Vancomycin-resistant Enterococcus in liver transplant patients

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.

The Role of Microbiota in Liver Transplantation and Liver Transplantation-Related Biliary Complications

Liver transplantation as a treatment option for end-stage liver diseases is associated with a relevant risk for complications. On the one hand, immunological factors and associated chronic graft rejection are major causes of morbidity and carry an increased risk of mortality due to liver graft failure. On the other hand, infectious complications have a major impact on patient outcomes. In addition, abdominal or pulmonary infections, and biliary complications, including cholangitis, are common complications in patients after liver transplantation and can also be associated with a risk for mortality. Thereby, these patients already suffer from gut dysbiosis at the time of liver transplantation due to their severe underlying disease, causing end-stage liver failure. Despite an impaired gut-liver axis, repeated antibiotic therapies can cause major changes in the gut microbiome. Due to repeated biliary interventions, the biliary tract is often colonized by several bacteria with a high risk for multi-drug resistant germs causing local and systemic infections before and after liver transplantation. Growing evidence about the role of gut microbiota in the perioperative course and their impact on patient outcomes in liver transplantation is available. However, data about biliary microbiota and their impact on infectious and biliary complications are still sparse. In this comprehensive review, we compile the current evidence for the role of microbiome research in liver transplantation with a focus on biliary complications and infections due to multi-drug resistant germs.

Vancomycin-resistant Enterococcus outbreak in a pre- and post-cardiothoracic transplant population: Impact of discontinuing multidrug-resistant organism surveillance during the coronavirus disease 2019 pandemic

INTRODUCTION

Many institutions suspended surveillance and contact precautions for multidrug-resistant organisms (MDROs) at the outset of the coronavirus disease 2019 (COVID-19) pandemic due to a lack of resources. Once our institution reinstated surveillance in September 2020, a vancomycin-resistant Enterococcus (VRE) faecium outbreak was detected in the cardiothoracic transplant units, a population in which we had not previously detected outbreaks.

METHODS

An outbreak investigation was conducted using pulsed-field gel electrophoresis for strain typing and electronic medical record review to determine the clinical characteristics of involved patients. The infection prevention (IP) team convened a multidisciplinary process improvement team comprised of IP, cardiothoracic transplant nursing and medical leadership, environmental services, and the microbiology laboratory.

RESULTS

Between December 2020 and March 2021, the outbreak involved thirteen patients in the cardiothoracic transplant units, four index cases, and nine transmissions. Of the 13, seven (54%) were on the transplant service, including heart and lung transplant recipients, patients with ventricular assist devices, and a patient on extracorporeal membrane oxygenation as a bridge to lung transplantation. Four of 13 (31%) developed a clinical infection.

DISCUSSION

Cardiothoracic surgery/transplant patients may have a similar risk for VRE-associated morbidity as abdominal solid organ transplant and stem cell transplant patients, highlighting the need for aggressive outbreak management when VRE transmission is detected. Our experience demonstrates an unintended consequence of discontinuing MDRO surveillance in this population and highlights a need for education, monitoring, and reinforcement of foundational infection prevention measures to ensure optimal outcomes.

Importance of daptomycin dosage on the clinical outcome in liver transplant recipients with vancomycin-resistant enterococci infection

We retrospectively studied 16 (3 colonization and 13 infections) early post-liver transplant (≤60-day after transplantation) patients with vancomycin-resistant enterococci (VRE) colonization/infection from 2016 to 2019. All VRE isolates were Enterococcus faecium. Of 13 patients with VRE infection, 12 (92.3%) underwent living-donor liver transplantation and 1 underwent deceased donor liver transplantation. Among these 13 patients, the median time from transplant to emergence of VRE infection was 12 days. The median interval from VRE infection to death was 27 days. Of these 13 patients, eleven patients (8 survived; 3 died) received daptomycin therapy for VRE. Among them, 4 (36.3%) received daptomycin doses <8 mg/kg. Non-survivors (n = 3) received significantly lower daptomycin dose than survivors (n = 8; p = .040). Daptomycin doses <8mg/kg were more frequently associated with non-survivors (n = 3) than with survivors (n = 8; p = .024). In summary, the suboptimal dosage of daptomycin may have contributed to a higher rate of in-hospital mortality. Doses ≥8 mg/kg may be needed to adequately treat VRE infection in liver transplant recipients.

Daptomycin perioperative prophylaxis for the prevention of vancomycin-resistant Enterococcus infection in colonized liver transplant recipients

BACKGROUND

Vancomycin-resistant Enterococcus (VRE)-colonized liver transplantation (LT) recipients have increased post-LT morbidity, mortality, and higher rates of VRE infections compared with their non-colonized counterparts. Pre-LT screening for VRE colonization and inclusion of daptomycin in the perioperative antibiotic prophylaxis regimen may mitigate this risk.

METHODS

We performed a retrospective chart review of liver transplant recipients aged ≥ 18 years between 2013 and August 2019 to identify pre-LT VRE-colonized recipients and whether they received daptomycin perioperative prophylaxis (DPP). Demographic and clinical characteristics, including risk factors for VRE infection, were collected. Outcomes measured were VRE-related infection and all-cause mortality within 90 days of LT.

RESULTS

Of the 27 VRE-colonized liver transplant recipients within the study period, 25 received DPP. All recipients were admitted to the intensive care unit postoperatively, six (24%) required reoperation, fifteen (60%) required renal replacement therapy, and eight (32%) experienced postoperative hemorrhage within 90 days post-transplant. Two recipients (8%) experienced acute cellular rejection, but no primary graft failure was seen within 90 days. Among those who received DPP, no infections related to VRE or death was seen within 90 days of LT. The two VRE-colonized recipients who did not receive DPP both developed VRE bacteremia in the early post-LT period.

CONCLUSION

Despite having multiple risk factors for post-LT VRE infection, VRE-colonized recipients who received DPP did not develop VRE-related infections in the first 90 days post-LT. Our experience demonstrates that pre-LT VRE screening and DPP may be associated with a reduction in VRE infection in the early post-LT period, but this strategy warrants further evaluation in prospective studies.

Microbiota in organ transplantation: An immunological and therapeutic conundrum?

The gastrointestinal (GI) tract microbiota is an environmental factor that regulates host immunity in allo-transplantation (allo-Tx). It is required for the development of resistance against pathogens and the stabilization of mucosa-associated lymphoid tissue. The gut-microbiota axis may also precipitate allograft rejection by producing metabolites that activate host cell-mediated and humoral immunity. Here, we discuss new insights into microbial immunomodulation, highlighting ongoing attempts to affect commensal colonization in an attempt to ameliorate allograft rejection cascade. Recent progress on the use of antibiotics to modulate GI microbiota diversity and innate-adaptive immune interface are discussed. Our focus on the microbiota's influence of endoplasmic reticulum (ER) stress and autophagy signaling through hepatic EP4/CHOP/LC3B platforms reveals a novel molecular pathway and potential biomarkers determining the progression of allo-Tx damage. Understanding and harnessing the potential of microbiome/bacteriophage therapies may offer safe and effective means for personalized treatment to reduce risks of infections and immunosuppression in allo-Tx.

