Systemic inflammatory response syndrome in adult patients with nosocomial bloodstream infections due to enterococci

Sexual Dimorphism in Lipid Metabolism and Gut Microbiota in Mice Fed a High-Fat Diet

The gut microbiome plays an essential role in regulating lipid metabolism. However, little is known about how gut microbiome modulates sex differences in lipid metabolism. The present study aims to determine whether gut microbiota modulates sexual dimorphism of lipid metabolism in mice fed a high-fat diet (HFD). Conventional and germ-free male and female mice were fed an HFD for four weeks, and lipid absorption, plasma lipid profiles, and apolipoprotein levels were then evaluated. The gut microbiota was analyzed by 16S rRNA gene sequencing. After 4-week HFD consumption, the females exhibited less body weight gain and body fat composition and significantly lower triglyceride levels in very-low-density lipoprotein (VLDL) and cholesterol levels in high-density lipoprotein (HDL) compared to male mice. The fecal microbiota analysis revealed that the male mice were associated with reduced gut microbial diversity. The female mice had considerably different microbiota composition compared to males, e.g., enriched growth of beneficial microbes (e.g., Akkermansia) and depleted growth of Adlercreutzia and Enterococcus. Correlation analyses suggested that the different compositions of the gut microbiota were associated with sexual dimorphism in body weight, fat mass, and lipid metabolism in mice fed an HFD. Our findings demonstrated significant sex differences in lipid metabolism and the microbiota composition at baseline (during LFD), along with sex-dependent responses to HFD. A comprehensive understanding of sexual dimorphism in lipid metabolism modulated by microbiota will help to develop more sex-specific effective treatment options for dyslipidemia and metabolic disorders in females.

Role of the fsr Quorum-Sensing System in Enterococcus faecalis Bloodstream Infection

Enterococcus faecalis is an important intestinal colonizing bacteria and can cause various tissue infections, including invasive blood infection (BI). The annual incidence of E. faecalis BI has been estimated to be ~4.5 per 100,000, with a fatality rate that can reach 20%. However, whether bacterial colonization or invasive infections are tissue based has not been thoroughly studied. In this study, we analyzed 537 clinical isolates from 7 different tissues to identify the key genomic elements that facilitate the colonization and invasive infection of E. faecalis. Comparative genomic analysis revealed that the BI E. faecalis isolates had the largest genome size but the lowest GC content, fsr quorum-sensing system genes were enriched in the BI E. faecalis, and the fsr gene cluster could enhance biofilm formation and serum resistance ability. Our findings also provide deep insight into the genomic differences between different tissue isolates, and the fsr quorum-sensing systems could be a key factor promoting E. faecalis invasion into the blood. IMPORTANCE First, we conducted an advanced study on the genomic differences between colonizing and infecting E. faecalis, which provides support and evidence for early and accurate diagnoses. Second, we discovered that fsr was significantly associated with blood infections, which also provides additional information for studies exploring the invasiveness of E. faecalis. Most importantly, we found that fsr played an important role in both biofilm formation and serum resistance ability in E. faecalis.

Sepsis secondary to multifocal Enterococcus faecium infection: A case report

INTRODUCTION

Nosocomial Enterococcus faecium (E faecium) infections are common among immunocompromised patients; however, sepsis caused by E faecium is rarely encountered in the clinical setting.

PATIENT CONCERNS

A 69-year-old woman with a previous history of tuberculosis (TB), developed symptoms of recurrent fever, paroxysmal cough, and exertional dyspnea for over 2 months before she presented to the hospital.

DIAGNOSIS

The patient was initially misdiagnosed with recurrent TB, and did not respond to anti-TB therapy. Culture results of blood, endotracheal necrotic tissue, and urine confirmed a diagnosis of multifocal E faecium infection.

INTERVENTIONS

On definitive diagnosis, the patient received intensive antimicrobial combination treatment with linezolid, teicoplanin, caspofungin, and voriconazole on the basis of antimicrobial susceptibility results.

OUTCOMES

After transient improvement, the patient's condition deteriorated due to secondary infections, and the patient died after discharge against medical advice.

