Bacterial bloodstream infections in liver transplantation: etiologic agents and antimicrobial susceptibility profiles. Transplant Proc. 2012;44:1973-1976. [PMID: 22974885 DOI: 10.1016/j.transproceed.2012.06.055]

Bloodstream infections after solid organ transplantation: clinical epidemiology and antimicrobial resistance (2016-21)

Background

Solid organ transplant (SOT) recipients are at risk of bloodstream infections (BSIs) with MDR organisms (MDROs).

Objectives

To describe the epidemiology of BSI in the year after several types of SOT, as well as the prevalence of MDRO infections in this population.

Methods

We conducted a single-centre, retrospective study of kidney, liver, heart, and multi-organ transplantation patients. We examined BSIs ≤1 year from SOT and classified MDRO phenotypes for Staphylococcus aureus, enterococci, Enterobacterales, Pseudomonas aeruginosa and Candida spp. We compared BSI characteristics between SOT types and determined risk factors for 90 day mortality.

Results

We included 2293 patients [1251 (54.6%) kidney, 663 (28.9%) liver, 219 (9.6%) heart and 160 (7.0%) multi-organ transplant]. Overall, 8.5% of patients developed a BSI. BSIs were most common after multi-organ (23.1%) and liver (11.3%) transplantation (P < 0.001). Among 196 patients with BSI, 323 unique isolates were recovered, 147 (45.5%) of which were MDROs. MDROs were most common after liver transplant (53.4%). The most frequent MDROs were VRE (69.8% of enterococci) and ESBL-producing and carbapenem-resistant Enterobacterales (29.2% and 27.2% of Enterobacterales, respectively). Mortality after BSI was 9.7%; VRE was independently associated with mortality (adjusted OR 6.0, 95% CI 1.7-21.3).

Conclusions

BSI incidence after SOT was 8.5%, with a high proportion of MDROs (45.5%), especially after liver transplantation. These data, in conjunction with local antimicrobial resistance patterns and prescribing practices, may help guide empirical antimicrobial selection and stewardship practices after SOT.

Impact of Invasive Pulmonary Aspergillosis in Critically Ill Surgical Patients with or without Solid Organ Transplantation

BACKGROUND

Critically ill patients, especially those who have undergone solid organ transplantation (SOT), are at risk of invasive pulmonary aspergillosis (IPA). The outcome relevance of adequately treated putative IPA (pIPA) is a matter of debate. The aim of this study is to assess the outcome relevance of pIPA in a cohort of critically ill patients with and without SOT.

METHODS

Data from 121 surgical critically ill patients with pIPA (n = 30) or non-pIPA (n = 91) were included. Cox regression analysis was used to identify risk factors for mortality and unfavourable outcomes after 28 and 90 days.

RESULTS

Mortality rates at 28 days were similar across the whole cohort of patients (pIPA: 31% vs. non-pIPA: 27%) and did not differ in the subgroup of patients after SOT (pIPA: 17% vs. non-pIPA: 22%). A higher Sequential Organ Failure Assessment (SOFA) score and evidence of bacteraemia were identified as risk factors for mortality and unfavourable outcome, whereas pIPA itself was not identified as an independent predictor for poor outcomes.

CONCLUSIONS

Adequately treated pIPA did not increase the risk of death or an unfavourable outcome in this mixed cohort of critically ill patients with or without SOT, whereas higher disease severity and bacteraemia negatively affected the outcome.

Bacteremia in Pediatric Liver Transplant Recipients

BACKGROUND

We aimed to determine the frequency of bacteremia, septic shock and bacterial meningitis in pediatric liver transplant recipients (pLTRs) in the outpatient setting and to identify clinical factors associated with bacteremia.

METHODS

Multicenter retrospective study of pLTRs evaluated in the emergency department or outpatient clinic between 2010 and 2018 for suspected infection, defined as fever ≥38 °C or a blood culture obtained. We excluded patients with nontransplant immunodeficiency, multiorgan transplants or intestinal failure. The primary outcome was bacteremia; secondary outcomes included fluid-refractory septic shock, bacterial meningitis and antibiotic resistance. The unit of analysis was the encounter.

RESULTS

A total of 151 children had 336 encounters for infection evaluation within 2 years of transplant. Of 307 (91.4%) encounters with blood cultures, 17 (5.5%) had bacteremia, with 10 (58.8%) occurring within 3 months of transplant. Fluid-refractory septic shock and bacterial meningitis occurred in 7 out of 307 (2.8%) and 0 out of 307 encounters, respectively. Factors associated with bacteremia included closer proximity to transplant (<3 months) [odds ratio (OR): 3.6; 95% confidence interval (CI): 1.3-9.8; P = 0.01], shorter duration of illness (OR: 4.3; 95% CI: 1.5-12.0; P < 0.01) and the presence of a central venous catheter (CVC) (OR: 12.7; 95% CI: 4.4-36.6; P < 0.01). However, 5 (29.4%) encounters with bacteremia had none of these factors. Among Gram-positive pathogens, 1 out of 7 (14.2%) isolates were resistant to vancomycin. Among Gram-negative pathogens, 3 out of 13 (23.1%) isolates were resistant to 3rd generation cephalosporins.

CONCLUSIONS

Bacteremia was an important cause of infection within 2 years of pLTR. Clinical factors increased the risk of bacteremia. Further, large sample studies should derive multivariable models to identify those at high and low risk of bacteremia to optimize antibiotic use.

The Role of Pretransplant Infections in Pediatric Receiving LDLT in Indonesia: A 7-y Retrospective Study

Liver transplantation is the definitive treatment for pediatric end-stage liver disease. Infections posttransplantation might significantly affect the outcome of the surgery. This study aimed to identify the role of pretransplant infection among children who underwent living donor liver transplantation (LDLT) in Indonesia.

Methods

This is an observational, retrospective cohort study. A total of 56 children were recruited between April 2015 and May 2022. Patients were categorized into 2 according to the presence of pretransplantation infections requiring hospitalization before the surgery. Diagnosis of posttransplantation infection was observed for up to 1 y based on the clinical features and laboratory parameters.

Results

The most common indication for LDLT was biliary atresia (82.1%). Fifteen of 56 patients (26.7%) had a pretransplant infection, whereas 73.2% of patients were diagnosed with a posttransplant infection. There was no significant association between pretransplant and posttransplant infection in all 3-time points (≤1 mo, 2-6 mo, and 6-12 mo). The most common organ involvement posttransplantation was respiratory infections (50%). The pretransplant infection did not significantly affect posttransplant bacteremia, length of stay, duration of mechanical ventilation, initiation of enteral feeding, hospitalization cost, and graft rejection.

