Ceftaroline fosamil doses and breakpoints for Staphylococcus aureus in complicated skin and soft tissue infections

Integrative model-based comparison of target site-specific antimicrobial effects: A case study with ceftaroline and lefamulin

OBJECTIVE

Predictions of antimicrobial effects typically rely on plasma-based pharmacokinetic-pharmacodynamic (PK-PD) targets, ignoring target-site concentrations and potential differences in tissue penetration between antibiotics. In this study, we applied PK-PD modelling to compare target site-specific effects of antibiotics by integrating clinical microdialysis data, in vitro time-kill curves, and antimicrobial susceptibility distributions. As a case study, we compared the effect of lefamulin and ceftaroline against methicillin-resistant Staphylococcus aureus (MRSA) at soft-tissue concentrations.

METHODS

A population PK model describing lefamulin concentrations in plasma, subcutaneous adipose and muscle tissue was developed. For ceftaroline, a similar previously reported PK model was adopted. In vitro time-kill experiments were performed with six MRSA isolates and a PD model was developed to describe bacterial growth and antimicrobial effects. The clinical PK and in vitro PD models were linked to compare antimicrobial effects of ceftaroline and lefamulin at the different target sites.

RESULTS

Considering minimum inhibitory concentration (MIC) distributions and standard dosages, ceftaroline showed superior anti-MRSA effects compared to lefamulin both at plasma and soft-tissue concentrations. Looking at the individual antibiotics, lefamulin effects were highest at soft-tissue concentrations, while ceftaroline effects were highest at plasma concentrations, emphasising the importance of considering target-site PK-PD in antibiotic treatment optimisation.

CONCLUSION

Given standard dosing regimens, ceftaroline appeared more effective than lefamulin against MRSA at soft-tissue concentrations. The PK-PD model-based approach applied in this study could be used to compare or explore the potential of antibiotics for specific indications or in populations with unique target-site PK.

Impact of Key Components of Intensified Ceftaroline Dosing on Pharmacokinetic/Pharmacodynamic Target Attainment

BACKGROUND AND OBJECTIVE

Ceftaroline fosamil is a β-lactam antibiotic approved as a 600 mg twice daily dose (≤1 h infusion, 'standard dosing') or a 600 mg thrice daily dose (2 h infusion) to treat complicated skin and soft tissue infections caused by Staphylococcus aureus (minimum inhibitory concentration [MIC] 2-4 mg/L). We sought to systematically evaluate the relative impact of the three key components of the intensified dosing regimen (i.e. shortened dosing interval, prolonged infusion duration and increased total daily dose [TDD]) on the pharmacokinetic/pharmacodynamic (PK/PD) target attainment given different grades of bacterial susceptibility.

METHODS

A population PK model was developed using data from 12 healthy volunteers (EudraCT-2012-005134-11) receiving standard or intensified dosing. PK/PD target attainment (ƒT>MIC = 35% and 100%) after 24 h was compared following systematically varied combinations of the (1) dosing interval (every 12 h [q12h]→ every 8 h [q8h]); (2) infusion duration (1 h→2 h); and (3) individual and total daily dose (400→900 mg, i.e. TDD 1200→1800 mg), as well as for varying susceptibility of S. aureus (MIC 0.032-8 mg/L).

RESULTS

A two-compartment model with linear elimination adequately described ceftaroline concentrations (n = 274). The relevance of the dosing components dosing interval/infusion duration/TDD for ƒT>MIC systematically changed with pathogen susceptibility. For susceptible pathogens with MIC ≤1 mg/L, shortened dosing intervals appeared as the main driver of the improved target attainment associated with the intensified dosing regimen, followed by increased TDD and infusion duration. For less susceptible pathogens, the advantage of q8h dosing and 2 h infusions declined, and increased TDD improved ƒT>MIC the most.

CONCLUSION

The analysis calls to mind consideration of dose increases when prolonging the infusion duration in the case of low bacterial susceptibility.

Efficacy of ceftaroline and rifampin, alone or combined, in a rat model of methicillin-resistant Staphylococcus epidermidis osteomyelitis without implant

IMPORTANCE

Methicillin-resistant Staphylococcus epidermidis (MRSE) contributes to a high percentage of orthopedic infections, and their treatment represents a huge challenge. The present study aimed to evaluate the efficacy of ceftaroline alone or combined with rifampin in a rat MRSE osteomyelitis model and the bone penetration of ceftaroline. A ceftaroline monotherapy showed a significant bacterial reduction in infected bones after a 7-day period of treatment. The combination ceftaroline plus rifampin leveraged rifampin's bactericidal activity, shortening the duration of positive culture in infected animals. These results suggest that ceftaroline and rifampin combination therapy could represent a valuable therapeutic option for human MRSE osteomyelitis and deserves further preclinical and clinical evaluation.

Physiologically based pharmacokinetic modelling to inform combination dosing regimens of ceftaroline and daptomycin in special populations

AIMS

The combination of daptomycin and ceftaroline used as salvage therapy is associated with higher survival and decreased clinical failure in complicated methicillin-resistant Staphylococcus aureus (MRSA) infections that are resistant to standard MRSA treatment. This study aimed to evaluate dosing regimens for coadministration of daptomycin and ceftaroline in special populations including paediatrics, renally impaired (RI), obese and geriatrics that generate sufficient coverage against daptomycin-resistant MRSA.

