Daptomycin

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.

Comparison of daptomycin and glycopeptide efficacy and safety for the treatment of Gram-positive infections: a systematic review and meta-analysis

BACKGROUND

The indications of daptomycin have been extended to off-label indications including prosthesis-related infection, and bone and joint infection (BJI). However, efficacy and safety have not been thoroughly demonstrated compared with the standard of care. This systematic review and meta-analysis aimed to compare the treatment effect of daptomycin and glycopeptides for complicated infections.

MATERIALS AND METHODS

MEDLINE, Embase and Web of Science were searched for randomized controlled trials (RCTs) comparing daptomycin and standard of care for Gram-positive infections, published until 30 June 2021. The primary outcome was defined as all-cause mortality. Secondary outcomes were clinical and microbiological success. The main safety outcome was any severe adverse event (SAE) (grade  ≥3).

RESULTS

Overall, eight RCTs were included in the meta-analysis, totalling 1095 patients. Six (75%) were in complicated skin and soft-structure infections, one (12.5%) in bacteraemia and one (12.5%) in a BJI setting. Six RCTs used vancomycin as a comparator and two used either vancomycin or teicoplanin. All-cause mortality and clinical cure were not different between groups. The microbiological cure rate was superior in patients who received daptomycin [risk ratio (RR) = 1.17 (95% CI: 1.01-1.35)]. The risk of SAEs [RR = 0.57 (95% CI: 0.36-0.90)] was lower in the daptomycin arm.

CONCLUSIONS

While daptomycin is associated with a significantly lower risk of SAEs and a better microbiological eradication, substantial uncertainty remains about the best treatment strategy in the absence of good-quality evidence, especially in bacteraemia and endocarditis where further RCTs should be conducted.

Daptomycin-Induced Pulmonary Toxicity: A Case Series

Daptomycin is a bactericidal antibiotic used to treat methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococcus (VRE). Eosinophilic pneumonia is an uncommon but significant adverse effect of daptomycin. We present two patients treated with daptomycin who subsequently developed eosinophilic pneumonia (EP).

Seventeen Cases of Daptomycin-Induced Eosinophilic Pneumonia in a Cohort of Patients Treated for Bone and Joint Infections: Proposal for a New Algorithm

BACKGROUND

Daptomycin is increasingly used in the treatment of bone and joint infections (BJIs) and may be responsible for daptomycin-induced eosinophilic pneumonia (DIEP), a potentially severe adverse drug reaction. The aim of this study was to describe DIEP in patients treated at a referral center for the management of BJI, and to revisit current definitions of this disease.

METHODS

Patients treated from 1 January 2012 to 31 March 2021 were included in a prospective cohort (NCT02817711), in which all potential serious adverse events are prospectively recorded. Patients diagnosed with DIEP were retrospectively analyzed using different definitions.

RESULTS

In a total of 4664 patients included in the cohort during the study period, 1021 patients (21.9%) received daptomycin, of whom 17 (1.7%) were diagnosed with DIEP. Most patients were male (n = 11 [64.7%]), and periprosthetic joint infection was the commonest BJI (n = 12 [70.6%]). Only 1 patient had bronchoalveolar lavage (BAL) eosinophil count ≥25%, while most patients had peripheral blood eosinophilia (n = 15 [88.2%]). Chest computed tomography (CT) was compatible with eosinophilic pneumonia in 13 of 14 cases (92.9%). All patients recovered upon discontinuation of daptomycin. Using the different definitions available, only a minority of cases fulfilled existing criteria for DIEP. We propose a new algorithm that includes specific CT scan signs, and systemic instead of BAL eosinophilia.

CONCLUSIONS

DIEP is a rare event that requires prompt discontinuation of the causative antibiotic. Current criteria to diagnose definite DIEP are too restrictive and not easily applicable in clinical practice. A new algorithm is proposed here (Lyon algorithm) to facilitate the early identification of DIEP.

Meeting the Unmet Need in the Management of MDR Gram-Positive Infections with Oral Bactericidal Agent Levonadifloxacin

Levonadifloxacin (intravenous) and its oral prodrug alalevonadifloxacin are broad-spectrum antibacterial agents developed for the treatment of difficult-to-treat infections caused by multidrug-resistant Gram-positive bacteria, especially methicillin-resistant Staphylococcus aureus, atypical bacteria, anaerobic bacteria, and biodefence pathogens as well as Gram-negative bacteria. Levonadifloxacin has a well-defined mechanism of action involving a strong affinity for DNA gyrase as well as topoisomerase IV. Alalevonadifloxacin with widely differing solubility and oral bioavailability has pharmacokinetic profile identical to levonadifloxacin. Unlike existing MRSA drugs such as vancomycin and linezolid, which cause unfavorable side effects like nephrotoxicity, bone-marrow toxicity, and muscle toxicity, levonadifloxacin/alalevonadifloxacin has demonstrated superior safety and tolerability features with no serious adverse events. Levonadifloxacin/alalevonadifloxacin could be a useful weapon in the battle against infections caused by resistant microorganisms and could be a preferred antibiotic of choice for empirical therapy in the future.