VRE in cirrhotic patients

Background

Vancomycin resistant enterococci (VRE) infections are of increasing concern in many hospitalized patients. Patients with cirrhosis are at added risk of infection with VRE, with associated increased risk for complications from infections. The goals of this study were to: [1] identify risk factors for VRE amongst cirrhotic patients before liver transplantation, and [2] evaluate risk of morbidity and mortality at 30-days and one-year after VRE infection.

Methods

Chart review of 533 cirrhotic patients hospitalized at a tertiary medical center was performed. Patients infected with VRE (n = 65) were separately compared to patients infected with gram-negative organisms (n = 80) and uninfected patients (n = 306).

Results

In multivariable logistic regression analyses, female gender (OR 3.73(95% CI1.64,8.49)), severity of liver disease measured by higher Child Pugh scores (OR 0.37(95%CI 0.16,0.84)), presence of ascites (OR 9.43(95% CI 3.22,27.65) and any type of dialysis (OR 3.31,95% CI (1.21,9.04), oral antibiotic prophylaxis for spontaneous bacterial peritonitis and rifaximin use were statistically significantly associated with VRE infection (OR 2.37 (95%CI 1.27, 4.42)). VRE-infected patients had significantly longer mean ICU and total hospital stays (both p < 0.0001), with increased one-year mortality compared to cirrhotic patients without VRE infection, adjusted for age, sex, Hispanic ethnicity, and disease severity.

Conclusions

It is unclear whether VRE infection serves as an independent risk factor for increased mortality or an indicator for patients with more severe illnesses and thus a higher risk for death.

The direct and indirect effects of vancomycin-resistant enterococci colonization in liver transplant candidates and recipients

Introduction: Vancomycin-resistant enterococci (VRE) colonization and subsequent infection results in increased morbidity, mortality and use of health-care resources. The burden of VRE colonization in liver transplant candidates and recipients is significant. VRE colonization is a marker of gut dysbiosis and its impact on the microbiota-liver axis, may negatively affect graft function and result in negative outcomes pre- and post-transplantation. Areas covered: In this article we describe the epidemiology of VRE colonization, risk factors for VRE infection, health-care costs associated with VRE, with a focus on the impact of VRE colonization on liver transplant recipients' fecal microbiota, the therapeutic strategies for VRE decolonization and proposed pathophysiologic mechanisms of VRE colonization in liver transplant recipients. Expert opinion: VRE colonization results in a significant loss of bacterial microbiome diversity. This may have metabolic consequences, with low production of short-chain fatty acids which may, in turn, result in immune dysregulation. As antibiotics have failed to decolonize the gut, alternative strategies such as fecal microbiota transplantation (FMT), stimulation of intestinal antimicrobial peptides and phage therapy warrants future studies.

Infections in Liver Transplantation

Liver transplantation has become an important treatment modality for patients with end-stage liver disease/cirrhosis, acute liver failure, and hepatocellular carcinoma. Although surgical techniques and immunosuppressive regimens for liver transplantation have improved significantly over the past 20 years, infectious complications continue to contribute to the morbidity and mortality in this patient population. The use of standardized screening protocols for both donors and recipients, coupled with targeted prophylaxis against specific pathogens, has helped to mitigate the risk of infection in liver transplant recipients. Patients with chronic liver disease and cirrhosis have immunological deficits that place them at increased risk for infection while awaiting liver transplantation. The patient undergoing liver transplantation is prone to develop healthcare-acquired infections due to multidrug-resistant organisms that could potentially affect patient outcomes after transplantation. The complex nature of liver transplant surgery that involves multiple vascular and hepatobiliary anastomoses further increases the risk of infection after liver transplantation. During the early post-transplantation period, healthcare-acquired bacterial and fungal infections are the most common types of infection encountered in liver transplant recipients. The period of maximal immunosuppression that occurs at 1–6 months after transplantation can be complicated by opportunistic infections due to both primary infection and reactivation of latent infection. Severe community-acquired infections can complicate the course of liver transplantation beyond 12 months after transplant surgery. This chapter provides an overview of liver transplantation including indications, donor-recipient selection criteria, surgical procedures, and immunosuppressive therapies. A focus on infections in patients with chronic liver disease/cirrhosis and an overview of the specific infectious complications in liver transplant recipients are presented.

Ceftriaxone Administration Disrupts Intestinal Homeostasis, Mediating Noninflammatory Proliferation and Dissemination of Commensal Enterococci

Enterococci are Gram-positive commensals of the mammalian intestinal tract and harbor intrinsic resistance to broad-spectrum cephalosporins. Disruption of colonization resistance in humans by antibiotics allows enterococci to proliferate in the gut and cause disseminated infections. In this study, we used Enterococcus faecalis (EF)-colonized mice to study the dynamics of enterococci, commensal microbiota, and the host in response to systemic ceftriaxone administration. We found that the mouse model recapitulates intestinal proliferation and dissemination of enterococci seen in humans. Employing a ceftriaxone-sensitive strain of enterococci (E. faecalis JL308), we showed that increased intestinal abundance is critical for the systemic dissemination of enterococci. Investigation of the impact of ceftriaxone on the mucosal barrier defenses and integrity suggested that translocation of enterococci across the intestinal mucosa was not associated with intestinal pathology or increased permeability. Ceftriaxone-induced alteration of intestinal microbial composition was associated with transient increase in the abundance of multiple bacterial operational taxonomic units (OTUs) in addition to enterococci, for example, lactobacilli, which also disseminated to the extraintestinal organs. Collectively, these results emphasize that ceftriaxone-induced disruption of colonization resistance and alteration of mucosal homeostasis facilitate increased intestinal abundance of a limited number of commensals along with enterococci, allowing their translocation and systemic dissemination in a healthy host.

Epidemiological Analysis of Extended-Spectrum Beta-Lactamase-Producing Bacterial Infections in Adult Live Donor Liver Transplant Patients

Introduction:

Bacterial infections are a leading cause of morbidity and mortality in patients receiving solid-organ transplants. Extended-spectrum beta-lactamases (ESBL) pathogens are the most important pathogenic bacteria infecting these patients.

Aim:

This study aims to evaluate for the incidence and characteristics of ESBL-positive organism, to look for the clinical outcomes in ESBL-positive infected cases, and to evaluate and draft the antibiotic policy in posttransplant patients during the first 28 days posttransplant.

Materials and Methods:

This is a retrospective data analysis of liver transplant recipients infected with ESBL culture-positive infections. All the culture sites such as blood, urine, and endotracheal tube aspirates were screened for the first ESBL infection they had and noted. This data were collected till day 28 posttransplant. The antibiotic susceptibility pattern and the most common organism were also noted.

