Daptomycin for the treatment of enterococcal bacteraemia: results from the Cubicin Outcomes Registry and Experience (CORE)

Population pharmacokinetics of intravenous daptomycin in critically ill patients: implications for selection of dosage regimens

Daptomycin is gaining prominence for the treatment of methicillin-resistant Staphylococcus aureus infections. However, the dosage selection for daptomycin in critically ill patients remains uncertain, especially in Chinese patients. This study aimed to establish the population pharmacokinetics of daptomycin in critically ill patients, optimize clinical administration plans, and recommend appropriate dosage for critically ill patients in China. The study included 64 critically ill patients. Blood samples were collected at the designated times. The blood daptomycin concentration was determined using validated liquid chromatography-tandem mass spectrometry. A nonlinear mixed-effects model was applied for the population pharmacokinetic analysis and Monte Carlo simulations of daptomycin. The results showed a two-compartment population pharmacokinetic model of daptomycin in critically ill adult Han Chinese patients. Monte Carlo simulations revealed that a daily dose of 400 mg of daptomycin was insufficient for the majority of critically ill adult patients to achieve the anti-infective target. For critically ill adult patients with normal renal function (creatinine clearance rate >90 mL/min), the probability of achieving the target only reached 90% when the daily dose was increased to 700 mg. For patients undergoing continuous renal replacement therapy (CRRT), 24 h administration of 500 mg met the pharmacodynamic goals and did not exceed the safety threshold in most patients. Therefore, considering its efficacy and safety, intravenous daptomycin doses are best scaled according to creatinine clearance, and an increased dose is recommended for critically ill patients with hyperrenalism. For patients receiving CRRT, medication is recommended at 24 h intervals.

Vancomycin-resistant enterococci infection and predisposing factors for infection and mortality in patients with acute leukaemia and febrile neutropenia

BACKGROUND

Vancomycin-resistant enterococcus (VRE) is an infectious agent that can increase morbidity and mortality, especially in patients with neutropenia in haematology departments. We analysed VRE infections and mortality rates among VRE colonized patients with acute leukaemia, defined predisposing risk factors for infection and mortality, and investigated the influence of daptomycin or linezolid treatment on mortality.

PATIENTS-METHODS

We included 200 VRE colonized adult acute leukaemia patients with febrile neutropenia between January 2010 and January 2016. Data were collected from electronic files.

RESULTS

There were 179 patients in the colonized group, and 21 patients in the infected group. Enterococcus faecium (van A) was isolated from all patients. The infection rate was 10.5 %, and the types of infections noted were as follows: bloodstream (n = 14; 66.7 %), skin and soft tissue (n = 3; 14.3 %), urinary (n = 2; 9.5 %), and others (9.5 %). In the multivariate logistic regression analysis, exposure to invasive procedures, coinfection status, and >15 days of VRE positivity were independent risk factors for VRE infections. In hospital mortality rates were 57.1 % in the infected group, and 9.5 % in the colonized group (p < 0.001). Older age, female gender, absolute neutropenia, and coinfection status were statistically significant predictor of survival.

CONCLUSION

Vancomycin-resistant enterococcus infections are associated with high morbidity and mortality in haematology patients with neutropenia. Clinicians should be aware of predisposing risk factors for VRE infection to avoid unfavourable outcomes. We believe that larger studies are necessary regarding the influence of treatment with daptomycin and linezolid.

A new validated HPLC-UV method for therapeutic monitoring of daptomycin in comparison with reference mass spectrometry

Daptomycin, a cyclic lipopeptide antibiotic with a broad spectrum of activity against Gram-positive bacteria, is also active against multi-resistant bacterial strains, as well as methicillin-resistant S. aureus, vancomycin-resistant enterococci or penicillin-resistant S. pneumoniae. For these reasons it is a viable alternative for the treatment of persisting infections. However, the therapeutic drug monitoring of daptomycin is recommended because the known variability in drug disposition and the severe clinical conditions of patients. Therefore, we developed a simple and fast UV-HPLC method according to FDA guidelines to monitor plasma concentrations of the drug. Briefly, after a liquid-liquid extraction, plasma calibration samples, quality controls and patients' samples were injected in a HPLC instrument and peaks of daptomycin and gentamicin (internal standard) were resolved by a C₁₈ 250 × 4.6 mm, 5 μm stationary phase and peaks were monitored at UV = 262 nm. Mobile phase (isocratic flow of 1 mL/min) consisted of acetonitrile-buffer (KH₂PO₄ 20 mM pH = 3.2) 46:54, vol/vol. Under these conditions, IS and daptomycin peaked at 4.1 and 5.8 min after injection. Values of limits of detection and quantitation accounted for 1.65 and 5.00 (μg/ml), respectively. Values of method linearity (r²) in range 5-100 mg/L were 0.9975 and 0.9956 plasma samples and solvent standard, respectively. Inter- and intra-day variability coefficients were lower than 15 %. The comparison with a reference, commercially-available LC-MS/MS method on 122 patient plasma samples returned excellent correlation (r² = 0.9474). In conclusion, the present method demonstrated to be reliable and suitable for daptomycin TDM in clinical routine.

Impact on Public Health of the Spread of High-Level Resistance to Gentamicin and Vancomycin in Enterococci