METHODS

Physiologically based pharmacokinetic models were developed from pharmacokinetic studies of healthy adults, geriatric, paediatric, obese and RI patients. The predicted profiles were used to evaluate joint probability of target attainment (PTA), as well as tissue-to-plasma ratios.

RESULTS

The adult dosing regimens of 6 mg/kg every (q)24h or q48h daptomycin and 300-600 mg q12h ceftaroline fosamil by RI categories achieved ≥90% joint PTA when the minimum inhibitory concentrations in the combination are at or below 1 and 4 μg/mL against MRSA. In paediatrics, wherein there is no recommended daptomycin dosing regimen for S. aureus bacteraemia, ≥90% joint PTA is achieved when the minimum inhibitory concentrations in the combination are up to 0.5 and 2 μg/mL for standard paediatric dosing regimens of 7 mg/kg q24h daptomycin and 12 mg/kg q8h ceftaroline fosamil. Model predicted tissue-to-plasma ratios of 0.3 and 0.7 in the skin and lung, respectively, for ceftaroline and 0.8 in the skin for daptomycin.

CONCLUSION

Our work illustrates how physiologically based pharmacokinetic modelling can inform appropriate dosing of adult and paediatric patients and thereby enable prediction of target attainment in the patients during multitherapies.

Contemporary pharmacologic treatments of MRSA for hospitalized adults: rationale for vancomycin versus non-vancomycin therapies as first line agents

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) remains an important pathogen in the hospital setting and causes significant morbidity and mortality each year. Since the initial discovery over 60 years ago, vancomycin has remained a first-line treatment for many different types of MRSA infections. However, significant concerns related to target attainment and nephrotoxicity have spurred efforts to develop more effective agents in the last two decades.

AREAS COVERED

Newer anti-MRSA antibiotics that have been approved since 2000 include linezolid, daptomycin, and ceftaroline. As clinical evidence has accumulated, these newer agents have become more frequently used, and some are now recommended as co-first-line options (along with vancomycin) in clinical practice guidelines. For this review, a scoping review of the literature was conducted to support our findings and recommendations.

EXPERT OPINION

Vancomycin remains an important standard of care for MRSA infections but is limited with respect to nephrotoxicity and rapid target attainment. Newer agents such as linezolid, daptomycin, and ceftaroline have specific indications for treating different types of MRSA infections; however, newer agents also have unique attributes which require consideration during therapy.

Clinical evidence supporting ceftaroline fosamil and ceftobiprole for complicated skin and soft tissue infections

PURPOSE OF REVIEW

Ceftaroline and ceftobiprole are advanced generation cephalosporins with activity against methicillin-resistant Staphylococcus aureus (MRSA). This review summarizes their clinical efficacy for complicated skin and soft tissue infections (cSSTIs).

RECENT FINDINGS

Both these agents retain excellent in vitro activity against both MRSA and Gram-negative isolates from patients with CSSTIs. Both these agents are registered for the management of cSSTIs based on the results of large scale phase III noninferiority trials. Ceftaroline and ceftobiprole are noninferior to the combination of vancomycin and aztreonam as this was assessed by their clinical cure rate at the test-of-cure visits. Furthermore, ceftobiprole is noninferior to comparators for the achievement of early clinical success at 72 h. Ceftaroline achieves 81% clinical cure against diabetic foot infections.

SUMMARY

Ceftaroline and ceftobiprole can be used as monotherapy for the treatment of cSSTIs.

A novel sprayable thermosensitive hydrogel coupled with zinc modified metformin promotes the healing of skin wound

A novel sprayable adhesive is established (ZnMet-PF127) by the combination of a thermosensitive hydrogel (Pluronic F127, PF127) and a coordination complex of zinc and metformin (ZnMet). Here we demonstrate that ZnMet-PF127 potently promotes the healing of traumatic skin defect and burn skin injury by promoting cell proliferation, angiogenesis, collagen formation. Furthermore, we find that ZnMet could inhibit reactive oxygen species (ROS) production through activation of autophagy, thereby protecting cell from oxidative stress induced damage and promoting healing of skin wound. ZnMet complex exerts better effects on promoting skin wound healing than ZnCl₂ or metformin alone. ZnMet complex also displays excellent antibacterial activity against Staphylococcus aureus or Escherichia coli, which could reduce the incidence of skin wound infections. Collectively, we demonstrate that sprayable PF127 could be used as a new drug delivery system for treatment of skin injury. The advantages of this sprayable system are obvious: (1) It is convenient to use; (2) The hydrogel can cover irregular skin defect sites evenly in a liquid state. In combination with this system, we establish a novel sprayable adhesive (ZnMet-PF127) and demonstrate that it is a potential clinical treatment for traumatic skin defect and burn skin injury.

