Evolving trends in multiple-antibiotic-resistant bacteria in liver transplant recipients: a longitudinal study of antimicrobial susceptibility patterns

Epidemiology and Risk Prediction Model of Multidrug-Resistant Organism Infections After Liver Transplant Recipients: A Single-Center Cohort Study

Objective: Accurate risk stratification at an early stage may reduce the incidence of infection and improve the survival rate of recipients by adopting targeted interventions. This study aimed to develop a nomogram to predict the risk of multidrug-resistant organism (MDRO) infections in liver transplant (LT) recipients. Methods: We retrospectively collected clinical data from 301 LT recipients and randomly divided them into a training set (210 cases) and validation set (91 cases) using a 7:3 split ratio. Factors related to the risk of MDRO infection after LT were determined using univariate and multivariate bidirectional stepwise logistic regression. The model's predictive performance and discrimination ability were evaluated using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA). Results: 56 (18.60%) patients developed a MDRO infection, including 37 (17.62%) in the training cohort and 19 (20.88%) in the validation cohort. Ultimately, five factors related to MDRO infection after LT surgery were established: ascites (OR = 3.48, 95% CI [1.33-9.14], p = 0.011), total bilirubin (OR = 1.01, 95% CI [1.01-1.01], p < 0.001), albumin (OR = 0.85, 95% CI [0.75-0.96], p = 0.010), history of preoperative ICU stay (OR = 1.09, 95% CI [1.01-1.17], p = 0.009), and length of ICU stay (OR = 3.70, 95% CI [1.39-9.84], p = 0.019). The model demonstrated strong discrimination, and the area under the curve (AUC), sensitivity, and specificity of the training set were 0.88 (95% CI [0.81-0.94]), 0.82 (95% CI [0.76-0.87]), and 0.86 (95% CI [0.75-0.98]), respectively, while for the validation set, they were 0.77 (95% CI [0.65-0.90]), 0.76 (95% CI [0.67-0.86]), and 0.68 (95% CI [0.48-0.89]). The mean absolute error (MAE) in the validation cohort was 0.029, indicating a high accuracy. DCA showed a clinical benefit within a threshold probability range of 0.1 to 0.7. Conclusions: This study developed a clinically accessible nomogram to predict the risk of MDRO infection in LT recipients, enabling early risk stratification and the real-time assessment of infection risk based on the length of postoperative ICU stay. The model incorporates five easily obtainable clinical parameters (ascites, total bilirubin, albumin, preoperative ICU stay history, and length of ICU stay) and demonstrates strong predictive performance, facilitating the early identification of high-risk patients. Future research should focus on refining the model by incorporating additional clinical factors (e.g., immunosuppressive therapy adherence) and validating its generalizability in multicenter, large-sample cohorts to enhance its clinical utility.

Early Intra-Abdominal Bacterial Infections after Orthotopic Liver Transplantation: A Narrative Review for Clinicians

Despite recent advances in the transplant field, infectious complications after orthotopic liver transplantation (OLT) are major causes of morbidity and mortality. Bacterial intra-abdominal infections (IAIs) are predominant during the first month post-transplantation and affect patient and graft survival. Recently, the emergence of multidrug resistant bacteria has generated great concern in OLT patients. We performed this narrative review of the literature in order to propose a "ready-to-use" flowchart for reasoned empirical antibiotic therapy in the case of suspected post-OLT IAIs. The review was ultimately organized into four sections: "Epidemiology and predisposing factors for IAI"; "Surgical-site infections and perioperative prophylaxis"; "MDRO colonization and infections"; and "Reasoned-empirical antibiotic therapy in early intra-abdominal infections post OLT and source control". Multidisciplinary teamwork is warranted to individualize strategies for the prevention and treatment of IAIs in OLT recipients, taking into account each patient's risk factors, the surgical characteristics, and the local bacterial epidemiology.

Epidemiology and Prevention of Early Infections by Multi-Drug-Resistant Organisms in Adults Undergoing Liver Transplant: A Narrative Review

Invasive bacterial infections are a leading cause of morbidity and mortality after liver transplant (LT), especially during the first months after LT, and infections due to multi-drug-resistant organisms (MDRO) are increasing in this setting. Most of the infections in patients in intensive care unit arise from the endogenous microflora and, for this reason, pre-LT MDRO rectal colonization is a risk factor for developing MDRO infections in the post-LT. Moreover, the transplanted liver may carry an increased risk of MDRO infections due to organ transportation and preservation, to donor intensive care unit stay and previous antibiotic exposure. To date, little evidence is available about how MDRO pre-LT colonization in donors and recipients should address LT preventive and antibiotic prophylactic strategies, in order to reduce MDRO infections in the post-LT period. The present review provided an extensive overview of the recent literature on these topics, with the aim to offer a comprehensive insight about the epidemiology of MDRO colonization and infections in adult LT recipients, donor-derived MDRO infections, possible surveillance, and prophylactic strategies to reduce post-LT MDRO infections.

Infection with Two Multi-Drug-Resistant Organisms in Solid Organ Transplant Patients Is Associated with Increased Mortality and Prolonged Hospitalization

Background: Solid organ transplant recipients have several risk factors for peri-operative multi-drug-resistant infection: their immune system is dampened as a result of critical illness and surgical stress that may be further impaired by induction immunotherapy and broad-spectrum antibiotic prophylaxis promotes selection for resistant pathogens. Infection with multi-drug-resistant organisms (MDRO) results in morbidity and mortality for solid organ transplant recipients. Patients and Methods: To assess in-hospital mortality and hospitalization duration associated with these infections, we analyzed cross-sectional, retrospective data from the 2016 Agency for Healthcare and Quality, Healthcare Cost and Utilization Project's National Inpatient Sample. Our analysis included 31,105 index admissions records for liver, kidney, heart, lung, and pancreas transplant recipients in the United States. Outcomes were assessed by multivariable regression analysis adjusting for covariables. Results: One percent (355/29,451) of patients with diagnosis of no MDRO infections died, 3% (40/1491) with diagnosis of one MDRO infection died, and 15% (25/166) with diagnosis of two MDRO infections died. Diagnosis of one MDRO infection was associated with a 20-day increase in hospitalization duration (95% confidence interval [CI], 17-22) but not increased odds of death (odds ratio [OR], 1.2; 95% CI, 0.5-2.5). Diagnosis of two MDRO infections was associated with an increased odds of death (OR, 9.6' 95% CI, 3.3-27.9) and a 41-day increase in hospitalization duration (95% CI, 34-49). Conclusions: Strategies to decrease peri-operative MDRO infection may improve survival and decrease duration of hospitalization for solid organ transplant patients.