Antibiotic resistance has turned into a global public health issue. Enterococci are intrinsically resistant to many antimicrobials groups. These bacteria colonize dairy and meat products and integrate the autochthonous microbiota of mammal's gastrointestinal tract. Over the last decades, detection of vanA genotype in Enterococcus faecium from animals and from food of animal origin has been reported. Vancomycin-resistant E. faecium has become a prevalent nosocomial pathogen. Hospitalized patients are frequently treated with broad-spectrum antimicrobials and this leads to an increase in the presence of VanA or VanB vancomycin-resistant enterococci in patients' gastrointestinal tract and the risk of invasive infections. In humans, E. faecium is the main reservoir of VanA and VanB phenotypes. Acquisition of high-level aminoglycoside resistance is a significant therapeutic problem for patients with severe infections because it negates the synergistic effect between aminoglycosides and a cell-wall-active agent. The aac(6')-Ie-aph (2″)-Ia gene is widely spread in E. faecalis and has been detected in strains of human origin and in the food of animal origin. Enzyme AAC(6')-Ie-APH(2″)-Ia confers resistance to available aminoglycosides, except to streptomycin. Due to the fast dissemination of this genetic determinant, the impact of its horizontal transferability among enterococcal species from different origin has been considered. The extensive use of antibiotics in food-producing animals contributes to an increase in drug-resistant animal bacteria that can be transmitted to humans. Innovation is needed for the development of new antibacterial drugs and for the design of combination therapies with conventional antibiotics. Nowadays, semi-purified bacteriocins and probiotics are becoming an attractive alternative to the antibiotic in animal production. Therefore, a better understanding of a complex and relevant issue for Public Health such as high-level vancomycin and gentamicin resistance in enterococci and their impact is needed. Hence, it is necessary to consider the spread of vanA E. faecium and high-level gentamicin resistant E. faecalis strains of different origin in the environment, and also highlight the potential horizontal transferability of these resistance determinants to other bacteria.

[Enterococci and surgical site infections : Causal agent or harmless commensals?]

BACKGROUND

The role of enterococci in the context of peritonitis and surgical site infections (SSI) has not yet been definitively clarified but enterococci are being detected more frequently. Numerous resistances reduce the available antibiotic options.

OBJECTIVE

This article gives an overview of the pathogenic importance of enterococci and of current recommendations for therapy and prophylaxis. On the basis of our own data we discuss the relevance of enterococci for SSI.

MATERIAL AND METHODS

All colorectal resections carried out between January 2008 and September 2016 were retrospectively documented. Revision surgery, SSI and intra-abdominally or subcutaneously detected pathogens were recorded.

RESULTS

A total of 2713 interventions were evaluated with 28.3% having primary peritonitis. In 587 patients (21.6%) SSI followed, and pathogen determination was possible in 431 cases (73.4%). Enterococci were frequently found in re-operations (58.4%) and SSI (46.1%), with E. faecalis and E. faecium in approximately equal proportions. If intra-abdominal enterococci were detectable in patients with primary peritonitis, it was more common to develop SSI and enterococci were more frequently detected subcutaneously. Enterococci in SSI were found to be significantly more frequent in left hemicolectomies as well as in pre-existing renal insufficiency.

CONCLUSION

It can be inferred that enterococci are not adequately covered by commonly used perioperative antibiotic therapy or preoperative prophylaxis, which increases the risk for SSI by enterococci. This could be favored by selection of these pathogens due to the use of antibiotics without enterococcal efficacy (e. g. cephalosporins). The consideration in the choice of perioperative antibiotic prophylaxis by the additional administration of ampicillin or vancomycin could be advantageous.

Plasma Protein Binding Structure-Activity Relationships Related to the N-Terminus of Daptomycin

Daptomycin is a lipopeptide antibiotic that is highly bound to plasma proteins. To date, the plasma components and structure-activity relationships responsible for the plasma protein binding profile of daptomycin remain uncharacterized. In the present study we have employed a surface plasmon resonance assay together with molecular docking techniques to investigate the plasma protein binding structure-activity relationships related to the N-terminal fatty acyl of daptomycin. Three compounds were investigated: (1) native daptomycin, which displays an N-terminal n-decanoyl fatty acid side chain, and two analogues with modifications to the N-terminal fatty acyl chain; (2) des-acyl daptomycin; and (3) acetyl-daptomycin. The surface plasmon resonance (SPR) data showed that the binding profile of native daptomycin was in the rank order human serum albumin (HSA) ≫ α-1-antitrypsin > low-density lipoprotein ≥ hemoglobin > sex hormone binding globulin > α-1-acid-glycoprotein (AGP) > hemopexin > fibrinogen > α-2-macroglobulin > β2-microglobulin > high-density lipoprotein > fibronectin > haptoglobulin > transferrin > immunoglobulin G. Notably, binding to fatty acid free HSA was greater than binding to nondelipidated HSA. SPR and ultrafiltration studies also indicated that physiological concentrations of calcium increase binding of daptomycin and acetyl-daptomycin to HSA and AGP. A molecular model of the daptomycin-human serum albumin A complex is presented that illustrates the pivotal role of the N-terminal fatty acyl chain of daptomycin for binding to drug site 1 of HSA. In proof-of-concept, the capacity of physiological cocktails of the identified plasma proteins to inhibit the antibacterial activity of daptomycin was assessed with in vitro microbiological assays. We show that HSA, α-1-antitrypsin, low-density lipoprotein, sex hormone binding globulin, α-1-acid-glycoprotein, and hemopexin are responsible for the majority of the sequestering activity in human plasma. The findings are relevant to medicinal chemistry programs focused on the development of next-generation daptomycin lipopeptides. Tailored modifications to the N-terminal fatty acyl domain of the daptomycin molecule should yield novel daptomycin lipopeptides with more ideal plasma protein binding profiles to increase the levels of active (free) drug in plasma and improved in vivo activity.

Daptomycin: an evidence-based review of its role in the treatment of Gram-positive infections

Infections caused by Gram-positive pathogens remain a major public health burden and are associated with high morbidity and mortality. Increasing rates of infection with Gram-positive bacteria and the emergence of resistance to commonly used antibiotics have led to the need for novel antibiotics. Daptomycin, a cyclic lipopeptide with rapid bactericidal activity against a wide range of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus, has been shown to be effective and has a good safety profile for the approved indications of complicated skin and soft tissue infections (4 mg/kg/day), right-sided infective endocarditis caused by S. aureus, and bacteremia associated with complicated skin and soft tissue infections or right-sided infective endocarditis (6 mg/kg/day). Based on its pharmacokinetic profile and concentration-dependent bactericidal activity, high-dose (>6 mg/kg/day) daptomycin is considered an important treatment option in the management of various difficult-to-treat Gram-positive infections. Although daptomycin resistance has been documented, it remains uncommon despite the increasing use of daptomycin. To enhance activity and to minimize resistance, daptomycin in combination with other antibiotics has also been explored and found to be beneficial in certain severe infections. The availability of daptomycin via a 2-minute intravenous bolus facilitates its outpatient administration, providing an opportunity to reduce risk of health care-associated infections, improve patient satisfaction, and minimize health care costs. Daptomycin, not currently approved for use in the pediatric population, has been shown to be widely used for treating Gram-positive infections in children.

