Risk factors for mortality after linezolid treatment of vancomycin-resistant Enterococcus bloodstream infection

OBJECTIVES

We analyzed the risk factors affecting linezolid treatment outcome in vancomycin-resistant Enterococcus (VRE) bloodstream infection (BSI).

METHODS

We conducted a multicenter observational study of patients who received linezolid 600 mg every 12 hours for VRE BSI. The primary outcome was 28-day mortality. The estimated area under the concentration-time curve and trough concentration were calculated. Multivariable logistic regression was used for the outcome analysis.

RESULTS

A total of 170 patients were included: 114 (67.1%) survived and 56 (32.9%) did not. A total of 26 (18.2%) isolates showed a linezolid minimum inhibitory concentration (MIC) of ≤1 mg/l, 113 (79.0%) of 2 mg/l, and 4 (2.8%) of 4 mg/l. The univariable analysis showed that the linezolid MIC and concentration-time curve/MIC were not associated with mortality (P = 0.95 and P = 0.42, respectively). After adjusting for underlying comorbidity and disease severity, the linezolid dose per body weight (LDBW), body height, and interaction between them were independent risks for mortality. Marginal analysis showed that increasing the LDBW was protective in patients with a body height <160 cm. A trough concentration of >12.2 mg/l was a risk factor for thrombocytopenia.

CONCLUSION

The LDBW and body height were interactively associated with clinical outcomes of linezolid treatment for VRE BSI.

Clinical manifestations, characteristics, and outcome of infections caused by vancomycin-resistant enterococci at a tertiary care center in Lebanon: A case-case-control study

BACKGROUND

Vancomycin-resistant enterococci (VRE) are prevalent infectious agents that particularly affect critically-ill patients, and they are on the rise in Lebanon. We aim at determining the potential risk factors and complications for VRE and vancomycin-susceptible enterococci (VSE) infections in a hospital setting and identify risk factors for in-hospital mortality.

METHODS

A case-case-control study design was used where patients with VRE and VSE were included as two separate groups and each group was compared to uninfected controls. We also constructed binary regression models to detect risk factors that were associated with the acquisition of a VRE or a VSE infection. We also identified independent mortality predictors for all patients with enterococcal infection as well as patients with only a VRE infection.

RESULTS

A total of 142 patients with enterococcal infections (VRE and VSE) were compared to 142 in-patients not infected with Enterococcus spp. independent risk factors for a VRE infection were steroid therapy within 30 days and the presence of another infection preceding the VRE infection (aOR 15.4, 95 % CI 2.4-99.3 and 23.9, 95 % CI 3.9-1482, respectively). An independent risk factor for VSE was diabetes mellitus (aOR 5.4, 95 % CI 1.1-26.6). Based on these risk factors, we developed a risk score to be used in quantifying the risk of VRE in a patient with an enterococcal infection. Male sex and low albumin were significant risk factors for mortality in our patient cohort.

CONCLUSIONS

VRE and VSE infections have distinct risk factors that can be used to guide empiric antimicrobial therapy.

Risk factors and outcomes associated with persistent vancomycin resistant Enterococcal Bacteremia

Background

Prior studies have identified that vancomycin resistant enterococcus (VRE) bacteremia that persists for four days or more is an independent predictor of mortality. Despite this, there is no published data to identify those patients at highest risk of developing persistent VRE bacteremia.

Methods

This was a single center, retrospective, case-control study of adult patients with a VRE bloodstream infection (BSI). Case patients were those with persistent bacteremia (≥ 4 days despite VRE-directed therapy) and control patients were those with non-persistent bacteremia. Logistic regression was used to assess risk factors associated with persistent VRE BSIs. Secondary outcomes included in-hospital mortality, recurrent bacteremia, and breakthrough bacteremia.

Results

During the study period, 24/108 (22%) patients had persistently positive blood cultures. Risk factors for persistent bacteremia included severe neutropenia (OR 2.13), 4 out of 4 positive index blood cultures (OR 11.29) and lack of source control (OR 11.88). In an unadjusted analysis, no statistically significant differences in in-hospital mortality (58% versus 40%; p = 0.121), recurrent bacteremia (17% versus 6%; p = 0.090), or breakthrough bacteremia (13% versus 7%; p = 0.402) were observed between groups.

Conclusion

Patients with severe neutropenia, 4 out of 4 positive index blood culture bottles, and lack of source control were more likely to develop persistent VRE bacteremia despite directed antibiotic treatment.