Pseudomonas aeruginosa Pneumonia: Evolution of Antimicrobial Resistance and Implications for Therapy

Pseudomonas aeruginosa (PA), a non-lactose-fermenting gram-negative bacillus, is a common cause of nosocomial infections in critically ill or debilitated patients, particularly ventilator-associated pneumonia (VAP), and infections of urinary tract, intra-abdominal, wounds, skin/soft tissue, and bloodstream. PA rarely affects healthy individuals, but may cause serious infections in patients with chronic structural lung disease, comorbidities, advanced age, impaired immune defenses, or with medical devices (e.g., urinary or intravascular catheters, foreign bodies). Treatment of pseudomonal infections is difficult, as PA is intrinsically resistant to multiple antimicrobials, and may acquire new resistance determinants even while on antimicrobial therapy. Mortality associated with pseudomonal VAP or bacteremias is high (> 35%) and optimal therapy is controversial. Over the past three decades, antimicrobial resistance (AMR) among PA has escalated globally, via dissemination of several international multidrug resistant "epidemic" clones. We discuss the importance of PA as a cause of pneumonia including health care-associated pneumonia, hospital-acquired pneumonia, VAP, the emergence of AMR to this pathogen, and approaches to therapy (both empirical and definitive).

Prevalence, Risk Factors And Treatment Of The Most Common Gram-Negative Bacterial Infections In Liver Transplant Recipients: A Review

Advances in surgical techniques and immunosuppressive agents have made solid organ transplant (Tx) an important strategy for treatment of end-stage organ failures. However, the incidence of infections following Tx due to Gram-negative pathogens is on the rise. These infections are associated with increased mortality and morbidity in patients following transplantation, including liver Tx. Thus, managing infections in liver Tx recipients is a big challenge, requiring prompt medical attention. Considering the important effect of Gram-negative bacterial infections on the outcomes of liver Tx recipients, the most prevalent Gram-negative pathogens including Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli will be discussed in this review.

Multidrug-resistant Gram-negative bacterial infections in solid organ transplant recipients-Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of infections due to multidrug-resistant (MDR) Gram-negative bacilli in the pre- and post-transplant period. MDR Gram-negative bacilli, including carbapenem-resistant Enterobacteriaceae, MDR Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii, remain a threat to successful organ transplantation. Clinicians now have access to at least five novel agents with activity against some of these organisms, with others in the advanced stages of clinical development. No agent, however, provides universal and predictable activity against any of these pathogens, and very little is available to treat infections with MDR nonfermenting Gram-negative bacilli including A baumannii. Despite advances, empiric antibiotics should be tailored to local microbiology and targeted regimens should be tailored to susceptibilities. Source control remains an important part of the therapeutic armamentarium. Morbidity and mortality associated with infections due to MDR Gram-negative organisms remain unacceptably high. Heightened infection control and antimicrobial stewardship initiatives are needed to prevent these infections, curtail their transmission, and limit the evolution of MDR Gram-negative pathogens, especially in the setting of organ transplantation.

Management of bacterial and fungal infections in end stage liver disease and liver transplantation: Current options and future directions

Patients with liver cirrhosis are susceptible to infections due to various mechanisms, including abnormalities of humoral and cell-mediated immunity and occurrence of bacterial translocation from the intestine. Bacterial infections are common and represent a reason for progression to liver failure and increased mortality. Fungal infections, mainly caused by Candida spp., are often associated to delayed diagnosis and high mortality rates. High level of suspicion along with prompt diagnosis and treatment of infections are warranted. Bacterial and fungal infections negatively affect the outcomes of liver transplant candidates and recipients, causing disease progression among patients on the waiting list and increasing mortality, especially in the early post-transplant period. Abdominal, biliary tract, and bloodstream infections caused by Gram-negative bacteria [e.g., Enterobacteriaceae and Pseudomonas aeruginosa (P. aeruginosa)] and Staphylococcus spp. are commonly encountered in liver transplant recipients. Due to frequent exposure to broad-spectrum antibiotics, invasive procedures, and prolonged hospitalizations, these patients are especially at risk of developing infections caused by multidrug resistant bacteria. The increase in antimicrobial resistance hampers the choice of an adequate empiric therapy and warrants the knowledge of the local microbial epidemiology and the implementation of infection control measures. The main characteristics and the management of bacterial and fungal infections in patients with liver cirrhosis and liver transplant recipients are presented.

Methicillin-resistant Staphylococcus aureus bacteremia among liver transplant recipients: epidemiology and associated risk factors for morbidity and mortality

Bacteremia due to Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), complicates the clinical course of liver transplantation and is associated with high morbidity and mortality. Intravascular catheters had been reported to be the most frequent source of MRSA bacteremia. Among bacteremic liver recipients, 26.3%-100% of S. aureus were MRSA. Previous studies identified pre-transplant and post-transplant acquired S. aureus carriage, greater severity of liver disease, hepatocellular carcinoma and infection with immuno-modulatory viruses as predictors of S. aureus bacteremia in liver recipients. MRSA bacteremia accompanied by pneumonia and abdominal infections was related to mortality. Vancomycin, as well as daptomycin, is a first-line antibiotic for MRSA bacteremia. The purpose of this review is to better understand the characteristics of MRSA bacteremia by summarizing the epidemiology and antimicrobial resistance of S. aureus, the primary source, and related risk factors for morbidity and mortality of MRSA bacteremia. We have also explored the diagnostic, therapeutic and preventive measures for MRSA bacteremia to improve the outcomes of liver recipients.

Genitourinary Tract Infections

Similarly to the general population, genitourinary tract infections are common conditions in theimmunocompromised host. They can be furthermore divided into infections of the urinary tract and genital tract infections. Transplant recipients are more likely to have infections of the urinary tract infections while persons with human immunodeficiency virus (HIV) are at higher risk for the second group of infections, especially sexually transmitted infections (STIs). Manifestations of these diseases can be associated with more complications and can be more severe. We provide an overview of manifestations, diagnosis, and management of these disorders.

Surgical Site Infections After Liver Transplantation: Emergence of Multidrug-Resistant Bacteria and Implications for Prophylaxis and Treatment Strategies

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.