CONCLUSION

E faecium bacteremia may cause sepsis in immunocompromised patients, and has a high mortality rate. Careful pathogen detection and early initiation of treatment is crucial to good patient outcome.

Incidence, Microbiology, and Outcomes in Patients Hospitalized With Infective Endocarditis

Supplemental Digital Content is available in the text.

Background:

Despite improvements in management, infective endocarditis remains associated with high mortality and morbidity. We describe temporal changes in the incidence, microbiology, and outcomes of infective endocarditis and the effect of changes in national antibiotic prophylaxis guidelines on incident infective endocarditis.

Methods:

Using a Scotland-wide, individual-level linkage approach, all patients hospitalized with infective endocarditis from 1990 to 2014 were identified and linked to national microbiology, prescribing, and morbidity and mortality datasets. Linked data were used to evaluate trends in the crude and age- and sex-adjusted incidence and outcomes of infective endocarditis hospitalizations. From 2008, microbiology data and associated outcomes adjusted for patient demographics and comorbidity were also analyzed. An interrupted time series analysis was performed to evaluate incidence before and after changes to national antibiotic prophylaxis guidelines.

Results:

There were 7638 hospitalizations (65±17 years, 51% females) with infective endocarditis. The estimated crude hospitalization rate increased from 5.3/100 000 (95% CI, 4.8-5.9) to 8.6/100 000 (95% CI, 8.1–9.1) between 1990 and 1995 but remained stable thereafter. There was no change in crude incidence following the 2008 change in antibiotic prophylaxis guidelines (relative risk of change 1.06 [95% CI, 0.94–1.20]). The incidence rate in patients >80 years of age doubled from 1990 to 2014 (17.7/100 000 [95% CI, 13.4–23.3] to 37.9/100 000 [95% CI, 31.5–45.5]). The predicted 1-year age- and comorbidity-adjusted case fatality rate for a 65-year-old patient decreased in women (27.3% [95% CI, 24.6–30.2] to 23.7% [95% CI, 21.1–26.6]) and men (30.7% [95% CI, 27.7–33.8] to 26.8% [95% CI, 24.0–29.7]) from 1990 to 2014. Blood culture data were available from 2008 (n=2267/7638, 30%), with positive blood cultures recorded in 42% (950/2267). Staphylococcus (403/950, 42.4%) and streptococcus (337/950, 35.5%) species were most common. Staphylococcus aureus and enterococcus had the highest 1-year mortality (adjusted odds ratio 4.34 [95% CI, 3.12–6.05] and 3.41 [95% CI, 2.04–5.70], respectively).

Conclusions:

Despite changes in antibiotic prophylaxis guidelines, the crude incidence of infective endocarditis has remained stable. However, the incidence rate has doubled in the elderly. Positive blood cultures were observed in less than half of patients, with Staphylococcus aureus and enterococcus bacteremia associated with worse outcomes.

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).

The learning hospital: From theory to practice in a hospital infection prevention program

The learning hospital is distinguished by ceaseless evolution of erudition, enhancement, and implementation of clinical best practices. We describe a model for the learning hospital within the framework of a hospital infection prevention program and argue that a critical assessment of safety practices is possible without significant grant funding. We reviewed 121 peer-reviewed manuscripts published by the VCU Hospital Infection Prevention Program over 16 years. Publications included quasi-experimental studies, observational studies, surveys, interrupted time series analyses, and editorials. We summarized the articles based on their infection prevention focus, and we provide a brief summary of the findings. We also summarized the involvement of nonfaculty learners in these manuscripts as well as the contributions of grant funding. Despite the absence of significant grant funding, infection prevention programs can critically assess safety strategies under the learning hospital framework by leveraging a diverse collaboration of motivated nonfaculty learners. This model is a valuable adjunct to traditional grant-funded efforts in infection prevention science and is part of a successful horizontal infection control program.

Early alert from the microbiology laboratory improves the outcome of elderly patients with Enterococcus spp. bloodstream infection: Results from a multicentre prospective study

OBJECTIVES

This study describes the clinical features and outcomes of patients with bloodstream infection (BSI) due to Enterococcus spp. and identified factors predictive of mortality.