Results:

A total of 484 patients was screened and 116 patients had ESBL-positive cultures. Out of these, 54 patients had infections and 62 patients were ESBL colonizers. The primary infection site was abdominal fluid (40.7%), with Klebsiella accounting for most of the ESBL infections. Colistin was the most sensitive antibiotic followed by tigecycline. The overall mortality was 11.4% and 31 out of 54 ESBL-infected patients died.

Conclusions:

Infections with ESBL-producing organism in liver transplant recipients has a high mortality and very limited therapeutic options.

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.

Emergence of linezolid resistance in hepatobiliary infections caused by Enterococcus faecium

Enterococcal infections are common in liver transplantation and hepatopancreaticobiliary (HPB) surgery. Linezolid is frequently used to treat not only vancomycin-resistant Enterococcus (VRE), but also vancomycin-sensitive Enterococcus (VSE) infections, and resistance can develop. This study evaluated all the Liver Unit patients who developed infections with linezolid-resistant Enterococcus (LRE) in order to elicit the association with prior linezolid usage, to explore possible risk factors for infection, and to better understand the epidemiology of these isolates in this patient group. Between 2010 and 2015, infections with LRE developed in 10 patients (8 following liver transplantation and 2 following HPB surgery) after 22-108 days of treatment. Selected pulsed-field gel electrophoresis demonstrated that 2 out of 10 patients were cocolonized with different strains and indicated that cross-transmission may have occurred. In conclusion, in this group of patients with complex hepatobiliary infections, the optimal antibiotic strategies for the treatment of Enterococcus faecium infections are not clearly defined, and there is a significant risk of emergence of resistance to linezolid in E. faecium after exposure to this agent in patients, especially in the presence of a deep source of infection on a background of hepatic artery insufficiency. Caution is needed when using prolonged courses of linezolid in this setting, and further studies are necessary to determine the optimum treatment.

Differential Effects of Penicillin Binding Protein Deletion on the Susceptibility of Enterococcus faecium to Cationic Peptide Antibiotics

Beta-lactam antibiotics sensitize Enterococcus faecium to killing by endogenous antimicrobial peptides (AMPs) of the innate immune system and daptomycin through mechanisms yet to be elucidated. It has been speculated that beta-lactam inactivation of select E. faecium penicillin binding proteins (PBPs) may play a pivotal role in this sensitization process. To characterize the specific PBP inactivation that may be responsible for these phenotypes, we utilized a previously characterized set of E. faecium PBP knockout mutants to determine the effects of such mutations on the activity of daptomycin and the AMP human cathelicidin (LL-37). Enhanced susceptibility to daptomycin was dependent more on a cumulative effect of multiple PBP deletions than on inactivation of any single specific PBP. Selective knockout of PBPZ rendered E. faecium more vulnerable to killing by both recombinant LL-37 and human neutrophils, which produce the antimicrobial peptide in high quantities. Pharmacotherapy targeting multiple PBPs may be used as adjunctive therapy with daptomycin to treat difficult E. faecium infections.

Risk of vancomycin-resistant enterococci bloodstream infection among patients colonized with vancomycin-resistant enterococci

Background

Vancomycin-resistant enterococci colonization has been reported to increase the risk of developing infections, including bloodstream infections.

Aim

In this study, we aimed to share our experience with the vancomycin-resistant enterococci bloodstream infections following gastrointestinal vancomycin-resistant enterococci colonization in pediatric population during a period of 18 months.

Method

A retrospective cohort of children admitted to a 400-bed tertiary teaching hospital in Izmir, Turkey whose vancomycin-resistant enterococci colonization was newly detected during routine surveillances for gastrointestinal vancomycin-resistant enterococci colonization during the period of January 2009 and December 2012 were included in this study. All vancomycin-resistant enterococci isolates found within 18 months after initial detection were evaluated for evidence of infection.

Findings

Two hundred and sixteen patients with vancomycin-resistant enterococci were included in the study. Vancomycin-resistant enterococci colonization was detected in 136 patients (62.3%) while they were hospitalized at intensive care units; while the remaining majority (33.0%) were hospitalized at hematology-oncology department. Vancomycin-resistant enterococci bacteremia was present only in three (1.55%) patients. All these patients were immunosuppressed due to human immunodeficiency virus (one patient) and intensive chemotherapy (two patients).

Conclusion

In conclusion, our study found that 1.55% of vancomycin-resistant enterococci-colonized children had developed vancomycin-resistant enterococci bloodstream infection among the pediatric intensive care unit and hematology/oncology patients; according to our findings, we suggest that immunosupression is the key point for developing vancomycin-resistant enterococci bloodstream infections.

MRSA and VRE colonization in solid organ transplantation: a meta-analysis of published studies

The burden of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE) colonization among the increasing number of solid organ transplant patients has not been systematically explored. We searched PubMed and EMBASE for pertinent articles, performed a meta-analysis of prevalence across eligible studies and estimated the risk of ensuing MRSA or VRE infections relative to colonization status. We stratified effects in the pretransplant and posttransplant period. Twenty-three studies were considered eligible. Seventeen out of 23 (74%) referred to liver transplants. Before transplantation, the pooled prevalence estimate for MRSA and VRE was 8.5% (95% confidence interval [CI] 3.2–15.8) and 11.9% (95% CI 6.8–18.2), respectively. MRSA estimate was influenced by small studies and was lower (4.0%; 95% CI 0.4–10.2) across large studies (>200 patients). After transplantation, the prevalence estimates were 9.4% (95% CI 3.0–18.5) for MRSA and 16.2% (95% CI 10.7–22.6) for VRE. Pretransplant as well as posttransplant MRSA colonization significantly increased the risk for MRSA infections (pooled risk ratio [RR] 5.51; 95% CI 2.36–12.90 and RR 10.56; 95% CI 5.58–19.95, respectively). Pretransplant and posttransplant VRE colonization were also associated with significant risk of VRE infection (RR 6.65; 95% CI 2.54–17.41 and RR 7.93; 95% CI 2.36–26.67, respectively). Solid organ transplantation is a high-risk setting for MRSA and VRE colonization, and carrier state is associated with infection. Upgraded focus in prevention and eradication strategies is warranted.

