Daptomycin: pharmacology and clinical use

Light-activated molecular machines are fast-acting broad-spectrum antibacterials that target the membrane

The increasing occurrence of antibiotic-resistant bacteria and the dwindling antibiotic research and development pipeline have created a pressing global health crisis. Here, we report the discovery of a distinctive antibacterial therapy that uses visible (405 nanometers) light-activated synthetic molecular machines (MMs) to kill Gram-negative and Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus, in minutes, vastly outpacing conventional antibiotics. MMs also rapidly eliminate persister cells and established bacterial biofilms. The antibacterial mode of action of MMs involves physical disruption of the membrane. In addition, by permeabilizing the membrane, MMs at sublethal doses potentiate the action of conventional antibiotics. Repeated exposure to antibacterial MMs is not accompanied by resistance development. Finally, therapeutic doses of MMs mitigate mortality associated with bacterial infection in an in vivo model of burn wound infection. Visible light-activated MMs represent an unconventional antibacterial mode of action by mechanical disruption at the molecular scale, not existent in nature and to which resistance development is unlikely.

Discovery of Highly Active Derivatives of Daptomycin by Assessing the Effect of Amino Acid Substitutions at Positions 8 and 11 on a Daptomycin Analogue

Daptomycin is an important antibiotic used for treating serious infections caused by Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci. Establishing structure-activity relationships of daptomycin is important for developing new daptomycin-based antibiotics with expanded clinical applications and for tackling the ever-increasing problem of antimicrobial resistance. Toward this end, Dap-K6-E12-W13, an active analogue of daptomycin in which the uncommon amino acids in daptomycin are replaced with their common counterparts, was used as a model system for studying the effect of amino acid variation at positions 8 and 11 on in vitro biological activity against a model organism, Bacillus subtilis, and calcium-dependent insertion into model membranes. None of the new peptides were more active than Dap-K6-E12-W13; however, substitution at positions 8 and/or 11 with cationic residues resulted in little or no loss of activity, and some of these analogues were able to insert into model membranes at lower calcium ion concentrations than the parent peptide. Incorporation of these cationic residues into positions 8 and/or 11 of daptomycin itself yielded some derivatives that exhibited lower minimum inhibitory concentrations than daptomycin against B. subtilis 1046 as well as comparable and sometimes superior activity against clinical isolates of MRSA.

The Chiral Target of Daptomycin Is the 2R,2'S Stereoisomer of Phosphatidylglycerol

Daptomycin (dap) is an important antibiotic that interacts with the bacterial membrane lipid phosphatidylglycerol (PG) in a calcium-dependent manner. The enantiomer of dap (ent-dap) was synthesized and was found to be 85-fold less active than dap against B. subtilis, indicating that dap interacts with a chiral target as part of its mechanism of action. Using liposomes containing enantiopure PG, we demonstrate that the binding of dap to PG, the structural transition that occurs upon dap binding to PG, and the subsequent oligomerization of dap, depends upon the configuration of PG, and that dap prefers the 1,2-diacyl-sn-glycero-3-phospho-1'-sn-glycerol stereoisomer (2R,2'S configuration). Ent-dap has a lower affinity for 2R,2'S liposomes than dap and cannot oligomerize to the same extent as dap, which accounts for why ent-dap is less active than dap. To our knowledge, this is the first example whereby the activity of an antibiotic depends upon the configuration of a lipid head group.

Systematical Characterization of Impurity Profiles in Daptomycin Raw Material by 2-Dimentional HPLC Tandem with MS Detector

Objective:

To systematically characterize the impurity profile in Daptomycin raw material by 2 Dimensional LC/MSn.

Method:

The target impurity was separated by first Dimensional HPLC and enriched by a 500μl loop, then desalted using the on-line second Dimensional HPLC and analyzed by MS detector in positive mode. Their structures were characterized based on the degradation mechanism and mass fragmentation regularity of the cyclic lipopeptide, as well as the molecular thermodynamic calculation.

Results:

A total of 12 impurities were characterized in the raw material, including 6 degradation products; 8 impurities are reported for the first time. The mass fragmentation regularities of 2 β-isomers of Asp residue were summarized.