METHODS

This analysis is part of a prospective multicentre observational study of consecutive hospitalised patients with BSI conducted from March 2012 to December 2012 in 31 internal medicine wards in Italy. Patients with enterococcal BSI were selected from the entire cohort. Patient characteristics, therapeutic interventions and outcome were reviewed. Cox regression analysis was performed to identify factors associated with in-hospital mortality. Hazard ratios (HRs) and 95% interval confidences (CIs) were calculated.

RESULTS

Among 533 patients with BSI, 41 (7.7%) had BSI by Enterococcus spp. (28 Enterococcus faecalis, 4 Enterococcus faecium and 3 each of Enterococcus avium, Enterococcus casseliflavus and Enterococcus gallinarum). Six BSIs (14.6%) were polymicrobial. Median (IQR) patient age was 73 (66-85.5) years. In-hospital mortality was 24.4%. Polymicrobial infection (HR = 9.100, 95% CI 1.295-63.949; P = 0.026), age (HR = 1.261, 95% CI 1.029-1.546; P = 0.025) and SOFA score (HR = 1.244, 95% CI 1.051-1.474; P = 0.011) were risk factors for in-hospital mortality. Conversely, receiving an alert from the microbiology laboratory before obtaining final antimicrobial susceptibility results was associated with survival (HR = 0.073, 95% CI 0.007-0.805; P = 0.033).

CONCLUSION

BSI due to Enterococcus spp. in elderly patients is associated with high mortality. Polymicrobial infection, age and SOFA score are factors associated with poor outcome. Conversely, early alert from the microbiology laboratory improves patient survival.

Burn injury alters the intestinal microbiome's taxonomic composition and functional gene expression

Burn patients have a high risk of sepsis-related mortality even after surviving the initial injury. Immunosuppression increases the risk of sepsis after burn injury, as does the disruption of the intestinal epithelial barrier, which allows the translocation of bacteria and bacterial products into the circulation. The integrity of the intestinal epithelial barrier is largely maintained by the intestinal microbiota. Burn injury has been reported to result in significant changes in the intestinal microbiome composition. In this mouse study, we confirm these taxonomic differences in a full-thickness scald injury model using CF-1 mice. For the first time, we also address alterations in functional gene expression of the intestinal microbiota after burn injury to assess the microbiome's physiological capabilities for overgrowth and pathogenic invasion: 38 pathways were differentially abundant between the sham and burn injury mice, including bacterial invasion of epithelial cells and gap- and adherens junction pathways.

Bacterial Infections

Bacterial infections are the most significant infectious source of morbidity and mortality in cirrhotic patients. Bacteria infections result is both acute decompensation in chronic liver disease and mortality in patients with decompensated cirrhosis. Spontaneous bacterial peritonitis (SBP), bacteremia, pneumonia, urinary tract infections (UTI) and skin and soft tissue infection (SSTI) are the most significant sources of infection in cirrhosis. Bacterial infections can precipitate renal failure and worsening hepatic encephalopathy, and patients with sepsis and liver disease have higher rates of acute respiratory distress syndrome (ARDS) and coagulopathy.

The Enterococcus faecalis virulence factor ElrA interacts with the human Four-and-a-Half LIM Domains Protein 2

The commensal bacterium Enterococcus faecalis is a common cause of nosocomial infections worldwide. The increasing prevalence of multi-antibiotic resistant E. faecalis strains reinforces this public health concern. Despite numerous studies highlighting several pathology-related genetic traits, the molecular mechanisms of E. faecalis virulence remain poorly understood. In this work, we studied 23 bacterial proteins that could be considered as virulence factors or involved in the Enterococcus interaction with the host. We systematically tested their interactions with human proteins using the Human ORFeome library, a set of 12,212 human ORFs, in yeast. Among the thousands of tested interactions, one involving the E. faecalis virulence factor ElrA and the human protein FHL2 was evidenced by yeast two-hybrid and biochemically confirmed. Further molecular characterizations allowed defining an FHL2-interacting domain (FID) of ElrA. Deletion of the FID led to an attenuated in vivo phenotype of the mutated strain clearly indicating that this interaction is likely to contribute to the multifactorial virulence of this opportunistic pathogen. Altogether, our results show that FHL2 is the first host cellular protein directly targeted by an E. faecalis virulence factor and that this interaction is involved in Enterococcus pathogenicity.