Conclusions

Our data showed that pretransplant infections did not significantly affect clinical outcomes in post-LDLT procedures. A prompt and sufficient diagnosis and treatment before and after the LDLT procedure is the best way to obtain an optimal outcome.

High mortality associated with gram-negative bacterial bloodstream infection in liver transplant recipients undergoing immunosuppression reduction

BACKGROUND

Immunosuppression is an important factor in the incidence of infections in transplant recipient. Few studies are available on the management of immunosuppression (IS) treatment in the liver transplant (LT) recipients complicated with infection. The aim of this study is to describe our experience in the management of IS treatment during bacterial bloodstream infection (BSI) in LT recipients and assess the effect of temporary IS withdrawal on 30 d mortality of recipients presenting with severe infection.

AIM

To assess the effect of temporary IS withdrawal on 30 d mortality of LT recipients presenting with severe infection.

METHODS

A retrospective study was conducted with patients diagnosed with BSI after LT in the Department of Liver Surgery, Renji Hospital from January 1, 2016 through December 31, 2017. All recipients diagnosed with BSI after LT were included. Univariate and multivariate Cox regression analysis of risk factors for 30 d mortality was conducted in the LT recipients with Gram-negative bacterial (GNB) infection.

RESULTS

Seventy-four episodes of BSI were identified in 70 LT recipients, including 45 episodes of Gram-positive bacterial (GPB) infections in 42 patients and 29 episodes of GNB infections in 28 patients. Overall, IS reduction (at least 50% dose reduction or cessation of one or more immunosuppressive agent) was made in 28 (41.2%) cases, specifically, in 5 (11.9%) cases with GPB infections and 23 (82.1%) cases with GNB infections. The 180 d all-cause mortality rate was 18.5% (13/70). The mortality rate in GNB group (39.3%, 11/28) was significantly higher than that in GPB group (4.8%, 2/42) (P = 0.001). All the deaths in GNB group were attributed to worsening infection secondary to IS withdrawal, but the deaths in GPB group were all due to graft-versus-host disease. GNB group was associated with significantly higher incidence of intra-abdominal infection, IS reduction, and complete IS withdrawal than GPB group (P < 0.05). Cox regression showed that rejection (adjusted hazard ratio 7.021, P = 0.001) and complete IS withdrawal (adjusted hazard ratio 12.65, P = 0.019) were independent risk factors for 30 d mortality in patients with GNB infections after LT.

CONCLUSION

IS reduction is more frequently associated with GNB infection than GPB infection in LT recipients. Complete IS withdrawal should be cautious due to increased risk of mortality in LT recipients complicated with BSI.

IS

Infections developing in patients undergoing liver transplantation: Recipients of living donors may be more prone to bacterial/fungal infections

BACKGROUND/AIMS

Despite surgical advances in liver transplantation and effective prophylactic strategies, posttransplant infections are the most important cause of morbidity and mortality. Diagnosis and management of infections because of developing immunosuppression is difficult and adversely affects mortality. This study aimed to review bacterial and fungal infections in patients after liver transplantation and to reveal the resistance rates.

MATERIALS AND METHODS

A total of 107 patients who underwent liver transplantation between January 2017 and February 2018 were evaluated retrospectively with regard to demographic characteristics, causes of transplantation, conditions that may lead to infection, postoperative infections, pathogens, and resistance patterns.

RESULTS

Of the 107 patients who underwent liver transplantation, 48 (44.8%) had an infection. Bacterial infections were detected in 41% of the patients, and fungal infections were found in 13%. When we compared living and cadaveric transplants in terms of infection development, these rates were found to be 53% and 33%, respectively (p=0.034). No statistically significant results could be obtained when evaluating conditions such as sex, presence of underlying primary disease, Model for End-Stage Liver Disease MELD score, diabetes status, total parenteral nutrition, and risk factors for infection.

CONCLUSION

After liver transplantation, infections are often seen in the first month of the postoperative period. Knowing the most common pathogens and resistance states in this process reduces infection-related deaths by providing appropriate treatment regimens at the right time.

Poor outcomes of early recurrent post-transplant bloodstream infection in living-donor liver transplant recipients

Bloodstream infection (BSI) is a common complication after living-donor liver transplantation (LDLT). Some patients develop recurrent BSIs. We evaluated the impacts of early recurrent BSIs (ER-BSIs) on outcomes in LDLT recipients. LDLT cases between 2008 and 2016 were included. Early BSI (E-BSI) was defined as a BSI event that occurred within 2 months after LDLT. ER-BSIs were defined as new-onset BSIs within 2 months due to another pathogen at a ≥ 48-h interval or a relapse of BSIs by the same pathogen at a ≥ 1-week interval, with negative cultures in between. The primary objective was evaluating the all-cause mortality of each group of LDLT recipients (90 days and 1 year). The secondary objectives were analyzing associated factors of each all-cause mortality and risk factors for early single BSI and ER-BSI. Among 727 LDLT recipients, 108 patients experienced 149 events of E-BSI with 170 isolated pathogens. Twenty-eight patients (25.9%, 28/108) experienced ER-BSI. The 1-year survival rates of patients without BSI, with early single BSI event, and with ER-BSIs were 92.4%, 81.3%, and 28.6%, respectively. ER-BSI was the most significant risk factor for 1-year mortality (adjusted HR = 5.31; 95% CI = 2.27–12.40). Intra-abdominal and/or biliary complications and early allograft dysfunction were risk factors for both early single BSI and ER-BSI. Interestingly, longer cold ischemic time and recipient operative time were associated with ER-BSI. LDLT recipients with ER-BSI showed very low survival rates accompanied by intra-abdominal complications. Clinicians should prevent BSI recurrence by being aware of intra-abdominal complications.