Conclusion:

The structures of impurities in Daptomycin raw material, especially for β-isomer impurities, could be rapidly identified by on-line 2 Dimensional LC/MSn method together with the molecular thermodynamic calculation.

Comparative Metabologenomics Analysis of Polar Actinomycetes

Biosynthetic and chemical datasets are the two major pillars for microbial drug discovery in the omics era. Despite the advancement of analysis tools and platforms for multi-strain metabolomics and genomics, linking these information sources remains a considerable bottleneck in strain prioritisation and natural product discovery. In this study, molecular networking of the 100 metabolite extracts derived from applying the OSMAC approach to 25 Polar bacterial strains, showed growth media specificity and potential chemical novelty was suggested. Moreover, the metabolite extracts were screened for antibacterial activity and promising selective bioactivity against drug-persistent pathogens such as Klebsiella pneumoniae and Acinetobacter baumannii was observed. Genome sequencing data were combined with metabolomics experiments in the recently developed computational approach, NPLinker, which was used to link BGC and molecular features to prioritise strains for further investigation based on biosynthetic and chemical information. Herein, we putatively identified the known metabolites ectoine and chrloramphenicol which, through NPLinker, were linked to their associated BGCs. The metabologenomics approach followed in this study can potentially be applied to any large microbial datasets for accelerating the discovery of new (bioactive) specialised metabolites.

Necrotizing Soft Tissue Infections: A Focused Review of Pathophysiology, Diagnosis, Operative Management, Antimicrobial Therapy, and Pediatrics

Background: Necrotizing fasciitis is a major health problem throughout the world. The purpose of this review is to assist providers with the care of these patients through a better understanding of the pathophysiology and management options. Methods: This is a collaborative review of the literature between members of the Surgical Infection Society of North America and World Society of Emergency Surgery. Results: Necrotizing fasciitis continues to be difficult to manage with the mainstay being early diagnosis and surgical intervention. Recognition of at-risk populations assists with the initiation of treatment, thereby impacting outcomes. Conclusions: Although there are some additional treatment strategies available, surgical debridement and antimicrobial therapy are central to the successful eradication of the disease process.

Daptomycin to bone and joint infections and prosthesis joint infections: a systematic review

Backgroud

Daptomycin has been used in bone and joint infections (BJI) and prosthesis joint infections (PJI) considering spectrum of activity and biofilm penetration. However, the current experience is based on case reports, case series, cohorts, and international surveys. The aim of this systematic review was to evaluate studies about daptomycin treatment efficacy in BJI/PJI compared to other antibiotic regimens.

Methods

PubMed, LILACS, Scielo and Web of Science databases were searched for articles about daptomycin and treatment of BJI and PJI from inception to March 2018. Inclusion criteria were any published researches that included patients with BJI treated with daptomycin. Diagnosis of BJI was based on clinical, laboratory and radiological findings according to IDSA guidelines.

Results

From 5107 articles, 12 articles were included. Only three studies described the outcomes of patients with BJI treated with daptomycin with comparator regimen (vancomycin, teicoplanin and oxacillin). Studies presented large heterogeneity regarding device related infections, surgical procedures, and daptomycin regimens (varied from 4 mg/kg to 10 mg/kg). A total of 299 patients have been included in all studies (184 infections associated with orthopedic disposal and 115 osteomyelitis/septic arthritis). Two hundred and thirty-three patients were treated with daptomycin. The clinical cure rates on device related and non-device related infections (i.e. osteomyelitis) were 70% and 78%, respectively. Compared to all regimens evaluated, daptomycin group outcomes were non-inferior.

Conclusion

Although a randomized clinical trial is needed, this systematic review tends to support daptomycin usage for bone and joint infections.

