organ Transplantation

The prevention, diagnosis, and management of infectious disease in transplantation are major contributors to improved outcomes in organ transplantation. The risk of serious infections in organ recipients is determined by interactions between the patient's epidemiological exposures and net state of immune suppression. In organ recipients, there is a significant incidence of drug toxicity and a propensity for drug interactions with immunosuppressive agents used to maintain graft function. Thus, every effort must be made to establish specific microbiologic diagnoses to optimize therapy. A timeline can be created to develop a differential diagnosis of infection in transplantation based on common patterns of infectious exposures, immunosuppressive management, and antimicrobial prophylaxis. Application of quantitative molecular microbial assays and advanced antimicrobial therapies have advanced care. Pathogen-specific immunity, genetic polymorphisms in immune responses, and dynamic interactions between the microbiome and the risk of infection are beginning to be explored. The role of infection in the stimulation of alloimmune responses awaits further definition. Major hurdles include the shifting worldwide epidemiology of infections, increasing antimicrobial resistance, suboptimal assays for the microbiologic screening of organ donors, and virus-associated malignancies. Transplant infectious disease remains a key to the clinical and scientific investigation of organ transplantation.

Selected Topics in Aerobic Bacteriology

Aerobic Gram-positive and Gram-negative bacteria can be important pathogens in the immunocompromised host. These bacteria can be found in many environments, as part of the normal microbiota of the human host and animals, in soil and water, on plants, on fomites in the hospital, and on hospital equipment. This review provides information from relevant studies about what are the most common aerobic bacteria associated with patients who have cancer and/or are being treated for it, or who have other diseases which lead to immunodeficiencies, such as HIV, multiple myeloma, aplastic anemia, chronic diseases, and aging. A discussion of the appropriate laboratory tests needed for diagnosis of aerobic infections and information about antibiotics and susceptibility testing are also included.

Surgical site infection in patients submitted to heart transplantation

OBJECTIVES

to analyze the occurrence and predisposing factors for surgical site infection in patients submitted to heart transplantation, evaluating the relationship between cases of infections and the variables related to the patient and the surgical procedure.

METHOD

retrospective cohort study, with review of the medical records of patients older than 18 years submitted to heart transplantation. The correlation between variables was evaluated by using Fisher's exact test and Mann-Whitney-Wilcoxon test.

RESULTS

the sample consisted of 86 patients, predominantly men, with severe systemic disease, submitted to extensive preoperative hospitalizations. Signs of surgical site infection were observed in 9.3% of transplanted patients, with five (62.5%) superficial incisional, two (25%) deep and one (12.5%) case of organ/space infection. There was no statistically significant association between the variables related to the patient and the surgery.

CONCLUSION

there was no association between the studied variables and the cases of surgical site infection, possibly due to the small number of cases of infection observed in the sample investigated.

The Etiology, Incidence, and Impact of Preservation Fluid Contamination during Liver Transplantation

The role of contaminated preservation fluid in the development of infection after liver transplantation has not been fully elucidated. To assess the incidence and etiology of contaminated preservation fluid and determine its impact on the subsequent development of infection after liver transplantation, we prospectively studied 50 consecutive liver transplants, and cultured the following samples in each instance: preservation fluid (immediately before and at the end of the back-table procedure, and just before implantation), blood, and bile from the donor, and ascitic fluid from the recipient. When any culture was positive, blood cultures were obtained and targeted antimicrobial therapy was started. We found that the incidence of contaminated preservation fluid was 92% (46 of 50 cases of liver transplantation per year), but only 28% (14/50) were contaminated by recognized pathogens. Blood and bile cultures from the donor were positive in 28% and 6% respectively, whereas ascitic fluid was positive in 22%. The most frequently isolated microorganisms were coagulase-negative staphylococci. In nine cases, the microorganisms isolated from the preservation fluid concurred with those grown from the donor blood cultures, and in one case, the isolate matched with the one obtained from bile culture. No liver transplant recipient developed an infection due to the transmission of an organism isolated from the preservation fluid. Our findings indicate that contamination of the preservation fluid is frequent in liver transplantation, and it is mainly caused by saprophytic skin flora. Transmission of infection is low, particularly among those recipients given targeted antimicrobial treatment for organisms isolated in the preservation fluid.