Sequence-identification of Candida species isolated from candidemia

Background:

Candida species are the most prevalent cause of invasive fungal infections such as candidemia. Candidemia is a lethal fungal infection among immunocompromised patients worldwide. Main pathogen is Candida albicans but a global shift in epidemiology toward non-albicans species have reported. Species identification is imperative for good management of candidemia as a fatal infection. The aim of the study is to identify Candida spp. obtained from candidemia and determination of mortality rate among this population.

Materials and Methods:

The study was performed during February 2014 to March 2015 in Tehran, Iran. Two-hundred and four blood cultures were evaluated for fungal bloodstream infection. Identification of isolates was carried out using phenotypic tests and polymerase chain reaction sequencing technique.

Results:

Twenty-two out of 204 patients (10.8%) had candidemia. Candida parapsilosis was the most prevalent species (45.4%), followed by C. albicans (31.8%) and Candida glabrata (22.7%). Male to female sex ratio was 8/14.

Conclusions:

The emergence of resistant strains of Candida species should be considered by physicians to decrease the mortality of this fatal fungal infection by appropriate treatment.

Evaluation of Vancomycin-Resistant Enterococci (VRE)–Associated Morbidity Following Relaxation of VRE Screening and Isolation Precautions in a Tertiary Care Hospital

Objective

To determine whether relaxing vancomycin-resistant enterococci (VRE) precautions results in an increase in the incidence of invasive VRE infections over time.

Design

Retrospective analysis of a microbiology database before and after relaxation of VRE screening and isolation precautions.

Setting

Urban tertiary care teaching hospital in Montreal, Canada.

Participants.

All hospitalized and emergency room patients over a 13-year period from January 1, 2000, to March 31, 2013.

Methods

We assessed the results of all microbiology cultures for the presence of VRE as well as the results of all polymerase chain reaction assays forvanAandvanBduring the study period. Applying criteria for 4 clinical situations (bacteremia, definite infection, possible infection, and colonization with VRE), we analyzed the effects of relaxed VRE screening and isolation precautions on the incidence of each of these outcomes over the time preceding and following this change.

Results

When VRE screening and isolation precautions were relaxed, a marked rise in VRE colonization was observed, with a lesser but definite rise in the 3 other outcomes. Despite this initial rise in all measures, all incidences other than colonization plateaued during the 34 months of follow-up.

Conclusions

Relaxation of VRE screening and isolation precautions was associated with an immediate increase in colonization and infection incidence. Despite increasing colonization, infection outcomes remained infrequent and stable, suggesting a finite number of susceptible hosts at risk. Relaxation of VRE protocols may not lead to increasing infection incidence in a hospital setting, advocating that cost effectiveness exercises, with targeted screening and isolation precautions, are crucial.

Surface protein Esp enhances pro-inflammatory cytokine expression through NF-κB activation during enterococcal infection

Enterococcal surface protein (Esp) is encoded on a pathogenicity island in Enterococcus faecalis and E. faecium and is involved in biofilm formation and binding to epithelial cells. In this study, using Esp-expressing E. faecalis MMH594 and its isogenic Esp-deficient strain, as well as purified Esp, we show that Esp is sufficient for activation of NF-κB and the subsequent production of pro-inflammatory cytokines IL-1β and TNF-α in macrophages in vitro. In a mouse peritonitis model, we also show that mice infected with Esp-expressing E. faecalis showed comparatively higher levels of cytokines TNF-α, IL-1β and IL-6 in peritoneal fluid, and IL-6 in serum. Moreover, neutrophil infiltration and tissue damage in the liver was higher in the mice infected with the Esp-expressing strain compared with mice infected with the Esp-deficient mutant. These results add Esp to the growing list of enterococcal virulence factors that can modulate inflammation during infection and has implications for enterococcal pathogenesis.