Library Screening for Synergistic Combinations of FDA-Approved Drugs and Metabolites with Vancomycin against VanA-Type Vancomycin-Resistant Enterococcus faecium

Antimicrobial resistance is a major public health threat, and there is an urgent need for new strategies to address this issue. In a recent study, a library screening strategy was developed in which an FDA-approved drug library was screened against methicillin-resistant Staphylococcus aureus (MRSA) in both its original (unmetabolized [UM]) and its human liver microsome metabolized (postmetabolized [PM]) forms and in the absence and presence of a resistant-to antibiotic. This allows the identification of agents with active metabolites and agents that can act synergistically with the resistant-to antibiotic. In this study, this strategy is applied to VanA-type vancomycin-resistant Enterococcus faecium (VREfm) in the absence and presence of vancomycin. Thirteen drugs with minimum MICs that were ≤12.5 μM under any tested condition (UM/PM vs. -/+vancomycin) were identified. Seven of these appeared to act synergistically with vancomycin, and follow-up checkerboard analyses confirmed synergy (∑FICmin ≤0.5) for six of these. Ultimately four rifamycins, two pleuromutilins, mupirocin, and linezolid were confirmed as synergistic. The most synergistic agent was rifabutin (∑FICmin = 0.19). Linezolid, a protein biosynthesis inhibitor, demonstrated relatively weak synergy (∑FICmin = 0.5). Only mupirocin showed significantly improved activity after microsomal metabolism, indicative of a more active metabolite, but efforts to identify an active metabolite were unsuccessful. Spectra of activity of several hits and related agents were also determined. Gemcitabine showed activity against a number vancomycin-resistant E. faecium and E. faecalis strains, but this activity was substantially weaker than previously observed in MRSA. IMPORTANCE Resistance to currently used antibiotics poses a serious threat to public health. This study reports a complete screen of 1,000 FDA-approved drugs and their metabolites against vancomycin-resistant Enterococcus faecium (VREfm) in both the absence and presence of vancomycin. This identified potentially synergistic combinations of FDA-approved drugs with vancomycin, and a number of these were confirmed in follow-up checkerboard assays. Among intrinsically active FDA-approved drugs, gemcitabine was identified as having activity against a panel of VRE strains.

Antibiogram Pattern and Virulence Trait Characterization of Enterococcus Species Clinical Isolates in Eastern India: A Recent Analysis

Objective We aimed to evaluate the current antimicrobial susceptibility pattern and characterize putative virulence traits among Enterococcus species isolates from various clinical specimens in view of their increased isolation rates in both community-related and serious nosocomial infections, as well as resistance to many antibiotics.

Methods Study (April 2017–March 2018) included consecutive, nonrepeated, discrete, and clinically significant isolates of enterococci. Susceptibility testing included detection of high-level aminoglycoside-resistant (HLAR) and glycopeptide-resistant enterococci (GRE). All screen-positive GRE isolates were investigated by polymerase chain reaction for species confirmation and presence of vanA/vanB genes. Virulence genes ace, asa1, cyt, efa, esp, gelE, and hyl were investigated by molecular methods. Hemolysin and biofilm production were studied using phenotypic methods.

Results Of 111 isolates, 89 (80.1%), 16 (14.4%), and 6 (5.4%) were from urine, pus, and blood, respectively, consisting predominantly of E. faecalis (67, 60.4%) and E. faecium (32, 28.8%). E. hirae (5, 4.5%) was the predominant non-E. faecalis non-E. faecium isolate. Other species were E. durans (4, 3.6%), E. avium (2, 1.8%), and E. mundtii (1, 0.9%). Seven (6.3%) out of the 111 isolates were GRE, all vanA genotype. HLAR was observed in 70 (63.1%) isolates, significantly higher in E. faecium than E. faecalis (81.2 vs. 58.2%; p < 0.05). All were susceptible to daptomycin. Hemolysin activity and biofilm production were observed in 38 (34.2%) and 36 (32.4%) isolates. Most frequent virulence genes were efa (77, 69.4%), ace (71, 63.9%), asa1 (67, 60.3%), and gelE (66, 59.4%). There was a predominant association of esp and hyl genes with E. faecium and that of the other genes with E. faecalis.