Blood stream infections in children in the first year after liver transplantation at Wits Donald Gordon Medical Centre, South Africa

Children who undergo liver transplantation and subsequently develop BSI are at risk for adverse outcomes. Research from high-income settings contrasts the dearth of information from transplant centers in low- and middle-income countries, such as South Africa. Therefore, this study from Johannesburg aimed to describe the clinical and demographic profile of children undergoing liver transplantation, and determine the incidence and pattern of BSI and associated risk factors for BSI during the first year after liver transplant. Pediatric liver transplants performed from 2005 to 2014 were reviewed. Descriptive analyses summarized donor, recipient, and post-transplant infection characteristics. Association between BSI and sex, cause of liver failure, age, nutritional status, PELD/MELD score, graft type, biliary complications, and acute rejection was determined by Fisher's exact test; and association with length of stay by Cox proportional hazards regression analysis. Survival estimates were determined by the Kaplan-Meier method. Sixty-five children received one transplant and four had repeat transplants, totaling 69 procedures. Twenty-nine BSI occurred in 19/69 (28%) procedures, mostly due to gram-negative organisms, namely Klebsiella species. Risk for BSI was independently associated with biliary atresia (44% BSI in BA compared to 17% in non-BA transplants; P = .014) and post-operative biliary complications (55% BSI in transplants with biliary complications compared to 15% in those without; P = .0013). One-year recipient and graft survival was 78% (CI 67%-86%) and 77% (CI 65%-85%), respectively. In Johannesburg, incident BSI, mostly from gram-negative bacteria, were associated with biliary atresia and post-operative biliary complications in children undergoing liver transplantation.

Does vancomycin resistance increase mortality in Enterococcus faecium bacteraemia after orthotopic liver transplantation? A retrospective study

BACKGROUND

The relevance of vancomycin resistance in enterococcal blood stream infections (BSI) is still controversial. Aim of this study was to outline the effect of vancomycin resistance of Enterococcus faecium on the outcome of patients with BSI after orthotopic liver transplantation (OLT).

METHODS

The outcome of OLT recipients developing BSI with vancomycin-resistant (VRE) versus vancomycin-susceptible Enterococcus faecium (VSE) was compared based on data extraction from medical records. Multivariate regression analyses identified risk factors for mortality and unfavourable outcomes (defined as death or prolonged intensive care stay) after 30 and 90 days.

RESULTS

Mortality was similar between VRE- (n = 39) and VSE- (n = 138) group after 30 (p = 0.44) or 90 days (p = 0.39). Comparable results occurred regarding unfavourable outcomes. Mean SOFA_Non-GCS score during the 7-day-period before BSI onset was the independent predictor for mortality at both timepoints (HR 1.32; CI 1.14-1.53; and HR 1.18; CI 1.08-1.28). Timely appropriate antibiotic therapy, recent ICU stay and vancomycin resistance did not affect outcome after adjusting for confounders.

CONCLUSION

Vancomycin resistance did not influence outcome among patients with Enterococcus faecium bacteraemia after OLT. Only underlying severity of disease predicted poor outcome among this homogenous patient population.

TRIAL REGISTRATION

This study was registered at the German clinical trials register (DRKS-ID: DRKS00013285).

Effect of Pretransplant Infections on Clinical Outcomes in Live-Donor Liver Transplant Recipients

Owing to impaired immune function, surgical procedures, and multiple hospitalizations, patients with end-stage liver disease are at risk for numerous infectious complications while waiting for transplantation. Infection in transplant recipients remains the main cause of mortality and morbidity, despite advances in surgical techniques and the development of new repressive agents. The purpose of this study is to examine the infections that develop during the pretransplantion period in live donor liver transplant recipients and their effect on post-transplant clinical outcomes. The retrospective analysis of adult live donor liver transplant recipients in the last 4 years was conducted at Ankara University Hospital, a 1900-bed tertiary-care university hospital, in Ankara, Turkey. Demographic characteristics, preoperative infections, and clinical outcomes were analyzed. Patients were divided into 2 groups according to whether they had developed an infection before transplantation. The diagnoses were based on clinical, laboratory, and microbiological findings. Statistical analyses were performed using Stata version 9.0 (StataCorp, College Station, Tex., United States), and P < .05 were considered statistically significant. In univariate analyses, having diabetes mellitus or a pretransplant infection, the number of pretransplant infection attacks, the need for a reoperation, and developing a post-transplant infection were the statistically significant factors associated with 1-year mortality (P < .001, χ² test). In multivariate analyses, diabetes mellitus (Odds ratio [OR] = 7.44, 95% confidence interval [CI], .03-45.79; P = .013), reoperation (OR = .33, 95% CI, .25-2.20; P < .001), having a pretransplantation infection (OR = 12.47, 95% CI, .011-87.67; P = .013), and the number of pretransplantation infection attacks (OR = .028, 95% CI, .013-.47; P < .001) were found to be statistically significant risk factors for 1-year mortality. Our study showed the effect of pretransplantation infections on post-transplant morbidity but not on rejection or mortality. According to the situation of patients, manageable pretransplantation infection is not an absolute contraindication for liver transplantation. Awareness of the increased risk for post-transplant infections and fast-acting antimicrobial coverage are the most important facts for patient survival.

Bloodstream Infections in Early Postsurgery Liver Transplant: An Analysis of 401 Patients Over 10 Years

Bloodstream infections are a major factor contributing to morbidity and mortality following liver transplantation. The increasing occurrence of multidrug-resistant bloodstream infections represents a challenge for the prevention and treatment of those infections. The aim of this study was to evaluate the occurrence and microbiological profile of bloodstream infections during the early postoperative period (from day 0 to day 60) in patients undergoing liver transplantation from January 2005 to June 2016 at the State University of Campinas General Hospital. A total of 401 patients who underwent liver transplantation during this period were included in the study. The most common cause of liver disease was hepatitis C virus cirrhosis (34.01%), followed by alcoholic disease (16.24%). A total of 103 patients had 139 microbiologically proven bloodstream infections. Gram-negative bacteria were isolated in 63.31% of the cases, gram-positive bacteria in 28.78%, and fungi in 7.91%. Fifty-six infections (43.75%) were multidrug-resistant bacteria, and 72 (56.25%) were not. There was no linear trend concerning the occurrence of multidrug-resistant organisms throughout the study period. Patients with multidrug-resistant bloodstream infections had a significantly lower survival rate than those with no bloodstream infections and those with non-multidrug-resistant bloodstream infections. In conclusion, the occurrence of bloodstream infections during the early postoperative period was still high compared with other profile patients, as well as the rates of multidrug-resistant organisms. Even though the occurrence of multidrug resistance has been stable for the past decade, the lower survival rates associated with that condition and the challenge related to its treatment are of major concern.