Selected Topics in Anaerobic Bacteriology

Alteration in the host microbiome at skin and mucosal surfaces plays a role in the function of the immune system, and may predispose immunocompromised patients to infection. Because obligate anaerobes are the predominant type of bacteria present in humans at skin and mucosal surfaces, immunocompromised patients are at increased risk for serious invasive infection due to anaerobes. Laboratory approaches to the diagnosis of anaerobe infections that occur due to pyogenic, polymicrobial, or toxin-producing organisms are described. The clinical interpretation and limitations of anaerobe recovery from specimens, anaerobe-identification procedures, and antibiotic-susceptibility testing are outlined. Bacteriotherapy following analysis of disruption of the host microbiome has been effective for treatment of refractory or recurrent Clostridium difficile infection, and may become feasible for other conditions in the future.

Antibiotic prophylaxis for surgical site infection in people undergoing liver transplantation

BACKGROUND

Surgical site infection is more frequent in liver transplantation than in other types of solid organ transplantation with different antibiotics. Studies have shown that the rate of surgical site infection varies from 8.8% to 37.5% after liver transplantation. Therefore, antimicrobial prophylaxis is likely an essential tool for reducing these infections. However, the literature lacks evidence indicating the best prophylactic antibiotic regimen that can be used for liver transplantation.

OBJECTIVES

To assess the benefits and harms of antibiotic prophylactic regimens for surgical site infection in people undergoing liver transplantation.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Science Citation Index Expanded and Latin American Caribbean Health Sciences Literature (LILACS). The most recent search was performed on 11 September 2015.

SELECTION CRITERIA

All eligible randomised clinical trials comparing any antibiotic regimen versus placebo, versus no intervention or versus another antibiotic regimen for surgical site infection in liver transplant recipients, regardless of age, sex and reason for transplantation. Quasi-randomised studies and other observational studies were considered for data on harm if retrieved with search results for randomised clinical trials.

DATA COLLECTION AND ANALYSIS

Two review authors selected relevant trials, assessed risk of bias of studies and extracted data.

MAIN RESULTS

The electronic search identified 786 publications after removal of duplicates. From this search, only one seemingly randomised clinical trial, published in abstract form, fulfilled the inclusion criteria of this review. This trial was conducted at Shiraz Transplant Centre, Shiraz, Iran, where investigators randomly assigned a total of 180 consecutive liver transplant recipients. We judged the overall risk of bias of the trial published in abstract form as high. Researchers reported no numerical data but mentioned that 163 participants met the inclusion criteria after randomisation, and hence were included in the analyses. Most probably, the 17 excluded participants were high-risk liver transplant recipients. Trial authors concluded that they could find no differences between the two antibiotic regimens - ceftriaxone plus metronidazole versus ampicillin-sulbactam plus ceftizoxime - when given to liver transplant recipients. Review authors could not reconfirm the analyses because, as it has been mentioned, trial authors provided no trial data for analyses.

AUTHORS' CONCLUSIONS

Benefits and harms of antibiotic prophylactic regimens for surgical site infection in liver transplantation remain unclear. Additional well-conducted randomised clinical trials adhering to SPIRIT (Spirit Protocol Items: Recommendations for Interventional Trials) and CONSORT (Consolidated Standards of Reporting Trials) guidelines are needed to determine the exact role of antibiotic prophylactic regimens in patients undergoing liver transplantation.

Gut microbiota and allogeneic transplantation

The latest high-throughput sequencing technologies show that there are more than 1000 types of microbiota in the human gut. These microbes are not only important to maintain human health, but also closely related to the occurrence and development of various diseases. With the development of transplantation technologies, allogeneic transplantation has become an effective therapy for a variety of end-stage diseases. However, complications after transplantation still restrict its further development. Post-transplantation complications are closely associated with a host's immune system. There is also an interaction between a person's gut microbiota and immune system. Recently, animal and human studies have shown that gut microbial populations and diversity are altered after allogeneic transplantations, such as liver transplantation (LT), small bowel transplantation (SBT), kidney transplantation (KT) and hematopoietic stem cell transplantation (HTCT). Moreover, when complications, such as infection, rejection and graft versus host disease (GVHD) occur, gut microbial populations and diversity present a significant dysbiosis. Several animal and clinical studies have demonstrated that taking probiotics and prebiotics can effectively regulate gut microbiota and reduce the incidence of complications after transplantation. However, the role of intestinal decontamination in allogeneic transplantation is controversial. This paper reviews gut microbial status after transplantation and its relationship with complications. The role of intervention methods, including antibiotics, probiotics and prebiotics, in complications after transplantation are also discussed. Further research in this new field needs to determine the definite relationship between gut microbial dysbiosis and complications after transplantation. Additionally, further research examining gut microbial intervention methods to ameliorate complications after transplantation is warranted. A better understanding of the relationship between gut microbiota and complications after allogeneic transplantation may make gut microbiota as a therapeutic target in the future.