Conclusion The study will contribute to the existing limited data on virulence trait characterization of clinical E. spp. isolates in India. At the same time, it will help to serve as a guide in the choice of empirical therapy in enterococcal infections leading to favorable clinical outcomes by decreasing the clinical failure, microbiological persistence, and associated mortality, and will lead to future studies on controlling the spread of virulent and multiresistant isolates.

Panorama of Bacterial Infections Caused by Epidemic Resistant Strains

Antimicrobial resistance (AMR) represents a critical obstacle to public health worldwide, due to the high incidence of strains resistant to available antibiotic therapies. In recent years, there has been a significant increase in the prevalence of resistant epidemic strains, associated with this, public health authorities have been alarmed about a possible scenario of uncontrolled dissemination of these microorganisms and the difficulty in interrupting their transmission, as nosocomial pathogens with resistance profiles previously considered sporadic. They become frequent bacteria in the community. In addition, therapy for infections caused by these pathogens is based on broad-spectrum antibiotic therapy, which favors an increase in the tolerance of remaining bacterial cells and is commonly associated with a poor prognosis. In this review, we present the current status of epidemic strains of methicillin-resistant Staphylococcus aureus (MRSA), Vancomycin-resistant Enterococcus (VRE), MDR Mycobacterium tuberculosis, extended-spectrum β-lactamase-producing Enterobacterales (ESBL), Klebsiella pneumoniae carbapenemase (KPC), and—New Delhi Metallo-beta-lactamase-producing Pseudomonas aeruginosa (NDM).

Biofilm Time-Kill Curves to Assess the Bactericidal Activity of Daptomycin Combinations against Biofilm-Producing Vancomycin-Resistant Enterococcus faecium and faecalis

INTRODUCTION

E. faecium and E. faecalis are responsible for 13.9% of hospital-acquired infections with frequent resistance to vancomycin (82.6% of E. faecium, 9.5% of E. faecalis). Medical device infections secondary to enterococci often require combination therapy due to impaired activity against biofilm embedded cells. In vitro data demonstrate synergistic activity of daptomycin combinations. Using a novel, biofilm time-kill approach, we evaluated whether daptomycin combinations maintained synergy against biofilm-producing E. faecium and E. faecalis.

METHODS

Broth microdilution (BMD) and biofilm MIC (bMIC) values for daptomycin, ampicillin, ceftriaxone, fosfomycin, and rifampin were determined against biofilm-producing E. faecium and E. faecalis. Daptomycin combination bMIC values were determined in the presence of biologic concentrations of other antimicrobials. Synergy was evaluated against two E. faecalis (R6981, R7808) and two E. faecium (5938 and 8019) using a previously described biofilm time-kill method. Synergy was defined as ≥2 log10 CFU/cm2 reduction over the most active agent alone. Bactericidal activity was defined as ≥3 log10 CFU/cm2 reduction.

RESULTS

Daptomycin bMICs were 2-8-fold higher than BMD. In the presence of other antimicrobials, daptomycin bMICs were reduced ≥ two-fold in dilutions. Ceftriaxone and ampicillin demonstrated the most potent combinations with daptomycin, yielding synergy against three of four strains. Daptomycin plus rifampin was synergistic against E. faecium 5938 and E. faecalis 6981 and produced bactericidal kill. The combination of daptomycin plus fosfomycin displayed synergy solely against E. faecalis 6981.

CONCLUSIONS

Daptomycin combinations with beta-lactams demonstrated promising synergistic activity against both E. faecium and E. faecalis. While daptomycin plus rifampin yielded bactericidal results, the effect was not seen across all organisms. These combinations warrant further evaluation to determine the optimal dose and response.

Effect of Vancomycin on Cytoplasmic Peptidoglycan Intermediates and van Operon mRNA Levels in VanA-Type Vancomycin-Resistant Enterococcus faecium