Pseudomonas aeruginosa bacteremia among liver transplant recipients

Pseudomonas aeruginosa bacteremia remains as a life-threatening complication after liver transplantation (LT) and is intractable because of the high rate of drug resistance to commonly used antibiotics. To better understand the characteristics of this postoperative complication, PubMed and Embase searches as well as reference mining was done for relevant literature from the start of the databases through August 2018. Among LT recipients, the incidence of P. aeruginosa bacteremia ranged from 0.5% to 14.4% and mortality rates were up to 40%. Approximately 35% of all episodes of bloodstream infections (BSIs) were P. aeruginosa bacteremia, of which 47% were multidrug resistant and 63% were extensively drug resistant. Several factors are known to affect the mortality of LT recipients with P. aeruginosa bacteremia, including hypotension, mechanical ventilation, and increasing severity of illness. In LT recipients with P. aeruginosa bacteremia, alteration in DNA gyrase A genes and overexpression of proteins involved in efflux systems, namely the expression of KPC-2-type carbapenemase, NDM-1, and VIM-2-type MBL, contribute to the high resistance of P. aeruginosa to a wide variety of antibiotics. Because of complicated mechanisms of drug resistance, P. aeruginosa causes high morbidity and mortality in bacteremic LT patients. Consequently, early detection and treatment with adequate early targeted coverage for P. aeruginosa BSI are of paramount importance in the early posttransplantation period to obtain a better prognosis for LT patients.

Early Bacterial Pneumonia After Hepatic Transplantation: Epidemiologic Profile

BACKGROUND

Postoperative pulmonary complications are major cause of morbidity and mortality in patients receiving liver transplantation (LT), particularly bacterial pneumonia occurring within the first 100 days after transplantation. Our aim in this study was to determine the incidence, microorganisms involved, associated factors, and morbidity of bacterial pneumonia presenting in the first 100 days posttransplant.

METHODS

We performed a cohort study in which patients receiving liver transplantation were included prospectively in our national database (Database of Infections in Transplantation of Solid Organs). The study period was from July 14, 2009 to July 24, 2015.

RESULTS

One hundred six patients were transplanted during the 6-year period. We documented 9 bacterial pneumonia cases with an incidence of 8.5 per 100 patients; 2 patients had hospital-acquired pneumonia (HAP) and 7 had ventilator-associated pneumonia (VAP). In 4 of the 9 bacterial pneumonia cases, patients presented with bacteremia. Eleven microorganisms were isolated these 9 patients. Microbiologic diagnosis methods included 5 cases of alveolar bronchoalveolar lavage (BAL), 1 case of BAL and pleural fluid puncture, 1 case of pleural fluid puncture, and 1 case through sputum study. Of the 11 isolated organisms, 9 corresponded to Gram-negative bacilli (GNB): Klebsiella spp, n = 3; Acinetobacter baumannii, n = 4; Morganella morganii, n = 1; and Pseudomonas aeruginosa, n = 1. Regarding the resistance profile, 7 presented with a multiresistance profile (MDR) and extreme resistance (XDR). Univariate analysis identified the Model for End-Stage Liver Disease (MELD) pretransplant score as a factor associated with developing pneumonia (P < .001, 95% confidence interval [CI] 2.872-10.167), and early extubation, before 8 hours posttransplant, as a protective factor (P = .008; relative risk [RR] 0.124; 95% CI 0 .041-0.377). Hospital stay was longer in patients with pneumonia compared to those without pneumonia (P < .0001, 95% CI 17.79-43.11 days). There was also an increased risk of death in patients with pneumonia (RR 17.963; 95% CI 5106-63,195).

CONCLUSIONS

Early bacterial pneumonia after hepatic transplantation is associated with higher morbidity and mortality. At our center, 4 of 9 patients had bacteremia. GNB cases with MDR and XDR profiles are predominant. Early extubation is a protective factor.

Epidemiology, susceptibility, and risk factors for acquisition of MDR/XDR Gram-negative bacteria among kidney transplant recipients with urinary tract infections

Background

Multiple drug resistant/extensively drug resistant (MDR/XDR) Gram-negative urinary tract infections (UTIs) represent a growing threat to kidney transplant recipients. This retrospective study aimed to assess the incidence and microbiological profile of MDR/XDR Gram-negative UTIs, to identify drug susceptibility of MDR/XDR bacteria, and to determine the potential risk factors for MDR/XDR UTIs in kidney recipients.

Materials and methods

During the study period, 1569 patients underwent consecutive kidney transplantation in two transplantation centers. We studied the demographics, clinical characteristics, and urine culture data from kidney recipients with MDR/XDR Gram-negative UTIs, and verified the risk factors associated with MDR/XDR infections.

Results

Eighty-one kidney recipients yielded 88 episodes of MDR/XDR Gram-negative UTIs with five patients (6.2%) succumbing to all-cause in-hospital mortality. The most frequently isolated bacterium was Escherichia coli (62.5%). Almost all MDR/XDR Gram-negative bacteria were resistant to first- and second-generation cephalosporin, and monocyclic beta-lactam. They were relatively sensitive to meropenem, amikacin, and tigecycline. As for the 12 XDR bacteria, all of them were resistant to meropenem and 25% of them were resistant to tigecycline. All XDR Acinetobacter baumannii and E. coli were susceptible to tigecycline. Nosocomial infection (odds ratio [OR] = 11.429, 95% CI = 1.311–99.625, P = 0.027) was the only independent predictor of MDR/XDR Gram-negative UTIs. Non-fermenting bacterial infection (OR = 20.161, 95% CI = 3.409–119.240, P = 0.001), polycystic kidney disease (OR = 39.871, 95% CI = 1.979–803.384, P = 0.016), and serum creatinine level > 1.5 mg/dL (OR = 8.688, 95% CI = 1.354–55.747, P = 0.023) were significantly different between XDR and MDR Gram-negative UTIs.

Conclusion

Meropenem, amikacin, and/or tigecycline can be prescribed for MDR/XDR Gram-negative infections. Tigecycline can also be prescribed for XDR A. baumannii and E. coli. Nosocomial infection was a risk factor for MDR/XDR Gram-negative UTIs, while XDR UTIs were associated with non-fermenting bacterial infection, polycystic kidney disease, and impaired renal function.

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.

Characteristics and Risk Factors of Late-onset Bloodstream Infection Beyond 6 Months After Liver Transplantation in Children

BACKGROUND

Bloodstream infection (BSI) is a major cause of morbidity and mortality after pediatric liver transplantation (LT). However, most studies have focused on BSI occurring within a few months after LT. In this study, we evaluated the characteristics of BSI occurring beyond 6 months after pediatric LT.