Factors influencing mortality in abdominal solid organ transplant recipients with multidrug-resistant gram-negative bacteremia

BACKGROUND

Although multidrug-resistant (MDR) gram-negative bacteremia (GNB) has been recognized as an important cause of morbidity and mortality among abdominal solid organ transplant (ASOT) recipients, there are no data on its prognostic factors after an interim standard definition of MDR was proposed in 2012. The objective of this study was to describe the epidemiology, microbiology, and predictors of infection-related 30-day mortality in ASOT recipients with MDR GNB.

METHODS

We performed a retrospective, double-center analysis of ASOT patients with MDR GNB over a 13-year study period. Univariate and multivariate analyses were performed to identify the risk factors for mortality.

RESULTS

During the observational period, 2169 subjects underwent ASOT. Ninety-nine episodes of MDR GNB were diagnosed in 91 (4.6%) ASOT recipients, with a predominance of E.coli (29 isolates, 29.3%) and A.baumanii (24 isolates, 24.2%). The median age of these 91 recipients was 45 years (interquartile range 35-54). Mortality after the first episode of MDR GNB was 39.6% (36 deaths). The univariate analysis identified the following variables as predictors of MDR GNB-related mortality: lung focus (P = 0.001),nosocomial origin (P = 0.002), graft from donation after cardiac death or deceased donors (P = 0.023), presence of other concomitant bloodstream infection (P < 0.001), temperature of 40 °C or greater at the onset of MDR GNB (P = 0.039), creatinine > 1.5 mg/dl (P = 0.006), albumin < 30 g/L (P = 0.009), platelet count < 50,000/mm3 (P < 0.001), and septic shock (P < 0.001). In the multivariate logistic regression analysis, septic shock (odds ratio (OR) = 160.463, 95% confidence interval (CI) = 19.377-1328.832, P < .001), as well as creatinine > 1.5 mg/dl (OR = 24.498, 95% CI = 3.449-173.998, P = 0.001), nosocomial origin (OR = 23.963, 95% CI = 1.285-46.991, P = 0.033), and presence of other concomitant bloodstream infections (OR = 27.074, 95% CI = 3.937-186.210, P = 0.001) were the variables associated with MDR GNB-related 30-day mortality.

CONCLUSIONS

MDR GNB was associated with high morbidity and mortality in ASOT recipients, with a predominant causative organisms being E.coli and A.baumanii. Nosocomial origin, as well as presence of other concomitant bloodstream infections, increased creatinine level and septic shock were the main predictors of MDR GNB-related 30-day mortality.

Multidrug-resistant organisms in liver transplant: Mitigating risk and managing infections

Liver transplant (LT) recipients are vulnerable to infections with multidrug-resistant (MDR) pathogens. Risk factors for colonization and infection with resistant bacteria are ubiquitous and unavoidable in transplantation. During the past decade, progress in transplantation and infection prevention has contributed to the decreased incidence of infections with methicillin-resistant Staphylococcus aureus. However, even in the face of potentially effective antibiotics, vancomycin-resistant enterococci continue to plague LT. Gram-negative bacilli prove to be more problematic and are responsible for high rates of both morbidity and mortality. Despite the licensure of novel antibiotics, there is no universal agent available to safely and effectively treat infections with MDR gram-negative organisms. Currently, efforts dedicated toward prevention and treatment require involvement of multiple disciplines including transplant providers, specialists in infectious diseases and infection prevention, and researchers dedicated to the development of rapid diagnostics and safe and effective antibiotics with novel mechanisms of action. Liver Transplantation 22 1143-1153 2016 AASLD.

C7 genotype of the donor may predict early bacterial infection after liver transplantation

Post-transplantation infection causes high mortality and remains a significant challenge. High clinical risk factors for bacterial infection in recipients are often found in critically ill patients. However, for some recipients, bacterial infections are inevitable. It is conceivable that this susceptibility may be related to the genetics of the donor and recipient. Using expression quantitative trait loci (eQTL) analysis, we found that the C7 rs6876739 CC genotypes and mannan-binding lectin (MBL2) gene polymorphisms of liver donors were significantly associated with bacterial infection in recipients. In an extended validation group of 113 patients, donor C7 rs6876739 genetic variation was an independent risk factor for bacterial infection. The donor C7 rs6876739 CC genotype was associated with lower levels of recipient C7 protein, soluble membrane attack complex (MAC), and IL-1β expression compared with the donor C7 rs6876739 TT genotype. In vitro, the MAC significantly triggered NLRP3 inflammasome activation and IL-1β release, suggesting that the mechanism by which C7 defends against bacteria may involve MAC formation, leading to NLRP3 inflammasome activation and IL-1β release. Our findings may be helpful in identifying transplantation recipients at risk of bacterial infection prior to surgery and may contribute to novel infection prevention strategies and the improvement of postoperative outcomes.

Epidemiology of Bloodstream Infections in a Multicenter Retrospective Cohort of Liver Transplant Recipients

Although some studies have examined the epidemiology of bloodstream infections after liver transplantation, they were based in single centers and did not identify bloodstream infections treated in other hospitals.

METHODS

We retrospectively examined a cohort of 7912 adult liver transplant recipients from 24 transplant centers using 2004 to 2012 International Classification of Diseases, Ninth Revision, Clinical Modification billing data from 3 State Inpatient Databases, and identified bloodstream infections, inpatient death, and cumulative 1-year hospital costs. Multilevel Cox regression analyses were used to determine factors associated with bloodstream infections and death.

RESULTS

Bloodstream infections were identified in 29% (n = 2326) of liver transplant recipients, with a range of 19% to 40% across transplant centers. Only 63% of bloodstream infections occurring more than 100 days posttransplant were identified at the original transplant center. Bloodstream infections were associated with posttransplant laparotomy (adjusted hazard ratio [aHR], 1.52), prior liver transplant (aHR, 1.42), increasing age (aHR, 1.07/decade), and some comorbidities. Death was associated with bloodstream infections with and without septic shock (aHR, 10.96 and 3.71, respectively), transplant failure or rejection (aHR, 1.41), posttransplant laparotomy (aHR, 1.40), prior solid-organ transplant (aHR, 1.48), increasing age (aHR, 1.15/decade), and hepatitis C cirrhosis (aHR, 1.20). The risk of bloodstream infections and death varied across transplant centers. Median 1-year cumulative hospital costs were higher for patients who developed bloodstream infections within 1 year of transplant compared with patients who were bloodstream infection-free (US $229 806 vs US $111 313; P < 0.001).

CONCLUSIONS

Bloodstream infections are common and costly complications after liver transplantation that are associated with a markedly increased risk of death. The incidence and risk of developing bloodstream infections may vary across transplant centers.