Microwave-assisted preparation of Ag/Fe magnetic biochar from clivia leaves for adsorbing daptomycin antibiotics

Novel clivia biochar adsorbing daptomycin (DAP) was prepared by microwave digestion–anaerobic carbonization in this work. Fe/Ag submicron particles were introduced to the biochar surface based on the reducibility of biochar to enhance its adsorption capacity. Characterization confirmed that modified biochar (AF-biochar) had a higher particle size (126 μm), larger specific surface area (521.692 m2 g−1), richer pore structure, and higher thermal stability. The effects of the main variables (e.g., the solution pH, contact time, initial DAP concentration, and temperature) were investigated during adsorption. The results showed that AF-biochar could reach the adsorption equilibrium at pH 4.8 for 85 min. Besides, the adsorption capacity was 48.25 mg g−1, and the adsorption efficiency was 96.50% when the concentration of DAP was 25 mg L−1. The pseudo-second-order kinetics (R 2 = 0.9997), Langmuir equation (R 2 = 0.9999), and thermodynamics (R 2 = 0.9631) of AF-biochar fit well, indicating that the main adsorption process of AF-biochar was spontaneous, exothermic, and monolayer. Their adsorption was analyzed by physical and chemical adsorption. The main adsorption mechanisms included the electron donor–acceptor interaction, electrostatic force interaction, Lewis acid–base interaction, and H-bond interaction.

Repurposing clinical drugs is a promising strategy to discover drugs against Zika virus infection

Zika virus (ZIKV) is an emerging pathogen associated with neurological complications, such as Guillain-Barré syndrome in adults and microcephaly in fetuses and newborns. This mosquito-borne flavivirus causes important social and sanitary problems owing to its rapid dissemination. However, the development of antivirals against ZIKV is lagging. Although various strategies have been used to study anti-ZIKV agents, approved drugs or vaccines for the treatment (or prevention) of ZIKV infections are currently unavailable. Repurposing clinically approved drugs could be an effective approach to quickly respond to an emergency outbreak of ZIKV infections. The well-established safety profiles and optimal dosage of these clinically approved drugs could provide an economical, safe, and efficacious approach to address ZIKV infections. This review focuses on the recent research and development of agents against ZIKV infection by repurposing clinical drugs. Their characteristics, targets, and potential use in anti-ZIKV therapy are presented. This review provides an update and some successful strategies in the search for anti-ZIKV agents are given.

Lesson from Ecotoxicity: Revisiting the Microbial Lipopeptides for the Management of Emerging Diseases for Crop Protection

Microorganisms area treasure in terms of theproduction of various bioactive compounds which are being explored in different arenas of applied sciences. In agriculture, microbes and their bioactive compounds are being utilized in growth promotion and health promotion withnutrient fortification and its acquisition. Exhaustive explorations are unraveling the vast diversity of microbialcompounds with their potential usage in solving multiferous problems incrop production. Lipopeptides are one of such microbial compounds which havestrong antimicrobial properties against different plant pathogens. These compounds are reported to be produced by bacteria, cyanobacteria, fungi, and few other microorganisms; however, genus Bacillus alone produces a majority of diverse lipopeptides. Lipopeptides are low molecular weight compounds which havemultiple industrial roles apart from being usedas biosurfactants and antimicrobials. In plant protection, lipopeptides have wide prospects owing totheirpore-forming ability in pathogens, siderophore activity, biofilm inhibition, and dislodging activity, preventing colonization bypathogens, antiviral activity, etc. Microbes with lipopeptides that haveall these actions are good biocontrol agents. Exploring these antimicrobial compounds could widen the vistasof biological pest control for existing and emerging plant pathogens. The broader diversity and strong antimicrobial behavior of lipopeptides could be a boon for dealing withcomplex pathosystems and controlling diseases of greater economic importance. Understanding which and how these compounds modulate the synthesis and production of defense-related biomolecules in the plants is a key question—the answer of whichneeds in-depth investigation. The present reviewprovides a comprehensive picture of important lipopeptides produced by plant microbiome, their isolation, characterization, mechanisms of disease control, behavior against phytopathogens to understand different aspects of antagonism, and potential prospects for future explorations as antimicrobial agents. Understanding and exploring the antimicrobial lipopeptides from bacteria and fungi could also open upan entire new arena of biopesticides for effective control of devastating plant diseases.

Daptomycin adsorption on magnetic ultra-fine wood-based biochars from water: Kinetics, isotherms, and mechanism studies

The adsorption of a new antibiotic, daptomycin, on two magnetic ultra-fine wood-based biochars were investigated in detail using batch experiments. The adsorbent materials was prepared by ball milling method, which was characterized by laser particle size analyzer, elemental analyzer, ICP-OES, VSM, BET, TG-DTG, FTIR and SEM. Furthermore, the effects of most important variables in the adsorption process, including solution pH, contact time, initial concentration and temperatures were investigated. The results exhibited that the adsorption of daptomycin was highly pH-dependent, and the capacity decreased with increasing pH. The adsorption process follows pseudo-first order and pseudo-second order models, analysis indicated that their adsorption was dominantly by physisorption. Equilibrium data were fitted well with Freundlich isotherm model, implying a multilayer adsorption. Thermodynamic parameters demonstrated that the adsorption was spontaneous, endothermic and increased randomness process. Mechanism study suggested the boundary layer diffusion was the rate limiting step.

Lipid composition in fungal membrane models: effect of lipid fluidity

The creation of effective fungal membrane models for neutron and X-ray reflectometry experiments is a key step in the development of new antifungal pharmaceuticals and agrochemicals to allow in vitro investigation of their mode of interaction with target cells. The structure of the obtained models depends on the properties of the lipids used and the final composition of the leaflets, and can be subject to the spontaneous translocation of phospholipids across the bilayer. The effect of phospholipid acyl-chain unsaturation and the presence of steroids in the membrane on the bilayer asymmetry were examined by means of neutron reflectometry. The measurements showed that membrane stability was higher if a zwitterionic, saturated acyl-chain phospholipid is present as the inner leaflet. Furthermore, membrane asymmetry was higher in the case of fully saturated lipid systems. As a result, membrane models consisting of fully saturated acyl chains within the inner leaflet are recommended as the starting point for subsequent studies of antifungal interactions owing to the simplicity of the models and their relative stability, thus allowing better control over the exact lipid composition facing the tested antifungal.