METHODS

We conducted a retrospective cohort study at a pediatric LT center in Japan from November 2005 to March 2016. We evaluated the causative organisms and site of late-onset BSI in children ≤ 18 years of age. The risk factors for developing late-onset BSI and the associations of late-onset BSI with long-term outcomes were also evaluated.

RESULTS

Three hundred forty cases of LT were evaluated. Thirty-eight BSI developed in 29 (9%) LT recipients. There were 42 organisms (nine Gram-positive cocci, 33 Gram-negative rods) isolated from the blood cultures of recipients with late-onset BSI. The most frequent sites of late-onset BSI was intraabdominal infection (18/38; 47%). There were also 14 (39%) episodes with no apparent focus. In multivariate analysis, a prolonged operative time > 12 hours (odds ratio [OR] = 3.55; P = 0.04) and biliary stenosis (OR = 4.60; P = 0.006) were independent risk factors for developing late-onset BSI. Late-onset BSI was associated with increased retransplantation rate (P = 0.04) and mortality (P < 0.001).

CONCLUSION

Late-onset BSI developed in 9% of recipients after pediatric LT. Gram-negative rods accounted for the majority of late-onset BSI as a consequence of abdominal infection, but the focus was often unclear. Prolonged operative time at LT and biliary stenosis were independent risk factors for developing late-onset BSI.

Early infections in the intensive care unit after liver transplantation-etiology and risk factors: A single-center experience

BACKGROUND

Infectious complications represent one of the main causes of perioperative morbidity and mortality of liver transplant recipients. The primary objective of this retrospective observational study was to evaluate incidence and etiology of early (within 1 month from surgery and occurring in the intensive care unit [ICU]) postoperative infections as well as donor- and recipient-related risk factors.

METHODS

The data of 280 patients undergoing 299 consecutive liver transplant procedures from January 2012 to December 2015 were extracted from the Italian ICU registry database and hospital registries. Perioperative risk factors, etiology of infections, and antibiotic susceptibility of isolated microorganisms were taken into consideration.

RESULTS

Global incidence of postoperative infections was 21%. Pneumonia was the most frequent infection and, globally, gram-negative bacteria were the most common agents. Septic shock was present in 22% of infection cases and hospital mortality was higher in patients with postoperative infection. Preoperative chronic obstructive pulmonary disease, malnutrition, preoperative ascites, encephalopathy, and early re-transplantation were significantly associated to post orthotopic LT infections.

CONCLUSION

Infections represent a major cause of early postoperative morbidity and mortality. The impact of single risk factors and the results of their preoperative management should be further investigated in order to reduce the incidence and evolution of postoperative infections.

Incidence of cross infection in liver transplant patients. Risk factors and role of nursinge

OBJECTIVE

To determine the incidence and risk factors of infection in liver transplant recipients immediately post-transplant, during admission to a liver transplant unit during the immediate post-transplant admission.

METHODOLOGY

Descriptive, prospective study performed in the Liver Transplant Unit of Hospital Clínic, Barcelona. All liver transplant recipients between January 2012 and August 2015 (n=241) were included. Statistical analysis was performed with R Commander. Variables were compared with Chi-square and Student's t-test. A value of p≤.05 was considered significant.

RESULTS

The incidence of infection was 34.8%. The most frequent infections were bacterial (75.3%), particularly urinary infections (34.6%) caused by Escherichia coli and Klebsiella pneumoniae. Independent risk factors for the development of bacterial infections according to multivariate analysis were sex, age and length of hospital stay.

CONCLUSIONS

Infections are a significant problem in the early post-transplant period, and are associated with longer hospitalisation periods. The role of nursing in preventing infections, by identifying risk factors, correctly applying nursing protocols in insertion, maintenance and early withdrawal of medical devices and fulfilling hand hygiene, is essential.

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.

Adjuvant Antibiotic Activity of Acidic Sophorolipids with Potential for Facilitating Wound Healing

The sophorolipid class of biosurfactants is finding increasing use in personal care as well as pharmaceutical products and has the potential to disrupt biofilm formation and inhibit the growth of a variety of clinically relevant organisms. In order to investigate potential biomedical applications of sophorolipids derived from nonpathogenic organisms, we fractionated and purified glycolipid biosurfactant sophorolipids produced by the yeast Starmerella bombicola, which yielded nonacetylated acidic C_18:1 congeners that were essentially free from other contaminants (>95% purity). These acidic sophorolipids have antimicrobial activities against the nosocomial infective agents Enterococcus faecalis and Pseudomonas aeruginosa, with significant reductions in CFU at concentrations of as low as 5 mg ml^-1 In addition, the sophorolipid showed similar effects against the same two bacterial strains when combined with kanamycin or cefotaxime. As a potential use of these sophorolipids is as a component of topically applied creams for the treatment of wound infections, it is clear that they must have no demonstrable adverse effect on wound healing. To assess this, we evaluated mammalian cell toxicity in vitro using viability tests, which revealed no adverse effect on either endothelial or keratinocyte-derived cell lines with sophorolipid concentrations of < 0.5 mg ml^-1 In addition, in vivo experiments using a mouse skin wounding assay revealed that the time course of healing wounds was unaffected by the application of sophorolipid-containing creams, and histological examination of regenerated skin tissue confirmed that the healing process was similar to that observed for control animals, with no evidence of inflammation. These results are consistent with the suggestion that acidic sophorolipids can be used as a component of antimicrobial creams to reduce the risk of wound infection during healing.

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.

Infectious agents after liver transplant: etiology, timeline and patients' cell-mediated immunity responses

Infections continue to be one of the leading causes of morbidity and mortality in liver transplant recipients. We retrospectively reviewed the symptomatic infectious episodes that occurred during the first year post-transplant to determine time of onset, causative pathogens and cell-mediated immunity response patterns. Ninety-eight of the 202 (48.5%) recipients enrolled developed at least one infectious episode. The total number of infectious episodes was 135: 77 (57.1%) bacterial, 45 (33.3%) viral and 13 (9.6%) fungal. The most frequently isolated bacteria were Escherichia coli (21 isolates) and Klebsiella pneumoniae (19 isolates). Overall, extended-spectrum beta lactamase-producing and methicillin-resistant organisms were responsible for 29 (29/77; 37.7%) infectious episodes. Members of the herpes virus group, in particular cytomegalovirus (34/45 viral infections, 75.5%), were detected. Candida species (9 isolates) followed by Aspergillus species (4 isolates) were isolated. The majority of infections (63%) occurred during the early post-transplant phase (<1 month), whereas only 8/135 episodes (5.9%) were detected after the sixth month (late phase). Significantly lower median ImmuKnow^® intracellular ATP values in patients who developed bacterial and fungal infections compared to infection-free patients were observed (P < 0.0001 and P = 0.0016, respectively), whereas patients who developed a viral infection had a median intracellular ATP level not statistically different compared to uninfected patients (P = 0.4). Our findings confirm that bacteria are responsible for the majority of symptomatic infections and occur more frequently during the first month post-transplant. The ImmuKnow^® measurements can be a useful tool for identifying patients at high risk of developing infection, particularly of fungal and bacterial etiology.