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

Optimizing therapy for vancomycin-resistant enterococcal bacteremia in children

PURPOSE OF REVIEW

Uncertainties exist regarding the optimal treatment for vancomycin-resistant enterococcal (VRE) bloodstream infections, particularly in settings in which ampicillin cannot be used.

RECENT FINDINGS

Quinupristin-dalfopristin, linezolid, and daptomycin, all approved between 1999 and 2003, represent the mainstays of therapy for VRE bacteremia, although only linezolid has been specifically approved by the United States Food and Drug Administration for this indication. The main objective of this review is to compare the relative efficacies, dosing strategies, and side-effect profiles of quinupristin-dalfopristin, linezolid, and daptomycin for VRE bacteremia in the pediatric population. A brief description of recently approved broad-spectrum Gram-positive agents that may have a role in the management of VRE bacteremia in upcoming years is also provided.

SUMMARY

Linezolid, despite its bacteriostatic activity against VRE, may be the most versatile of the available drugs. It has activity against both Enterococcus faecalis and E. faecium, can be administered orally, and resistance appears to be less of a concern with linezolid compared with the other agents. Additionally, the results of two recent meta-analyses demonstrate more favorable outcomes with linezolid compared with daptomycin for the treatment of VRE bacteremia. The clinical pharmacokinetics of linezolid have been well described in children. The most notable concern with linezolid, however, is toxicities associated with prolonged use. Until more prospective data are available, we favor linezolid as first-line therapy for the treatment of VRE bacteremia in children.

Treatment of Gram-positive infections in critically ill patients

Gram-positive bacteria to include methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible Staphylococcus aureus (MSSA), and enterococci, to include vancomycin-resistant enterococci (VRE), display a remarkable array of resistance and virulence factors, which have contributed to their prominent role in infections of the critically ill. Over the last three decades infections with these pathogens has increased as has their overall resistance to available antimicrobial agents. This has led to the development of a number of new antibiotics for the treatment of Gram-positive bacteria. At present, it is important that clinicians recognize the changing resistance patterns and epidemiology of Gram-positive bacteria as these factors may impact patient outcomes. The increasing range of these pathogens, such as the emergence of community-associated MRSA clones, emphasizes that all specialties of physicians treating infections should have a good understanding of the infections caused by Gram-positive bacteria in their area of practice. When initiating empiric antibiotics, it is of vital importance that this therapy be timely and appropriate, as delays in treatment are associated with adverse outcomes. Although vancomycin has traditionally been considered a first-line therapy for serious MRSA infections, multiple concerns with this agent have opened the door for alternative agents demonstrating efficacy in this role. Similarly, the expansion of VRE as a pathogen in the ICU setting has required the development of agents targeting this important pathogen.

Vancomycin-Resistant Enterococcal Bacteremia Pharmacotherapy

Objective: To review the literature on the pharmacotherapy of bloodstream infections (BSI) caused by vancomycin-resistant enterococci (VRE). Data Sources: A MEDLINE literature search was performed for the period 1946 to May 2014 using the search terms Enterococcus, enterococci, vancomycin-resistant, VRE, bacteremia, and bloodstream infection. References were also identified from selected review articles. Study Selection and Data Extraction: English-language case series, cohort studies, and meta-analyses assessing the options in the pharmacotherapy of VRE BSIs in adult patients were evaluated. Data Synthesis: Studies were identified that utilized linezolid, quinupristin/dalfopristin (Q/D), and daptomycin. In all, 8 comparative retrospective cohort studies, 2 meta-analyses of daptomycin and linezolid, and 3 retrospective comparisons of linezolid and Q/D were included for review. Mortality associated with VRE BSIs was high across studies, and the ability to determine differences in outcomes between agents was confounded by the complex nature of the patients included. Two meta-analyses comparing daptomycin with linezolid for VRE BSIs found modest advantages for linezolid, but these conclusions may be hampered by heterogeneity within the included studies. Conclusions: VRE BSIs remain a difficult-to-treat clinical situation. Differences in toxicity between the agents used to treat it are clear, but therapeutic differences are more difficult to discern. Meta-analyses suggest that a moderate advantage for linezolid over daptomycin may exist, but problems with the nature of studies that they included make definitive conclusions difficult.

Daptomycin for the treatment of bacteraemia due to vancomycin-resistant enterococci

Treatment of severe infections caused by vancomycin-resistant enterococci (VRE) is challenging due to the scarcity of reliable therapeutic alternatives. In this context, daptomycin (DAP), a lipopeptide antibiotic, has emerged as an interesting alternative as it is one of the few compounds that retain in vitro bactericidal activity against VRE isolates, although it has not been approved for this purpose by regulatory agencies. In this review, we will summarise the clinical, animal and in vitro evidence evaluating the efficacy of DAP for the management of deep-seated VRE infections. In addition, we will address important clinical concerns such as the emergence of DAP resistance during therapy and reports of therapeutic failure with DAP monotherapy. Finally, we will discuss possible future strategies (such as the use of higher doses and/or combination therapies) to optimise the use of this antibiotic against VRE.

A multicentre evaluation of the effectiveness and safety of high-dose daptomycin for the treatment of infective endocarditis

OBJECTIVES

Despite significant medical advances, infective endocarditis (IE) remains an infection associated with high morbidity and mortality. The objective was to assess the safety and efficacy of high-dose daptomycin, defined as ≥ 8 mg/kg/day, in patients with confirmed or suspected staphylococcal and/or enterococcal IE.

METHODS

This was a multicentre, retrospective observational study (2005-11). Adult patients, not undergoing haemodialysis, with blood cultures positive for staphylococci or enterococci and a definitive or possible diagnosis of IE, who received daptomycin ≥ 8 mg/kg/day (based on total body weight) for ≥ 72 h were included.