Effect of a Point Mutation in mprF on Susceptibility to Daptomycin, Vancomycin, and Oxacillin in an MRSA Clinical Strain

We previously reported the sequential recovery of daptomycin-nonsusceptible MRSA clinical isolates with an L431F substitution in the MprF protein. The aim of the present study is to determine the effect of this mutation by replacing the mprF gene on the chromosome of a daptomycin-susceptible progenitor strain, CGK5, to obtain CGK5mut having the L431F MprF mutation. Compared to CGK5, the daptomycin and vancomycin MICs of CGK5mut increased from 0.5 to 3 μg/ml and from 1.5 to 3 μg/ml, respectively; however, its oxacillin MIC decreased from 128 to 1 μg/ml in medium without added 2% NaCl. The expression levels of vraSR and several other cell-wall synthesis-related genes were significantly increased in CGK5mut, and the mutant also had significantly reduced negative cell membrane charge, thicker cell wall, and longer doubling time. These features were abolished in the reverse mutant carrying F431L MprF, confirming the pleiotropic effects of the L431F MprF mutation. We believe that this is the first work that shows a single MprF missense mutation can lead to not only changes in the cell membrane but also increased expression of vraSR and subsequently increased resistance to daptomycin and vancomycin while simultaneously conferring increased susceptibility to oxacillin in an isogenic MRSA strain.

Efficient recombinant expression of SFTI-1 in bacterial cells using intein-mediated protein trans-splicing

We report for the first time the recombinant expression of bioactive wild-type sunflower trypsin inhibitor 1 (SFTI-1) inside E. coli cells by making use of intracellular protein trans-splicing in combination with a high efficient split-intein. SFTI-1 is a small backbone-cyclized polypeptide with a single disulfide bridge and potent trypsin inhibitory activity. Recombinantly produced SFTI-1 was fully characterized by NMR and was observed to actively inhibit trypsin. The in-cell expression of SFTI-1 was very efficient reaching intracellular concentration ≈ 40 µM. This study clearly demonstrates the possibility of generating genetically encoded SFTI-based peptide libraries in live E. coli cells, and is a critical first step for developing in-cell screening and directed evolution technologies using the cyclic peptide SFTI-1 as a molecular scaffold. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 818-824, 2016.

Daptomycin for the treatment of major gram-positive infections after cardiac surgery

Background

Infection is a main cause of morbidity and mortality after heart surgery, with multi-resistant pathogens increasingly representing a challenge. Daptomycin provides bactericidal activity against gram-positive organisms that are resistant to standard treatment including vancomycin.

Methods

A cohort of cardiac surgical patients, treated with daptomycin for major infection at two tertiary care centers, were retrospectively studied with a particular focus on the type of infection, causative pathogens and co-infections, daptomycin dosage, adverse events and outcome in order to provide evidence for the efficiency and safety of daptomycin in a distinct high-risk patient population.

Results

Sixty-five patients (87.7 % males, 60.4 ± 13.5 years) who had undergone aortic surgery (20.0 %), ventricular assist device (VAD) implantation (21.5 %), combined procedures (21.5 %), coronary artery bypass grafting (12.3 %), isolated valve surgery (15.4 %) and heart transplantation (7.7 %) were diagnosed with catheter-related infection (26.1 %), valve endocarditis (18.8 %), sternal wound (13.0 %), VAD-associated (11.6 %), cardiac implantable electrophysiological device (CIED)-associated (4.1 %), respiratory tract (4.3 %), bloodstream (4.3 %) and other infection (4.3 %). In 13.0 %, no focus of infection was identified though symptoms of severe infection were present. The most frequent pathogens were Staphylococcus epidermidis (30.4 %), Staphylococcus aureus (23.1 %) and Enterococcus species (10.1 %). Daptomycin doses ranging from 3 mg/kg every 48 h to 10 mg/kg every 24 h were administered for 15.4 ± 11.8 days. 87.0 % of the cases were classified as success, 7.2 % as treatment failure and 5.8 as non-evaluable. Adverse events were limited to one case of mild and one case of moderate neutropenia with recovery upon termination of treatment.

Conclusion

Daptomycin proved safe and effective in major infection in high-risk cardiac surgical patients.

A retrospective study of outcomes of device-associated osteomyelitis treated with daptomycin

Background

Daptomycin appears well tolerated and effective for osteomyelitis treatment. However, limited data exist regarding daptomycin use for treatment of device-associated osteomyelitis (DAO).

Methods

We used a retrospective, observational database (Cubicin® Outcomes Registry and Experience [CORE® 2007–2009]) that assessed patients treated with daptomycin to evaluate the characteristics of patients with DAO, outcomes after daptomycin treatment, and safety of daptomycin in this setting. Information from 54 institutions for patients with prosthetic joint infection (PJI) and other hardware-associated osteomyelitis (OHAO) who received daptomycin from January 2007 to December 2008 with follow-up data in 2009 was collected using a standardized data collection form.

Results

Eighty-two patients receiving daptomycin were identified in CORE 2007–2009; 48 patients (59 %) had follow-up data. Sixty-seven percent of patients had received a previous antibiotic. Surgical intervention was similar between the 2 groups: PJI, 22 of 27 (82 %) and OHAO, 17 of 21 (81 %). However, device removal or replacement was more frequent in the PJI patients (17 of 27, 63 %) than in the OHAO patients (8 of 21, 38 %). Clinical success was reported in 22 of 27 (82 %; 95 % confidence interval [CI], 62–94 %) patients with PJI and 18 of 21 (86 %; 95 % CI, 64–97 %) patients with OHAO at follow-up (13–402 days). Adverse events occurred in 8 of 50 (16 %) patients in the safety population and did not differ by daptomycin dose.

Conclusion

Daptomycin appeared effective and well tolerated in patients with DAO, including PJI or OHAO.