Staphylococcus aureus bacteremias following liver transplantation: a clinical analysis of 20 cases

BACKGROUND

To describe the incidence, clinical characteristics, and outcomes of Staphylococcus aureus bacteremia after liver transplantation and investigate the drug resistance of S. aureus to frequently used antibiotics to provide evidence for clinical prevention and therapy.

MATERIALS AND METHODS

In a double-center retrospective study, blood cultures positive for S. aureus were obtained from January 1, 2001 to December 31, 2014. The BACTEC 9120 blood culture system and the Vitek-2 system were used to process blood samples and identify species, respectively. We also collected these patients' data to confirm clinical and laboratory characteristics.

RESULTS

Twenty of 275 (7.3%) liver recipients developed S. aureus bacteremia during the study period. The median time to the onset of S. aureus bacteremias was 6 days after liver transplantation and all episodes of bacteremias were early onset. The lung was the most common source of primary infection, followed by the intra-abdominal/biliary tract. A total of nine (45%) liver recipients died due to S. aureus bacteremias. Of these 20 S. aureus cases, 80% were methicillin-resistant. S. aureus was highly resistant to erythromycin and penicillin (resistance rate >90%). No S. aureus resistant to glycopeptides and oxazolidone antibiotics was observed. There were seven (35%) liver recipients with an inappropriate antibiotic therapy. Between the periods of 2001-2007 and 2008-2014, the distribution of methicillin-resistant S. aureus was not significantly different (P=1.000). Pneumonia as a predominant primary source, a high body temperature, abnormal blood pressure, and decreased platelets, which occurred in the early period after liver transplantation, as well as high morbidity and mortality, were the main characteristics of S. aureus bacteremias.

CONCLUSION

S. aureus led to severe bacteremias in liver recipients, with high morbidity and mortality, and the majority of them comprised methicillin-resistant S. aureus.

Multidrug-resistant Gram-negative bacteria in solid organ transplant recipients with bacteremias

Bloodstream infections (BSIs) remain as life-threatening complications and are associated with significant morbidity and mortality among solid organ transplant (SOT) recipients. Multidrug-resistant (MDR) Gram-negative bacteria can cause serious bacteremias in these recipients. Reviews have aimed to investigate MDR Gram-negative bacteremias; however, they were lacking in SOT recipients in the past. To better understand the characteristics of bacteremias due to MDR Gram-negative bacteria, optimize preventive and therapeutic strategies, and improve the outcomes of SOT recipients, this review summarize the epidemiology, clinical and laboratory characteristics, and explores the mechanisms, prevention, and treatment of MDR Gram-negative bacteria.

Risk factors for mortality in liver transplant recipients with ESKAPE infection

BACKGROUND

Although infections caused by the pathogens Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp (ESKAPE) have recently been identified as serious emerging problems in solid organ transplant, no information in liver transplant (LT) recipients is available. We sought to investigate the risk factors for associated mortality in LT recipients with ESKAPE infections.

METHODS

A retrospective analysis of infection after LT was reviewed. Risk factors for mortality caused by ESKAPE infection were identified.

RESULTS

Fifty-three episodes of infections caused by ESKAPE were documented in 51 LT recipients. The main sites of infection were the bloodstream (49.0%), the lungs (33.3%), and the intra-abdominal/biliary tract (17.6%). The risk factors for mortality independently associated with ESKAPE infection were female sex (odds ratio [OR] = 6.6, 95% confidence interval [CI] = 1.1-40.8, P = .042), septic shock (OR = 30.1, 95% CI = 3.7-244.8, P = .001), and lymphocyte counts <300/mm(3) (OR = 20.2, 95% CI = 2.9-142.2, P = .003).

CONCLUSIONS

To improve the results of LT, more effective therapeutic treatments are of paramount importance when female LT recipients with ESKAPE infection present with septic shock and decreased lymphocyte counts.

Frequency and clinical outcomes of ESKAPE bacteremia in solid organ transplantation and the risk factors for mortality

BACKGROUND

Although bacteremias caused by the 6 ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) have recently been highlighted as a serious complication in solid organ transplant (SOT), more information is urgently needed. We sought to investigate the frequency and clinical outcomes of ESKAPE bacteremia in SOT and determine the risk factors for mortality.

METHODS

A retrospective analysis of bacteremia after SOT was reviewed. Risk factors for mortality caused by ESKAPE bacteremia were identified.

RESULTS

Eighty-four episodes of bacteremia were caused by ESKAPE strains. Of these strains, 41 were caused by resistant ESKAPE (rESKAPE) organisms. The only factor for bacteremia-related mortality independently associated with ESKAPE was septic shock (odds ratio [OR] = 21.017, 95% confidence interval [CI] = 5.038-87.682, P < 0.001). The factors for bacteremia-related mortality independently associated with rESKAPE bacteremia were septic shock (OR = 16.558, 95% CI = 6.620-104.668, P = 0.003) and age ≥40 years (OR = 7.521, 95% CI = 1.196-47.292, P = 0.031).

CONCLUSIONS

To improve the outcomes of transplantation, more effective therapeutic treatments are of paramount importance when older SOT recipients with bacteremia due to ESKAPE/rESKAPE organisms present with septic shock.

Bloodstream infections among solid organ transplant recipients: epidemiology, microbiology, associated risk factors for morbility and mortality

Bloodstream infections (BSIs) remain important causes of morbidity and mortality among solid organ transplant (SOT) recipients and still threaten the success of SOT. In general, among SOT recipients, risk factors for BSIs are associated with prior ICU admission, catheterization, older recipient or donor age…etc. Pulmonary focus, nosocomial source of BSIs, lack of appropriate antibiotic therapy and other variables have significant impacts on BSIs-related mortality in SOT. Most of BSIs in SOT are caused by gram-negative bacteria. However, all aspects including microbiological spectrum, morbidity and mortality rates, risk factors of BSIs and BSIs-related death depend on the type of transplantation. The purpose of this review is to summarize the epidemiology, microbiologic features including antimicrobial resistance of organisms, and associated risk factors for morbidity and mortality of BSIs according to different type of transplantation to better understand the characteristics of BSIs and improve the outcomes after SOT.

Carbapenem-resistant Enterobacteriaceae and Acinetobacter baumannii: assessing their impact on organ transplantation

PURPOSE OF REVIEW

This review highlights the impact of carbapenem-resistant Enterobacteriaceae and carbapenem-resistant Acinetobacter baumannii on patients who have undergone organ transplantation and explores both available and potential agents to treat infections caused by these multidrug-resistant (MDR) pathogens.