Daptomycin

Daptomycin is a cyclic lipopeptide antibiotic used for the treatment of Gram-positive infections including complicated skin and skin structure infections, right-sided infective endocarditis, bacteraemia, meningitis, sepsis and urinary tract infections. Daptomycin has distinct mechanisms of action, disrupting multiple aspects of cell membrane function and inhibiting protein, DNA and RNA synthesis. Although daptomycin resistance in Gram-positive bacteria is uncommon, there are increasing reports of daptomycin resistance in Staphylococcus aureus, Enterococcus faecium and Enterococcus faecalis. Such resistance is seen largely in the context of prolonged treatment courses and infections with high bacterial burdens, but may occur in the absence of prior daptomycin exposure. Furthermore, use of inadequate treatment regimens, irregular drug supply and poor drug quality have also been recognized as other important risk factors for emergence of daptomycin-resistant strains. Antimicrobial susceptibility testing of Gram-positive bacteria, communication between clinicians and laboratories, establishment of internet-based reporting systems, development of better and more rapid diagnostic methods and continuous monitoring of drug resistance are urgent priorities.

Membrane Binding and Oligomerization of the Lipopeptide A54145 Studied by Pyrene Fluorescence

A54145 is a lipopeptide antibiotic related to daptomycin that permeabilizes bacterial cell membranes. Its action requires both calcium and phosphatidylglycerol in the target membrane, and it is accompanied by the formation of membrane-associated oligomers. We here probed the interaction of A54145 with model membranes composed of dimyristoylphosphatidylcholine and dimyristoylphosphatidylglycerol, using the steady-state and time-resolved fluorescence of a pyrene-labeled derivative (Py-A54145). In solution, the labeled peptide was found to exist as a monomer. Its membrane interaction occurred in two stages that could be clearly distinguished by varying the calcium concentration. In the first stage, which was observed between 0.15 and 1 mM calcium, Py-A54145 bound to the membrane, as indicated by a strong increase in pyrene monomer emission. At the same calcium concentration, excimer emission increased also, suggesting that Py-A54145 had oligomerized. A global analysis of the time-resolved pyrene monomer and excimer fluorescence confirmed that Py-A54145 forms oligomers quantitatively and concomitantly with membrane binding. When calcium was raised beyond 1 mM, a distinct second transition was observed that may correspond to a doubling of the number of oligomer subunits. The collective findings confirm and extend our understanding of the action mode of A54145 and daptomycin.

Dose-dependent artificial prolongation of prothrombin time by interaction between daptomycin and test reagents in patients receiving warfarin: a prospective in vivo clinical study

Background

Daptomycin has been reported to cause artificial prolongation of prothrombin time (PT) by interacting with some test reagents of PT. This prolongation was particularly prominent with high concentrations of daptomycin in vitro. However, whether this prolongation is important in clinical settings and the optimal timing to assess PT remain unclear.

Methods

A prospective clinical study was conducted with patients who received daptomycin for confirmed or suspected drug-resistant, gram-positive bacterial infection at a university hospital in Japan. PT at the peak and trough of daptomycin was tested using nine PT reagents. Linear regression analyses were used to examine the difference in daptomycin concentration and the relative change of PT-international normalized ratios (PT-INR).

Results

Thirty-five patients received daptomycin (6 mg/kg). The mean ± standard deviation of the trough and peak concentrations of daptomycin were 13.5 ± 6.3 and 55.1 ± 16.9 μg/mL, respectively. Twelve patients (34%) received warfarin. With five PT reagents, a significant proportion of participants experienced prolongation of PT-INR at the daptomycin peak concentration compared to the PT-INR at the trough, although the mean relative change was less than 10%. None of the participants clinically showed any signs of bleeding. A linear, dose-dependent prolongation of PT was observed for one reagent [unadjusted coefficient β 3.1 × 10⁻³/μg/mL; 95% confidence interval (CI) 2.3 × 10⁻⁵–6.3 × 10⁻³; p = 0.048]. When patients were stratified based on warfarin use, this significant linear relationship was observed in warfarin users for two PT reagents (adjusted coefficient β, 6.4 × 10⁻³/μg/mL; 95% CI 3.5 × 10⁻³–9.3 × 10⁻³; p < 0.001; and adjusted coefficient β, 8.3 × 10⁻³/μg/mL; 95% CI 4.4 × 10⁻³–1.2 × 10⁻²; p < 0.001). In non-warfarin users, this linear relationship was not observed for any PT reagents.

Conclusions

We found that a higher concentration of daptomycin could lead to artificial prolongation of PT-INR by interacting with some PT reagents. This change may not be clinically negligible, especially in warfarin users receiving a high dose of daptomycin. It may be better to measure PT at the trough rather than at the peak daptomycin concentration.