Study on daptomycin use and implementation of an antimicrobial stewardship program

BACKGROUND

Treatment of Gram-positive pathogens remains a major health issue due to the presence of methicillin-resistant Staphylococcus aureus (MRSA) and Vancomycin-Resistant Enterococcus spp. Daptomycin offers an alternative after therapeutic failure using glycopeptides. Yet its use requires strict control given its financial impact and environmental risks. Since 2014, the use of daptomycin within our hospital has intensified, occasionally outside the scope of its approved indications.

OBJECTIVES

The aim of this study is to analyze the appropriateness of daptomycin prescriptions.

SETTING

This work was conducted in a 1500-bed University Hospital.

METHOD

A descriptive retrospective study was conducted from November 2013 to July 2014. All patients having received at least 2 days of treatment were included. Analysis of the appropriateness of daptomycin prescriptions was conducted by a multidisciplinary team comprised of infectious diseases specialists, pharmacists and a microbiologist. The appropriateness of daptomycin prescriptions was established based on Infectious Diseases Society of America recommendations published in 2011.

MAIN OUTCOME MEASURES

The indicators chosen to determine appropriateness of prescription were: treatment indication, prescribed dose and other antibiotics associated with the daptomycin prescription.

RESULTS

19 patients (14 men/5 women) were included. Observed indications were: bone and joint infection (n = 6; 32 %), infectious endocarditis (n = 5; 26 %), bacteremia (n = 5; 26 %) and complicated skin and soft tissue infection (n = 3; 16 %). Identified pathogens were: MRSA (n = 14; 74 %), methicillin-resistant coagulase-negative Staphylococcus (n = 4; 21 %) and Streptococcus mitis (n = 1; 5 %). Daptomycin was prescribed as first-line treatment in 32 % of cases (n = 6). The mean dosage was 9 mg/kg/day (5-11 mg/kg/day) for a mean duration of 11 days (2; 55 days). Clinical success was observed in 42 % of cases (n = 8). Appropriateness for daptomycin use was only established for 15 % of prescriptions (n = 3).

CONCLUSION

Faced with a lack of recent recommendations on the subject, our multidisciplinary team issued a local consensus, defining the indications and dosage modalities for this reserve antibiotic. This multidisciplinary approach enables improved use of recent anti-MRSA drugs.

Origin of de novo daptomycin non susceptible enterococci

The emergence of daptomycin non-susceptible enterococci (DNSE) poses both treatment and infection control challenges. Clinicians should be vigilant that DNSE may be isolated from patients with or without (de novo DNSE) prior use of daptomycin. Recent epidemiological data suggest the presence of a community reservoir for DNSE which may be associated with environmental, foodborne and agricultural exposures. The mechanisms of nonsusceptibility to daptomycin have not been well characterized and may not parallel those for Staphylococcus aureus. The identification of daptomycin resistance genes in anaerobes, in farm animals and in an ecosystem that has been isolated for million years, suggest that the environmental reservoir for de novo DNSE may be larger than previously thought. Herein, the limited available scientific evidence regarding the possible origin of de novo DNSE is discussed. The current existing evidence is not sufficient to draw firm conclusions on the origin of DNSE. Further studies to determine the mechanisms of de novo daptomycin nonsusceptibility among enterococci are needed.

Role of daptomycin in the induction and persistence of the viable but non-culturable state of Staphylococcus aureus biofilms

We have recently demonstrated that antibiotic pressure can induce the viable but non-culturable (VBNC) state in Staphylococcus aureus biofilms. Since dormant bacterial cells can undermine anti-infective therapy, a greater understanding of the role of antibiotics of last resort, including daptomycin, is crucial. Methicillin-resistant S. aureus 10850 biofilms were maintained on non-nutrient (NN) agar in the presence or absence of the MIC of daptomycin until loss of culturability. Viable cells were monitored by epifluorescence microscopy and flow cytometry for 150 days. All biofilms reached non-culturability at 40 days and showed a similar amount of viable cells; however, in biofilms exposed to daptomycin, their number remained unchanged throughout the experiment, whereas in those maintained on NN agar alone, no viable cells were detected after 150 days. Gene expression assays showed that after achievement of non-culturability, 16S rDNA and mecA were expressed by all biofilms, whereas glt expression was found only in daptomycin-exposed biofilms. Our findings suggest that low daptomycin concentrations, such as those that are likely to obtain within biofilms, can influence the viability and gene expression of non-culturable S. aureus cells. Resuscitation experiments are needed to establish the VBNC state of daptomycin-exposed biofilms.

The Interplay between Daptomycin and the Immune System

Antibiotics may have bacteriostatic or bactericidal effects but may also cause immunomodulation. Lipopeptides are known immunomodulators that interact with pattern recognition receptors such as Toll-like receptors in antigen presenting cells. Daptomycin is a novel lipopeptide antibiotic with a lipid moiety and unique structure that in the presence of divalent ions may directly interact with lipid membrane phospholipids, the major component of lipid membranes in immune cells. Daptomycin may also penetrate immune cells including neutrophils and macrophages. However, the possible immunomodulatory effects of daptomycin remain unknown. Understanding these effects is important to determine whether this agent can provide protection against infectious challenge through multiple mechanisms. Preliminary studies suggest that daptomycin may have minimal effects on cytokine production and may have synergistic immunomodulatory effects in combination with other immunomodulators. This review focuses on the hypothesis that daptomycin may also have immunomodulatory effects but further studies are needed to investigate this hypothesis.

A retrospective study of daptomycin use in a Paris teaching-hospital

OBJECTIVE

We retrospectively studied daptomycin use during 2010 at the Bichat-Claude-Bernard teaching-hospital (Paris) to observe the evolution of daptomycin prescriptions.