VRE and VSE Bacteremia Outcomes in the Era of Effective VRE Therapy: A Systematic Review and Meta-analysis

BACKGROUND

Prior data suggest that vancomycin-resistant Enterococcus (VRE) bacteremia is associated with worse outcomes than vancomycin-sensitive Enterococcus (VSE) bacteremia. However, many studies evaluating such outcomes were conducted prior to the availability of effective VRE therapies.

OBJECTIVE

To systematically review VRE and VSE bacteremia outcomes among hospital patients in the era of effective VRE therapy.

METHODS

Electronic databases and grey literature published between January 1997 and December 2014 were searched to identify all primary research studies comparing outcomes of VRE and VSE bacteremias among hospital patients, following the availability of effective VRE therapies. The primary outcome was all-cause, in-hospital mortality, while total hospital length of stay (LOS) was a secondary outcome. All meta-analyses were conducted in Review Manager 5.3 using random-effects, inverse variance modeling.

RESULTS

Among all the studies reviewed, 12 cohort studies and 1 case control study met inclusion criteria. Similar study designs were combined in meta-analyses for mortality and LOS. VRE bacteremia was associated with increased mortality compared with VSE bacteremia among cohort studies (odds ratio [OR], 1.80; 95% confidence interval [CI], 1.38–2.35; I²=0%; n=11); the case-control study estimate was similar, but not significant (OR, 1.93; 95% CI, 0.97–3.82). LOS was greater for VRE bacteremia patients than for VSE bacteremia patients (mean difference, 5.01 days; 95% CI, 0.58–9.44]; I²=0%; n=5).

CONCLUSIONS

Despite the availability of effective VRE therapy, VRE bacteremia remains associated with an increased risk of in-hospital mortality and LOS when compared to VSE bacteremia.

Infect. Control Hosp. Epidemiol. 2015;37(1):26–35

Roles of TLR/MyD88/MAPK/NF-κB Signaling Pathways in the Regulation of Phagocytosis and Proinflammatory Cytokine Expression in Response to E. faecalis Infection

Enterococcus faecalis is a commensal bacterium residing in the gastrointestinal tract of mammals, but in certain situations it is also an opportunistic pathogen which can cause serious disease. Macrophages have been shown to play a critical role in controlling infections by commensal enterococci and also have an important role in mediating chromosomal instability and promoting colon cancer during high-level enterococcal colonization in genetically susceptible mice. However, the molecular mechanisms involved in the interaction of macrophages with enterococci during infection are not fully understood. In this study, using BMDM and RAW264.7 macrophages we show that enterococcal infection activates ERK, JNK and p38 MAPK as well as NF-κB, and drives polarization of macrophages towards the M1 phenotype. Inhibition of NF-κB activation significantly reduced the expression of TNF-α and IL-1β, as did the inhibition of ERK, JNK and p38 MAPK, although to differing extent. Enterococci-induced activation of these pathways and subsequent cytokine expression was contact dependent, modest compared to activation by E. coli and, required the adaptor protein MyD88. Phagocytosis of enterococci by macrophages was enhanced by preopsonization with E. faecalis antiserum and involved the ERK and JNK signaling pathways, with the adaptor protein MyD88 as an important mediator. This study of the interaction of macrophages with enterococci could provide a foundation for studying the pathogenesis of infection by this opportunistic pathogen and to developing new therapeutic approaches to combat enterococcal infection.

Evaluation of blood cultures in a children's hospital located in Southeastern Anatolia

AIM

Bloodstream infections in hospitalized patients are one of the most important causes of morbidity and mortality despite antimicrobial therapy. Early diagnosis and treatment of these infections is crucial. The aim of this study was to evaluate the distribution and antibiotic susceptibility of bacteria isolated from blood cultures in a children's hospital in the Southeastern Anatolia during an 18-month period.

MATERIAL AND METHODS

7 040 blood cultures which were sent from hospitalized patients in Gaziantep Children's Hospital between 01.07.2010 and 01.01.2012 were evaluated.