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.

Towards a definition of daptomycin optimal dose: Lessons learned from experimental and clinical data

Daptomycin exhibits excellent antibacterial activity against a wide range of Gram-positive bacteria. The on-label standard daily doses for daptomycin are 4 mg/kg for skin infections and 6 mg/kg for bacteraemia or right-sided endocarditis. Daptomycin bactericidal activity is predominantly concentration-dependent and by considering the values of pharmacokinetic targets established by several authors as well as the peak and trough concentrations of daptomycin obtained at various daily dosages, it appears that these targets can easily be reached with a dose of 6 mg/kg but only for a minimum inhibitory concentration (MIC) at 0.1 mg/L, and that for increasing MICs (e.g. 0.5 mg/L or 1 mg/L) these targets may only be attained with higher dosages (i.e. ≥10 mg/kg). High-dose (HD) daptomycin therapy has also been proven to be effective for reducing the risk of selection of daptomycin-resistant strains. Given the concentration-dependent bactericidal activity of daptomycin, the absence of a dose-toxicity relationship and the need to prevent the selection of resistant strains, we propose to consider for staphylococcal (i) skin and soft-tissue infections, daily doses of daptomycin of 6 mg/kg (new standard dose) and (ii) endocarditis or bacteraemia including those associated with intravascular catheter and implant-related infections, ≥10 mg/kg (HD) when the MIC is unknown or >0.25 mg/L, and 6-10 mg/kg (intermediate doses) when the MIC is ≤0.25 mg/L. For severe and deep-seated enterococcal infections, we propose high (≥10 mg/kg) daily doses of daptomycin in combination with another active agent, especially a β-lactam.

Daptomycin versus vancomycin for osteoarticular infections due to methicillin-resistant Staphylococcus aureus (MRSA): a nested case-control study

Vancomycin is the standard antibiotic for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. While daptomycin is approved for MRSA bacteremia, its effectiveness in osteoarticular infections (OAIs) has not been established. A 1:2 nested case-control study of adult patients with MRSA OAIs admitted to an academic center from 2005 to 2010 was carried out. Clinical outcomes and drug toxicity in patients treated with daptomycin versus vancomycin were compared. Twenty patients with MRSA OAIs treated with daptomycin were matched to 40 patients treated with vancomycin. The median age of the patients was 52 years (range, 25-90), and 40 (67%) were male. Most patients had osteomyelitis (82%), predominantly from a contiguous source (87%). Forty percent were diabetics. Diabetic patients were more likely to receive vancomycin than daptomycin [20 (50%) vs. 4 (20%); p = 0.03]. Vancomycin was more often combined with antibiotics other than daptomycin [22 (55%) vs. 5 (25%); p = 0.03]. The median total antibiotic treatment duration was 48 (daptomycin) vs. 46 days (vancomycin) (p = 0.5). Ninety percent of daptomycin-treated patients had previously received vancomycin for a median of 14.5 days (range, 2-36). Clinical success rates were similar between daptomycin and vancomycin at 3 months [15 (75%) vs. 27 (68%); p = 0.8] and 6 months [14 (70%) vs. 23 (58%); p = 0.5], even after propensity score-based adjustment for antibiotic assignment. The frequency of adverse events was similar between treatment groups [1 (5%) vs. 7 (18%); p = 0.2]. Daptomycin and vancomycin achieved similar rates of clinical success and drug tolerability. Daptomycin is a reasonable alternative for treating MRSA OAIs, particularly in patients where therapy with vancomycin has not been well tolerated.

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.

Eosinophilic pneumonia in patients treated with daptomycin: review of the literature and US FDA adverse event reporting system reports

BACKGROUND

Eosinophilic pneumonia (EP) has been noted in association with daptomycin use. The product labelling was recently updated to include EP in the Warnings and Precautions and Post-Marketing Experience sections.

OBJECTIVE

The objective of this study was to analyse adverse event (AE) reports submitted to the US FDA as well as published cases to characterize the clinical features and course of EP in daptomycin-treated patients.