Population Pharmacokinetic Modeling and Probability of Target Attainment of Ceftaroline in Brain and Soft Tissues

Ceftaroline, approved to treat skin infections and pneumonia due to methicillin-resistant Staphylococcus aureus (MRSA), has been considered for the treatment of central nervous system (CNS) infections. A population pharmacokinetic (popPK) model was developed to describe ceftaroline soft tissue and cerebrospinal fluid (CSF) distributions and investigate the probability of target attainment (PTA) of the percentage of the dosing interval that the unbound drug concentration exceeded the MIC (%fT_>MIC) to treat MRSA infections. Healthy subjects' plasma and microdialysate concentrations from muscle and subcutaneous tissue following 600 mg every 12 h (q12h) and q8h and neurosurgical patients' plasma and CSF concentrations following single 600-mg dosing were used. Plasma concentrations were described by a two-compartment model, and tissue concentrations were incorporated as three independent compartments linked to the central compartment by bidirectional transport (clearance in [CL_in] and CL_out). Apparent volumes were fixed to physiological interstitial values. Healthy status and body weight were identified as covariates for the volume of the central compartment, and creatinine clearance was identified for clearance. The CSF glucose concentration (GLUC) was inversely correlated with CL_in,CSF. Simulations showed a PTA of >90% in plasma and soft tissues for both regimens assuming an MIC of 1 mg/L and a %fT_>MIC of 28.8%. Using the same target, patients with inflamed meninges (0.5 < GLUC ≤ 2 mmol/L) would reach PTAs of 99.8% and 97.2% for 600 mg q8h and q12h, respectively. For brain infection with mild inflammation (2 < GLUC ≤ 3.5 mmol/L), the PTAs would be reduced to 34.3% and 9.1%, respectively. Ceftaroline's penetration enhanced by meningeal inflammation suggests that the drug could be a candidate to treat MRSA CNS infections.

Population pharmacokinetic/pharmacodynamic study suggests continuous infusion of ceftaroline daily dose in ventilated critical care patients with early-onset pneumonia and augmented renal clearance

OBJECTIVES

Ceftaroline could be suitable to treat early-onset ventilator-associated pneumonia (VAP) because of its antibacterial spectrum. However, augmented renal clearance (ARC) is frequent in ICU patients and may affect ceftaroline pharmacokinetics and efficacy. The objective of the study was to explore the impact of ARC on ceftaroline pharmacokinetics and evaluate whether the currently recommended dosing regimen (600 mg every 12 h) is appropriate to treat VAP in ICU patients.

METHODS

A population pharmacokinetic model was developed using pharmacokinetic data from 18 patients with measured creatinine clearance (CLCR) ranging between 83 and 309 mL/min. Monte Carlo simulations were conducted to determine the PTA and the cumulative fraction of response (CFR) against Streptococcus pneumoniae and MRSA for five dosing regimens. Study registered at ClinicalTrials.gov (NCT03025841).

RESULTS

Ceftaroline clearance increased non-linearly with CLCR, with lower concentrations and lower probability of reaching pharmacokinetic/pharmacodynamic targets when CLCR increases. For the currently recommended dosing regimen, the probability of having unbound ceftaroline concentrations above the MIC over the entire dose range is greater than 90% for MICs below 0.125 mg/L. Considering the distribution of MICs, this regimen would not be effective against MRSA infections (CFR between 21% and 67% depending on CLCR), but would be effective against S. pneumoniae infections (CFR >86%).

CONCLUSIONS

The recommended dosing regimen of ceftaroline seems sufficient for covering S. pneumoniae in ICU patients with ARC, but not for MRSA. Among the dosing regimens tested it appears that a constant infusion (50 mg/h) after a loading dose of 600 mg could be more appropriate for MRSA infections.

Efficacy and Safety of Ceftaroline Fosamil in Hospitalized Patients with Community-Acquired Pneumonia in China: Subset Analysis of an International Phase 3 Randomized Controlled Trial

Background

Methods

Results

Conclusion

Trial Registration

Efficacy and appropriateness of novel antibiotics in response to antimicrobial-resistant Gram-negative bacteria in patients with sepsis in the ICU

INTRODUCTION

There is an ever-increasing range of antibiotic-resistant pathogens that have led to higher community-acquired infections, and substantial mortality rates in critically ill patients.

AREAS COVERED

We have critically appraised available evidence through a structured literature review, investigating effective empiric antibiotic administration and appropriateness on outcomes of critically ill patients with an increased risk of developing resistant pathogens. The use of new antibiotics should be determined based on relevant knowledge of their spectrum and properties to provide effective mode of action for critically ill patients.

EXPERT OPINION

Restricting severely ill patients access to new broad-spectrum empirical drugs is not the answer. Rather there should be a focus on identifying host response to infection to differentiate between colonization or contamination and true infection, and the sensitivity to antibiotics used in the intensive care unit (ICU).

Management relies on adequate antibiotic administration, the ability to monitor response, and facilitate the cessation of antibiotic treatment. The major determinant of patient success in a patient with a severe infection is the 'right' antibiotic or complementary course of treatment. As an overarching criterion, the following 3 appropriate "Ds" should be considered: Dosing, Duration and De-escalation to empirically assess the right antibiotic optimal antimicrobial selection.

Ceftaroline Fosamil for Treatment of Pediatric Complicated Skin and Soft Tissue Infections and Community-Acquired Pneumonia