Ceftaroline restores daptomycin activity against daptomycin-nonsusceptible vancomycin-resistant Enterococcus faecium

Daptomycin-nonsusceptible vancomycin-resistant Enterococcus faecium (VRE) strains are a formidable emerging threat to patients with comorbidities, leaving few therapeutic options in cases of severe invasive infections. Using a previously characterized isogenic pair of VRE strains from the same patient differing in their daptomycin susceptibilities (Etest MICs of 0.38 mg/liter and 10 mg/liter), we examined the effect of ceftaroline, ceftriaxone, and ampicillin on membrane fluidity and susceptibility of VRE to surface binding and killing by daptomycin and human cathelicidin antimicrobial peptide LL37. Synergy was noted in vitro between daptomycin, ampicillin, and ceftaroline for the daptomycin-susceptible VRE strain, but only ceftaroline showed synergy against the daptomycin-nonsusceptible VRE strain (∼2 log10 CFU reduction at 24 h). Ceftaroline cotreatment increased daptomycin surface binding with an associated increase in membrane fluidity and an increase in the net negative surface charge of the bacteria as evidenced by increased poly-l-lysine binding. Consistent with the observed biophysical changes, ceftaroline resulted in increased binding and killing of daptomycin-nonsusceptible VRE by human cathelicidin LL37. Using a pair of daptomycin-susceptible/nonsusceptible VRE strains, we noted that VRE is ceftaroline resistant, yet ceftaroline confers significant effects on growth rate as well as biophysical changes on the cell surface of VRE that can potentiate the activity of daptomycin and innate cationic host defense peptides, such as cathelicidin. Although limited to just 2 strains, these finding suggest that additional in vivo and in vitro studies need to be done to explore the possibility of using ceftaroline as adjunctive anti-VRE therapy.

Systematic review and meta-analysis of linezolid and daptomycin for treatment of vancomycin-resistant enterococcal bloodstream infections

Bloodstream infections due to vancomycin-resistant enterococci (VRE-BSI) result in substantial patient mortality and cost. Daptomycin and linezolid are commonly prescribed for VRE-BSI, but there are no clinical trials to determine optimal antibiotic selection. We conducted a systematic review for investigations that compared daptomycin and linezolid for VRE-BSI. We searched Medline from 1966 through 2012 for comparisons of linezolid and daptomycin for VRE-BSI. We included searches of EMBASE, clinicaltrials.gov, and national meetings. Data were extracted using a standardized instrument. Pooled odds ratios (OR) and 95% confidence intervals (95% CI) were calculated using a fixed-effects model. Our search yielded 4,243 publications, of which 482 contained data on VRE treatment. Most studies (452/482) did not present data on BSI or did not provide information on linezolid or daptomycin. Among the remaining 30 studies, 9 offered comparative data between the two agents. None were randomized clinical trials. There was no difference in microbiologic (n = 5 studies, 517 patients; OR, 1.0; 95% CI, 0.4 to 1.7; P = 0.95) and clinical (n = 3 studies, 357 patients; OR, 1.2; 95% CI, 0.7 to 2.0; P = 0.7) cures between the two antibiotics. There was a trend toward increased survival with linezolid compared to daptomycin treatment (n = 9 studies, 1,074 patients; OR, 1.3; 95% CI, 1.1 to 1.8; I(2) = 0 [where I(2) is a measure of inconsistency]), but this did not reach statistical significance (P = 0.054). There are limited data to inform clinicians on optimal antibiotic selection for VRE-BSI. Available studies are limited by small sample size, lack of patient-level data, and inconsistent outcome definitions. Additional research, including randomized clinical trials, is needed before conclusions can be drawn about treatment options for VRE therapy.

A prospective study of the impact of colonization following hospital admission by glycopeptide-resistant Enterococci on mortality during a hospital outbreak

BACKGROUND

This study was designed to investigate the impact on mortality of colonization by glycopeptide-resistant Enterococci (GRE) during hospitalization.

METHODS

Between 2004 and 2006, a hospital in Nancy, France, was subject to a GRE van A outbreak. Some 113 patients who had acquired GRE after hospital admission were matched with 113 controls. Basic demographic data, such as sex, age, principal pathology, history of surgery, and presence of associated pathology, were obtained for each case and control. Information on whether or not the case subject was still alive was obtained by searching the hospital mortality database and the civil death register and by phoning the patient's home. Statistical analysis used the Cox proportional hazards model for calculating survival function with SPSS software version 9.1 (SPSS Inc., Chicago, IL).

RESULTS

The mean age was 71.2 in the GRE+ group and 70.8 in the control group (P = .80). There was a significant difference between the groups for severity status health (P = .035). The mortality rate was 30.1% in the case group and 19.5% in the control group. Single predictor variable analysis showed a hazard ratio of death in the case group of 4.61 (95% confidence interval [CI]: 2.58-8.28], P = 2 x 10(-7)). The final Cox regression model with multiple predictor variables showed that only GRE presence (OR, 1.63 [95% CI: 1.04-2.57], P = .035) and severity of comorbidity (P = .013) were independently significant predictors of mortality.

CONCLUSION

This study shows that the GRE acquisition has a poor prognosis and that this is independent of the other prognostic factors such as age and severity of underlying disease. Survival in GRE+ patients was significantly shorter.

Early intra-abdominal infections associated with orthotopic liver transplantation

BACKGROUND

Postoperative infections remain a significant problem among liver transplant recipients (LTRs). An early cause of morbidity after liver transplantation is intra-abdominal infection (IAI) about which there are limited data.

METHODS

We report a retrospective review of 169 adult LTRs from January 1, 2002 to June 9, 2006, comparing those who developed early postoperative IAI (peritonitis, biliary tract infection, abdominal abscess, or enteritis) with those who did not to identify clinical features and risk factors, analyze epidemiology, and assess graft and patient survival.

RESULTS

Sixty-eight patients (40%) had 104 infections, with 148 pathogens isolated. Leukocytosis (53%) and fever (34%) were the most common clinical features, and peritonitis (43%) was the most common manifestation. Enterococcus spp., the most frequent single pathogens, comprised 26% of organisms cultured. There were significant associations of IAI with pretransplant ascites (P=0.002), posttransplant dialysis (P=0.015), and non-IAI surgical complications (P<0.001). There was a trend toward graft failure in patients with IAI (P=0.051) but increased mortality was not associated with IAI. Use of pretransplant antibiotics was significantly associated with development of multiple drug-resistant organisms in IAI (P=0.032).

CONCLUSION

IAI occurred at a relatively high rate in the early postoperative period, and fever was not a major indicator. In patients receiving antibiotics within 2 weeks before transplantation, multiple drug-resistant organisms often caused IAI. In addition, the presence of pretransplant ascites, posttransplant dialysis, and wound infection or reoperation after transplant should alert one to the increased risk of IAI in LTRs.

Influence of pretransplantation bacterial and fungal culture positivity on outcome after living donor liver transplantation

BACKGROUND

Bacterial and fungal infections are serious complications in patients with cirrhosis and are among the main causes of morbidity and mortality. The effects of pretransplantation infection on the outcome after orthotopic liver transplantation (OLT), however, have not been fully described.

OBJECTIVE

To assess the influence of pretransplantation infection on OLT by analyzing the clinical profiles of liver recipients with preexisting bacterial or fungal infection.

PATIENTS AND METHODS

We retrospectively reviewed the medical records of 223 adult patients who underwent living donor OLT between October 1, 2005, and September 30, 2006. In all patients, routine blood culture, was performed, and in patients with suspected bacterial or fungal infection; sputum, urine, and ascitic fluid cultures were performed.