METHODS

We searched for EP cases associated with daptomycin administration in the FDA Adverse Event Reporting System (AERS) submitted from 2004 to 2010, and the published literature. Cases were defined as definite, probable, possible and unlikely in terms of the diagnosis of EP and the potential association with daptomycin exposure. Definite cases had concurrent exposure to daptomycin, fever, dyspnoea with increased oxygen requirement or required mechanical ventilation, new infiltrates on chest imaging, bronchoalveolar lavage with >25% eosinophils and clinical improvement following daptomycin withdrawal. Additionally, we assessed inpatient daptomycin utilization.

RESULTS

We identified 7 definite, 13 probable, 38 possible cases of daptomycin-induced EP, and 23 unlikely cases. The seven definite EP cases had resolution after daptomycin was stopped, including two with EP recurrence following daptomycin rechallenge. Regarding the definite cases: (i) ages ranged from 60 to 87 years; (ii) dosing ranged from 4.4 to 8.0 mg/kg/day; and (iii) EP developed 10 days to 4 weeks after starting daptomycin. There was a gradual increase in the number of patients with an inpatient hospital discharge billing for daptomycin from the year 2004 to 2010.

CONCLUSIONS

We report 7 definite, 13 probable and 38 possible EP cases associated with daptomycin administration. As AERS is based on voluntary reporting, the incidence of EP cannot be assessed. Healthcare providers should have heightened awareness of this serious AE associated with daptomycin use.

Daptomycin compared to vancomycin for the treatment of osteomyelitis: a single-center, retrospective cohort study

BACKGROUND

Osteomyelitis (OM) is a serious infection with high rates of recurrence. Vancomycin has been used for decades in the treatment of OM, but, despite adequate dosing, 30% to 50% of patients experience infection recurrence within 12 months. Daptomycin, a novel lipopetide antibiotic, is also active against resistant gram-positive organisms, but there is little published about its efficacy and tolerability in the treatment of OM.

OBJECTIVE

Our aim was to compare the recurrence rates of OM in patients treated with daptomycin or vancomycin.

METHODS

A retrospective cohort study of all patients at a VA Medical Center between January 1, 2003, and July 31, 2009, who received daptomycin for the treatment of OM was undertaken. Patients with a diagnosis of OM who received at least 2 weeks of daptomycin and had at least 1 follow-up visit within 6 months after completion of therapy were included. Each patient was matched with 2 controls treated with at least 2 weeks of vancomycin for OM. Matching criteria included previous OM, diabetes, peripheral vascular disease, hardware involvement, and surgical therapy. Patients were excluded from the evaluation if they received <14 days of therapy, had no follow-up in the 6 months after therapy was discontinued, had an absolute neutrophil count <500 cells/mm(3), or were receiving vancomycin and daptomycin concurrently. The primary outcome was recurrence of infection within 6 months after the discontinuation of therapy. Secondary outcomes included mean change in creatine phosphokinase (CPK), incident thrombocytopenia, and mean doses of antibiotics. The χ(2) test was used to compare rates of recurrence between groups.

RESULTS

Seventeen patients received at least 2 weeks of daptomycin for the treatment of OM and were matched to 34 vancomycin controls. Twenty-nine percent of patients receiving daptomycin had a recurrence of infection compared with 61.7% in the vancomycin group (P = 0.029). The mean change in CPK for the daptomycin group was +28.8 U/L. No thrombocytopenia developed in any patients receiving daptomycin compared with 2 (5.9%) patients in the vancomycin group.

CONCLUSIONS

In a limited number of cases, significantly fewer patients treated with daptomycin for OM had a recurrence of their infection. Daptomycin may be a tolerable and effective alternative to vancomycin for the treatment of OM.