RESULTS

Seventy patients met the inclusion criteria and comprised 33 (47.1%) with right-sided IE (RIE), 35 (50%) with left-sided IE (LIE) and 2 with both RIE and LIE. Several patients had concomitant sites of infection, with bone/joint infection being most prevalent (12.9%). Sixty-five patients received daptomycin as salvage therapy. Pathogens were isolated from 64 patients, with methicillin-resistant Staphylococcus aureus as the most common organism (84.4%), followed by vancomycin-resistant Enterococcus faecium (7.8%). The median (IQR) daptomycin dose was 9.8 mg/kg/day (8.2-10.0 mg/kg/day), and was similar in RIE and LIE patients (9.8 and 9.3 mg/kg/day, respectively). A total of 24 (34.3%) received combination therapy. For those patients with pathogens isolated (n = 64), the organism was eradicated in 57 (89.1%) patients. Among 64 clinically evaluable patients, 55 (85.9%) achieved clinical success. No patients required discontinuation of high-dose daptomycin due to creatine phosphokinase elevations.

CONCLUSIONS

Patients with both RIE and LIE had successful outcomes with high-dose daptomycin therapy. Additional clinical trials evaluating high daptomycin dosages in patients with IE are warranted.

Treatment considerations in vancomycin-resistant enterococcal bacteremia: daptomycin or linezolid? A review

BACKGROUND

Vancomycin resistant enterococcal bloodstream infections are an important cause of morbidity and mortality in hospitalized patients.

AIM OF THE REVIEW

A search of the literature was undertaken to determine the optimal antimicrobial therapy for the management of vancomycin resistant enterococcal bloodstream infections.

METHOD

MEDLINE, EMBASE, and the Cochrane Library (unrestricted to time or language) were searched for studies of vancomycin resistant enterococcal bloodstream infections in adults reporting outcomes of direct comparisons of linezolid versus daptomycin on November 26, 2012. Studies of basic science, reviews, commentaries, pharmacologic, epidemiologic, or pediatric studies, and those studies examining conditions other than enterococcal bacteremia, a single antimicrobial agent or other antimicrobials were excluded.

RESULTS

226 studies were screened for eligibility and yielded eight studies evaluating a total of 807 patients. Inter-rater agreement was 100 %. Qualitative evaluation of the studies was performed using the Newcastle-Ottawa scale. No randomized controlled trials were identified. All studies were retrospective cohorts and non-randomized. 458 (57 %) patients treated with linezolid and 349 (43 %) with daptomycin were analyzed. Variable comorbidities and severity of illness were described in the included studies and reported here for comparison.

CONCLUSION

The optimal treatment of vancomycin resistant enterococcal bloodstream infections is yet to be determined. Well-designed prospective studies are needed to lend more convincing evidence regarding choice of antimicrobial therapy for this important multidrug resistant organism.

Population pharmacokinetics of daptomycin in patients affected by severe Gram-positive infections

A population pharmacokinetic analysis of daptomycin was performed based on therapeutic drug monitoring (TDM) data from 58 patients receiving doses of 4-12 mg/kg for the treatment of severe Gram-positive infections. At a daily dose of 8 mg/kg, daptomycin plasma concentrations (mean ± S.D.) were 76.9 ± 9.8 mg/L at the end of infusion and 52.7 ± 15.4 mg/L and 11.4 ± 5.4 mg/L at 0.5 h and 23 h after drug administration, respectively. The final model was a one-compartmental model with first-order elimination, with estimated clearance (CL) of 0.80 ± 0.14 L/h and a volume of distribution (V(d)) of 0.19 ± 0.05 L/kg. Creatinine clearance (CL(Cr)) was identified as having a significant influence on daptomycin CL, and a decrease in CL(Cr) of 30 mL/min from the median value (80 mL/min) was associated with a reduction of daptomycin CL from 0.80 L/h to 0.73 L/h. These results confirm that the presence of severe infection may be associated with an altered disposition of daptomycin, with an increased Vd. MICs were available in 41 patients and results showed that 38 and 31 subjects achieved AUC/MIC values associated with bacteriostatic (>400) and bactericidal effects (>800), respectively. Of note, 31 of these 41 subjects experienced a clinical improvement or were cured. Although daptomycin pharmacokinetics may be influenced by infections, effective AUC/MIC values were achieved in the majority of patients. The present model may be applied in clinical settings for a TDM routine on the basis of a sparse blood sampling protocol.

Current and prospective treatments for multidrug-resistant gram-positive infections

INTRODUCTION

Staphylococcus aureus and Enterococcus spp. are two of the most common organisms causing nosocomial infections today; and are consistently associated with high mortality rates (approximately 20 and 44%, respectively). Resistance among these pathogens to first line agents such as methicillin and vancomycin continues to rise while isolates with reduced susceptibility to newer agents including linezolid and daptomycin continue to emerge, representing a serious concern for clinicians.

AREAS COVERED

Mechanisms of action and resistance as well as in vitro and clinical experience in the treatment of resistant staphylococci and enterococci with currently available agents are discussed. Additionally, novel combination regimens showing enhanced efficacy and available data pertaining to prospective therapies including solithromycin, tedizolid, dalbavancin and oritavancin will be covered.

EXPERT OPINION

With an increase in organisms displaying reduced susceptibility to vancomycin and the associated treatment failures, the significance of alternative therapies such as daptomycin, linezolid, ceftaroline, and prospective anti-gram-positive agents is on the rise. As our understanding of antimicrobial pharmacokinetic-pharmacodynamics principles continues to evolve, the selection of highly effective agents and optimization of dosages may lead to improved patient outcomes and delay the development of resistance.