RECENT FINDINGS

Few antimicrobials exist to treat carbapenem-resistant Gram-negative infections, and resistance to salvage therapies is escalating. Organ transplantation appears to be a risk factor for infections with Klebsiella pneumoniae carbapenemase-producing Enterobacteriaceae. Isolation of these MDR bacteria is increasing and may be associated with allograft failure and mortality. In the majority of cases, aminoglycosides, polymyxins, and tigecycline have been employed to treat these infections. Anecdotal successes exist but these antibiotics may be unreliable. Few novel agents are in development.

SUMMARY

Bacterial infections remain a leading cause of posttransplantation morbidity and mortality. Carbapenem resistance is a significant threat to allograft and patient survival. With few antimicrobials being developed, transplant centers may be forced to make decisions regarding surveillance, empiric antimicrobial regimens, and transplant candidacy in the setting of carriage of MDR pathogens. There is an urgent need for collaborative studies to address the clinical impact of these infections on transplantation.

Prevalence of multidrug-resistant gram-negative bacilli producing extended-spectrum β-lactamases (ESBLs) and ESBL genes in solid organ transplant recipients

BACKGROUND

Multidrug-resistant (MDR) gram-negative bacilli pose a serious and rapidly emerging threat to recipients of solid organ transplants (SOTs). However, extended-spectrum β-lactamases (ESBLs), as one of the cardinal mechanisms of resistance to antimicrobial agents in SOT recipients, remain obscure. The aim of this study was to investigate the prevalence of strains producing ESBLs in SOT patients with MDR gram-negative bacilli infections and to identify the ESBL genes carried by them.

MATERIALS AND METHODS

Isolates from various clinical specimens of SOT recipients were identified using the VITEK 2 system, and their antibiotic sensitivity was determined by the 2-fold agar dilution method. Isolates suspected of producing ESBL enzymes were tested by an ESBL phenotypic confirmatory method, and the ESBL genotypes were determined by the polymerase chain reaction and sequencing.

RESULTS

A total of 80 MDR gram-negative strains were isolated from 350 SOT recipients. Among these strains, 42 (52.5%) had an ESBL-positive phenotype; 33 (42.3%) patients with ESBL-positive infection were found. Molecular analysis showed that most of the isolates harbored blaCTX-M-9 (78.6%), blaTEM (81.0%), and blaSHV (69.0%) genes. All the ESBL-producing strains were susceptible to carbapenems.

CONCLUSIONS

MDR gram-negative isolates from SOT recipients are frequently ESBL producers. TEM and CTX-M9 were the predominant ESBL types.

Multidrug-resistant gram-negative bacterial infections after liver transplantation - spectrum and risk factors

OBJECTIVES

Gram-negative bacilli infections, especially multidrug-resistant gram-negative bacilli infections, are the leading cause of high mortality after liver transplantation. This study sought to investigate the type of infection, infection rate, pathogenic spectrum, antibiotic-resistance profile, risk factors, and epidemiology of multidrug-resistant gram-negative bacterial infection.

METHODS

A retrospective cohort study was conducted and data of 217 liver transplant patients receiving cadaveric livers between January 2007 and April 2010 were analyzed. Antibiotic susceptibility was determined by minimum inhibitory concentration test. Extended-spectrum and metallo-β-lactamase assays were used to analyze β-lactamase-produced isolates, and repetitive-sequence polymerase chain reaction was used to differentiate bacterium subspecies.

RESULTS

Sixty-seven isolates of multidrug-resistant gram-negative bacteria were isolated from 66 infected liver transplant patients. Stenotrophomonas maltophilia (100%, 8/8), Klebsiella pneumoniae (61.5%, 8/13), Enterobacter cloacae (75%, 3/4) and Escherichia coli (81.3%, 13/16) were the most common extended-spectrum β-lactamase-producing bacilli. Metallo-β-lactamase expressing isolates were identified as S. maltophilia (100%, 8/8), Pseudomonas aeruginosa (83.3%, 5/6), Acinetobacter baumannii (95%, 19/20). Significant independent risk factors for multidrug-resistant gram-negative infection were extended use of pre-transplant broad-spectrum antibiotics (OR 9.027, P=0.001) and prolonged (≧72h) endotracheal intubation (OR 3.537, P=0.033).

CONCLUSIONS

To reduce the risk of acquiring MDR gram-negative bacillus infections after liver transplant, control measures are required to limit the use of prophylactic antibiotic in preventing infection during liver transplant and to shorten endotracheal intubation time.

Extended-spectrum beta-lactamase-producing bacterial infections in adult solid organ transplant recipients

BACKGROUND

Limited research is available evaluating infections due to extended-spectrum β-lactamase (ESBL)-producing organisms in adult recipients of solid organ transplant (SOT).

OBJECTIVE

To evaluate clinical response and rate of recurrence of ESBL-producing organisms in 20 SOT recipients.

METHODS

In a retrospective case series, records of adult SOT recipients with an admitting diagnosis of infection and a positive culture for an ESBL-producing organism from January 2003 through August 2006 were reviewed.

RESULTS

Twenty patients met inclusion criteria. The median time to infection following transplant was 3.5 years (range 1-23 years). Overall, 85% of the patients received inadequate empiric antibiotic therapy, including ciprofloxacin or piperacillin/tazobactam, to manage their infection. Nineteen patients had clinical resolution; however, 12 patients required at least 1 readmission due to infection recurrence. One patient's death occurred during the study period. The median time to readmission for a recurrence was 41 days (18-455 days). All recurrent infections were caused by the same ESBL-producing pathogen and 10 of 12 (83%) infections occurred at the same site as the initial infection. Among patients with recurrent infections, 75% received inadequate empiric therapy upon readmission. All 12 patients with recurrent infections had successful clinical responses to both initial and recurrent infections.

CONCLUSIONS

The provision of inadequate empiric therapy for new and recurrent infections due to ESBL-producing pathogens was common in this study population. SOT recipients with a history of infection due to an ESBL-producing organism presenting with a new infection should receive adequate empiric therapy with a carbapenem agent until a definitive diagnosis can be established.