Community-acquired pneumonia (CAP)/community-acquired bacterial pneumonia (CABP) and complicated skin and soft tissue infection (cSSTI)/acute bacterial skin and skin structure infection (ABSSSI) represent major causes of morbidity and mortality in children. β-Lactams are the cornerstone of antibiotic treatment for many serious bacterial infections in children; however, most of these agents have no activity against methicillin-resistant Staphylococcus aureus (MRSA). Ceftaroline fosamil, a β-lactam with broad-spectrum in vitro activity against Gram-positive pathogens (including MRSA and multidrug-resistant Streptococcus pneumoniae) and common Gram-negative organisms, is approved in the European Union and the United States for children with CAP/CABP or cSSTI/ABSSSI. Ceftaroline fosamil has completed a pediatric investigation plan including safety, efficacy, and pharmacokinetic evaluations in patients with ages ranging from birth to 17 years. It has demonstrated similar clinical and microbiological efficacy to best available existing treatments in phase III-IV trials in patients aged ≥ 2 months to < 18 years with CABP or ABSSSI, with a safety profile consistent with the cephalosporin class. It is also approved in the European Union for neonates with CAP or cSSTI, and in the US for neonates with ABSSSI. Ceftaroline fosamil dosing for children (including renal function adjustments) is supported by pharmacokinetic/pharmacodynamic modeling and simulations in appropriate age groups, and includes the option of 5- to 60-min intravenous infusions for standard doses, and a high dose for cSSTI patients with MRSA isolates, with a ceftaroline minimum inhibitory concentration of 2-4 mg/L. Considered together, these data suggest ceftaroline fosamil may be beneficial in the management of CAP/CABP and cSSTI/ABSSSI in children.

Plasma and Lung Tissue Pharmacokinetics of Ceftaroline Fosamil in Patients Undergoing Cardiac Surgery with Cardiopulmonary Bypass: an In Vivo Microdialysis Study

Ceftaroline fosamil, a fifth-generation cephalosporin antibiotic with activity against methicillin-resistant Staphylococcus aureus (MRSA), is currently approved for the treatment of pneumonia and complicated skin and soft tissue infections. However, pharmacokinetics data on free lung tissue concentrations in critical patient populations are lacking. The aim of this study was to evaluate the pharmacokinetics of the high-dose regimen of ceftaroline in plasma and lung tissue in cardiac surgery patients during intermittent and continuous administration. Nine patients undergoing elective cardiac surgery on cardiopulmonary bypass were included in this study and randomly assigned to intermittent or continuous administration. Eighteen hundred milligrams of ceftaroline fosamil was administered intravenously as either 600 mg over 2 h every 8 h (q8h) (intermittent group) or 600 mg over 2 h (loading dose) plus 1,200 mg over 22 h (continuous group). Interstitial lung tissue concentrations were measured by in vivo microdialysis. Relevant pharmacokinetics parameters were calculated for each group. Plasma exposure levels during intermittent and continuous administration were comparable to those of previously published studies and did not differ significantly between the two groups. In vivo microdialysis demonstrated reliable and adequate penetration of ceftaroline into lung tissue during intermittent and continuous administration. The steady-state area under the concentration-time curve from 0 to 8 h (AUCss 0-8) and the ratio of AUCSS 0-8 in lung tissue and AUC in plasma (AUClung/plasma) were descriptively higher in the continuous group. Continuous administration of ceftaroline fosamil achieved a significantly higher proportion of time for which the free drug concentration remained above 4 times the minimal inhibitory concentration (MIC) during the dosing interval (% fT>4xMIC) than intermittent administration for pathogens with a MIC of 1 mg/liter. Ceftaroline showed adequate penetration into interstitial lung tissue of critically ill patients undergoing major cardiothoracic surgery, supporting its use for pneumonia caused by susceptible pathogens.

The use of extrapolation based on modeling and simulation to support high-dose regimens of ceftaroline fosamil in pediatric patients with complicated skin and soft-tissue infections

A model-informed drug development approach was used to select ceftaroline fosamil high-dose regimens for pediatric patients with complicated skin and soft-tissue infections caused by Staphylococcus aureus with a ceftaroline minimum inhibitory concentration (MIC) of 2 or 4 mg/L. Steady-state ceftaroline concentrations were simulated using a population pharmacokinetics (PK) model for ceftaroline fosamil and ceftaroline including data from 304 pediatric subjects and 944 adults. Probability of target attainment (PTA) for various simulated pediatric high-dose regimens and renal function categories were calculated based on patients achieving 35% fT>MIC (S. aureus PK/pharmacodynamic target for 2-log10 bacterial killing). For extrapolation of efficacy, simulated exposures and PTA were compared to adults with normal renal function receiving high-dose ceftaroline fosamil (600 mg 2-h infusions every 8 h). For safety, predicted ceftaroline exposures were compared with observed pediatric and adult data. Predicted ceftaroline exposures for the approved pediatric high-dose regimens (12, 10, or 8 mg/kg by 2-h infusions every 8 h for patients aged >2 to <18 years with normal/mild, moderate, or severe renal impairment, respectively; 10 mg/kg by 2-h infusions every 8 h for patients aged ≥2 months to <2 years with normal renal function/mild impairment) were well matched to adults with normal renal function. Median predicted maximum concentration at steady state (Cmax,ss ) and area under the plasma concentration-time curve over 24 h at steady state pediatric to adult ratios were 0.907-1.33 and 0.940-1.41, respectively. PTAs (>99% and ≥81% for MICs of 2 and 4 mg/L, respectively) matched or exceeded the adult predictions. Simulated Cmax,ss values were below the maximum observed data in other indications, including a high-dose pediatric pneumonia trial, which reported no adverse events related to high exposure.