Resistance in VanA-type vancomycin-resistant Enterococcus faecium (VREfm) is due to an inducible gene cassette encoding seven proteins (vanRSHAXYZ). This provides for an alternative peptidoglycan (PG) biosynthesis pathway whereby D-Ala-D-Ala is replaced by D-Ala-d-lactate (Lac), to which vancomycin cannot bind effectively. This study aimed to quantify cytoplasmic levels of normal and alternative pathway PG intermediates in VanA-type VREfm by liquid chromatography-tandem mass spectrometry before and after vancomycin exposure and to correlate these changes with changes in vanA operon mRNA levels measured by real-time quantitative PCR (RT-qPCR). Normal pathway intermediates predominated in the absence of vancomycin, with low levels of alternative pathway intermediates. Extended (18-h) vancomycin exposure resulted in a mixture of the terminal normal (UDP-N-acetylmuramic acid [NAM]-l-Ala-D-Glu-l-Lys-D-Ala-D-Ala [UDP-Penta]) and alternative (UDP-NAM-l-Ala-γ-D-Glu-l-Lys-D-Ala-D-Lac [UDP-Pentadepsi]) pathway intermediates (2:3 ratio). Time course analyses revealed normal pathway intermediates responding rapidly (peaking in 3 to 10 min) and alternative pathway intermediates responding more slowly (peaking in 15 to 45 min). RT-qPCR demonstrated that vanA operon mRNA transcript levels increased rapidly after exposure, reaching maximal levels in 15 min. To resolve the effect of increased van operon protein expression on PG metabolite levels, linezolid was used to block protein biosynthesis. Surprisingly, linezolid dramatically reduced PG intermediate levels when used alone. When used in combination with vancomycin, linezolid only modestly reduced alternative UDP-linked PG intermediate levels, indicating substantial alternative pathway presence before vancomycin exposure. Comparison of PG intermediate levels between VREfm, vancomycin-sensitive Enterococcus faecium, and methicillin-resistant Staphylococcus aureus after vancomycin exposure demonstrated substantial differences between S. aureus and E. faecium PG biosynthesis pathways. IMPORTANCE VREfm is highly resistant to vancomycin due to the presence of a vancomycin resistance gene cassette. Exposure to vancomycin induces the expression of genes in this cassette, which encode enzymes that provide for an alternative PG biosynthesis pathway. In VanA-type resistance, these alternative pathway enzymes replace the D-Ala-D-Ala terminus of normal PG intermediates with D-Ala-D-Lac terminated intermediates, to which vancomycin cannot bind. While the general features of this resistance mechanism are well known, the details of the choreography between vancomycin exposure, vanA gene induction, and changes in the normal and alternative pathway intermediate levels have not been described previously. This study comprehensively explores how VREfm responds to vancomycin exposure at the mRNA and PG intermediate levels.

Competence Mining of Vancomycin (VAN) in the Management of Infections Due to Bacterial Strains With High VAN Minimum Inhibitory Concentrations (MICs): A Novel Dosing Strategy Based on Pharmacokinetic/Pharmacodynamic Modeling

The increasing emergence of bacterial strains with high VAN MICs (BS_H–VAN–M), such as Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus bovis, results in growing concern that VAN is not effective against these isolates. Due to the limited data on VAN against BS_H–VAN–M and the application limits of drugs currently considered to be effective for BS_H–VAN–M, exploration of “new usages for old drugs” is reasonable to improve and maximize the efficacy of existing antibiotics. This study aimed to construct a novel dosing strategy to mine the competence of VAN in the management of BS_H–VAN–M infections. Herein, we optimized the traditional intermittent i.v. infusion (TIII) method to create an optimal two-step infusion (OTSI). With pharmacokinetic (PK)/pharmacodynamic (PD) modeling at the targeted ratio of the daily area under the concentration-time curve (AUC_0–24) to the minimum inhibitory concentration (MIC) (AUC_0–24/MIC) of 400, we used Monte Carlo simulations to evaluate the efficacy of 25 VAN regimens (including 15 OTSI regimens and 10 TIII regimens with daily doses of up to 6 g) to treat pneumonia, meningitis, sternal osteomyelitis, mastitis, pleuritis, bacteremia, and bacterial pericarditis resulting from isolates with MICs of ≤64 mg/L and to the current E. faecalis, E. faecium, S. aureus, S. epidermidis, and S. bovis populations with a pooled MIC distribution. Our data indicated that 4 g/day VAN, with an OTSI but not a TIII, for mastitis, pleuritis, bacteremia, and bacterial pericarditis due to isolates with MICs of ≤4 mg/L or to the current E. faecalis, S. aureus, S. epidermidis, and S. bovis populations achieved the desired PK/PD exposure at the AUC_0–24/MIC target of 400. This study suggests the superiority and feasibility of OTSI relative to TIII for the competence mining of VAN against BS_H–VAN–M from the perspective of PK/PD and provides a new resource for understanding how PK/PD modeling shapes the performance of VAN to meet the growing challenges of BS_H–VAN–M infections.