RESULTS

Of 223 patients, 37 (16.6%) had a positive culture in one or more samples. Culture-positive and culture-negative groups differed significantly in end-stage liver disease score but showed no differences in Child-Turcotte-Pugh score, existence of spontaneous bacterial peritonitis, hemodialysis, or duration of stay in the intensive care unit or hospital. Six of 37 patients with positive cultures (16.2%) and 4 (2.2%) of 186 patients with negative cultures (2.2%) died during the first 90 days after OLT (P = .007). The causes of death among culture-positive patients were brain edema (n = 2), brain hemorrhage (n = 1), hepatic dysfunction (n = 1), and sepsis (n = 2), whereas all 4 culture-negative patients died of infectious complications.

CONCLUSION

Prompt OLT accompanied by adequate antibiotic or antifungal therapy may be acceptable in patients with preexisting bacterial or fungal infection unless there are overt manifestations of active infection.

[Emergence of vancomycin-dependent enterococci following glycopeptide therapy: case report and review]

INTRODUCTION

Outbreaks of vancomycin-resistant enterococci have been increasingly reported in France over the last three years. We report here, the emergence of a vancomycin-dependent enterococci isolate following glycopeptide therapy.

PATIENTS AND METHODS

An Enterococcus faecium isolate that required vancomycin for growth was cultured from the stools of a liver transplant recipient who was colonised with vancomycin-resistant enterococci and who received vancomycin treatment for methicillin-resistant Staphylococcus aureus infection. The resistant isolate and the dependent isolate were typed by pulsed-field gel electrophoresis. The sequence of the ddl gene coding for the D-Ala: D-Ala ligase was analysed.

RESULTS

The dependent isolate was primary cultured onto a vancomycin-containing screening medium and could not be subcultured in the absence of vancomycin. Both the resistant and dependent isolates harboured the vanA gene and they had the same DNA restriction pattern after pulsed-field gel electrophoresis. Dependence on vancomycin was associated with a 1-bp deletion in the D-Ala: D-Ala ligase gene leading to an early stop odon.

CONCLUSION

Cultures onto vancomycin-containing media are warranted for clinical specimens from patients, who are known to carry vancomycin-resistant enterococci and receive vancomycin therapy.

Outcomes of colonization with MRSA and VRE among liver transplant candidates and recipients

Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE) infections cause significant morbidity and mortality among liver transplant candidates and recipients. To assess rates of MRSA and VRE colonization, we obtained active surveillance cultures from 706 liver transplant candidates and recipients within 24 h of admission to an 11-bed liver transplant ICU from October 2000 to December 2005. Patients were followed prospectively to determine the cumulative risk of MRSA or VRE infection or death by colonization status. Outcomes were assessed by Kaplan-Meier survival analysis and Cox regression and multivariate logistic regression adjusting for covariates. The prevalence of newly detected MRSA nasal and VRE rectal colonization was 6.7% and 14.6%, respectively. Liver transplant candidates and recipients with MRSA colonization had an increased risk of MRSA infection (adjusted OR = 15.64, 95% CI 6.63-36.89) but not of death (adjusted OR = 1.00, 95% CI 0.43-2.30), whereas those with VRE colonization had an increased risk both of VRE infection (adjusted OR = 3.61, 95% CI 2.01-6.47) and of death (adjusted OR = 2.12, 95% CI 1.27-3.54) compared with noncolonized patients. Prevention and control strategies, including use of active surveillance cultures, should be implemented to reduce the rates of both MRSA and VRE colonization in this high-risk patient population.

Prevalence of vancomycin-resistant Enterococcus fecal colonization among kidney transplant patients

Background

End stage renal disease patients are at risk of Vancomycin-Resistant Enterococcus (VRE) infections. The first reports of VRE isolation were from hemodialysis patients. However, to date, VRE fecal colonization rates as well as associated risk factors in kidney transplant patients have not yet been established in prospective studies.

Methods

We collected one or two stool samples from 280 kidney transplant patients and analysed the prevalence of VRE and its associated risk factors. Patients were evaluated according to the post-transplant period: group 1, less than 30 days after transplantation (102 patients), group 2, one to 6 months after transplantation (73 patients) and group 3, more than 6 months after transplantation (105 patients).

Results

The overall prevalence rate of fecal VRE colonization was 13.6% (38/280), respectively 13.7% for Group 1, 15.1% for group 2 and 12.4% for group 3. E. faecium and E. faecalis comprised 50% of all VRE isolates. No immunologic variables were clearly correlated with VRE colonization and no infections related to VRE colonization were reported.

Conclusion

Fecal VRE colonization rates in kidney transplant patients were as high as those reported for other high-risk groups, such as critical care and hemodialysis patients. This high rate of VRE colonization observed in kidney transplant recipients may have clinical relevance in infectious complications.

Vancomycin-resistant enterococci: colonization, infection, detection, and treatment

Vancomycin-resistant enterococci (VRE) are becoming a major concern in medical practice. Their increased prevalence and their ability to transfer vancomycin resistance to other bacteria (including methicillin-resistant Staphylococcus aureus) have made them a subject of close scrutiny and intense investigation. Colonization is usually acquired by susceptible hosts in an environment with a high rate of patient colonization with VRE (eg, intensive care units, oncology units). Vancomycin-resistant enterococci can survive in the environment for prolonged periods (>1 week), can contaminate almost any surface, and can be passed from one patient to another by health care workers. Whether VRE colonization leads to infection depends on the health status of the patient. Whereas immunocompetent patients colonized with VRE are at low risk for infection, weakened hosts (patients with hematologic disorders, transplant recipients, or severely ill patients) have an increased likelihood of developing infection following colonization. Quinupristin-dalfopristin and linezolid are among the anti-infective agents that have recently become available to treat infection caused by VRE. Other antimicrobials are currently under development. Molecular techniques such as polymerase chain reaction and standard culture studies are being used to detect VRE colonization, infection, and outbreaks.

Consequences of vancomycin-resistant Enterococcus in liver transplant recipients: a matched control study

BACKGROUND

Liver transplant recipients are at high risk for multi-drug resistant infections because of broad-spectrum antibiotic and immunosuppression. This study evaluates the clinical and financial impact of vancomycin resistant Enterococcus (VRE) in liver transplant recipients.

METHODS

Liver transplant recipients with VRE from 1995 to 2002 were identified and matched (age, gender, UNOS status, liver disease and transplant date) to controls. Demographics, clinical factors, co-infections, antibiotic use, length of stay, abdominal surgeries, biliary complications, survival and resource utilization were compared with matched controls.