PATIENTS AND METHODS

Twenty-one patients were included and several parameters were documented: site of infection, bacterial species involved, reason for daptomycin use, dose and clinical outcome.

RESULTS

Ninety-five percent of daptomycin prescritions were off-label and most did not comply with local guidelines. Fifteen of the 21 patients were cured (71%), including 9 patients of the 12 with off-label and off-local recommendation prescriptions (75%). Osteitis and Enterococcus spp endocarditis were the new indications. Daptomycin was increasingly used at higher doses: 52% of our patients were given doses above 6mg/kg. Staphylococcus spp. was the most frequent pathogen responsible for infection is our patients, followed by Enterococcus spp.

CONCLUSION

Daptomycin use is likely to evolve because of its effectiveness in the treatment of osteitis, left-sided and Enterococcus spp. infective endocarditis. It is generally used at higher doses, which are well tolerated. However, therapeutic monitoring needs to be developed. The antibiotic commission of our hospital gave new recommendations for daptomycin use in 2011.

Targeted therapy against multi-resistant bacteria in leukemic and hematopoietic stem cell transplant recipients: guidelines of the 4th European Conference on Infections in Leukemia (ECIL-4, 2011)

The detection of multi-resistant bacterial pathogens, particularly those to carbapenemases, in leukemic and stem cell transplant patients forces the use of old or non-conventional agents as the only remaining treatment options. These include colistin/polymyxin B, tigecycline, fosfomycin and various anti-gram-positive agents. Data on the use of these agents in leukemic patients are scanty, with only linezolid subjected to formal trials. The Expert Group of the 4(th) European Conference on Infections in Leukemia has developed guidelines for their use in these patient populations. Targeted therapy should be based on (i) in vitro susceptibility data, (ii) knowledge of the best treatment option against the particular species or phenotype of bacteria, (iii) pharmacokinetic/pharmacodynamic data, and (iv) careful assessment of the risk-benefit balance. For infections due to resistant Gram-negative bacteria, these agents should be preferably used in combination with other agents that remain active in vitro, because of suboptimal efficacy (e.g., tigecycline) and the risk of emergent resistance (e.g., fosfomycin). The paucity of new antibacterial drugs in the near future should lead us to limit the use of these drugs to situations where no alternative exists.

Chitosan nanoparticles for daptomycin delivery in ocular treatment of bacterial endophthalmitis

CONTEXT

Chitosan nanoparticles were prepared to encapsulate daptomycin and proposed as a delivery system of this antibiotic to the eye for the treatment of bacterial endophthalmitis.

OBJECTIVE

The aim of this study was to develop daptomycin-loaded nanoparticles to apply directly to the eye, as a possible non-invasive and less painful alternative for the treatment of endophthalmitis, increasing the effectiveness of treatment and reducing toxicity associated with systemic administration.

MATERIALS AND METHODS

Nanoparticles were obtained by ionotropic gelation between chitosan and sodium tripolyphosphate (TPP). Physicochemical and morphological characteristics of nanoparticles were evaluated, as well as determination of antimicrobial efficiency of encapsulated daptomycin and stability of the nanoparticles in the presence of lysozyme and mucin.

RESULTS

Loaded nanoparticles presented mean particle sizes around 200 nm, low polydispersity index, and positive zeta potential. Morphological examination by scanning electron microscopy (SEM) confirmed their small size and round-shaped structure. Encapsulation efficiency ranged from 80 to 97%. Total in vitro release of daptomycin was obtained within 4 h. Determination of minimum inhibitory concentrations (MICs) showed that bacteria were still susceptible to daptomycin encapsulated into the nanoparticles. Incubation with lysozyme did not significantly affect the integrity of the nanoparticles, although mucin positively affected their mucoadhesive properties.

DISCUSSION AND CONCLUSION

The obtained nanoparticles have suitable characteristics for ocular applications, arising as a promising solution for the topical administration of daptomycin to the eye.

Invasive Staphylococcus aureus infections in diabetes mellitus

Staphylococcus aureus, the most virulent of the many staphylococcal species, has remained a major cause of morbidity and mortality despite the availability of numerous effective anti-staphylococcal antibiotics. S. aureus causes disease through both toxin-mediated and non-toxin-mediated mechanisms. This organism is responsible for both healthcare associated and community-based infections ranging from relatively minor skin and soft tissue infections to severe life threatening systemic infections. Patients with diabetes mellitus are at increased risk of invasive S. aureus infections. This article focuses on the spectrum of invasive S. aureus infections and discusses the clinical features, investigations and management of these infections in patients with diabetes mellitus.

Current use of daptomycin in cardiac surgery and postoperative intensive care

Infections due to multidrug-resistant pathogens have an increasing impact on patients undergoing cardiac surgery. Preoperative infections, such as endocarditis, and postoperative infections, including wound and device infection, influence patient outcomes. Special interest needs to be taken in patients admitted to cardiac surgical intensive care units, as these patients are at high risk for infections, particularly nosocomial pneumonia, catheter-related and wound infections. The increasing numbers of infections due to Gram-positive multidrug-resistant pathogens underline the necessity for newer antibiotics with bactericidal effects and a more favorable profile of side effects. Daptomycin, a lipopeptide antimicrobial agent with bactericide activity against Gram-positive organisms, has been successfully used in the treatment of complicated infections due to Gram-positive multidrug-resistant pathogens, especially regarding endocarditis, wound infections, device and catheter-related infections in intensive care units. In this review, the authors will summarize therapeutic potential of daptomycin in cardiac surgery and postoperative intensive care.