RESULTS

A total of 7 040 blood cultures were evaluated in this study. Microbial growth was detected in 2075 (29.47%) blood cultures. The most frequently isolated bacteria were coagulase-negative staphylococci (%45.97) which were followed by Salmonella spp. (%7.8). 12.12% of enterococcal isolates were resistant to glycopeptide antibiotics. The most frequently isolated gram negative bacterium was Salmonella spp. 15.43% of Salmonella spp. showed decreased susceptibility against quinolones. The ESBL positivity rate of E. coli and K. pneumoniae strains was found to be 35.08% and 57.14%, respectively. The imipenem resistance rate of P. aeruginosa was found to be 33.33%. The most common nonfermentative bacterium was S. maltophilia.

CONCLUSIONS

The distribution of bacteria isolated from blood cultures and antibiotic resistance rates differ among different regions of Turkey. Different results obtained in our study may be related with regional tendencies to infections and patient population. Distribution of infectious agents and antibiotic resistance rates should be evaluated at regular intervals. This will lead to establishment of proper antibiotic usage policies in our country.

Rapid detection of Enterococcus spp. direct from blood culture bottles using Enterococcus QuickFISH method: a multicenter investigation

The performance of a diagnostic method for detection and identification of Enterococcus spp. directly from positive blood culture was evaluated in a clinical study. The method, Enterococcus QuickFISH BC, is a second-generation peptide nucleic acid (PNA) fluorescence in situ hybridization (FISH) test, which uses a simplified, faster assay procedure. The test uses fluorescently labeled PNA probes targeting 16S rRNA to differentiate Enterococcus faecalis from other Enterococcus spp. by the color of the cellular fluorescence. Three hundred fifty-six routine blood culture samples were tested; only 2 discordant results were recorded. The sensitivities for detection of Enterococcus faecalis and non-faecalis Enterococcus were 100% (106/106) and 97.0% (65/67), respectively, and the combined specificity of the assay was 100%. The combined positive and negative predictive values of the assay were 100% (171/171) and 98.9% (185/187), respectively.

Invasive candidiasis: update on current pharmacotherapy options and future perspectives

INTRODUCTION

Invasive candidiasis (IC), mainly candidemia, is a leading cause of morbidity and mortality among immunocompromised patients and those admitted to intensive care units. Despite the recognition of risk factors and advances in disease prevention, Candida-related hospitalizations and mortality continue to rise. For treatment, four classes of older and newer antifungal agents are currently available. Adjunctive immunotherapies and a monoclonal antibody against heat shock protein 90 (efungumab) are promising novel therapeutic approaches.

AREAS COVERED

In this article, approaches and therapeutic agents for candidemia and other forms of IC are reviewed.

EXPERT OPINION

The thorough understanding of the available antifungal agents in combination with the increasing knowledge of the mechanisms that underlie the pathogenesis of Candida infections and the development of newer approaches such as efungumab and immunotherapy with adjunctive cytokines may improve the prognosis of patients with life-threatening invasive Candida infections.

Enterococcal Rgg-like regulator ElrR activates expression of the elrA operon

The Enterococcus faecalis leucine-rich protein ElrA promotes virulence by stimulating bacterial persistence in macrophages and production of the interleukin-6 (IL-6) cytokine. The ElrA protein is encoded within an operon that is poorly expressed under laboratory conditions but induced in vivo. In this study, we identify ef2687 (renamed elrR), which encodes a member of the Rgg (regulator gene for glucosyltransferase) family of putative regulatory proteins. Using quantitative reverse transcription-PCR, translational lacZ fusions, and electrophoretic mobility shift assays, we demonstrate that ElrR positively regulates expression of elrA. These results correlate with the attenuated virulence of the ΔelrR strain in a mouse peritonitis model. Virulence of simple and double elrR and elrA deletion mutants also suggests a remaining ElrR-independent expression of elrA in vivo and additional virulence-related genes controlled by ElrR.