Pathogenesis of the hyperlipidemia of Gram-negative bacterial sepsis may involve pathomorphological changes in liver sinusoidal endothelial cells

The Gram-negative bacterium Pseudomonas aeruginosa is one of the most common opportunistic pathogens, especially after liver transplantation. Pathophysiological alterations of liver sinusoidal endothelial cells (LSECs) have far-reaching repercussions on the liver and on metabolism. LSECs are perforated with fenestrations, pores that facilitate the transfer of lipoproteins and macromolecules between blood and hepatocytes. Gram-negative bacterial endotoxin (lipopolysaccharide, LPS) and the P. aeruginosa toxin, pyocyanin, have marked effects on LSECs. Initial loss of LSEC porosity (defenestration) induced by P. aeruginosa pyocyanin and LPS may confer subsequent immune tolerance to circulating bacterial antigens and toxins. This review collates the known immune responses of the liver to Gram-negative bacterial toxins, with a focus on LSECs. Hyperlipidemia is an important response to Gram-negative bacterial sepsis. The mechanisms proposed for sepsis-associated hyperlipidemia include tissue lipoprotein lipase inhibition and upregulated hepatic triglyceride production. In this review, we propose defenestration of the LSECs by bacterial toxins as an additional mechanism for the hyperlipidemia of sepsis. Given the role of LSECs in hyperlipidemia and liver allograft rejection, LSEC changes induced by P. aeruginosa toxins including LPS and pyocyanin may have significant clinical implications.

Identifying a targeted population at high risk for infections after liver transplantation in the MELD era

Impact of model for end-stage liver disease (MELD) scoring system on post-transplant infections and associated risk factors are unknown. Infections <90 d post-transplant were assessed in 277 consecutive liver transplant recipients from 1999 to 2008. "High-risk" factors for infections were pre-defined as MELD score >30, ICU stay >48 h prior to transplant, intraoperative transfusion ≥15 units, retransplantation, post-transplant dialysis, or reoperation. Of the 240 recipients in the MELD era (2002-2008), 48.5% had any high-risk factor. The OR for infection was 1.69, 2.00, 18.00, and 4.50 in recipients with any 1, 2, 3, and ≥4 high-risk factors, respectively (χ(2) for trend, p < 0.001). In logistic regression model, recipient age (OR 1.12, p < 0.05) and any high-risk factor (OR 2.42, p < 0.05) were associated with infections. Compared with 37 pre-MELD recipients, the overall infections and mortality at 12 months did not differ in the two eras. In Cox regression model, recipient age (OR 1.09, p < 0.05) and any high-risk factor (OR 2.42, p < 0.05) remained associated with infections. The overall frequency of infections did not increase in the MELD era. Pre-defined risk factors accurately predicted the risk of infections in these patients.

Microbial epidemiology and outcome of bloodstream infections in liver transplant recipients: an analysis of 259 episodes

Bloodstream infections (BSIs) are a major cause of mortality in liver transplant recipients. The incidence, microbiology, and outcome of BSIs in the first year after liver transplantation were analyzed in 704 patients who underwent transplantation at a single center between 1997 and 2007. BSIs occurred in 205 (29.1%) of the 704 patients. Overall, 259 episodes were documented, and they resulted in an incidence rate of 36.8%. Of these episodes, 39.4%, 27.8%, 17%, and 15.8% occurred in the very early period (< or = 10 days after liver transplantation), the early period (days 11-30), the intermediate period (days 31-90), and the late period (days 91-365), respectively. The most frequent pathogens were Enterobacteriaceae members (41%), Staphylococcus aureus (19.8%), enterococci (13.1%), Pseudomonas aeruginosa (8.8%), and yeasts (7.1%). The median time of onset ranged from 7 days for methicillin-resistant S. aureus to 25 days for Enterobacteriaceae. Mortality at 15 days after BSIs was 16.2%. Kaplan-Meier survival curves showed that patients with BSIs had a significantly higher 1-year mortality rate than those without BSIs (28.3% versus 16.6%, P < 0.001 with the log-rank test). When the time of BSI onset was considered, 1-year mortality was significantly associated with very early and early episodes (P < 0.001) but not with intermediate and late episodes (P = 0.47). In conclusion, BSIs are frequent and early complications after liver transplantation and are mostly caused by gram-negative bacilli. A BSI in the first posttransplant month is a significant predictor of 1-year survival.

Impact of pretransplant infections on clinical outcomes of liver transplant recipients

Whether pretransplant nonviral infections influence outcomes after transplantation in liver transplant recipients in the current era is not well defined. One hundred consecutive patients undergoing liver transplantation in 2005-2008 were studied. Demographics, posttransplant clinical events, and mortality were compared between recipients with and without infections within 12 months before transplantation. In all, 32% of the patients (32/100) developed 45 episodes of pretransplant infections, which included spontaneous bacterial peritonitis (35.6%), bloodstream infections (28.9%), cellulitis (13.3%), pneumonia (8.9%), urinary tract infections (6.7%), and other infections (6.7%). Compared with 68 recipients without pretransplant infections, those with infections had a higher Model for End-Stage Liver Disease score and a lower likelihood of transplantation from home and required longer and more frequent hospital care before and after transplantation (P < 0.05). Mortality at 90 (9.4% versus 2.9%) and 180 days (15.6% versus 10.3%) post-transplant did not differ significantly between recipients with and without pretransplant infections (P = not significant). A higher Model for End-Stage Liver Disease score (P < 0.05) and posttransplant infections (P < 0.05 and P < 0.001), but not pretransplant infections, were associated with posttransplant mortality at 90 and 180 days. In conclusion, pretransplant infections that have been adequately treated do not pose a significant risk for poor outcomes, including posttransplant mortality.

Carbapenem-resistant Acinetobacter baumannii infections after organ transplantation

Multi-drug resistant (MDR) gram-negative infections among solid organ transplant (SOT) recipients have long been associated with high morbidity and mortality. Acinetobacter baumannii has emerged as a potent nosocomial pathogen with the recent acquisition of resistance to broad-spectrum beta-lactams, aminoglycosides, fluoroquinolones, and most notably, carbapenems. Despite a national rise in carbapenem-resistant A. baumannii (CRAB) infections, outcomes among SOT recipients with this emerging MDR pathogen are largely unknown. This single-center cohort is the first to describe the characteristics, complications, and outcomes among abdominal organ transplant recipients with CRAB. The current study suggests that SOT patients with CRAB suffer from prolonged hospitalization, infection with other MDR organisms, allograft dysfunction and loss, and high overall infection-related mortality.

Multidrug resistant gram-negative bacilli as predominant bacteremic pathogens in liver transplant recipients

BACKGROUND

Bacteremias, which are often caused by gram-negative bacteria, are the most frequently occurring infectious complications after liver transplantation (LT). The aim of this study was to investigate bacteremic incidence, pathogenic spectrum, risk factors for bacteremia due to multidrug resistant (MDR) gram-negative bacilli, and its impact on mortality after LT.