The Distribution and Resistance of Pathogens Among Solid Organ Transplant Recipients with Pseudomonas aeruginosa Infections

Background

Pseudomonas aeruginosa infection remains a life-threatening complication after solid organ transplantation (SOT). We aimed to investigate the distribution and drug susceptibility of pathogens, and clinical characteristics of SOT recipients with Pseudomonas aeruginosa infections.

Material/Methods

A total of 55 SOT recipients who developed 61 episodes of Pseudomonas aeruginosa infections between January 1, 2003 and July 31, 2015 were retrospectively analyzed. The distribution and the drug susceptibility of Pseudomonas aeruginosa were reviewed.

Results

The most common site from which 61 Pseudomonas aeruginosa rods were isolated were the lungs (57.4%, n=37), followed by the blood (27.9%, n=17). There were 35, 18, and 9 recipients accompanied with a serum creatinine level of >1.5 mg/dL, lymphocyte count of <300/mm³, and a serum albumin level of <30 g/L, respectively. Seven patients each presented with white blood cell count of >15 000/mm³ and platelet count of <50 000/mm³. There were 6 (10.9%) cases of septic shocks and 18 (32.7%) deaths. Antibiotic resistance rate of all Pseudomonas aeruginosa to 4 of 10 antibiotics investigated was more than 50%. Of these 61 Pseudomonas aeruginosa isolates, 47.5% were carbapenem-resistant. The rods were relatively sensitive to piperacillin-tazobactam, levofloxacin, amikacin, and cefoperazone-sulbactam (resistance rate <40%).

Conclusions

The clinical presentation of Pseudomonas aeruginosa infections included high body temperature, decreased platelet count, elevated white blood cell count, a high nosocomial origin and mortality, and onset in the late period after transplantation. According to our findings, piperacillin-tazobactam, levofloxacin, amikacin, and cefoperazone-sulbactam, alone or combination, are recommended to treat SOT recipients with Pseudomonas aeruginosa infections.

Rapid Detection of Bloodstream Pathogens in Liver Transplantation Patients With FilmArray Multiplex Polymerase Chain Reaction Assays: Comparison With Conventional Methods

BACKGROUND

Bloodstream infection (BSI) is an important concern in transplant patients. Early intervention with appropriate antimicrobial therapy is critical to better clinical outcome; however, there is significant delay when conventional identification methods are used.

METHODS

We aimed to determine the diagnostic performance of the FilmArray Blood Culture Identification Panel, a recently approved multiplex polymerase chain reaction assay detecting 24 BSI pathogens and 3 resistance genes, in comparison with the performances of conventional identification methods in liver transplant (LT) patients. A total of 52 defined sepsis episodes (signal-positive by blood culture systems) from 45 LT patients were prospectively studied.

RESULTS

The FilmArray successfully identified 37 of 39 (94.8%) bacterial and 3 of 3 (100%) yeast pathogens in a total of 42 samples with microbial growth, failing to detect only 2 of 39 (5.1%) bacterial pathogens that were not covered by the test panel. The FilmArray could also detect additional pathogens in 3 samples that had been reported as having monomicrobial growth, and it could detect Acinetobacter baumannii in 2 samples suspected of skin flora contamination. The remaining 8 blood cultures showing a positive signal but yielding no growth were also negative by this assay. Results of MecA, KPC, and VanA/B gene detection were in high accordance. The FilmArray produced results with significantly shorter turnaround times (1.33 versus 36.2, 23.6, and 19.5 h; P < .05) than standard identification methods, Vitek II, and Vitek MS, respectively.

CONCLUSIONS

This study showed that the FilmArray appeared as a reliable alternative diagnostic method with the potential to mitigate problems with protracted diagnosis of the BSI pathogens in LT patients.

Predictors of shock and mortality in solid organ transplant recipients with bacteremia caused by non-lactose-fermenting gram-negative bacilli

BACKGROUND

More data on bacteremia due to non-lactose fermenting gram-negative bacilli (NLF GNB) in solid organ transplant (SOT) recipients are needed. We aimed to investigate the epidemiology, microbiology, and risk factors for mortality and septic shock due to NLF GNB bacteremia in SOT recipients.

METHODS

We performed a retrospective, double-center study over a 12-year study period. The risk factors for mortality and septic shock in SOT recipients with NLF GNB bacteremia were assessed with multivariate logistic regression analysis.

RESULTS

A total of 230 episodes of bloodstream infections (BSIs) occurred in 159 SOT recipients. Fifty episodes of NLF GNB bacteremia were detected in 47 SOT recipients, with a predominance of Acinetobacter baumanii (27 isolates, 54.0%). The antibiotic resistance rate of all NLF GNB to 10 of 12 antibiotics investigated was more than 50%. The independent risk factors associated with septic shock were platelet count < 50 000/mm(3) (odds ratio (OR) = 14.41, 95% confidence interval (CI) = 2.64-78.71, p = 0.002) and late-onset bacteremia (time of onset more than 2 months post-transplant) (OR = 10.87, 95% CI = 1.79-65.89, p = 0.009). Lung focus (OR = 32.91, 95% CI = 2.56-423.18, p = 0.007) and septic shock (OR = 70.38, 95% CI = 4.21-1176.21, p = 0.003) were risk factors for bacteremia-related mortality.

CONCLUSIONS

The drug resistance of the pathogens and the morbidity and mortality rates of NLF GNB bacteremia were high in SOT recipients. For septic shock, associated risk factors were thrombocytopenia and late-onset bacteremia. The risk factors significantly associated with mortality were lung focus and septic shock.