Multicenter study of high-dose daptomycin for treatment of enterococcal infections

Enterococci are among the leading pathogens isolated in hospital-acquired infections. Current antimicrobial options for vancomycin-resistant enterococci (VRE) are limited. Prior data suggest that daptomycin at >6 mg/kg of body weight/day may be used to treat enterococcal infections. We retrospectively evaluated the effectiveness and safety of high-dose daptomycin (HD-daptomycin) therapy (>6 mg/kg) in a multicenter cohort of adult patients with enterococcal infections to describe the characteristics and outcomes. Two hundred forty-five patients were evaluated. Enterococcus faecium was identified in 175 (71%), followed by Enterococcus faecalis in 49 (20%) and Enterococcus spp. in 21 (9%); overall, 204 (83%) isolates were VRE. Enterococcal infections included bacteremia (173, 71%) and intra-abdominal (35, 14%) and bone and joint (25, 10%) infections. The median dosage and duration of HD-daptomycin were 8.2 mg/kg/day (interquartile range [IQR], 7.7 to 9.7) and 10 days (IQR, 6 to 15), respectively. The overall clinical success rate was 89% (193/218), and microbiological eradication was observed in 93% (177/191) of patients. The median time to clearance of blood cultures on HD-daptomycin was 3 days (IQR, 2 to 5). The 30-day all-cause mortality rate was 27%, and 5 (2%) patients developed daptomycin-nonsusceptible enterococcal strains while on HD-daptomycin. Seven patients (3%) had creatine phosphokinase (CPK) elevation, yet no HD-daptomycin regimen was discontinued due to an elevated CPK and all patients were asymptomatic. Overall, there was a high frequency of clinical success and microbiological eradication in patients treated with HD-daptomycin for enterococcal infections, even in patients with complicated and difficult-to-treat infections. No adverse event-related discontinuation of HD-daptomycin was noted. HD-daptomycin may be an option for the treatment of enterococcal infections.

Susceptibility of enterococci to daptomycin is dependent upon testing methodology

An increase in daptomycin nonsusceptible enterococci (DNSE) was noted in our institution (8.3% 2008 to 34.5% 2011) using MicroScan methods which may overestimate DNSE prevalence. DNSE (N = 150) from the clinical laboratory (2008-2011) underwent susceptibility testing using broth microdilution (BMD), Etest, Sensititire, MicroScan prompt (MSP), and MicroScan turbidity (MST) with only 20% of isolates confirmed as nonsusceptible. Categorical and essential agreement were highest with MSP and MST, but both missed the majority of resistant isolates (70% and 87% missed). Etest MIC values were statistically higher, more likely to be nonsusceptible, had the lowest very major error rate (37%), and the highest falsely nonsusceptible rate (22%). Sensititre MIC values were not statistically different from BMD, but missed 57% of DNSE. PFGE analysis did not define a clonal outbreak. These findings suggest that MicroScan methods overestimate nonsusceptibility, and the lack of correlation between methods raises questions regarding which method is most effective at confirming nonsusceptibility.

Relationship of in vitro synergy and treatment outcome with daptomycin plus rifampin in patients with invasive methicillin-resistant Staphylococcus aureus infections

We report the findings of a study examining the relationship between in vitro daptomycin-rifampin synergy and the therapeutic outcome of 12 patients with complex deep methicillin-resistant Staphylococcus aureus (MRSA) infections treated for prolonged periods with this combination. Checkerboard synergy was found in nine cases and was 100% predictive of therapeutic success; absence of synergy was found in three cases, two of which were therapeutic failures (P = 0.045). No relationship was observed between synergy and outcome by time-kill assessment. Checkerboard synergy may predict clinical response to daptomycin plus rifampin for complex invasive MRSA infections requiring prolonged treatment.

Evaluation of standard- and high-dose daptomycin versus linezolid against vancomycin-resistant Enterococcus isolates in an in vitro pharmacokinetic/pharmacodynamic model with simulated endocardial vegetations

Daptomycin MICs for enterococci are typically 1- to 2-fold higher than those for Staphylococcus aureus, and there is an imminent need to establish the optimal dose for appropriate treatment of enterococcal infections. We investigated the bactericidal activity of daptomycin at various dose exposures compared to that of linezolid against vancomycin-resistant enterococcus (VRE) in an in vitro pharmacokinetic/pharmacodynamic model utilizing simulated endocardial vegetations over 96 h. Daptomycin at doses of 6, 8, 10, and 12 mg/kg of body weight/day and linezolid at a dose of 600 mg every 12 h were evaluated against two clinical vancomycin-resistant Enterococcus faecium strains (EFm11499 and 09-184D1051), one of which was linezolid resistant (09-184D1051), and one clinical vancomycin-resistant Enterococcus faecalis strain (EFs11496). Daptomycin MICs were 4, 2, and 0.5 μg/ml for EFm11499, 09-184D1051, and EFs11496, respectively. Bactericidal activity, defined as a ≥ 3 log(10) CFU/g reduction from the initial colony count, was demonstrated against all three isolates with all doses of daptomycin; however, bactericidal activity was not sustained with the daptomycin 6- and 8-mg/kg/day regimens. Linezolid was bacteriostatic against EFm11499 and displayed no appreciable activity against 09-184D1051 or EFs11496. Concentration-dependent killing was displayed with more sustained reduction in colony count (3.58 to 6.46 and 5.89 to 6.56 log(10) CFU/g) at 96 h for the simulated regimen of daptomycin at doses of 10 and 12 mg/kg/day, respectively (P ≤ 0.012). No E. faecium mutants with reduced susceptibility were recovered at any dosage regimen; however, the E. faecalis strain developed reduced daptomycin susceptibility with daptomycin at 6, 8, and 10 but not at 12 mg/kg/day. Daptomycin displayed a dose-dependent response against three VRE isolates, with high-dose daptomycin producing sustained bactericidal activity. Further research is warranted.

High-dose daptomycin for treatment of complicated gram-positive infections: a large, multicenter, retrospective study

STUDY OBJECTIVE

To evaluate the clinical response and safety of high-dose daptomycin for treatment of complicated gram-positive infections.

DESIGN

Multicenter, retrospective, observational, case series analysis.

SETTING

Five academic medical centers in four major United States cities.

PATIENTS

Two hundred fifty adults, not undergoing dialysis, who received high-dose daptomycin (≥ 8 mg/kg/day) for at least 72 hours for complicated gram-positive infections between January 1, 2005, and March 1, 2010.