Daptomycin versus vancomycin in a methicillin-resistant Staphylococcus aureus endophthalmitis rabbit model: bactericidal effect, safety, and ocular pharmacokinetics

Staphylococcus aureus is a frequent cause of acute endophthalmitis, and infection with this virulent bacterium is often associated with a poor visual outcome. In this study, we investigated the bactericidal efficacy and the safety of intravitreal daptomycin (DAP), a lipopeptide antibiotic with broad-spectrum activity against Gram-positive bacteria, compared with those of intravitreal vancomycin (VAN) in a methicillin-resistant S. aureus endophthalmitis rabbit model. The pharmacokinetics and pharmacodynamics of daptomycin in the infected eyes were also studied. Rabbits were randomly divided into three treatment groups (n = 8) and one untreated group (n = 4), to compare the effect of single intravitreal injections of 0.2 mg and 1 mg of daptomycin (DAP 0.2 and DAP 1 groups, respectively) with that of 1 mg of intravitreal vancomycin (VAN 1 group). Vitreal aspirates were regularly collected and grading of ocular inflammation was regularly performed until euthanasia on day 7. In the DAP 0.2 group, 62.5% of the eyes were sterilized and the mean bacterial count presented a reduction of 1 log unit. In the DAP 1 and VAN 1 groups, the infection was eradicated (100% and 87.5% of eyes sterilized, respectively), with a 4-log-unit reduction of the mean bacterial count. The bactericidal efficacy in the DAP 1 group was not inferior to that in the VAN 1 group and was superior to that of the other regimens in limiting the ocular inflammation and preserving the architecture of the ocular structures (P < 0.05). The elimination half-life (t(1/2β)) of daptomycin was independent of the administered dose (38.8 ± 16.5 h and 40.9 ± 6.7 h, respectively, for the DAP 0.2 and DAP 1 groups) and was significantly longer than the t(1/2β) of vancomycin (20.5 ± 2.0 h for the VAN 1 group) (P < 0.05). This antibiotic could therefore be considered for the treatment of intraocular infections caused by Gram-positive bacteria.

Serum levels of daptomycin in pediatric patients

BACKGROUND

Limited data are available on the pharmacokinetics and optimal dosage of daptomycin, a lipopeptide compound possessing activity against Gram-positive bacteria, in the pediatric population, particularly in neonates and infants. We determined serum levels of daptomycin in hospitalized pediatric patients treated with various dosages of this agent.

METHODS

Blood samples were obtained from pediatric patients of all ages with normal renal function who had received daptomycin between May 2009 and December 2010. Serum levels prior ("trough") and 30 min after end of the infusion ("peak") were determined using an ultra-performance liquid chromatography-UV detection method.

RESULTS

A total of four daptomycin dosages and four patients were studied. Three patients were infants (gestational age: 29-38 weeks, age at sampling 26-65 days) and the fourth was a 7-year-old boy. A dosage of 6 mg/kg/12 h of daptomycin to the infants resulted in trough concentrations of <4-8.4 mg/l and peak concentrations of 10.9-17.7 mg/l. Comparable levels were observed after one of the infants received a dosage of 11 mg/kg/12 h, while a further dosage increase to 15 mg/kg/12 h yielded peak concentrations of 35.5 mg/l. The 7-year-old child received a daptomycin dosage of 12 mg/kg once daily; trough and peak levels were 4.2 and 103.4 mg/l, respectively.

CONCLUSIONS

A dosage of daptomycin 6 mg/kg/12 h in small infants results in lower peak and similar trough concentrations compared with a dosage of 4 mg/kg/day administered to adults. This results suggests that daptomycin dosages of more than 6 mg/kg/12 h may be needed for this pediatric age group to achieve a similar drug exposure as adults.

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.

Emerging drugs for complicated skin and skin-structure infections

IMPORTANCE OF THE FILED: With the worldwide surge of MRSA, skin and skin-structure infection (SSTI) treatment has become a challenge for physicians. Cultures and antibiotic susceptibility tests for SSTIs are the rule due to the implication in morbidity and mortality rates associated with MRSA infections. The need for new antibiotics is evident and the effort to decrease antibiotic resistance is a world priority.

AREAS COVERED IN THIS REVIEW

This manuscript accesses the actual treatments and the developing of antibiotics for MRSA SSTIs.

WHAT THE READER WILL GAIN

This is a review of the data on the available and emerging treatments for MRSA SSTIs.

TAKE HOME MESSAGE

There is an unmet medical need for new antibiotics in the new millennium. As physicians, we must assure all appropriate procedures are completed in order to reduce the bacterial resistance, especially for MRSA.