Pharmacokinetic and Pharmacodynamic Target Attainment in Adult and Pediatric Patients Following Administration of Ceftaroline Fosamil as a 5-Minute Infusion

The key pharmacokinetic/pharmacodynamic (PK/PD) efficacy index for β-lactam antibiotics is the percentage of time that free drug concentrations exceed the minimum inhibitory concentration (MIC) of bacteria during each dosing interval (fT>MIC). Ceftaroline fosamil, the prodrug of the β-lactam ceftaroline, was initially approved for administration as 60-minute intravenous (IV) infusions. Population PK analyses comparing exposure and PK/PD target attainment for 5-minute and 60-minute IV infusions, described here, have supported ceftaroline fosamil labeling updates to include variable infusion durations of 5 to 60 minutes in adults and children aged ≥2 months. A 2-compartment disposition PK model for ceftaroline fosamil and ceftaroline was used to predict steady-state ceftaroline exposures (maximum plasma concentrations [Cmax,ss ] and area under the plasma concentration-time curve over 24 hours [AUCss,0-24 ]) and probability of target attainment in simulated adult and pediatric patients with various degrees of renal function receiving standard doses of ceftaroline fosamil as 5-minute or 60-minute IV infusions. Across age groups and renal function categories, median ceftaroline AUCss,0-24 values were similar for 5-minute and 60-minute infusions, whereas Cmax,ss was up to 42% higher for 5-minute infusions. Both infusion durations achieved >99% probability of target attainment based on PK/PD targets for Staphylococcus aureus (35% fT>MIC) and Streptococcus pneumoniae (44% fT>MIC) at European Committee on Antimicrobial Susceptibility Testing/Clinical and Laboratory Standards Institute MIC breakpoints (1 mg/L and 0.25/0.5 mg/L, respectively). These findings support administration of standard ceftaroline fosamil doses over 5 to 60 minutes for adults and children aged ≥2 months, providing added flexibility to clinicians and patients.

Comparing probability of target attainment against Staphylococcus aureus for ceftaroline fosamil, vancomycin, daptomycin, linezolid, and ceftriaxone in complicated skin and soft tissue infection using pharmacokinetic/pharmacodynamic models

For recently licensed antibiotics, such as the cephalosporin ceftaroline fosamil, probability of target attainment (PTA) curves, showing the percentage of patients reaching a predefined pharmacokinetic (PK)/pharmacodynamic (PD) target at different bacterial minimum inhibitory concentrations (MICs), have been used to support and justify dose recommendations across patient populations. However, information on PTA for older antibiotics is limited. A retrospective analysis was conducted to construct PTA curves for 4 antibiotics against Staphylococcus aureus in patients with complicated skin and soft tissue infections (cSSTIs). PK models for vancomycin, linezolid, daptomycin, and ceftriaxone were selected from the literature based on large numbers of subjects with covariates representative of patients in Europe and/or the United States. An existing model was available for ceftaroline fosamil. Standard and high-dosage regimens were used to compare the PTA of each antibiotic at MIC values 0.03 to 64 mg/L for a simulated set of patients with cSSTI caused by S. aureus. These were compared to proportions of S. aureus isolates at each MIC from global surveillance data. Ceftaroline achieved PTAs >99.9% for bacteriostatic and bactericidal targets at the MIC90 (1 mg/L), whereas the comparators failed to achieve PTAs >90%, at bacteriostatic or bactericidal targets, even when clinical doses were increased beyond those recommended. PTA analysis can be used to compare different drugs with the same simulated patient dataset, subject to availability of an appropriate PK model and robust exposure targets. This analysis shows that some antibiotics commonly used to treat cSSTIs may fail to reach high PTAs relative to contemporary MIC90 estimates.

Combination ceftaroline and daptomycin salvage therapy for complicated methicillin-resistant Staphylococcus aureus bacteraemia compared with standard of care

Complicated methicillin-resistant Staphylococcus aureus bloodstream infections (MRSA-BSIs), particularly those with delayed culture clearance, are associated with high mortality. Combination therapy with daptomycin and ceftaroline (DAP+CPT) represents a novel therapeutic approach to MRSA-BSI owing to synergistic bactericidal activity. This study aimed to compare DAP+CPT with historical standard of care (SoC) for treatment of complicated MRSA-BSI. This single-centre retrospective cohort study included patients with complicated MRSA-BSI at University of Colorado Hospital. Patients receiving DAP+CPT for ≥48 h between November 2013 and March 2020 or SoC with vancomycin or DAP ± gentamicin and/or rifampicin from November 2011 to December 2013 were compared. The primary outcome was clinical failure defined as a composite of MRSA-related mortality and recurrent infection at 60 days. A total of 60 patients received DAP+CPT (n = 30) or SoC (n = 30). Median age was 56 years and median Pitt bacteremia score was 3. Common infectious sites were endovascular (63%) and musculoskeletal (40%). DAP+CPT was associated with a numerically lower incidence of clinical failure compared with SoC (20% vs. 43%; P = 0.052). Multivariable analysis controlling for immunocompromised status (OR, 6.90, 95% CI 1.08-44.15), Charlson comorbidity index (OR, 1.12, 95% CI 0.90-1.39) and source control (OR, 0.35, 95% CI 0.08-1.46) associated DAP+CPT with 77% lower odds of clinical failure (OR, 0.23, 95% CI 0.06-0.89). In patients with complicated MRSA-BSI with delayed clearance, DAP+CPT trended towards lower rates of clinical failure than SoC and was significantly associated with decreased clinical failure after adjustment for baseline differences.

Ceftaroline activity against Staphylococcus aureus isolated from patients with infective endocarditis, worldwide (2010-2019)

OBJECTIVE

To evaluate the antimicrobial activity of ceftaroline against Staphylococcus aureus isolated from patients with infective endocarditis (IE).