Purification and characterization of bacteriocins-like inhibitory substances from food isolated Enterococcus faecalis OS13 with activity against nosocomial enterococci

Nosocomial infections caused by enterococci are an ongoing global threat. Thus, finding therapeutic agents for the treatment of such infections are crucial. Some Enterococcus faecalis strains are able to produce antimicrobial peptides called bacteriocins. We analyzed 65 E. faecalis isolates from 43 food samples and 22 clinical samples in Egypt for 17 common bacteriocin-encoding genes of Enterococcus spp. These genes were absent in 11 isolates that showed antimicrobial activity putatively due to bacteriocins (three from food, including isolate OS13, and eight from clinical isolates). The food-isolated E. faecalis OS13 produced bacteriocin-like inhibitory substances (BLIS) named enterocin OS13, which comprised two peptides (enterocin OS13α OS13β) that inhibited the growth of antibiotic-resistant nosocomial E. faecalis and E. faecium isolates. The molecular weights of enterocin OS13α and OS13β were determined as 8079 Da and 7859 Da, respectively, and both were heat-labile. Enterocin OS13α was sensitive to proteinase K, while enterocin OS13β was resistant. Characterization of E. faecalis OS13 isolate revealed that it belonged to sequence type 116. It was non-hemolytic, bile salt hydrolase-negative, gelatinase-positive, and sensitive to ampicillin, penicillin, vancomycin, erythromycin, kanamycin, and gentamicin. In conclusion, BLIS as enterocin OS13α and OS13β represent antimicrobial agents with activities against antibiotic-resistant enterococcal isolates.

Vancomycin modified copper sulfide nanoparticles for photokilling of vancomycin-resistant enterococci bacteria

Due to the overuse of antibiotics, vancomycin resistant enterococci (VRE) has caused serious infections and become more and more difficult to deal with. Herein, we reported a facile one-pot strategy to synthesize copper sulfide nanoparticles using vancomycin (Van) as reductant and capping agent (CuS@Van). The as-prepared CuS@Van nanocomposites presented excellent uniformity in particle size and strong near infrared (NIR) absorbance. Fourier Transform infrared spectroscopy (FTIR) and Energy dispersive spectrometry (EDS) analysis confirmed the successful modification of Van molecules on the surface of CuS@Van nanoparticles. Bacterial TEM images verified the specific binding affinity between CuS@Van and VRE pathogen. CuS@Van also exhibited effective photokilling capability based on a combination of photothermal therapy (PTT) and photodynamic therapy (PDT). Fluorescent bacterial viability staining and bacterial growth curves monitoring were performed to explore the photokilling ablation of CuS@Van against VRE pathogens. The in vitro results indicated that CuS@Van nanocomposites had no antibacterial activity in the dark but displayed satisfying bactericidal effect against VRE pathogens upon the NIR irradiation. Mouse infection assays were also implemented to evaluate in vivo antibacterial photokilling effectiveness. CuS@Van with NIR irradiation showed the highest antibacterial capability and fastest infection regression compared with the control groups. Considering the low cost, easy preparation, good biocompatibility and excellent photokilling capability, CuS@Van nanocomposites will shed bright light on the photokilling ablation of vancomycin-resistant pathogenic bacteria.

Current and emerging pharmacotherapy for the treatment of bacterial peritonitis

INTRODUCTION

Spontaneous bacterial peritonitis (SBP) is the quintessential model of bacterial infection in cirrhotic patients. In these particularly frail subjects, infections clearly worsen prognosis increasing substantially mortality. Furthermore, treatment of SBP has become more challenging because of the growing impact of multidrug-resistant (MDR) bacteria.

AREAS COVERED

This review addresses the reasons behind the change in therapeutic recommendations for SBP that have occurred in the past few years, by focusing on the following aspects: the importance of an early appropriate empirical treatment, the difference between nosocomial and non-nosocomial forms and the overall microbiological shift (rise of Gram-positive bacteria and MDR strains) that have affected SBP.

EXPERT OPINION

Until recently, third-generation cephalosporins have represented the cornerstone of SBP treatment, a safe choice covering the most important causative agents, namely Enterobacteriaceae. Unfortunately, massive exposure to health systems makes cirrhotic patients prone to MDR infections, which poses significant challenges, all the while not forgetting to strike a balance between effective antimicrobial activity and the risk of toxicity in these fragile subjects. Moreover, there is sparse information about new antibiotics in cirrhotic patients and about drugs levels in ascitic fluid. Therefore, further research is needed to optimize the treatment of SBP.