Cyclic lipodepsipeptides: a new class of antibacterial agents in the battle against resistant bacteria

In order to provide effective treatment options for infections caused by multidrug-resistant bacteria, innovative antibiotics are necessary, preferably with novel modes of action and/or belonging to novel classes of drugs. Naturally occurring cyclic lipodepsipeptides, which contain one or more ester bonds along with the amide bonds, have emerged as promising candidates for the development of new antibiotics. Some of these natural products are either already marketed or in advanced stages of clinical development. However, despite the progress in the development of new antibacterial agents, it is inevitable that resistant strains of bacteria will emerge in response to the widespread use of a particular antibiotic and limit its lifetime. Therefore, development of new antibiotics remains our most efficient way to counteract bacterial resistance.

Peptide antimicrobials: cell wall as a bacterial target

Endogenous host defense peptides (HDPs) are among the most ancient immune mediators, constituting a first line of defense against invading pathogens across the evolutionary continuum. Generally, HDPs are small (<10 kDa), cationic, and amphipathic polypeptides, often broadly classified based on structure. In eukaryotes, major HDP classes include disulfide-stabilized (e.g., defensins), and α-helical or extended (e.g., cathelicidins) peptides. Prokaryote HDPs are generally referred to as bacteriocins, colicins, or lantibiotics, many of which undergo extensive posttranslational modifications. One target for prokaryotic and eukaryotic HDPs is the bacterial cell wall, an essential structural feature conserved among broad classes of bacteria. A primary building block of the cell wall is peptidoglycan, a macromolecular complex that arises through a series of reactions including membrane translocation, extracellular anchoring, and side chain cross-linking. Each of these steps represents a potential target for HDP inhibition, leading to bacteriostatic or bactericidal outcomes. Thus, understanding the relationships between HDPs and cell wall targets may shed light on new peptide antimicrobial agents and strategies to meet the daunting challenge of antibiotic resistance.

[Daptomycin for the treatment of gram-positive infections after cardiac surgery]

BACKGROUND AND METHOD

Surgical infection remains a main cause of death after heart surgery, despite advances in pharmacological therapy. Daptomycin is a cyclic lipopeptide antibiotic, useful in gram-positive organisms resistant to standard treatment, including vancomycin. The aim of this study was to describe the use of daptomycin regarding efficacy, efficiency and safety in patients with gram-positive infections after heart surgery using a retrospective analysis on 49 adult patients.

CONCLUSION

Daptomycin shows excellent in vitro and in vivo activity against gram-positive organisms, such as Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, especially MRSA. Daptomycin is also effective against increasing vancomycin-resistant or vancomycin-intermediate S. aureus.

Evaluation of a daptomycin dose-optimization protocol

PURPOSE

The impact of an institutional protocol intended to improve daptomycin dosing for vancomycin-resistant enterococci (VRE) infections was investigated.

SUMMARY

Daptomycin has been reported to have optimal activity against VRE at weight-based doses of ≥8 mg/kg. As part of an initiative to optimize daptomycin dosing for all indications and regimens, a large medical center implemented a protocol restricting daptomycin prescribing to infectious-diseases specialists and a nomogram recommending elevated daptomycin dosing for all VRE infections, with baseline and weekly creatinine phosphokinase (CPK) determinations during daptomycin therapy. Protocol implementation was preceded by educational efforts targeting medical and pharmacy staff. A retrospective study was conducted to compare prescribing behavior and safety monitoring rates during the 12 months before and 16 months after protocol implementation; the baseline characteristics of the preimplementation cohort (n = 95) and postimplementation cohort (n = 72) were similar. The mean daptomycin doses before and after the protocol was implemented were 453 mg (6.1 mg/kg) and 576 mg (7.6 mg/kg), respectively. After protocol implementation, there were significant increases in the proportion of patients who received doses of ≥8 mg/kg (52% in the postimplementation period versus 4% in the preimplementation period, p < 0.05) and in the rate of baseline CPK assessment (64% versus 43%, p < 0.05).

CONCLUSION

Implementation of a daptomycin dosing protocol by a multidisciplinary antimicrobial stewardship team optimized treatment by increasing the mean dose of daptomycin administered to hospitalized adults with non-urinary VRE infections and improved the rate of safety monitoring.

LC-MS/MS characterization of phospholipid content in daptomycin-susceptible and -resistant isolates of Staphylococcus aureus with mutations in mprF

Daptomycin (DAP) is a cyclic lipopeptide antibiotic used for the treatment of certain Staphylococcus aureus infections. Although rare, strains have been isolated that are DAP resistant. These strains usually have mutations in mprF, a gene encoding a membrane protein with both lysylphosphatidylglycerol (LPG) synthase and flippase activities. Because ΔmprF strains have increased DAP susceptibility, the mechanism of resistance is not likely due to a loss of mprF function. In this study, we developed an LC-MS assay to examine the effect of different mprF mutations on the ratio of phosphatidylglycerol (PG) to LPG in the membrane. Our assay demonstrated that some, but not all, mutations in the flippase and synthase domains result in small but reproducible increases in the proportion of LPG relative to PG. Techniques described herein represent a higher throughput and more sensitive method for measuring relative phospholipids levels. These results offer guidance in the understanding of how mprF confers DAP resistance; namely, mprF-mediated resistance may be through more than one mechanism, including increased overall LPG synthesis and increased LPG present on the outer leaflet of the cytoplasmic membrane.