METHODS

23,833 S. aureus isolates were collected consecutively from patients with bloodstream infections (BSI) from 2010 to 2019, via the SENTRY Antimicrobial Surveillance Program, including 396 isolates from patients with a diagnosis of IE. Isolates were collected from 340 medical centers worldwide and susceptibility tested by reference broth microdilution in a monitoring laboratory.

RESULTS

The oxacillin resistance (MRSA) rate was 29.0% among IE isolates, and was higher in North America (40.3%) than in Europe (25.4%) or the Latin America/Asia-Pacific region (LATAM-APAC; 18.6%). Ceftaroline was active against 95.2% of IE isolates (MIC50/90, 0.25/1 mg/L), with ceftaroline susceptibility higher in North America (99.2%) and LATAM-APAC (98.3%) than in Europe (92.0%). Among MRSA isolates from IE (n = 115; MIC50/90, 1/2 mg/L), ceftaroline susceptibility was 98.0% in North America, 90.9% in LATAM-APAC, and 68.5% in Europe. Among BSI isolates, MRSA rates were 43.6% in North America and 25.6% in Europe, while ceftaroline susceptibility rates were 98.1% in North America and 95.4% in Europe.

CONCLUSIONS

Ceftaroline demonstrated potent in vitro activity against a large collection of S. aureus isolates recovered from patients with BSI, including IE.

The Emerging Role of β-Lactams in the Treatment of Methicillin-Resistant Staphylococcus aureus Bloodstream Infections

Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSI) are associated with substantial morbidity and mortality. Monotherapy with first-line antimicrobials such as vancomycin (VAN; glycopeptide) and daptomycin (DAP; lipopeptide) are inadequate in some cases due to reduced antibiotic susceptibilities or therapeutic failure. In recent years, β-lactam antibiotics have emerged as a potential option for combination therapy with VAN and DAP that may meet an unmet therapeutic need for MRSA BSI. Ceftaroline (CPT), the only commercially available β-lactam in the United States with intrinsic in vitro activity against MRSA, has been increasingly studied in the setting of VAN and DAP failures. Novel combinations of first-line agents (VAN and DAP) with β-lactams have been the subject of many recent investigations due to in vitro findings such as the "seesaw effect," where β-lactam susceptibility may be improved in the presence of decreased glycopeptide and lipopeptide susceptibility. The combination of CPT and DAP, in particular, has become the focus of many scientific evaluations, due to intrinsic anti-MRSA activities and potent in vitro synergistic activity against various MRSA strains. This article reviews the available literature describing these innovative therapeutic approaches for MRSA BSI, focusing on preclinical and clinical studies, and evaluates the potential benefits and limitations of each strategy.

One Size Fits All? Application of Susceptible-Dose-Dependent Breakpoints to Pediatric Patients and Laboratory Reporting

The Clinical and Laboratory Standards Institute antimicrobial and antifungal standards define a susceptible-dose-dependent (SDD) category for certain organisms and drug combinations. Reporting MICs within the SDD category suggests that treatment success is likely with increased drug exposure. These breakpoints are based on pharmacokinetic, pharmacodynamic, and clinical outcome data from adults and not pediatric patients. This commentary aims to discuss the implications of reporting SDD interpretations for pediatric patients and recommends laboratory reporting comments.

Impact of EUCAST ceftaroline breakpoint change on the susceptibility of methicillin-resistant Staphylococcus aureus isolates collected from patients with complicated skin and soft-tissue infections

OBJECTIVES

In 2018, the European Committee on Antimicrobial Susceptibility Testing (EUCAST) introduced an intermediate breakpoint for ceftaroline against Staphylococcus aureus. The objective of this study was to compare data on resistance to ceftaroline among methicillin-resistant S. aureus (MRSA) isolates using versions 7.1 (March 2017) and 8.0 (January 2018) of the EUCAST breakpoints.

METHODS

Participating centers were located in Africa, Asia, Europe, Oceania and South America. Isolates were collected from patients with complicated skin and soft-tissue infections and were cultured from integumentary sources. Methicillin resistance among S. aureus was confirmed locally using the oxacillin method. The CLSI broth microdilution method was used to measure ceftaroline MICs at the central laboratory. Versions 7.1 and 8.0 of the EUCAST breakpoints were used to interpret MIC data.

RESULTS

Between 2015 and 2016, 9559 isolates of S. aureus were collected, of which 5566 (58.2%) isolates were MRSA. Overall, the lowest rate of MRSA was in Asia (56.5%; 705/1247) and the highest rate was in Oceania (62.7%; 299/477). Using version 7.1 of the EUCAST breakpoints, 4.5% (250/5566) of all MRSA isolates were resistant to ceftaroline and when version 8.0 of the breakpoints was applied, 4.2% (235/5566) of MRSA were in the intermediate category and 0.3% (15/5566) of all isolates were considered resistant.

CONCLUSIONS

By applying version 8.0 of the EUCAST breakpoints, the majority of MRSA isolates that were resistant are now in the intermediate category for ceftaroline. Ceftaroline resistance among MRSA now appears rare.