Large-scale screening of a targeted Enterococcus faecalis mutant library identifies envelope fitness factors

Spread of antibiotic resistance among bacteria responsible for nosocomial and community-acquired infections urges for novel therapeutic or prophylactic targets and for innovative pathogen-specific antibacterial compounds. Major challenges are posed by opportunistic pathogens belonging to the low GC% Gram-positive bacteria. Among those, Enterococcus faecalis is a leading cause of hospital-acquired infections associated with life-threatening issues and increased hospital costs. To better understand the molecular properties of enterococci that may be required for virulence, and that may explain the emergence of these bacteria in nosocomial infections, we performed the first large-scale functional analysis of E. faecalis V583, the first vancomycin-resistant isolate from a human bloodstream infection. E. faecalis V583 is within the high-risk clonal complex 2 group, which comprises mostly isolates derived from hospital infections worldwide. We conducted broad-range screenings of candidate genes likely involved in host adaptation (e.g., colonization and/or virulence). For this purpose, a library was constructed of targeted insertion mutations in 177 genes encoding putative surface or stress-response factors. Individual mutants were subsequently tested for their i) resistance to oxidative stress, ii) antibiotic resistance, iii) resistance to opsonophagocytosis, iv) adherence to the human colon carcinoma Caco-2 epithelial cells and v) virulence in a surrogate insect model. Our results identified a number of factors that are involved in the interaction between enterococci and their host environments. Their predicted functions highlight the importance of cell envelope glycopolymers in E. faecalis host adaptation. This study provides a valuable genetic database for understanding the steps leading E. faecalis to opportunistic virulence.

Organ failure in sepsis

The development of organ failure determines the course and prognosis of the septic patient. Although several successful clinical trials in recent years have raised the enthusiasm of intensivists, severe sepsis and septic shock still have an increasing incidence with more or less unchanged mortality. Recent sepsis research, including progress made in definitions, epidemiology, pathophysiology, diagnosis, standard and adjunctive therapy, and experimental approaches, is encouraging. This includes genomic information for stratifying subgroups of patients, a broader field of laboratory diagnostics due to clinical studies, and basic research on the cellular mechanisms of inflammation and organ dysfunction. Furthermore, new findings in pathogenesis and therapeutic approaches to organ failure merit attention. In this review, state-of-the-art publications are presented to elucidate the possible impact of sepsis-induced organ failure on clinical routine.

Peptide nucleic acid fluorescent in situ hybridization for hospital-acquired enterococcal bacteremia: delivering earlier effective antimicrobial therapy

Hospital-acquired vancomycin-resistant enterococcal bacteremia has been associated with increased hospital costs, length of stay, and mortality. The peptide nucleic acid fluorescent in situ hybridization (PNA FISH) test for Enterococcus faecalis and other enterococci (EFOE) is a multicolor probe that differentiates E. faecalis from other enterococcal species within 3 h directly from blood cultures demonstrating gram-positive cocci in pairs and chains (GPCPC). A quasiexperimental study was performed over two consecutive years beginning in 2005 that identified GPCPC by conventional microbiological methods, and in 2006 PNA FISH was added with a treatment algorithm developed by the antimicrobial team (AMT). The primary outcome assessed was the time from blood culture draw to the implementation of effective antimicrobial therapy before and after PNA FISH. The severity of illness, patient location, and empirical antimicrobial therapy were measured. A total of 224 patients with hospital-acquired enterococcal bacteremia were evaluated, with 129 in the preintervention period and 95 in the PNA FISH period. PNA FISH identified E. faecalis 3 days earlier than conventional cultures (1.1 versus 4.1 days; P < 0.001). PNA FISH identified Enterococcus faecium a median 2.3 days earlier (1.1 versus 3.4 days; P < 0.001) and was associated with statistically significant reductions in the time to initiating effective therapy (1.3 versus 3.1 days; P < 0.001) and decreased 30-day mortality (26% versus 45%; P = 0.04). The EFOE PNA FISH test in conjunction with an AMT treatment algorithm resulted in earlier initiation of appropriate empirical antimicrobial therapy for patients with hospital-acquired E. faecium bacteremia.

Determination of risk factors associated with isolation of linezolid-resistant strains of vancomycin-resistant Enterococcus

OBJECTIVE

To identify independent risk factors associated with isolation of linezolid-resistant, vancomycin-resistant Enterococcus (VRE).

DESIGN

A retrospective, case-case-control study.