RESULTS

Nineteen patients were found to have 28 VRE infections via evaluation of microbiologic culture results of all liver transplant patients in the transplant registry. Thirty-eight non-VRE patients served as matched controls. The four most common sites VRE was cultured from included blood (35%), peritoneal fluid (35%), bile (20%), and urine (12%). Median time from transplant to infection was 48 d (range of 4-348). No significant differences in demographics were observed. The VRE group had a higher incidence of prior antibiotic use than the non-VRE group (95% vs. 34%; p < 0.05). The VRE group also experienced more abdominal surgery (20/19 vs. 3/38; p = 0.029), biliary complications (9/19 vs. 9/38; p = 0.018) and a longer length of stay (42.5 vs. 21.7 d; p = .005). Survival in the VRE group was lower (52% vs. 82%; p = 0.048). Six of the 19 VRE patients were treated with linezolid for eight infection episodes, and four of six patients survived. Eight patients were treated with quinupristin/dalfopristin for nine infections, and two of eight survived. Increased cost of care was observed in the VRE group. Laboratory costs were higher in the VRE group (6500 dollars vs. 1750; p = 0.02) as well.

CONCLUSION

VRE was associated with prior antibiotic use, multiple abdominal surgeries, biliary complications and resulted in decreased survival compared to non-VRE control patients. VRE patients also utilized more hospital resources. Linezolid showed a trend toward improved survival.

Vancomycin-resistant enterococcal colonization and infection in liver transplant candidates and recipients: a prospective surveillance study

BACKGROUND

Vancomycin-resistant enterococcal (VRE) infections cause significant morbidity and mortality among patients undergoing liver transplantation. We performed a prospective study among patients awaiting transplantation to assess rates, risk factors, and outcomes associated with VRE colonization before and after transplantation.

METHODS

All adults on the transplantation waiting list from 2000-2003 were eligible. Demographic, historical, and laboratory data, as well as stool samples to be analyzed for VRE, were collected at enrollment and every 4-6 months thereafter until transplantation. After transplantation, samples were obtained every 3 days during hospitalization and were analyzed for VRE; outcomes were assessed at 90 days.

RESULTS

Overall, 375 patients were enrolled in our study, and 142 received transplants. VRE colonization occurred in 50 (13%) of 375 patients before transplantation and was independently associated with treatment with antianaerobic antimicrobials, third-generation cephalosporins, proton pump inhibitors, or neomycin; having a recent endoscopic retrograde cholangiopancreatogram or paracentesis procedure; and admission to the liver unit. Of these 50 patients, 22 (44%) received a transplant, and 7 (32%) of 22 developed a VRE infection after transplantation. An additional 22 patients (18%) who were not colonized before transplantation acquired VRE after transplantation; VRE infection developed in 5 (23%) of these patients. Patients colonized with VRE either before or after transplantation had longer stays in the intensive care unit and the hospital. Mortality at 90 days was significantly greater among those who acquired VRE after transplantation (5 [23%] of 22), compared with those who had VRE colonization before transplantation (2 [9%] of 22).

CONCLUSIONS

Liver transplantation candidates with VRE colonization before transplantation experience greater morbidity but not greater mortality, compared with noncolonized candidates. Transplant recipients who acquire VRE after transplantation have a higher mortality rate than noncolonized recipients. Strategies should be implemented to reduce nosocomial VRE acquisition after transplantation among this vulnerable group.

Endocarditis Due to Vancomycin-Resistant Enterococci: Case Report and Review of the Literature

BACKGROUND

Endocarditis due to vancomycin-resistant enterococci (VRE) is rare, and the literature consists almost exclusively of reports of single cases.

METHODS

We report a case of VRE prosthetic valve endocarditis and review 18 cases of native and prosthetic valve VRE endocarditis reported in the literature.

RESULTS

The majority of cases were due to Enterococcus faecium. Nearly all of these infections were hospital acquired, and the vast majority of patients had significant underlying disease processes, including dialysis and transplantation. More than three-quarters of cases were left-sided, and the aortic valve was most commonly involved. Peripheral stigmata of endocarditis were not reported in any of the cases. Approximately 40% of patients developed cardiac complications. Nearly three-quarters of patients survived, despite the difficulties associated with providing bactericidal antimicrobial therapy, and only 4 patients underwent valve replacement.

CONCLUSIONS

VRE endocarditis is an uncommon nosocomial infection that affects patients with significant comorbid conditions. Most cases are due to E. faecium, and the aortic valve is involved in at least one-half of cases. One-third of patients require surgical treatment. Optimal antimicrobial therapy remains undefined, but an attempt to identify bactericidal combination therapy should be sought.

Rationale for the development of immunotherapy regimens against enterococcal infections

Enterococci are the third most common pathogen isolated in bloodstream infections. Increasing resistance against multiple antimicrobial agents has left few treatment options for enterococcal infections, and alternative therapeutic approaches are needed. Although a variety of virulence factors have been described for Enterococcus faecalis, only aggregation substance (AS) and a teichoic acid-like capsular polysaccharide have been evaluated for their potential for vaccine development. Antibodies raised against purified capsular polysaccharide are highly opsonic and protect mice against bacteremia after active and passive immunization. Since E. faecalis expresses only a limited number of capsular serotypes, this antigen may be an attractive candidate for development of a conjugate vaccine.

Impact of a formulary switch from ticarcillin-clavulanate to piperacillin-tazobactam on colonization with vancomycin-resistant enterococci

BACKGROUND

The prevalence of vancomycin-resistant enterococci (VRE) is increasing, despite infection control measures. Limited data link ticarcillin-clavulanate to higher VRE prevalence.

METHODS

Active surveillance for VRE was conducted before and after a formulary switch from ticarcillin-clavulanate to piperacillin-tazobactam. Rectal swabs were obtained serially in 863 adult patients admitted to intensive care units (ICUs) between November 1, 2000 and September 30, 2004.

RESULTS

In the postswitch period, 38 of 497 (7.6%) patients acquired VRE versus 42 of 366 (11.5%) patients in the preswitch period. Survival analysis showed an overall hazard ratio (HR) of .68 postswitch versus preswitch ( P = .07), with the greatest change in the surgical ICU (HR = .17, P = .006). Multivariate analysis showed an overall HR = .51 ( P = .004). Hospital-wide, nonstool VRE clinical cultures fell from 39 (.58/1000 patient days) in the 10-month preswitch period to 27 (.33/1000 patient days) in the 12-month postswitch period. Infection control practices and use of other antibiotics remained stable.

CONCLUSIONS

VRE acquisition appeared to decrease in association with a formulary change from ticarcillin-clavulanate to piperacillin-tazobactam.