Ceftaroline fosamil as a potential treatment option for Staphylococcus aureus community-acquired pneumonia in adults

Staphylococcus aureus (S. aureus), including methicillin-resistant S. aureus (MRSA), is an important aetiological cause of community-acquired pneumonia (CAP) and associated with significant morbidity and mortality. Empiric therapy for CAP frequently consists of β-lactam monotherapy or β-lactam/macrolide combination therapy. However, such agents are often ineffective against S. aureus and do not reflect the emergence and increasing prevalence of MRSA in the community setting. Ceftaroline fosamil is a fifth-generation parenteral cephalosporin with broad-spectrum activity against Gram-positive pathogens - such as S. aureus (including MRSA), Streptococcus pneumoniae and Streptococcus pyogenes - and typical Gram-negative pathogens, including Haemophilus influenzae and Moraxella catarrhalis. The approval of ceftaroline fosamil in the United States and Europe for the treatment of adults with moderate-to-severe CAP was based on two phase 3 trials (FOCUS 1 and 2), which demonstrated that ceftaroline fosamil was non-inferior to ceftriaxone, a standard empiric treatment for CAP, while exhibiting a comparable safety profile. Although head-to-head trials of ceftaroline fosamil versus comparators against MRSA CAP are lacking, the effectiveness of ceftaroline fosamil in subpopulations of patients not covered by phase 3 trials (e.g. those with MRSA CAP or severe renal impairment) has been demonstrated in the Clinical Assessment Program and Teflaro Utilization Registry (CAPTURE) study. As ineffective empiric therapy is associated with adverse outcomes, including mortality and increased costs, ceftaroline fosamil, with its extended spectrum of activity, is an attractive alternative to standard antibiotic CAP regimens.

A comparative assessment of clinical, pharmacological and antimicrobial profile of novel anti-methicillin-resistant Staphylococcus aureus agent levonadifloxacin: Therapeutic role in nosocomial and community infections

Staphylococcus aureus is of significant clinical concern in both community- and hospital-onset infections. The key to the success of S. aureus as a pathogen is its ability to swiftly develop antimicrobial resistance. Methicillin-resistant S. aureus (MRSA) is not only resistant to nearly all beta-lactams but also demonstrates resistance to several classes of antibiotics. A high prevalence of MRSA is seen across worldwide. For many decades, vancomycin remained as gold standard antibiotic for the treatment of MRSA infections. In the past decades, linezolid, daptomycin, ceftaroline and telavancin received regulatory approval for the treatment of infections caused by resistant Gram-positive pathogens. Although these drugs may offer some advantages over vancomycin, they also have significant limitations. These includes vancomycin's slow bactericidal activity, poor lung penetration and nephrotxicity;linezolid therapy induced myelosuppression and high cost of daptomycin greatly limits their clinical use. Moreover, daptomycin also gets inactivated by lung naturally occurring surfactants. Thus, currently available therapeutic options are unable to provide safe and efficacious treatment for those patients suffering from hospital-acquired pneumonia, bloodstream infections (BSIs), bone and joint infections and diabetic foot infections (DFI). An unmet need also exists for a safe and efficacious oral option for switch-over convenience and community treatment. Herein, the review is intended to describe the supporting role of anti-staphylococcal antibiotics used in the management of S. aureus infections with a special reference to levonadifloxacin. Levonadifloxacin and its prodrug alalevonadifloxacin are novel benzoquinolizine subclass of quinolone with broad-spectrum of anti-MRSA activity. It has been recently approved for the treatment of complicated skin and soft-tissue infection as well as concurrent bacteraemia and DFI in India.

Population Pharmacokinetic Modeling and Probability of Target Attainment Analyses in Asian Patients With Community-Acquired Pneumonia Treated With Ceftaroline Fosamil

Efficacy of ceftaroline fosamil, the prodrug of the active metabolite ceftaroline, was demonstrated in a phase 3 study of hospitalized Asian patients with Pneumonia Outcomes Research Team (PORT) risk class III-IV community-acquired pneumonia (NCT01371838). The objectives of the current analysis were to expand an existing ceftaroline and ceftaroline fosamil population pharmacokinetic (PK) model with data from this phase 3 study and a phase 1 study (NCT01458743) assessing ceftaroline PK in healthy Chinese volunteers and to evaluate the probability of PK/pharmacodynamic (PK/PD) target attainment (PTA) in Asian patients with community-acquired pneumonia (CAP) treated with ceftaroline fosamil. The ceftaroline plasma concentration-time course was simulated for 5000 Asian patients with CAP for different renal function subgroups using the final model. PTA was calculated for Streptococcus pneumoniae, Staphylococcus aureus, and non-extended-spectrum β-lactamase-producing Enterobacteriaceae. PTA was also evaluated for ceftaroline MIC90 values of isolates collected from Asia-Pacific surveillance studies (2012-2014) and for EUCAST and FDA/CLSI ceftaroline susceptibility break points. The final model reasonably described the ceftaroline PK. Race was not found to be a significant covariate impacting ceftaroline PK, suggesting similar ceftaroline PK in Asian and Western populations when corrected for body weight. High PTAs (90%-100%) were predicted for Asian patients with CAP treated with ceftaroline fosamil, covering MIC90 values of target CAP pathogens from the region. Similarly, >90% PTAs were predicted at EUCAST and FDA/CLSI clinical break points for these pathogens. These results support the use of the ceftaroline fosamil dosing regimens approved in Europe and the United States in Asian patients with PORT III-IV CAP.