Clinical management of non-faecium non-faecalis vancomycin-resistant enterococci infection. Focus on Enterococcus gallinarum and Enterococcus casseliflavus/flavescens

Enterococcus gallinarum and Enterococcus casseliflavus/flavescens are enterococci intrinsically resistant to vancomycin belonging to the E. gallinarum group. They are responsible mainly for healthcare-associated infections, in particular bloodstream, urinary tract and surgical wound infections. Diseases due to these bacteria are significantly increasing worldwide, as they are prone to cause infection in patients with concurrent hepatobiliary or oncohematological disorders. Along with their distinguishing vancomycin resistance, due to a chromosomally-encoded VanC operon, their additional intrinsic resistance to many antibiotics other than glycopeptides limits the therapeutic choices. In addition, their intrinsic vancomycin resistance, unlike the vancomycin resistance of Enterococcus faecalis and Enterococcus faecium caused by transmissible plasmids, poses different infection control issues. We focused on the therapeutic and infection control issues of clinical syndromes caused by E. gallinarum and E. casseliflavus/flavescens. We propose therapeutic algorithms on bloodstream infections, endocarditis, central nervous system infections, endophthalmitis and urinary tract infections. The implementation of infection control measures in cases of E. gallinarum and E. casseliflavus/flavescens infection or colonization should be evaluated on a case-by-case basis, especially for epidemic outbreaks or for isolates supposed to harbor a potential transmissible vancomycin-resistance phenotype.

Advances in prevention and treatment of vancomycin-resistant Enterococcus infection

PURPOSE OF REVIEW

This article reviews data, particularly from the last 2 years, addressing the prevention and treatment of vancomycin-resistant Enterococcus (VRE). We focus on infection control, particularly active screening, use of contact precautions as well as pharmacologic options for therapy. This is timely given the evolving priorities in efforts towards the prevention and treatment of multidrug-resistant organisms globally.

RECENT FINDINGS

Key findings include new data regarding the impact of contact precautions on the incidence of VRE colonization and bloodstream infection, new laboratory screening methods, and novel decolonization strategies and treatments.

SUMMARY

Additional and specific measures beyond standard precautions for infection prevention of VRE remain controversial. Horizontal measures such as chlorhexidine bathing appear beneficial, as are nontouch environmental cleaning methods. Treatment options for invasive disease have improved considerably in the last decade. Decolonization strategies require further research. Overall, the threat of VRE seems exaggerated.

Vancomycin-resistant enterococcus infection in the hematopoietic stem cell transplant recipient: an overview of epidemiology, management, and prevention

Vancomycin-resistant enterococcus (VRE) is now one of the leading causes of nosocomial infections in the United States. Hematopoietic stem cell transplantation (HSCT) recipients are at increased risk of VRE colonization and infection. VRE has emerged as a major cause of bacteremia in this population, raising important clinical questions regarding the role and impact of VRE colonization and infection in HSCT outcomes as well as the optimal means of prevention and treatment. We review here the published literature and scientific advances addressing these thorny issues and provide a rational framework for their approach.

Predictive utility of swab screening for vancomycin-resistant Enterococcus in selection of empiric antibiotics for Enterococcus sterile-site infections: a retrospective cohort study

BACKGROUND

Swab screening for vancomycin-resistant Enterococcus (VRE) is used to identify VRE carriers and thus prevent transmission of this organism. We tested whether screening results could have unintended benefits in predicting the vancomycin susceptibility of subsequent Enterococcus infections experienced by these patients.

METHODS

We conducted a retrospective cohort study of all patients admitted to a large tertiary care hospital between 2010 and 2015 who underwent swab screening for VRE before experiencing an Enterococcus sterile-site infection. We derived test characteristics using the screening result as the test variable predicting the presence or absence of vancomycin resistance in the sterile-site Enterococcus species.

RESULTS

Culture results for sterile-site samples were positive for Enterococcus for 619 patients during the study period. Of these, 488 (79%) had previously undergone VRE screening. A total of 19 (4%) of the 488 screening results were positive for VRE, and 10 (2%) of the sterile-site Enterococcus isolates were resistant to vancomycin. The overall specificity of VRE swabs was 97% (95% confidence interval [CI] 96%-99%), sensitivity was 70% (95% CI 35%-93%), the positive likelihood ratio was 28 (95% CI 14-56), and the negative likelihood ratio was 0.31 (95% CI 0.12-0.79). The post-test probability of vancomycin resistance in a sterile-site culture, given a positive result with VRE screening swab, was 37% using study data and 83% using published aggregate prevalence data for VRE in the United States.