METHODS

A cohort analysis of prospectively recorded data was done in 475 LT recipients, who were divided into 3 categories: cases with gram-negative bacteremia, cases with MDR gram-negative bacteremia, and cases without bacteremia as controls.

RESULTS

In 475 LT recipients, there were 152 (32.0%) patients with gram-negative bacillus bacteremia in the first 6 months after LT. Out of 152 patients, there were 225 bacteremic episodes, which accounted for 69.7% in a total 323 bacteremic episodes. A total of 190 bacteremic episodes were caused by Stenotrophomonas maltophilia, Enterobacteriaceae, Ochrobactrum anthropi, Pseudomonas, and Acinetobacter baumanii, all of which were the most frequent gram-negative isolates in this study, and MDR bacilli constituted 56.3%. The most frequent source was intravascular catheters. There were 70 patients with MDR gram-negative bacillus bacteremia. Independent risk factors for bacteremia due to MDR gram-negative bacillus were as follows: post-LT abdominal infection (P<0.0001, odds ratio [OR] 0.066, 95% confidence interval [CI] 0.019-0.226), post-LT reoperative episodes (P<0.0001, OR 10.505, 95% CI 3.055-36.121), or one or more episodes of acute rejection (P=0.042, OR 4.457, 95% CI 0.988-20.103). In the first 6 months after LT, MDR gram-negative bacillus bacteremia-related mortality was significantly higher than that due to antibiotic-susceptible bacillus (38.6% vs. 14.6%, P<0.001).

CONCLUSION

Post-LT bacteremias caused by MDR gram-negative bacilli are common, and associated with allograft acute rejection, post-LT reoperation, and abdominal infection. The increasing isolates of MDR gram-negative bacilli pose a great challenge for clinical treatment.

Pseudomonas aeruginosa bacteremia over a 10-year period: multidrug resistance and outcomes in transplant recipients

AIM

Transplant recipients are at risk for hospital-acquired infections (HAIs), including those caused by Pseudomonas aeruginosa. Of all HAIs, bloodstream infection (BSI) remains one of the most life-threatening.

METHODS

Over a 10-year period, we studied 503 patients, including 149 transplant recipients, with pseudomonal BSI from the University of Pittsburgh Medical Center. Trends in antimicrobial susceptibility, risk factors for multidrug resistance (MDR), and outcomes were compared between transplant and non-transplant patients.

RESULTS

Resistance to all antibiotic classes was significantly greater in pseudomonal blood culture isolates from transplant compared with non-transplant patients (P<0.001). Of isolates from transplant recipients (n=207), 43% were MDR, compared with 18% of isolates from non-transplant patients (n=391) (odds ratio [OR] 3.47; 95% confidence interval [CI] 2.34-5.14, P<0.001). Among all patients, independent risk factors for MDR P. aeruginosa BSI included previous transplantation (OR 2.38; 95% CI 1.51-3.76, P<0.001), hospital-acquired BSI (OR 2.41; 95% CI 1.39-4.18, P=0.002), and prior intensive care unit (ICU) admission (OR 2.04; 95% CI 1.15-3.63, P=0.015). Mortality among transplant recipients was 42%, compared with 32% in non-transplant patients (OR 1.55; 95% CI 0.87-2.76, P=0.108). For transplant recipients, onset of BSI in the ICU was the only independent predictor of mortality (OR 8.00; 95% CI 1.71-37.42, P=0.008).

CONCLUSIONS

Transplant recipients are at greater risk of MDR P. aeruginosa BSI, with an appreciable mortality. Future management must concentrate on the implementation of effective preventative strategies.

Acquisition of methicillin-resistant Staphylococcus aureus after living donor liver transplantation: a retrospective cohort study

BACKGROUND

The incidence and risk factors of methicillin-resistant Staphylococcus aureus (MRSA) acquisition after living donor liver transplantation (LDLT) are unclear. The aim of the present study was to assess the incidence and to analyze the risk factors for the acquisition of MRSA after LDLT in adults by multivariate analysis.

METHODS

We retrospectively reviewed the data from 158 adult patients that underwent LDLT at the Tokyo University Hospital. The microbiologic and medical records of the patients from admission to 3 months after LDLT were reviewed. Uni- and multivariate analyses were performed to identify the risk factors for postoperative acquisition of MRSA.

RESULTS

Postoperative MRSA acquisition was detected in 35 of 158 patients by median postoperative day 18. Age (>or= 60 y) and perioperative dialysis and/or apheresis predicted postoperative MRSA acquisition by multivariate analysis. In contrast, postoperative use of fluoroquinolone was negatively associated with acquisition of MRSA.

CONCLUSION

MRSA arose early after LDLT in adults with a high incidence (35 of 158 patients). Surveillance culture should be checked periodically after LDLT to identify and prevent the transmission of MRSA.

Pseudomonas aeruginosa infection after living-donor liver transplantation in adults

OBJECTIVES

Pseudomonas aeruginosa infection is a major cause of bacterial infection after deceased-donor liver transplantation. The incidence and risk factors of P. aeruginosa infection after living-donor liver transplantation (LDLT), however, are not known.

METHODS

We retrospectively reviewed the data from 170 adult patients who underwent LDLT at the University of Tokyo Hospital. The microbiologic and medical records of the patients from admission to 3 months after LDLT were reviewed. Uni- and multivariate analyses were performed to identify the independent risk factors for postoperative P. aeruginosa infection.

RESULT

Preoperative P. aeruginosa carriage was identified in 15 (9%) patients. Only 2 of the 15 patients later presented with postoperative P. aeruginosa infection. Postoperative P. aeruginosa infection occurred in 27 (16%) of 170 patients by median postoperative day 38. Among those 27 patients, surgical site infections were recorded in 8 (30%) and intra-abdominal infections in 14 (52%). In 5 of the 27 (19%) patients, P. aeruginosa isolates were multiple antimicrobial resistant. Postoperative bile leakage independently predicted postoperative P. aeruginosa infection.

CONCLUSION

P. aeruginosa infections were frequently detected after LDLT, including those by multiple antimicrobial-resistant isolates. Postoperative bile leakage predisposed patients to P. aeruginosa infection. Surveillance culture should be checked periodically after LDLT to ensure that appropriate antimicrobials can be administered for postoperative infection.

Methicillin-resistant Staphylococcus aureus infection after living-donor liver transplantation in adults

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) infection frequently complicates the postoperative course in deceased-donor liver transplantation. The incidence and risk factors of MRSA infection after Living-donor Liver transplantation (LDLT), however, are unclear.