Incidence and clinical complications of vancomycin-resistant enterococcus in pediatric stem cell transplant patients

Vancomycin-resistant enterococcus (VRE) are increasingly important pathogens in stem cell transplant (SCT). In all, 61 pediatric SCT patients had surveillance stool cultures for VRE between July 1999 and November 2002. When VRE was identified, the patients were placed on strict contact isolation. VRE was detected in 15 patients (24.6%). The median age was 3.6 years (range 0.6-18.5 years). Of the 15, 13 (87%) received an allogeneic transplant (six unrelated and seven related). Five of the 15 (33%) colonized patients developed VRE bacteremia. The bacteremia resolved in all five patients after therapy with quinupristin/dalfopristin; three patients required central line removal. Four patients died (38-153 days) post-SCT due to relapse or transplant complication not related to VRE. Of the 11 surviving patients, seven cleared the colonization at a median of 144 days (range 61-198 days) postcolonization. Four patients remain colonized at 68-702 days after the first positive culture. Intestinal colonization with VRE occurred commonly in pediatric SCT patients. Although the morbidity from VRE was not substantial, transplant patients were colonized for prolonged periods. Our results indicate that surveillance for VRE is an effective way to identify colonized patients and may lead to a decrease in transmission to other patients.

Failure to develop vancomycin-resistant Enterococcus with oral vancomycin treatment of Clostridium difficile

OBJECTIVE

Oral vancomycin therapy has been a risk factor for turning culture positive for vancomycin-resistant Enterococcus (VRE). VRE colonization status was reviewed for all patients who received oral vancomycin and underwent prospective cultures.

METHODS

Data were extracted from the medical records of all patients receiving oral vancomycin between August 1995 and February 2001 regarding history, hospital course, and perirectal VRE cultures. Hospital policy required contact isolation for patients receiving oral vancomycin until colonization with VRE was excluded.

RESULTS

Twenty-six courses of oral vancomycin were given to 22 patients. VRE colonization status after completion of therapy was evaluated for 23 courses in 20 (91%) of these patients. None of these patients became VRE culture positive during a median follow-up of 18 days (range, 9 to 39 days), with a median duration of treatment of 10 days (range, 3 to 58 days), and with a median total dose of 6,500 mg (range, 1,250 to 29,000 mg). All patients received other antibiotics within 30 days prior to therapy with oral vancomycin, during therapy with oral vancomycin, or both; 95% had received anti-anaerobic therapy and 35% had received parenteral vancomycin.

CONCLUSIONS

Even when other risk factors were present, no patient receiving oral vancomycin at our facility subsequently became culture positive for VRE. This suggests that oral vancomycin therapy or other antibiotic use, including anti-anaerobic therapy, may not be a significant independent risk factor for turning culture positive for VRE among patients not previously exposed to the microbe.

Convenient selective differential broth for isolation of vancomycin-resistant enterococcus from fecal material

Studies have shown that vancomycin broth enrichment is superior to direct plating for the detection of vancomycin-resistant enterococcus (VRE), but vancomycin selective broth is not generally commercially available. We developed an easy-to-prepare VRE selective differential broth and compared it to direct plating on bile esculin azide (BEA) agar for the isolation of VRE from fecal samples. A total of 528 consecutive rectal swabs and stools were inoculated onto BEA agar and into BEA broth with vancomycin at a concentration of 15 microg/ml (BEA VAN15 microg/ml broth). After 1 to 2 days of incubation, broths were subcultured to BEA VAN6 microg/ml agar. Bile esculin-positive colonies from the direct and broth subculture plates were evaluated for the presence of VRE by standard microbiological techniques. Addition of the broth enrichment step led to the detection of significantly more VRE isolates than did direct plating alone (28 versus 18 VRE isolates, respectively). In all, 30 VRE strains were isolated from 29 cultures, all of which were Enterococcus faecium. MICs of vancomycin ranged from 32 microg/ml (n = 2) to > 256 microg/ml (n = 28). Twenty-two VRE isolates were available for further testing: sixteen exhibited a VanA phenotype and six were of the VanB phenotype. van genotypes were in agreement with phenotypes for all VRE isolates except one, which could not be genotyped. The broth method also resulted in significantly fewer bile esculin-positive, non-VRE isolates requiring further workup. We have thus developed an easily prepared vancomycin selective differential broth that is significantly more sensitive and specific in the detection of VRE than is direct fecal plating to BEA agar.

The role of selective digestive decontamination for reducing infection in patients undergoing liver transplantation: a systematic review and meta-analysis

Selective digestive decontamination (SDD) refers to the use of antimicrobials to reduce the burden of aerobic gram-negative bacteria and/or yeast in the intestinal tract to prevent infections caused by these organisms. Liver transplant patients are highly vulnerable to bacterial infection particularly with gram-negative organisms within the first month after transplantation, and SDD has been proposed as a potential measure to prevent these infections. However, the benefit of this procedure remains controversial. We undertook a systematic review and meta-analysis to determine whether SDD is beneficial in reducing infections overall and those caused by gram-negative bacteria in patients following liver transplantation. All studies that evaluated the efficacy of SDD in liver transplant patients were included. Randomized trials that included liver transplant patients given SDD versus either placebo or no treatment or minimal treatment (e.g., oral nystatin alone), and that provided adequate data to calculate a relative risk ratio, were included in the meta-analysis. Our review shows that most studies found SDD to be effective in reducing gram-negative infection. The nonrandomized and uncontrolled trials also showed benefit with SDD in reducing overall infection; however, the effect on overall infection was limited in the 4 randomized trials, in which the pooled relative risk was 0.88 (95% CI, 0.7-1.1), indicating no statistically significant reduction in infection with the use of SDD. The summary risk ratio for the association between SDD and gram-negative infection was 0.16 (95% CI, 0.07-0.37), indicating an 84% relative risk reduction in the incidence of infection caused by gram-negative bacteria in patients receiving SDD in randomized trials. In conclusion, the available literature supports a beneficial effect of SDD on gram-negative infection following liver transplantation; however, the risk of antimicrobial resistance must be considered. Larger multicenter randomized trials in this patient population to assess the effect of SDD in reducing infection and mortality, while assessing the risk of antimicrobial resistance, are needed.

Linezolid in the treatment of vancomycin-resistant Enterococcus faecium in solid organ transplant recipients: report of a multicenter compassionate-use trial

Vancomycin-resistant Enterococcus faecium (VRE) is increasing in incidence in solid organ transplant recipients and has a high (up to 83%) associated mortality rate. Until recently, there have been no consistently effective antimicrobial therapies for VRE infection. Linezolid is a new antibiotic that belongs to the class of oxazolidinones approved by the FDA for the treatment of VRE infections, including those with bacteremia. Here, we report the experience with linezolid in an open-label, compassionate-use trial at 53 US centers for the treatment of documented VRE infections in patients with solid organ transplants. Eighty-five patients with solid organ transplants and documented VRE infections were studied. Blood cultures were positive for VRE in 43 patients, while 42 patients had other, non-rectal, sites of infection. Fifty-three patients responded well to treatment, with clinical resolution of the infection (62.4% survival rate). Of these, 47 had documented negative cultures post therapy. The mean duration of therapy for cured patients was 23.5 days. Thirty-two (37.6%) patients died, 28 due to sepsis and organ failure (32.9% failure rate), and 4 due to unrelated causes. Mortality rates for patients with bacteremia were comparable to mortality rates observed with patients who had positive cultures from other sites. Adverse reactions to linezolid included thrombocytopenia (4.7%), decreased leukocyte count (3.5%), and an increase in blood pressure (1.2%), none of which led to discontinuation of therapy. Linezolid appears to be a safe and effective treatment option for VRE, even in the presence of bacteremia, and may lead to decreased mortality in solid organ transplant recipients with VRE infection.