Resistance phenotypes mediated by aminoacyl-phosphatidylglycerol synthases

The specific aminoacylation of the phospholipid phosphatidylglycerol (PG) with alanine or with lysine catalyzed by aminoacyl-phosphatidylglycerol synthases (aaPGS) was shown to render various organisms less susceptible to antibacterial agents. This study makes use of Pseudomonas aeruginosa chimeric mutant strains producing lysyl-phosphatidylglycerol (L-PG) instead of the naturally occurring alanyl-phosphatidylglycerol (A-PG) to study the resulting impact on bacterial resistance. Consequences of such artificial phospholipid composition were studied in the presence of an overall of seven antimicrobials (β-lactams, a lipopeptide antibiotic, cationic antimicrobial peptides [CAMPs]) to quantitatively assess the effect of A-PG substitution (with L-PG, L-PG and A-PG, increased A-PG levels). For the employed Gram-negative P. aeruginosa model system, an exclusive charge repulsion mechanism does not explain the attenuated antimicrobial susceptibility due to PG modification. Additionally, the specificity of nine orthologous aaPGS enzymes was experimentally determined. The newly characterized protein sequences allowed for the establishment of a significant group of A-PG synthase sequences which were bioinformatically compared to the related group of L-PG synthesizing enzymes. The analysis revealed a diverse origin for the evolution of A-PG and L-PG synthases, as the specificity of an individual enzyme is not reflected in terms of a characteristic sequence motif. This finding is relevant for future development of potential aaPGS inhibitors.

Evaluation of two sources of calcium sulfate for a local drug delivery system: a pilot study

BACKGROUND

Local drug delivery has substantial potential to prevent infections compared with systemic delivery. Although calcium sulfate (CaSO(4)) has been studied for local drug delivery and two types are commercially available, it is unknown whether they differentially release antibiotics.

QUESTIONS/PURPOSES

We determined the differences between two sources of CaSO(4) and the K(2)SO(4) catalyst's presence on the degradation, daptomycin elution, and activity against Staphylococcus aureus.

METHODS

We formed pellets from synthetic and naturally sourced (from gypsum) CaSO(4) and loaded with 5% daptomycin and 3% or 0% K(2)SO(4). We used in vitro experiments to determine the daptomycin concentration and degradation profiles over 10 days. Turbidity assays were used to evaluate the activity of the daptomycin eluates against S. aureus.

RESULTS

All pellets exhibited a bolus release with the highest daptomycin concentration on Day 1 with the sourced CaSO(4) pellets. The synthetic CaSO(4) pellets with 3% K(2)SO(4) exhibited a slower drug release compared with the synthetic CaSO(4) pellets with 0% K(2)SO(4), which degraded and eluted daptomycin too quickly to inhibit S. aureus. Turbidity assays demonstrated that all CaSO(4) pellets inhibit S. aureus for expected lengths of time.

CONCLUSIONS

Our preliminary in vitro data suggest differences in the degradation, elution, and activity properties between sourced and synthetic CaSO(4) pellets. The addition of K(2)SO(4) appeared beneficial when using synthetic CaSO(4). Synthetic CaSO(4) may be effective when slow degradation and longer elution times are needed.

CLINICAL RELEVANCE

Local delivery of eluted daptomycin can be tailored through material selection and K(2)SO(4) addition.

Road to clinical efficacy: challenges and novel strategies for antimicrobial peptide development

Since the discovery of magainins, cecropins and defensins 30 years ago, antimicrobial peptides (AMPs) have been hailed as a potential solution to the dearth of novel antibiotic development. AMPs have shown robust activity against a wide variety of pathogens, including drug-resistant bacteria. Unlike small-molecule antibiotics, however, AMPs have failed to translate this success to the clinic. Only the polymyxins, gramicidins, nisin and daptomycin are currently approved for medical use; the latter is the only example to have been developed in the last several decades. Nonetheless, researchers continue to isolate, modify and develop novel AMPs for therapeutic applications. Efforts have focused on increasing stability, reducing cytotoxicity, improving antimicrobial activity and incorporating AMPs in novel formulations, including nanoscale particles. As peptide synthesis and recombinant production methodologies improve, and more relevant bioassays become available, it becomes increasingly likely that AMPs will break the regulatory barrier and enter the marketplace as valuable antimicrobial weapons in the next 10 years.

Future challenges and treatment of Staphylococcus aureus bacteremia with emphasis on MRSA

Staphylococcus aureus bacteremia (SAB) is an urgent medical problem due to its growing frequency and its poor associated outcome. As healthcare delivery increasingly involves invasive procedures and implantable devices, the number of patients at risk for SAB and its complications is likely to grow. Compounding this problem is the growing prevalence of methicillin-resistant S. aureus (MRSA) and the dwindling efficacy of vancomycin, long the treatment of choice for this pathogen. Despite the recent availability of several new antibiotics for S. aureus, new strategies for treatment and prevention are required for this serious, common cause of human infection.

Antibiotic Combinations with Daptomycin for Treatment of Staphylococcus aureus Infections

Daptomycin is a lipopeptide antibiotic with a unique mechanism of action on Gram-positive bacteria. It is approved for treatment of skin and soft-tissue infections with Gram-positive bacteria, bacteraemia and right-sided infective endocarditis caused by Staphylococcus aureus. Diminishing susceptibility of S. aureus to daptomycin during treatment of complicated infections and clinical failure have been described. Combinations of daptomycin with other antibiotics including gentamicin, rifampin, beta-lactams, trimethoprim/sulfamethoxazole (TMP-SMX), or clarithromycin present a new approach for therapy. In vitro and animal studies have shown that such combinations may, in some cases, be superior to daptomycin monotherapy. In this paper we focus on the antibiotic combinations for complicated S. aureus infections.