MEASUREMENTS AND MAIN RESULTS

Clinical and microbiologic outcomes were assessed at the end of high-dose daptomycin therapy. Safety evaluations were recorded for all patients, and when available, baseline, end-of-therapy, and highest observed serum creatine phosphokinase (CPK) levels were recorded. Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) were the primary organisms isolated. The median dose of daptomycin was 8.9 mg/kg/day (interquartile range [IQR] 8.0-10.0 mg/kg/day). The median duration of daptomycin during hospitalization for MRSA and VRE infection was 10 days (IQR 5-16 days) and 13 days (IQR 6-18 days), respectively. Among the 250 patients, high-dose daptomycin was primarily used as salvage therapy after vancomycin treatment (184 patients [73.6%]). Primary infections included complicated bacteremia (119 patients [47.6%]), endocarditis (59 [23.6%]), skin or wound (70 [28.0%]), and bone or joint (67 [26.8%]). Overall, clinical response and microbiologic success were assessed in 83.6% (209/250 patients) and 80.3% (175/218 patients), respectively. Isolates from 13 patients (5.2%) developed nonsusceptibility to daptomycin, with most of these patients having extended vancomycin exposure. Three patients (1.2%) developed an adverse event attributable to high-dose daptomycin therapy, with the event considered either mild or moderate in severity. The median end-of-therapy CPK level was 39 U/L (IQR 26-67 U/L). No significant correlation was found between daptomycin dose and highest observed CPK level.

CONCLUSION

Daptomycin dosages of 8 mg/kg/day or greater may be safe and effective in patients with complicated gram-positive infections. Further clinical studies are warranted.

The potential of antimicrobial peptides as biocides

Antimicrobial peptides constitute a diverse class of naturally occurring antimicrobial molecules which have activity against a wide range of pathogenic microorganisms. Antimicrobial peptides are exciting leads in the development of novel biocidal agents at a time when classical antibiotics are under intense pressure from emerging resistance, and the global industry in antibiotic research and development stagnates. This review will examine the potential of antimicrobial peptides, both natural and synthetic, as novel biocidal agents in the battle against multi-drug resistant pathogen infections.

Evaluation of ceftaroline activity versus daptomycin (DAP) against DAP-nonsusceptible methicillin-resistant Staphylococcus aureus strains in an in vitro pharmacokinetic/pharmacodynamic model

The objective of this study was to investigate the potential role of ceftaroline, a new broad-spectrum cephalosporin, as a therapeutic option for the treatment of daptomycin-nonsusceptible (DNS) methicillin-resistant Staphylococcus aureus (MRSA) infections. Four clinical DNS MRSA strains, R5717, R5563, R5996 (heteroresistant vancomycin-intermediate S. aureus) and R5995 (vancomycin-intermediate S. aureus) were evaluated in a two-compartment hollow-fiber in vitro pharmacokinetic/pharmacodynamic model at a starting inoculum of 10(7) CFU/ml for 96 h. Simulated regimens were ceftaroline at 600 mg every 12 h (q12h) (maximum free-drug concentration [fC(max)], 15.2 μg/ml; serum half-life [t(1/2)], 2.3 h), daptomycin at 6 mg/kg q24h (fC(max), 7.9 μg/ml; t(1/2), 8 h), and daptomycin at 10 mg/kg q24h (fC(max), 15.2 μg/ml; t(1/2), 8 h). Differences in CFU/ml between 24 and 96 h were evaluated by analysis of variance with Tukey's post-hoc test. Bactericidal activity was defined as a ≥3-log(10) CFU/ml decrease in the colony count from the initial inoculum. The ceftaroline MIC values were 0.25, 0.5, 0.5, and 0.5 μg/ml, and the daptomycin MIC values were 2, 2, 4, and 4 μg/ml for R5717, R5563, R5996, and R5995, respectively. Ceftaroline displayed sustained bactericidal activity against 3 of the 4 strains at 96 h (R5717, -3.1 log(10) CFU/ml; R5563, -2.5 log(10) CFU/ml; R5996, -5.77 log(10) CFU/ml; R5995, -6.38 log(10) CFU/ml). Regrowth occurred during the daptomycin at 6-mg/kg q24h regimen (4 strains) and the daptomycin at 10-mg/kg q24h regimen (3 strains). At 96 h, ceftaroline was significantly more active, resulting in CFU/ml counts lower than those obtained with daptomycin at 6 mg/kg q24h (4 strains, P ≤ 0.008) and daptomycin at 10 mg/kg q24 h (3 strains, P ≤ 0.001). Isolates with increased MIC values for daptomycin (all 4 strains) but not for ceftaroline were recovered. Ceftaroline was effective against the 4 isolates tested and may provide a clinical option for the treatment of DNS MRSA infections.

Vancomycin-resistant enterococcal bacteraemia and daptomycin: are higher doses necessary?

BACKGROUND

The MIC corresponding to daptomycin susceptibility for vancomycin-resistant enterococci (VRE) is ≤ 4 mg/L. Based on the concentration-dependent killing properties of daptomycin, there may be concern about achieving adequate concentrations when the MIC approaches the upper end of the susceptible range (3-4 mg/L). Higher doses of daptomycin may be needed to treat VRE isolates with higher MICs.

METHODS

We conducted a single-centre retrospective chart review of adult cases with VRE bacteraemia who received daptomycin as initial therapy. The primary outcome was time to microbiological cure (TMC) between standard doses (≤ 6 mg/kg) and high doses (> 6 mg/kg) of daptomycin and whether TMC differed based on MICs. The secondary outcome evaluated the daptomycin MIC distribution and assessed whether recent exposure to vancomycin was associated with higher daptomycin MICs.

RESULTS

Forty-six cases were included in the primary analysis and 60.9% of patients were neutropenic. The two dose groups differed in the baseline characteristics of age, body mass index, blood culture source and catheter removal. Median TMC was 2 days for both dose groups. There was no significant difference in TMC between MIC subgroups of ≤ 2 mg/L versus >2 and ≤ 4 mg/L. For the secondary analysis 227 VRE isolates were evaluated and 62% had daptomycin MICs of 3-4 mg/L. Each daptomycin MIC group had a similar incidence of prior vancomycin exposure.

CONCLUSIONS

Based on this retrospective review we did not observe a difference in TMC based on daptomycin dose and MIC; however, there were various limitations to this study, and the study was not powered to detect a difference in TMC. Also, prior vancomycin exposure did not appear to influence daptomycin MICs. The frequency of daptomycin MICs of 3-4 mg/L reported in this study is higher than those reported in the literature.