The Bacteremia Caused by Non-Lactose Fermenting Gram-Negative Bacilli in Solid Organ Transplant Recipients

BACKGROUND

Blood stream infections (BSIs) remain as a serious life-threatening condition after solid organ transplant (SOT). In recent years, a progressive growth in the incidence of bacteremia caused by non-lactose fermenting gram-negative bacilli (NLF GNB) has been observed. NLF GNB led to high mortality among SOT recipients with bacteremia and were difficult to treat because of their high drug resistance to commonly used antibiotics.

METHODS

Two electronic databases, PUBMED and EMBASE, were searched for relevant literature published up to January 2015, to better understand the characteristics of bacteremia because of NLF GNB.

RESULTS

The morbidity and mortality rates of bacteremia because of NLF GNB depend on the types of organisms and transplantation. Multi-drug resistant NLF GNB ranged from 9.8% to 12.5% of all NLF GNB causing BSIs among SOT recipients. Certain factors can predispose SOT recipients to NLF GNB bacteremia, which included previous transplantation, hospital-acquired BSIs, and prior intensive care unit admission. Combination therapy may be beneficial in the treatment of NLF GNB bacteremia to enhance antimicrobial activity, provide synergistic interactions, relieve side effects, and minimize superinfections.

CONCLUSIONS

Prevention is pivotal in minimizing the morbidity and mortality associated with NLF GNB bacteremia after SOT. To improve the outcomes of SOT recipients with NLF GNB bacteremia, prevention is pivotal, and combination therapy of antibiotics may be beneficial.

Distribution and resistance of pathogens in liver transplant recipients with Acinetobacter baumannii infection

BACKGROUND

Drug-resistant Acinetobacter baumannii has become a major problem in liver transplant recipients. The aim of this study was to investigate the clinical presentation, distribution, and drug susceptibility characteristics in liver recipients with A. baumannii infection.

METHODS

We retrospectively investigated 17 liver recipients who developed A. baumannii infection between January 1, 2007 and December 31, 2014. The distribution of A. baumannii and drug susceptibility characteristics were reviewed.

RESULTS

Infectious complications due to A. baumannii appeared in 17 liver recipients, with a total of 24 episodes. Approximately 63% (15/24) of A. baumannii infections occurred within 2 weeks after transplantation. The most common source of infection was multiple culture-positive sites (35.3%, n=6), followed by the intra-abdominal/biliary tract (23.5%, n=4) and lung (23.5%, n=4). Eight patients (47.1%) had a body temperature of 38°C or higher at the onset of A. baumannii infection. Nine, seven, and 12 recipients had a serum creatinine level of >1.5 mg/dL, a white blood cell count of >15,000/mm(3), and a platelet count of <50,000/mm(3), respectively. There were five (29.4%) cases of septic shock and eight (47.1%) deaths. The rate of antibiotic resistance of A. baumannii to ten of 12 antibiotics investigated was more than 60%. Among the 24 infections caused by A. baumannii, 75% were carbapenem-resistant. The rods were relatively sensitive to tigecycline and cefoperazone-sulbactam.

CONCLUSION

The clinical manifestations of A. baumannii infection included a high body temperature, a decreased platelet count, an elevated white blood cell count, and onset in the early period after transplantation as well as high mortality. The antibiotic resistance rate of A. baumannii was extremely high. Prevention measures and combination antibiotic therapy are needed to improve the outcomes of liver recipients with A. baumannii infections.

Distribution and resistance of pathogens in liver transplant recipients with Acinetobacter baumannii infection

Background

Drug-resistant Acinetobacter baumannii has become a major problem in liver transplant recipients. The aim of this study was to investigate the clinical presentation, distribution, and drug susceptibility characteristics in liver recipients with A. baumannii infection.

Methods

We retrospectively investigated 17 liver recipients who developed A. baumannii infection between January 1, 2007 and December 31, 2014. The distribution of A. baumannii and drug susceptibility characteristics were reviewed.

Results

Infectious complications due to A. baumannii appeared in 17 liver recipients, with a total of 24 episodes. Approximately 63% (15/24) of A. baumannii infections occurred within 2 weeks after transplantation. The most common source of infection was multiple culture-positive sites (35.3%, n=6), followed by the intra-abdominal/biliary tract (23.5%, n=4) and lung (23.5%, n=4). Eight patients (47.1%) had a body temperature of 38°C or higher at the onset of A. baumannii infection. Nine, seven, and 12 recipients had a serum creatinine level of >1.5 mg/dL, a white blood cell count of >15,000/mm³, and a platelet count of <50,000/mm³, respectively. There were five (29.4%) cases of septic shock and eight (47.1%) deaths. The rate of antibiotic resistance of A. baumannii to ten of 12 antibiotics investigated was more than 60%. Among the 24 infections caused by A. baumannii, 75% were carbapenem-resistant. The rods were relatively sensitive to tigecycline and cefoperazone-sulbactam.

Conclusion

The clinical manifestations of A. baumannii infection included a high body temperature, a decreased platelet count, an elevated white blood cell count, and onset in the early period after transplantation as well as high mortality. The antibiotic resistance rate of A. baumannii was extremely high. Prevention measures and combination antibiotic therapy are needed to improve the outcomes of liver recipients with A. baumannii infections.

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.

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.

Surveillance of bacterial and fungal infections in the postoperative period following liver transplantation: a series from 2005-2011

Orthotopic liver transplantation (OLT) is a life-saving procedure for the treatment of many end-stage diseases, but infectious and acute rejection episodes remain major causes of morbidity and mortality. Bacterial and fungal infections can be due to intra-abdominal, biliary, respiratory, urinary, wound, central venous catheters (CVC) or unknown sources. Using the computerized database of our microbiology laboratory, we analyzed all the bacterial and fungal infections in the first three months following OLT among 151 consecutive adult recipients at single center between January 2005 and December 2011. Samples included blood, bile CVC, urine, and bronchoalveolar lavage (BAL) specimen. Culture and identification of the isolated microorganisms was done in accordance with standard microbiological procedures. Three hundred thirteen samples from the above sites showed positive results for gram-positive cocci (n = 137; 43.8%), gram-negative rods (n = 156; 49.8%), and Candida species (n = 19; 6.1%). One patient (0.3%) experienced a CVC-related infection caused by Fusarium oxysporum. Bacterial and particularly biliary tract infections seem to play major roles in morbidity and mortality in the first three months following OLT. The major contributors to patient morbidity and mortality were candidemia and/or invasive candidiasis mainly from the biliary tract and/or CVC-related infections.