INTERPRETATION

Prior VRE screening swab results represent a useful tool for predicting vancomycin resistance in sterile-site Enterococcus infections. Patients with a positive result for VRE screening swab and Enterococcus identified by culture of sterile-site samples should receive empiric treatment with linezolid or daptomycin until sensitivity results are available.

Management of multidrug resistant Gram-negative bacilli infections in solid organ transplant recipients: SET/GESITRA-SEIMC/REIPI recommendations

Solid organ transplant (SOT) recipients are especially at risk of developing infections by multidrug resistant (MDR) Gram-negative bacilli (GNB), as they are frequently exposed to antibiotics and the healthcare setting, and are regulary subject to invasive procedures. Nevertheless, no recommendations concerning prevention and treatment are available. A panel of experts revised the available evidence; this document summarizes their recommendations: (1) it is important to characterize the isolate's phenotypic and genotypic resistance profile; (2) overall, donor colonization should not constitute a contraindication to transplantation, although active infected kidney and lung grafts should be avoided; (3) recipient colonization is associated with an increased risk of infection, but is not a contraindication to transplantation; (4) different surgical prophylaxis regimens are not recommended for patients colonized with carbapenem-resistant GNB; (5) timely detection of carriers, contact isolation precautions, hand hygiene compliance and antibiotic control policies are important preventive measures; (6) there is not sufficient data to recommend intestinal decolonization; (7) colonized lung transplant recipients could benefit from prophylactic inhaled antibiotics, specially for Pseudomonas aeruginosa; (8) colonized SOT recipients should receive an empirical treatment which includes active antibiotics, and directed therapy should be adjusted according to susceptibility study results and the severity of the infection.

Incidence, clinical characteristics, and outcomes of nosocomial Enterococcus spp. bloodstream infections in a tertiary-care hospital in Beijing, China: a four-year retrospective study

Background

Enterococcus spp. are the common cause of nosocomial bloodstream infections (BSIs) with high morbidity and mortality. The purpose of this study was to characterize the incidence, clinical and microbiological features, and mortality of nosocomial enterococcal BSIs at a large Chinese tertiary-care hospital in Beijing, China.

Methods

A retrospective cohort study on adult patients with nosocomial BSIs due to Enterococcus spp. was performed between January 1, 2012, and December 31, 2015 at the Chinese People’s Liberation Army General Hospital. Patients’ data were gathered by reviewing electronic medical records.

Results

A total of 233 episodes of BSI due to Enterococcus spp. occurred among 224 patients during these 4 years. The overall incidence was 3.9 episodes per 10,000 admissions. Enterococcus faecium (E. faecium) was the major pathogen (74%, 95% CI 68–80%), followed by Enterococcus faecalis (E. faecalis) (20%, 95% CI 15–25%). E. faecium showed higher antimicrobial resistance than E. faecalis. The 30-day mortality of nosocomial enterococcal BSI was 24% (95% CI 18–29%). Predictors for mortality included the Acute Physiology and Chronic Health Evaluation II (APACHE II) score, Charlson comorbidity index (CCI), impaired renal function, prior use of immunosuppressive agents, and appropriate empirical antimicrobial treatment.

Conclusions

This study emphasizes that Enterococcus spp. were major pathogens for nosocomial BSIs and associated with high mortality. Appropriate empirical antimicrobial treatment can improve outcomes. Vancomycin is the best choice for patients with E. faecium BSIs. Penicillins, aminoglycosides, fluoroquinolones, and vancomycin can be considered for patients with E. faecalis BSIs.

Multidrug-Resistant Enterococcal Infections: New Compounds, Novel Antimicrobial Therapies?