Comparative genome sequencing of an isogenic pair of USA800 clinical methicillin-resistant Staphylococcus aureus isolates obtained before and after daptomycin treatment failure

We describe here a clinical daptomycin treatment failure in a patient with recurrent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia in whom daptomycin was administered after a failed empirical treatment course with vancomycin and piperacillin-tazobactam. We had the opportunity to compare the genome sequences of an isogenic pair of daptomycin-susceptible and -resistant MRSA isolates obtained before and after initiation of daptomycin therapy, respectively. The genotype of both isolates was USA800, ST5, SCCmec type IV, agr type II. There was no increase in cell wall thickness in the daptomycin-resistant strain despite having decreased susceptibility to both vancomycin and daptomycin. By comparing the genome sequences by pyrosequencing, we identified a polymorphism (S337L) in the tenth transmembrane segment of the multiple peptide resistance factor, MprF, encoding lysyl phosphatidylglycerol transferase. This enzyme has been shown previously to promote repulsion of daptomycin at the cell surface by addition of positively charged lysine to phosphatidylglycerol. Also, the hlb open reading frame (ORF) encoding the β-toxin was interrupted by a prophage in the daptomycin-susceptible strain; this phage was missing in the daptomycin-resistant isolate and the hlb ORF was restored. Loss of the phage in the resistant isolate also resulted in loss of the virulence factor genes clpP, scn, and sak. This is the first study to use pyrosequencing to compare the genomes of a daptomycin-susceptible/resistant MRSA isolate pair obtained during failed daptomycin therapy in humans.

Case Report: Persistent Elevation in Creatine Phosphokinase Associated with High-Dose Daptomycin Therapy

Objective

To report a persistent elevation in creatine phosphokinase (CPK) associated with high-dose daptomycin therapy that did not resolve following discontinuation of daptomycin.

Summary

A 34-year-old male with HIV/AIDS and stage IV Burkitt lymphoma was admitted for pain management. The patient's initial hospital course was complicated by left brachial deep vein thrombosis (DVT), Clostridium difficile colitis, and pancytopenia. The patient later developed severe sepsis and septic shock secondary to methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), Candida albicans, and Escherichia coli infection. High-dose daptomycin (12 mg/kg) was initiated to treat MRSA and VRE bacteremia. The patient's baseline CPK was 118 U/L, which increased to 327 U/L following 2 days of therapy. The patient's CPK continued to increase to 1648 U/L on day 10 of daptomycin, thereby necessitating a discontinuation of daptomycin and the initiation of linezolid. Six days after discontinuation of therapy, the patient's CPK remained elevated at 1940 U/L.

Discussion

A Naranjo scale score of 6 was calculated, indicating that daptomycin was the probable cause for the increase in CPK. Although daptomycin is known to cause elevations in CPK, there are limited published data describing this adverse event with high-dose daptomycin therapy.

Conclusion

High-dose daptomycin is becoming more frequently used in clinical practice, so clinicians should monitor for and report any adverse events associated with this dosing strategy.

Management of multidrug-resistant enterococcal infections

Enterococci are organisms with a remarkable ability to adapt to the environment and acquire antibiotic resistance determinants. The evolution of antimicrobial resistance in these organisms poses enormous challenges for clinicians when faced with patients affected with severe infections. The increased prevalence and dissemination of multidrug-resistant Enterococcus faecium worldwide has resulted in a major decrease in therapeutic options because the majority of E. faecium isolates are now resistant to ampicillin and vancomycin, and exhibit high-level resistance to aminoglycosides, which are three of the traditionally most useful anti-enterococcal antibiotics. Newer antibiotics such as linezolid, daptomycin and tigecycline have good in vitro activity against enterococcal isolates, although their clinical use may be limited in certain clinical scenarios as a result of reduced rates of success, possible underdosing for enterococci and low serum levels, respectively, and also by the emergence of resistance. The experimental agent oritavancin may offer some hope for the treatment of vancomycin-resistant enterococci but clinical data are still lacking. Thus, optimal therapies for the treatment of multidrug-resistant enterococcal infections continue to be based on empirical observations and extrapolations from in vitro and animal data. Clinical studies evaluating new strategies, including combination therapies, to treat severe vancomycin-resistant E. faecium infections are urgently needed.

Regulation of mprF by antisense RNA restores daptomycin susceptibility to daptomycin-resistant isolates of Staphylococcus aureus

Mutations in mprF have been shown to result in reduced susceptibility to daptomycin and other cationic antibacterials. An mprF antisense-inducible plasmid was constructed and used to demonstrate that depletion of mprF can reestablish susceptibility to daptomycin. Inducing antisense to mprF also resulted in increased susceptibility to vancomycin and gentamicin but, paradoxically, decreased susceptibility to oxacillin. These results suggest that mprF mutations that reduce susceptibility to cationic antibacterials result in a gain-of-function phenotype.

Determination of daptomycin in human plasma by liquid chromatography-tandem mass spectrometry. Clinical application

BACKGROUND

Daptomycin is a recently developed cyclic lipopeptide antibiotic active against most Gram-positive pathogens including vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus. To optimize treatment efficacy and safety, especially in patients undergoing multiple drug regimens and/or co-morbidities, a specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the quantification of daptomycin in plasma.

METHODS

A C18 column was used for separation, with a mobile phase initially consisting of 0.1% formic acid, water, and acetonitrile (ACN) in a linear gradient from 20% to 70%. After protein precipitation with ACN, the clear upper layer was diluted in water:ACN (50:50, v/v) before injection. Detection was performed using an electrospray ionization technique. MS/MS transitions, monitored in the positive ion mode were m/z 811.1 → m/z 313.1 for daptomycin, and m/z 609.4 → m/z 194.9 for reserpine, used as internal standard.

RESULTS

Elution of daptomycin and reserpine occurred at 4.5 and 3.9 min, respectively. The method was validated over a range of concentrations from 1 mg/L to 120 mg/L. The assay met recommended acceptance criteria: coefficients of variation were <6.3% and <7.4%, and accuracies were between -5.9% and +11.2% and between -3.5% and +3.7%, for intra- and inter-day validations, respectively.

CONCLUSIONS

This method appears well-adapted to routine hospital practice for therapeutic drug monitoring of daptomycin considering its time of analysis, range of concentrations measured, precision and accuracy.