Pharmacokinetics of single-dose daptomycin in patients with suspected or confirmed neurological infections

There are currently few or no published data on the amount of cerebrospinal fluid (CSF) penetration of daptomycin in patients with suspected or documented neurosurgical infections. We conducted a prospective study, assessing the pharmacokinetics and CSF penetration of a single intravenous daptomycin dose administered at 10 mg/kg, based on total body weight (TBW), in six neurosurgical patients with indwelling external CSF shunts with suspected or documented meningitis or ventriculitis. Each patient had four blood and CSF samples drawn simultaneously at specific times after the end of infusion: 30 min, 6 h, 12 h, and 24 h. Pharmacokinetic parameters of daptomycin in serum were calculated using standard noncompartmental methods, and daptomycin was assayed using high-performance liquid chromatography (for serum) or liquid chromatography with mass spectrometry (for CSF). The mean (± standard deviation [SD]) maximum measured daptomycin concentrations were 93.7 ± 17.3 mg/liter in serum at 0.5 h postinfusion and 0.461 ± 0.51 mg/liter in CSF at 6 h postinfusion. The mean (± SD) daptomycin minimum concentrations were 13.8 ± 4.8 mg/liter in serum at 24 h postinfusion and 0.126 ± 0.12 mg/liter in CSF at 0.5 h postinfusion. The mean daptomycin penetration, determined by the area under the concentration-time curve in CSF (AUC(CSF))/(AUC(serum) ratio), was 0.8%. Corrected for protein binding, the overall CSF penetration was 11.5%. Additional pharmacokinetic studies evaluating multiple and/or higher dosages of daptomycin are necessary in human subjects to better characterize the CSF penetration of daptomycin in neurosurgical patients.

Case report of a successful treatment of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia and MRSA/vancomycin-resistant Enterococcus faecium cholecystitis by daptomycin

A 72-year-old man, receiving 8 mg daptomycin/kg body weight/day for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia, was diagnosed with MRSA/vancomycin-resistant Enterococcus faecium (VRE) cholecystitis (daptomycin MIC values, 1 and 2 mg/liter, respectively). After the fifth drug dose, the bile concentration of daptomycin was 66 mg/liter 5 min after drug administration, with the biliary concentration/MIC values higher than 30 for both bacterial strains. Therefore, daptomycin achieved therapeutic levels in bile, hence suggesting a role for the drug in the treatment of MRSA/VRE cholecystitis.

Clinical experience with daptomycin in Europe: the first 2.5 years

Objectives

To describe the patient populations and infections being treated with daptomycin, as well as the efficacy and safety outcomes.

Patients and methods

Data from the European Cubicin Outcomes Registry and Experience (EU-CORE^SM), retrospectively collected at 118 institutions between January 2006 and August 2008, were analysed.

Results

Daptomycin treatment was documented in 1127 patients with diverse infections, including complicated skin and soft tissue infections (33%), bacteraemia (22%), endocarditis (12%) and osteomyelitis (6%). It was used empirically, before microbiological results became available, in 53% of patients. Staphylococcus aureus was the most common pathogen (34%), with 52% of isolates resistant to methicillin; coagulase-negative staphylococci and enterococci were also frequent, with 22% of Enterococcus faecium isolates resistant to vancomycin. Daptomycin was used as first-line therapy in 302 (27%) patients. When used second line, the most common reasons for discontinuation of previous antibiotic were treatment failure and toxicity or intolerance. The use of concomitant antibiotics was reported in 65% of patients. Most frequent doses were 6 mg/kg (47%) and 4 mg/kg (32%). The median duration of daptomycin therapy was 10 days (range 1–246 days) in the inpatient setting and 13 days (range 2–189 days) in the outpatient setting. The overall clinical success rate was 79%, with a clinical failure rate of <10% for all infection types. Low failure rates were observed in first- and second-line therapy (6% and 8%, respectively). Daptomycin demonstrated a favourable safety and tolerability profile regardless of treatment duration.

Conclusions

Daptomycin has a relevant role in the treatment of Gram-positive infections.

Eosinophilic pneumonia associated with daptomycin: a case report and a review of the literature

INTRODUCTION

Although several studies did not demonstrate that daptomycin may cause significantly higher rates of pulmonary adverse effects when compared with vancomycin or penicillinase-resistant penicillins, there have been a few case reports of severe pulmonary complications associated with daptomycin administration.

CASE PRESENTATION

A rare case of eosinophilic pneumonia occurring 10 days after daptomycin administration in a 78-year-old Caucasian man with possible infectious endocarditis is described. He developed new onset fever, up to 38.5°C, with bilateral pulmonary crackles on physical examination and with no signs of severe respiratory failure. A chest computed tomography-scan showed bilateral nodular consolidations with air bronchograms and pleural effusions. Immediate discontinuation of daptomycin was followed by vigorous improvement of clinical signs and symptoms with progressive resolution of pulmonary consolidations a month later.

CONCLUSION

Physicians should be aware of this rare but serious complication during daptomycin treatment, and prompt discontinuation of the offending agent, with or without additional supportive treatment, must occur immediately.

Daptomycin nonsusceptible enterococci: an emerging challenge for clinicians

Daptomycin is the only antibiotic with in vitro bactericidal activity against vancomycin-resistant Enterococcus (VRE) that is approved by the Food and Drug Administration (FDA). Data on the potential emergence of daptomycin nonsusceptibility among enterococci remain limited. We systematically reviewed the published literature for reports of isolates of enterococci that were daptomycin nonsusceptible and assessed the clinical significance and outcome of therapy. Based on susceptibility breakpoints approved by the Clinical Laboratory Standards Institute (CLSI), daptomycin has in vitro activity against >90% of enterococcal isolates. Less than 2% of enterococcal isolates were daptomycin nonsusceptible, with minimum inhibitory concentrations (MICs) >4 μg/mL. The prevalence of nonsusceptibility of VRE isolates to daptomycin may be overestimated due to the spread of clonally related isolates in health care settings. Clinicians should be aware of the possibility of the emergence of daptomycin nonsusceptibility and should closely monitor daptomycin MICs of enterococci isolated during treatment.