Bacterial biliary tract infections in liver transplant recipients

PURPOSE OF REVIEW

The purpose of this study is to provide an overview of bacterial biliary tract infections in liver transplant recipients with a focus on pathogenesis and conservative treatment strategies.

RECENT FINDINGS

The development of interventional endoscopic and radiologic interventions has improved the outcome of conservative treatments for bile tract strictures and bilomas. However, recent data show an important rise of infections with multidrug-resistant (MDR) pathogens in liver transplant recipients.

SUMMARY

Both recurrent cholangitis and infected bilomas are bacterial biliary tract infections in liver transplant recipients responsible for significant morbidity and graft loss, which require a multidisciplinary approach. Risk factors for biliary tract strictures and bilomas formation have recently been identified. With the improved outcome of a conservative management including prolonged and/or recurrent antibiotic treatments, the risk of selecting resistant pathogens is increased. There is an urgent need to develop new strategies to reduce the risk of secondary infections by MDR isolates in liver transplant recipients.

Bacterial infection after liver transplantation

Infectious complications are major causes of morbidity and mortality after liver transplantation, despite recent advances in the transplant field. Bacteria, fungi, viruses and parasites can cause infection before and after transplantation. Among them, bacterial infections are predominant during the first two months post-transplantation and affect patient and graft survival. They might cause surgical site infections, including deep intra-abdominal infections, bacteremia, pneumonia, catheter-related infections and urinary tract infections. The risk factors for bacterial infections differ between the periods after transplant, and between centers. Recently, the emergence of multi-drug resistant bacteria is great concern in liver transplant (LT) patients. The instructive data about effects of infections with extended-spectrum beta lactamase producing bacteria, carbapenem-resistant gram-negative bacteria, and glycopeptide-resistant gram-positive bacteria were reported on a center-by-center basis. To prevent post-transplant bacterial infections, proper strategies need to be established based upon center-specific data and evidence from well-controlled studies. This article reviewed the recent epidemiological data, risk factors for each type of infections and important clinical issues in bacterial infection after LT.

A non-interventional study of the genetic polymorphisms of NOD2 associated with increased mortality in non-alcoholic liver transplant patients

Background

Infections after liver transplantation are the main cause of death in the first year. Recent reports indicate that NOD2 gene mutations increase the risk for inflammatory bowl disease and the severity of graft-versus-host disease in bone marrow transplant patients. Data on polymorphisms in liver transplant patients are sparse. We analyzed 13 single-nucleotide polymorphisms (SNPs) of 13 different gene variants including the SNPs of NOD2 genes from liver recipients. The aim of the study was to evaluate the impact of the SNPs on dialysis-dependent kidney failure, the incidence of infections and patient survival.

Methods

During a period of 20-months, 231 patients were recruited in this non-interventional, prospective study. Thirteen different SNPs and their impact on the patients’ survival, infection rate, and use of dialysis were assessed.

Results

NOD 2 wildtype genes were protective with respect to the survival of non-alcoholic, cirrhotic transplant patients (3 year survival: 66.8% wildtype vs. 42.6% gene mutation, p = 0.026). This effect was not observed in alcoholic transplant recipients.

The incidence of dialysis-dependent kidney failure and infection in the liver transplant patients was not influenced by NOD 2 gene polymorphisms. No effect was noted in the remaining 12 SNPs.

Patients with early allograft dysfunction experienced significantly more infections, required dialysis and had significantly worse survival.

In contrast, the donor-risk-index had no impact on the infection rate, use of dialysis or survival.

Conclusion

NOD2 gene variants seem to play a key role in non-alcoholic, liver transplant recipients. However these data should be validated in a larger cohort.

Clinical characteristics of infections in humans due to Staphylococcus epidermidis

Staphylococcus epidermidis is the most common cause of primary bacteremia and infections of indwelling medical devices. The ability to cause disease is linked to its natural niche on human skin and ability to attach and form biofilm on foreign bodies. This review focuses on the S. epidermidis clinical syndromes most commonly encountered by clinicians and future potential treatment modalities.

Impacts of pretransplant infections on clinical outcomes of patients with acute-on-chronic liver failure who received living-donor liver transplantation

Background

Liver transplantation is the only therapeutic modality for patients with acute-on chronic liver failure (ACLF). These patients are at high risk for bacterial infections while awaiting transplantation. The aim of this study was to elucidate whether an adequately treated bacterial infection influences the outcomes after transplantation in this patient population.

Methodology/Principal Findings

54 recipients (median age, 49.5 years [range, 22–60]) of adult-to-adult living donor liver transplant (LDLT) for ACLF were categorized as those with pretransplant infection (Group 1, n = 34) or without pretransplant infection (Group 2, n = 20) for retrospective analyses. With the exception of a higher male-female ratio (P = 0.046) and longer length of pretransplant hospital stay (P = 0.026) in Group 1, similar demographic, laboratory and clinical features were found in both groups. Patients in Group 1 (totally 42 pretransplant infection episodes) were adequately treated with effective antibiotic(s) before receiving LDLT. All included patients were followed up until one year after transplantation or death. Sixty-one posttransplant infection episodes were found in an overall of 44 ACLF patients (27 in Group 1 vs. 15 in Group 2; P = 0.352). Frequently encountered posttransplant infections were intraabdominal infection, pneumonia, bloodstream infection and urinary tract infection. Two patients died in each group (P = 0.622). No significant difference was found in the length of posttransplant ICU stay, and in one-year survival, graft rejection, and posttransplant infection rate between both groups. The longer overall hospital stay (mean day, 89.0 vs. 65.5, P = 0.024) found in Group 1 resulted from a longer pretransplant hospital stay receiving treatment for pretransplant infection(s) and/or awaiting transplantation.

Conclusions

These data suggested that an adequately treated pretransplant infection do not pose a significant risk for clinical outcomes including posttransplant fatality in recipients in adult-to-adult LDLT for ACLF.

Current status of research on enterogenic infection following liver transplantation

Since the introduction of the Milan criteria in 1996, liver transplantation has become a standard therapy for end-stage liver diseases and hepatocellular carcinoma. In recent years, liver transplantation has developed greatly. Survival rates after liver transplantation have markedly improved as a result of improved operative techniques, use of immunosuppressants, etc. But infection, especially enterogenic infection, is still the most disturbing complication in patients undergoing liver transplantation. This article gives an overview of infection after liver transplantation and focuses on the discussion of enterogenic infection in terms of its pathophysiology, risk factors, outcome, diagnosis and treatment.