Ceftaroline fosamil therapy in patients with acute bacterial skin and skin-structure infections with systemic inflammatory signs: A retrospective dose comparison across three pivotal trials

This post-hoc analysis compared the pharmacokinetics and clinical outcomes of ceftaroline fosamil 600 mg every 12 (q12h) versus every 8 hours (q8h) in patients with acute bacterial skin and skin-structure infection (ABSSSI) and signs of sepsis. Clinical outcomes at test-of-cure in patients with ABSSSI and systemic inflammatory signs/systemic inflammatory response syndrome (SIRS) as well as ceftaroline minimum inhibitory concentrations (MICs) against baseline pathogens were compared between the COVERS trial (ceftaroline fosamil 600 mg q8h, 2-h infusion) and the CANVAS 1 and 2 trials (ceftaroline fosamil 600 mg q12h, 1-h infusion). Ceftaroline exposure among patients in COVERS with or without markers of sepsis was compared using population pharmacokinetic modelling. In COVERS, 62% (312/506) and 41% (208/506) of ceftaroline fosamil-treated patients had ≥1 systemic inflammatory sign or SIRS, respectively, compared with 55% (378/693) and 22% (155/693), respectively, in the CANVAS trials. Clinical cure rates for the modified intent-to-treat population in COVERS and CANVAS were similar for ceftaroline fosamil-treated patients with ≥1 sign of sepsis [82% (255/312) and 85% (335/394)] and for those with SIRS [84% (168/199) and 85% (131/155)]. Ceftaroline MIC distributions were similar across trials. Sepsis did not affect predicted individual steady-state ceftaroline exposure. Clinical cure rates in patients with ≥1 systemic inflammatory sign or SIRS were comparable for both ceftaroline fosamil dosage regimens. Pathogen susceptibilities to ceftaroline were similar across trials. Ceftaroline exposure was not affected by disease severity. Ceftaroline fosamil 600 mg q12h is a robust dosage regimen for most ABSSSI patients with sepsis [ClinicalTrials.gov ID: NCT01499277, NCT00424190, NCT00423657].

A Retrospective Analysis of Probability of Target Attainment in Community-Acquired Pneumonia: Ceftaroline Fosamil Versus Comparators

Introduction

This retrospective analysis compares the probability of target attainment (PTA) for ceftriaxone, levofloxacin and ceftaroline fosamil against Staphylococcus aureus, Streptococcus pneumoniae and Haemophilus influenzae in a representative patient population with moderate-to-severe community-acquired pneumonia (CAP).

Methods

Published pharmacokinetic (PK) models for levofloxacin and ceftriaxone, and an existing model for ceftaroline, were used with standard dosage regimens for simulating individual PK data with covariates representative of patients with CAP (5000 patients/drug regimen). PTA for clinically relevant pharmacokinetic/pharmacodynamic (PK/PD) targets was calculated from steady state PK profiles for a range of minimum inhibitory concentrations (MICs). Cumulative fractions of response (CFRs) were also calculated using MIC distributions from 2012 to 2017 global surveillance data.

Results

Ceftaroline fosamil (600 mg q12 h) achieved > 90% PTA at all exposure targets for each pathogen at European Committee on Antimicrobial Susceptibility Testing (EUCAST)/Clinical and Laboratory Standards Institute (CLSI) susceptibility breakpoints, and CFRs were > 99%. Ceftriaxone, but not levofloxacin, achieved 100% PTA and > 90% CFR against S. pneumoniae. Both levofloxacin and ceftriaxone achieved high PTA and CFR against H. influenzae. Levofloxacin achieved PTAs < 90% at EUCAST/CLSI breakpoints and ceftriaxone achieved PTAs < 90% at MICs up to 2 mg/L against S. aureus; both agents produced generally low CFRs against S. aureus (except levofloxacin against methicillin-sensitive S. aureus), reflecting the lack of activity of these agents against methicillin-resistant S. aureus.

Conclusion

Ceftaroline fosamil demonstrated higher overall PTA rates than levofloxacin and ceftriaxone, in particular against S. aureus. These results provide insight regarding the potential comparative efficacy of the described antibiotics for moderate-to-severe CAP.

Funding

Pfizer.

Mechanisms of action and antimicrobial activity of ceftobiprole

Ceftobiprole, a novel last generation parenteral cephalosporin, has an extended spectrum of activity, notably against methicillin-resistant Staphylococcus aureus (MRSA), ampicillin-susceptible enterococci, penicillin-resistant pneumococci, Enterobacterales and susceptible Pseudomonas aeruginosa. It exerts an inhibitory action on essential peptidoglycan transpeptidases, interfering with cell wall synthesis. The inhibitory action of ceftobiprole through binding to abnormal PBPs like PBP2a in methicillin-resistant staphylococci and PBP2b and PBP2x in the case of β-lactam-resistant pneumococci, ultimately leads to rapid bacterial cell death. In the case of Enterobacterales, ceftobiprole retains activity against narrow spectrum β-lactamases but is hydrolysed by their extended-spectrum counterparts, overexpressed Amp C, and carbapenemases. It is also affected by certain efflux pumps from P. aeruginosa. For anaerobic bacteria, ceftobiprole is active against Gram-positive Clostridioides difficile and Peptococcus spp. and Gram-negative Fusobacterium nucleatum but not against Bacteroides group or other anaerobic Gram-negatives. In in vitro studies, a low propensity to select for resistant subpopulations has been demonstrated. Currently, ceftobiprole is approved for the treatment of community-acquired pneumonia and hospital-acquired pneumonia with the exception of ventilator-associated pneumonia. Ceftobiprole's place in therapy appears to lie mainly in its combined activity against Gram-positive organisms, such as S. aureus and S. pneumoniae alongside that against Gram-negative organisms such as P. aeruginosa.