Over the past two decades infections due to antibiotic-resistant bacteria have escalated world-wide, affecting patient morbidity, mortality, and health care costs. Among these bacteria, Enterococcus faecium and Enterococcus faecalis represent opportunistic nosocomial pathogens that cause difficult-to-treat infections because of intrinsic and acquired resistance to a plethora of antibiotics. In recent years, a number of novel antimicrobial compound classes have been discovered and developed that target Gram-positive bacteria, including E. faecium and E. faecalis. These new antibacterial agents include teixobactin (targeting lipid II and lipid III), lipopeptides derived from nisin (targeting lipid II), dimeric vancomycin analogues (targeting lipid II), sortase transpeptidase inhibitors (targeting the sortase enzyme), alanine racemase inhibitors, lipoteichoic acid synthesis inhibitors (targeting LtaS), various oxazolidinones (targeting the bacterial ribosome), and tarocins (interfering with teichoic acid biosynthesis). The targets of these novel compounds and mode of action make them very promising for further antimicrobial drug development and future treatment of Gram-positive bacterial infections. Here we review current knowledge of the most favorable anti-enterococcal compounds along with their implicated modes of action and efficacy in animal models to project their possible future use in the clinical setting.

New agents approved for treatment of acute staphylococcal skin infections

Vancomycin has been a predominant treatment for methicillin-resistant Staphylococcus aureus (MRSA) infections for decades. However, growing reservations about its efficacy led to an urgent need for new antibiotics effective against MRSA and other drug-resistant Staphylococcus aureus strains. This review covers three new anti-MRSA antibiotics that have been recently approved by the FDA: dalbavancin, oritavancin, and tedizolid. The mechanism of action, indications, antibacterial activity profile, microbial resistance, pharmacokinetics, clinical efficacy, adverse effects, interactions as well as available formulations and administration of each of these new antibiotics are described. Dalbavancin is a once-a-week, two-dose, long-acting intravenous bactericidal lipoglycopeptide antibiotic. Oritavancin, a lipoglycopeptide with bactericidal activity, was developed as a single-dose intravenous treatment for acute bacterial skin and skin-structure infections (ABSSSI), which offers simplifying treatment of infections. Tedizolid is an oxazolidinone-class bacteriostatic once-daily agent, available for intravenous as well as oral use. Increased ability to overcome bacterial resistance is the main therapeutic advantage of the novel agents over existing antibiotics.

Multidrug-resistant bacteria in hematology patients: emerging threats

Multidrug-resistant (MDR) bacteria, particularly Gram negatives, such as Enterobacteriaceae resistant to third-generation cephalosporins or carbapenems and MDR Pseudomonas aeruginosa, are increasingly frequent in hematology patients. The prevalence of different resistant species varies significantly between centers. Thus, the knowledge of local epidemiology is mandatory for deciding the most appr-opriate management protocols. In the era of increasing antibiotic resistance, empirical therapy of febrile neutropenia should be individualized. A de-escalation approach is recommended in case of severe clinical presentation in patients who are at high risk for infection with a resistant strain. Targeted therapy of an MDR Gram negative usually calls for a combination treatment, although no large randomized trials exist in this setting. Infection control measures are the cornerstone of limiting the spread of MDR pathogens in hematology units.

Bacterial Infections in Hematopoietic Stem Cell Transplant Recipients

Bacterial infections are major complications after Hematopoietic Stem Cell Transplant (HSCT). They consist mainly of bloodstream infections (BSI), followed by pneumonia and gastrointestinal infections, including typhlitis and Clostridium difficile infection. Microbiological data come mostly from BSI. Coagulase negative staphylococci and Enterobacteriaceae are the most frequent pathogens causing approximately 25% of BSI each, followed by enterococci, P. aeruginosa and viridans streptococci. Bacterial pneumonia is frequent after HSCT, and Gram-negatives are predominant. Clostridium difficile infection affects approximately 15% of HSCT recipients, being more frequent in case of allogeneic than autologous HSCT. The epidemiology and the prevalence of resistant strains vary significantly between transplant centres. In some regions, multi-drug resistant (MDR) Gram-negative rods are increasingly frequent. In others, vancomycin-resistant enterococci are predominant. In the era of increasing resistance to antibiotics, the efficacy of fluoroquinolone prophylaxis and standard treatment of febrile neutropenia have been questioned. Therefore, a thorough evaluation of local epidemiology is mandatory to decide the need for prophylaxis and the choice of the best regimen for empirical treatment of febrile neutropenia. For the latter, individualised approach has been proposed, consisting of either escalation or de-escalation strategy. De-escalation strategy is recommended since resistant bacteria should be covered upfront, mainly in patients with severe clinical presentation and previous infection or colonisation with a resistant pathogen. Non-pharmacological interventions, such as screening for resistant bacteria, applying isolation and contact precautions should be put in place to limit the spread of MDR bacteria. Antimicrobial stewardship program should be implemented in transplant centres.