Association between antecedent intravenous antimicrobial exposure and isolation of vancomycin-resistant enterococci

Vancomycin-resistant enterococci (VRE) have become important causes of nosocomial infections. This study evaluated the association between a variety of intravenous antimicrobial exposures and the isolation of VRE using two control groups: (1) a vancomycin-susceptible enterococci (VSE) group, to assess factors associated with development of VRE, and (2) a nonenterococci control group, to assess factors associated with positive cultures for enterococci without regard to vancomycin resistance. After adjusting for the effect of other antimicrobials, time at risk, and patient morbidity, compared to vancomycin-susceptible enterococci controls, exposures to imipenem (OR = 4.9, 95% CI = 1.6-14.1) and ceftazidime (OR = 2.6, 95% CI = 1.1-6.1) were significant predictors of VRE. When compared to nonenterococci controls, exposures to ampicillin (OR = 20.1, 95% CI = 1.5-263.1) and imipenem (OR = 5.1, 95% CI = 1.5-17.1) were significantly associated with VRE. Neither piperacillin nor vancomycin was associated with VRE compared to either control group. This study offers further evidence that the replacement of broad-spectrum cephalosporins by extended-spectrum penicillins, specifically piperacillin, may be effective in reducing VRE.

Low prevalence of colonization with vancomycin-resistant Enterococcus in patients awaiting liver transplantation

The orthotopic liver transplant (OLT) population has been particularly affected by the increase in vancomycin-resistant enterococcus (VRE) infections in recent years. Pre-transplant colonization prevalence, the role of spontaneous bacterial peritonitis (SBP) antimicrobial prophylaxis as a risk factor, and the risk of post-OLT infection in colonized patients are all unknowns. We prospectively evaluated OLT candidates at our center with the aim of answering these questions. Vancomycin-resistant enterococcus colonization status was determined by rectal culture. Data collected included illness severity, antibiotic use (including SBP prophylaxis), waiting time, previous hospitalizations, and invasive procedures. Eighty-eight patients (31 female, 57 male, median age 52 years) were enrolled. The most common diagnoses were hepatitis C (49%), primary sclerosing cholangitis (13.6%), and alcoholic liver disease. Median MELD score was 11.5 (range 7-24), and median waiting time was 551 days (range 1-2224). Vancomycin-resistant enterococcus risk factors were common in our patients: recent hospitalization in 16%, recent antibiotic exposure in 39%, and renal insufficiency in 7%. Seventeen percent were receiving SBP prophylaxis. Despite the presence of established risk factors, VRE colonization prevalence was 3.4%. Preliminary limited data showed poor correlation between screening rectal cultures and operative/peri-operative cultures. Vancomycin-resistant enterococcus colonization prevalence in an OLT candidate population with mid-level MELD scores was low, and SBP prophylaxis was not a significant risk factor.

Vancomycin-resistant enterococci: 15 years and counting

We review the history of vancomycin-resistant enterococci (VRE) and propose a causal model illustrating the roles of exposure to VRE reservoirs, patient characteristics, antimicrobial exposure, and prevalence of VRE in the progression from potential VRE reservoirs to active disease in hospitalized patients. Differences in VRE colonization and VRE infection are discussed with respect to hospital surveillance methodology and implications for interventions. We further document clonal transmission of VRE in a large, urban, teaching hospital and demonstrate VRE susceptibility to a wide array of antimicrobial agents. This model can guide the identification of mutable factors that are focal points for intervention.

Epidemiology of vancomycin-resistant Enterococcus faecium under a selective isolation policy at an urban county hospital

BACKGROUND

We report our experience in a county hospital with the use of selective contact isolation for patients with vancomycin-resistant Enterococcus faecium (VREF). About 12% of patients with VREF are isolated for reasons such as draining wounds and uncontrolled diarrhea.

METHODS

Passive surveillance identified all inpatients (181) from 1995 to 1999 with cultures positive for VREF. Data were collected via electronic databases and from prospectively maintained infection control records. Isolates were typed with use of pulsed-field gel electrophoresis.

RESULTS

Nearly all patients (175/181) with VREF had been admitted at least 48 hours or had a history of previous hospitalization. Most patients (69%) had urine cultures positive for VREF without blood cultures positive for the organism. Only 12 of 127 (9.%) patients with complete data had VREF infection on the basis of receiving treatment and/or having more than 1 blood culture positive for VREF. After VREF became endemic, statistically significant increased prevalence was not detected via surveillance of clinical cultures nor sequential point-prevalence studies. Two major genotypes carrying vanB resistance genes were identified and persisted throughout the period studied. VREF persisted in individual patients up to 46 months.

CONCLUSIONS

The number of VREF infections in this facility has been low, despite appreciable colonization, for an extended period during which selective isolation was used.

Hyperbilirubinemia during quinupristin-dalfopristin therapy in liver transplant recipients: correlation with available liver biopsy results

STUDY OBJECTIVE

To review the liver histopathology in transplant recipients who developed hyperbilirubinemia during therapy with quinupristin-dalfopristin, a new streptogramin antibiotic, and to ascertain whether objective histologic evidence of adverse drug effect could be correlated to serum bilirubin levels.

DESIGN

Retrospective analysis.

SETTING

University of Pittsburgh Medical Center.

PATIENTS

From a database of 34 liver recipients who received quinupristin-dalfopristin for vancomycin-resistant Enterococcus faecium infection who were prospectively enrolled in a multicenter, open-label, emergency-use protocol, the data for a subset of 25 patients who underwent one or more liver biopsies during therapy were reviewed for this study.

INTERVENTIONS

Quinupristin-dalfopristin was administered intravenously at 7.5 mg/kg every 8 hours. Available serum bilirubin levels from before, during, and 1 week after therapy were tabulated. Liver biopsy results obtained within 1 week before and during therapy were retrospectively reviewed. Histopathologic results were characterized and correlated to bilirubin level.

MEASUREMENTS AND MAIN RESULTS

Cholestatic changes were already present in 15 of 17 patients who underwent biopsy before therapy. During therapy, the most common findings from 40 biopsies (25 patients) were cholestasis (33 biopsies), acute rejection (10), and periportal inflammation (8). There was no evidence of drug-specific histopathologic injury.

CONCLUSION

Hyperbilirubinemia in these patients was likely multifactorial and most frequently due to sepsis and prior graft injury.