Observational study of the epidemiology and outcomes of vancomycin-resistant Enterococcus bacteraemia treated with newer antimicrobial agents

Vancomycin-resistant Enterococcus bloodstream infections (VRE-BSI) are a growing problem with few clinical trials to guide therapy. We conducted a retrospective study of management and predictors of mortality for VRE-BSI at a tertiary-care centre from January 2005 to August 2008. Univariate and multivariable analyses examined the relationship of patient characteristics and antibiotic therapy with 30-day all-cause mortality. Rates of VRE-BSI increased from 0·06 to 0·17 infections/1000 patient-days (P=0·03). For 235 patients, 30-day mortality was 34·9%. Patients were primarily treated with linezolid (44·2%) or daptomycin (36·5%). Factors associated with mortality were haemodialysis [odds ratio (OR) 3·2, 95% confidence interval (CI) 1·6-6·3, P=0·007], mechanical ventilation (OR 3·7, 95% CI 1·3-10·4, P=0·01), and malnutrition (OR 2·0, 95% CI 1·0-4·0, P=0·046). Use of linezolid, but not daptomycin (P=0·052) showed a trend towards an association with survival. In conclusion, VRE-BSI is a growing problem, associated with significant 30-day mortality. Multiple factors were associated with poor outcomes at our hospital.

Current management of bloodstream infections

Bloodstream infection (BSI) is a frequent complication of invasive infections. The presence of bacteremia has therapeutic and prognostic implications. Here we review recent changes in the epidemiology, diagnosis and treatment of BSI (excluding candidemia). The evidence of the impact of healthcare-association in many community-onset episodes and the increase in drug-resistant pathogens causing BSI in the community and hospitals is reviewed. The emergence of molecular methods as an alternative tool for the diagnosis of BSI and novel aspects of clinical management, particularly of some multidrug-resistant organisms. Several quality indicators related to the diagnosis and management of bacteremia in hospitals are proposed.

A potential role for daptomycin in enterococcal infections: what is the evidence?

Nosocomial infections caused by enterococci present a challenge for clinicians because treatment options are often limited due to the widespread occurrence of strains resistant to multiple antibiotics, including vancomycin. Daptomycin is a first-in-class cyclic lipopeptide that has proven efficacy for the treatment of Gram-positive infections. Although methicillin-resistant Staphylococcus aureus has been the most prominent target in the clinical development of daptomycin, this agent has demonstrated potent bactericidal activity in enterococcal infection models and has been used for the treatment of enterococcal infections in humans. In recent years, large-scale susceptibility studies have shown that daptomycin is active against >98% of enterococci tested, irrespective of their susceptibility to other antibacterial agents. This lack of cross-resistance reflects the fact that daptomycin has a mode of action distinct from those of other antibiotics, including glycopeptides. While there are limited data available from randomized controlled trials, extensive clinical experience with daptomycin in enterococcal infections (including bacteraemia, endocarditis, skin and soft tissue infections, bone and joint infections and urinary tract infections) has been reported. This growing body of evidence provides useful insights regarding the efficacy of daptomycin against enterococci in clinical settings.

Daptomycin: pharmacology and clinical use

IMPORTANCE OF THE FIELD

Infections caused by Gram-positive organisms have increased in frequency and severity. Daptomycin offers a therapeutic option in an era of increasing resistance.

AREAS COVERED IN THIS REVIEW

Literature from 1986 to present was reviewed for pharmacological, preclinical and clinical studies on daptomycin.

WHAT THE READER WILL GAIN

The pharmacological properties, resistance mechanisms and clinical applications of daptomycin are discussed. Recommendations are offered on the use of this agent for the treatment of resistant Gram-positive infections.

TAKE HOME MESSAGE

Daptomycin is a reliable agent for the treatment of Gram-positive infections. It has been shown to be effective in bacteremia and endocarditis, as well as in soft-tissue infections caused by Gram-positive organisms. Its role in the treatment of bone and joint infections is not well-defined. Resistance is currently uncommon in clinical isolates. However, emergence of resistance during therapy is a concern. This may be prevented by use of higher doses.

Relapse of enterococcal prosthetic valve endocarditis with aortic root abscess following treatment with daptomycin in a patient not fit for surgery

Daptomycin is a novel lipopeptide with activity against Gram-positive organisms including enterococci. It is licensed for the treatment of Staphylococcus aureus bacteraemia and right-sided endocarditis, but not endocarditis due to Enterococcus spp. We report a case of enterococcal prosthetic valve endocarditis with an aortic root abscess in an elderly patient who was not fit for surgery. The patient's endocarditis relapsed 9 weeks after a 6 week course of daptomycin.

[Update on antimicrobial chemotherapy]

There is a constant need for new antibacterial agents because of the unavoidable development of bacterial resistance that follows the introduction of antibiotics in clinical practice. As observed in many fields, innovation generally comes by series. For instance, a wide variety of broad-spectrum antibacterial agents became available between the 1970s and the 1990s, such as cephalosporins, penicillin/beta-lactamase inhibitor combinations, carbapenems, and fluoroquinolones. Over the last 2 decades, the arrival of new antibacterial drugs on the market has dramatically slowed, leaving a frequent gap between isolation of resistant pathogens and effective treatment options. In fact, many pharmaceutical companies focused on the development of narrow-spectrum antibiotics targeted at multidrug-resistant Gram-positive bacteria (e.g. methicillin-resistant Staphylococcus aureus, penicillin resistant Streptococcus pneumoniae, and vancomycin-resistant Enterococcus faecium). Therefore, multidrug-resistant Gram-negative bacteria (e.g. extended-spectrum beta-lactamase-producing Enterobacteriaceae, carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter baumannii) recently emerged and rapidly spread worldwide. Even if some molecules were developed, new molecules for infections caused by these multidrug-resistant Gram-negative bacteria remain remarkably scarce compared to those for Gram-positive infections. This review summarises the major microbiological, pharmacological, and clinical properties of systemic antibiotics recently marketed in France (i.e. linezolid, daptomycin, tigecycline, ertapenem, and doripenem) as well as those of antibacterial drugs currently in development (i.e. ceftobiprole, ceftaroline, dalbavancin, telavancin, oritavancin, iclaprim, and ramoplanin) or available in other countries (i.e. garenoxacin, sitafloxacin, and temocillin).