METHODS

We retrospectively reviewed the data from 242 adult patients who underwent LDLT at the University of Tokyo Hospital. The microbiologic and medical records of the patients from admission to 3 months after LDLT were reviewed. Uni- and multivariate analyses were performed to identify the independent risk factors for postoperative MRSA infection.

RESULTS

Postoperative MRSA infection occurred in 25 of 242 patients by median postoperative day 23. Preoperative MRSA colonization, preoperative use of antimicrobials, operation time (> or =16 h), and postoperative apheresis independently predicted postoperative MRSA infection.

CONCLUSION

Surveillance culture should be checked periodically after admission to identify patients at high risk for MRSA infection and to administer appropriate antimicrobials for perioperative infection. Postoperative apheresis, suggesting postoperative liver dysfunction, predisposed patients to MRSA infection.

Bacteremia in lung transplant recipients in the current era

Current trends in the epidemiology, outcome and variables influencing mortality in bacteremic lung transplant recipients have not been fully described. We prospectively studied bacteremias in lung transplant recipients in a multicenter study between 2000-2004. Bacteremia was documented in 56 lung transplant recipients, an average of 172 days after transplantation. Multiple antibiotic resistance was documented in 48% of the isolates; these included 57% of the Gram-negative and 38% of the Gram-positive bacteria. Pulmonary infection was the most common source of resistant gram-negative bacteremias. Mortality rate at 28 days after the onset of bacteremia was 25% (14/56). Mechanical ventilation and abnormal mental status correlated independently with higher mortality (p < 0.05 for both variables). Bacteremia remains a significant complication in lung transplant recipients and is associated with considerable mortality. Recognition of variables portending a high risk for antibiotic resistance and for poor outcome has implications relevant for optimizing antibiotic prescription and for improving outcomes in lung transplant recipients.

Infections Complicating Solid Organ Transplantation

The requirements for immune suppression after solid organ transplantation increases the risk of infection with a myriad of organisms. There are many unique and evolving aspects of infection after solid organ transplantation. Advances in immunosuppressive therapy and improved protocols for infection prophylaxis have resulted in changes in the timing and clinical presentation of opportunistic infections. Vigilance in the diagnostic evaluation of suspected infection in the solid organ transplant recipient is essential. This article reviews the basic evaluation and treatment options for many of the infectious conditions peculiar to the immunosuppressed patient.

Infections in pediatric solid organ transplant recipients

Despite the progress made in graft and patient survival in recent years, infectious complications remain a major source of morbidity and mortality in pediatric solid organ transplant recipients. The risk of infection after transplant is determined by the interaction of several factors, including age, type of organ transplanted, type and intensity of immunosuppression, environmental exposures, and the consequences of invasive procedures. Compared with adult transplant recipients, children are at higher risk of developing primary infection with various organisms after transplantation, as they often lack previous immunity from natural exposure to many microbes and often have not completed their primary immunization series at the time of transplantation. This article provides an overview of the risk factors, timing, and types of infectious complications associated with organ transplantation in children.

Peritonitis after liver transplantation: Incidence, risk factors, microbiology profiles, and outcome

Peritonitis occurring after liver transplantation (PLT) has been poorly characterized to date. The aims of this study were to define the incidence, risk factors, microbiology profiles, and outcome of nonlocalized PLT. This was a retrospective study of 950 cadaveric liver transplantation (LT) procedures in 837 patients, followed for a mean of 1,086 days (range, 104-2,483 days) after LT. PLT was defined as the presence of at least one positive ascitic fluid culture after LT. There were 108 PLT episodes in 91 patients occurring at a median of 14 days (range, 1-102 days) after LT. Significant risk factors associated with the development of PLT by multivariate analysis included pre-LT model for end-stage liver disease score, duration of LT surgery, Roux-en-Y biliary anastomosis, and renal replacement therapy after LT. Biliary complications, intra-abdominal bleeding, and bowel leak/perforation were associated with 34.3%, 26.9%, and 18.5% of episodes, respectively. Multiple organisms, gram-positive cocci, fungus, and multidrug-resistant bacteria were isolated in 61.1%, 92.6%, 25.9%, and 76.9% of ascitic fluid cultures, respectively. The 28 fungal PLT episodes were associated with bowel leak/perforation and polymicrobial peritonitis. Patients who developed PLT after their first LT had a significantly greater risk of graft loss or mortality compared to unaffected patients. Parameters significantly associated with these adverse outcomes by multivariate analysis were recipient age at LT and bowel leak or perforation after LT. In conclusion, PLT is a serious infectious complication of LT, associated with significant intra-abdominal pathology and reduced recipient and graft survival.

Pretransplant survival is shorter in HIV-positive than HIV-negative subjects with end-stage liver disease

Despite improved survival after liver transplantation (OLTX) in HIV-positive individuals treated with highly active antiretroviral therapy (HAART), some transplant candidates do not survive to OLTX. To determine if pretransplant outcome is related to severity of liver disease and/or HIV infection, we prospectively evaluated 58 consecutive HIV-positive candidates seen at a single center from 1997-2002. Of the 58, 15 (25.9%) were transplanted, whereas 21 (36.2%) died before OLTX, a median one month of evaluation, with more than half of those (12 of 21, 57.1%) dying from infection. By contrast, of 1,359 HIV-negative candidates, 860 (63.3%) were transplanted, whereas 211 (15.5%) died before OLTX (P < 0.001). The cumulative survival following initial evaluation was significantly shorter among HIV-positive than HIV-negative candidates (880 vs. 1,427 days, P = 0.035, Breslow) but was not related to the initial pretransplant MELD score (16 vs. 15), INR (1.5 vs. 1.5), creatinine (1.3 vs. 1.3 mg/dL), or total bilirubin (6.6 vs. 5.7 mg/dL), respectively, all P > 0.05. Among untransplanted HIV-positive candidates, the 21 who died did not differ from the 22 surviving in initial MELD (15 vs. 13), CD4 (230 vs. 327/microL), HIV load (both < 400 copies/mL), HAART intolerance (10/21, 47.6% vs. 10/22, 45.4%), or HCV infection (16/21, 76.2% vs. 16/22, 72.3%), all P > 0.05. Further, the 21 did not differ from the 15 transplanted in pre-OLTX CD4, HIV load, or MELD score, all P > 0.05. In conclusion, pretransplant survival appears shorter in HIV-positive OLTX candidates and is unrelated to severity of liver or HIV disease. Further study is warranted to determine risk factors for poorer pretransplant outcomes.