SETTING

A tertiary care, academic medical center.Methods. VRE isolates from clinical cultures were retrospectively analyzed for linezolid resistance during our 18-month study period. Clinical data were obtained from electronic patient records, and the risk factors associated with isolation of linezolid-resistant VRE were determined by comparison of 2 case groups with a control group.

RESULTS

A total of 20% of the VRE isolates analyzed during the study period were linezolid resistant, and resistant isolates were most commonly recovered from the urine (40% of resistant isolates). Risk factors found to be associated with isolation of linezolid-resistant VRE were peripheral vascular disease and/or the receipt of a solid organ transplant, total parenteral nutrition, piperacillin-tazobactam, and/or cefepime. Only 25% of patients from whom linezolid-resistant VRE was isolated had previous linezolid exposure, and in the multivariate model this was not found to be a risk factor associated with the isolation of linezolid-resistant VRE.

CONCLUSIONS

The results of this analysis suggest that there is horizontal transmission of linezolid-resistant VRE in our institution and highlight the need for improved infection control measures. Furthermore, the high incidence of linezolid-resistant VRE demands a reassessment of our empirical antibiotic selection for patients infected with VRE.

Comparison of the BD GeneOhm VanR assay to culture for identification of vancomycin-resistant enterococci in rectal and stool specimens

Active screening for vancomycin-resistant enterococci (VRE) in rectal and stool specimens has been recommended to limit the spread of antimicrobial resistance within certain high-risk populations. Directly from 502 rectal swabs and stool specimens, we evaluated the diagnostic performance of the BD GeneOhm VanR assay (BD GeneOhm, San Diego, CA), a rapid real-time PCR test that detects the presence of vanA and/or vanB genes. The VanR assay was compared to culture consisting of both bile-esculin-azide agar with 6 mug/ml vancomycin (BEAV agar) (BD Diagnostics, Sparks, MD) and BEAV broth with 8 mug/ml vancomycin (Hardy Diagnostics, Santa Maria, CA). Enterococci were identified to the species level using standard biochemical tests and a Phoenix automated microbiology system (BD Diagnostics, Sparks, MD). The susceptibility of the enterococci to vancomycin and teicoplanin was determined using an Etest (AB Biodisk, Solna, Sweden). VRE were initially isolated from 147 cultures, and the VanR assay detected 142 of the 147 positive cultures for a sensitivity of 96.6%. The specificity was 87.0% (309/355) largely due to false positives seen with the vanB portion of the assay. The sensitivity when testing rectal swabs was 98.3%, and the sensitivity for stool samples was 95.4% (P = 0.643). The specificity of rectal swabs was comparable to that of the stool specimens (87.5% and 86.5%, respectively). When used only to detect VanA resistance, the VanR assay was 94.4% (136/144) sensitive and 96.4% (345/358) specific, with positive and negative predictive values of 91.3% and 97.7%, respectively. In summary, the BD GeneOhm VanR assay is a good screening test for VRE in our population of predominantly vanA-colonized patients. However, patient samples testing only vanB positive should be confirmed by another method for the presence of VRE.

Enterococcal leucine-rich repeat-containing protein involved in virulence and host inflammatory response

Enterococcus faecalis is an important nosocomial pathogen associated with high morbidity and mortality for patients who are immunocompromised or who have severe underlying diseases. The E. faecalis genome encodes numerous surface-exposed proteins that may be involved in virulence. This work describes the characterization of the first internalin-like protein in E. faecalis, ElrA, belonging to the recently identified WxL family of surface proteins. ElrA contains an N-terminal signal peptide for export, a leucine-rich repeat domain that may interact with host cells, and a C-terminal WxL domain that interacts with the peptidoglycan. Disruption of the elrA gene significantly attenuates bacterial virulence in a mouse peritonitis model. The elrA deletion mutant also displays a defect in infection of host macrophages and a decreased interleukin-6 response in vivo. Finally, elrA expression is induced in vivo. Altogether, these results demonstrate a role for ElrA in the E. faecalis infectious process in vivo and suggest that this surface protein may contribute to E. faecalis virulence by stimulating the host inflammatory response.