Evaluation of ceftobiprole medocaril against Enterococcus faecalis in a mouse peritonitis model

Evaluation of ampicillin plus ceftobiprole combination therapy in treating Enterococcus faecalis infective endocarditis and bloodstream infection

Enterococcus faecalis is responsible for numerous serious infections, and treatment options often include ampicillin combined with an aminoglycoside or dual beta-lactam therapy with ampicillin and a third-generation cephalosporin. The mechanism of dual beta-lactam therapy relies on the saturation of penicillin-binding proteins (PBPs). Ceftobiprole exhibits high affinity binding to nearly all E. faecalis PBPs, thus suggesting its potential utility in the treatment of severe E. faecalis infections. The availability of therapeutic drug monitoring (TDM) for ampicillin and ceftobiprole has prompted the use of this drug combination in our hospital. Due to the time-dependent antimicrobial properties of these antibiotics, an infusion administration longer than indicated was chosen. From January to December 2020, twenty-one patients were admitted to our hospital for severe E. faecalis infections and were treated with this approach. We retrospectively analyzed their clinical characteristics and pharmacological data. Most patients achieved an aggressive PK/PD target (T > 4-8 minimum inhibitory concentration, MIC) when this alternative drug combination regimen was used. Our analysis included the study of E. faecalis biofilm production, as well as the kinetics of bacterial killing of ceftobiprole alone or in combination with ampicillin. Time-kill experiments revealed strong bactericidal activity of ceftobiprole alone at concentrations four times higher than the MIC for some enterococcal strains. In cases where a bactericidal effect of ceftobiprole alone was not evident, synergism with ampicillin and bactericidal activity were demonstrated instead. The prolonged infusion of ceftobiprole, either alone or with ampicillin, emerges as a valuable option for the treatment of severe invasive E. faecalis infections.

Membrane Lipids Augment Cell Envelope Stress Signaling and Resistance to Antibiotics and Antimicrobial Peptides in Enterococcus faecalis

Enterococci have evolved resistance mechanisms to protect their cell envelopes against bacteriocins and host cationic antimicrobial peptides (CAMPs) produced in the gastrointestinal environment. Activation of the membrane stress response has also been tied to resistance to the lipopeptide antibiotic daptomycin. However, the actual effectors mediating resistance have not been elucidated. Here, we show that the MadRS (formerly YxdJK) membrane antimicrobial peptide defense system controls a network of genes, including a previously uncharacterized three gene operon (madEFG) that protects the E. faecalis cell envelope from antimicrobial peptides. Constitutive activation of the system confers protection against CAMPs and daptomycin in the absence of a functional LiaFSR system and leads to persistence of cardiac microlesions in vivo. Moreover, changes in the lipid cell membrane environment alter CAMP susceptibility and expression of the MadRS system. Thus, we provide a framework supporting a multilayered envelope defense mechanism for resistance and survival coupled to virulence.

Ampicillin and Ceftobiprole Combination for the Treatment of Enterococcus faecalis Invasive Infections: "The Times They Are A-Changin"

BACKGROUND

Enterococcus faecalis is responsible for a large variety of severe infections. This study is a case series reporting our experience in the treatment of E. faecalis invasive infections with ampicillin in combination with ceftobiprole (ABPR).

METHODS

We retrospectively analyzed all the medical records of patients admitted to the University Hospital of Udine from January to December 2020 with a diagnosis of infective endocarditis or primary or non-primary complicated or uncomplicated bacteremia caused by E. faecalis.

RESULTS

Twenty-one patients were included in the final analysis. The clinical success rate was very high, accounting for 81% of patients, and microbiological cure was obtained in 86% of patients. One relapse was recorded in one patient who did not adhere to the partial oral treatment prescribed. Therapeutic drug monitoring (TDM) was always performed for ampicillin and ceftobiprole, and serum concentrations of both drugs were compared to the MICs of the different enterococcal isolates.

CONCLUSIONS

ABPR is a well-tolerated antimicrobial regimen with anti-E. faecalis activity. TDM can help clinicians optimize medical treatments to achieve the best possible efficacy with fewer side effects. ABPR might be a reasonable option for the treatment of severe invasive infections caused by E. faecalis due to the high level of enterococcal penicillin-binding protein (PBP) saturation.

Treatment of Enterococcus faecalis Infective Endocarditis: A Continuing Challenge

Today, Enterococcus faecalis is one of the main causes of infective endocarditis in the world, generally affecting an elderly and fragile population, with a high mortality rate. Enterococci are partially resistant to many commonly used antimicrobial agents such as penicillin and ampicillin, as well as high-level resistance to most cephalosporins and sometimes carbapenems, because of low-affinity penicillin-binding proteins, that lead to an unacceptable number of therapeutic failures with monotherapy. For many years, the synergistic combination of penicillins and aminoglycosides has been the cornerstone of treatment, but the emergence of strains with high resistance to aminoglycosides led to the search for new alternatives, like dual beta-lactam therapy. The development of multi-drug resistant strains of Enterococcus faecium is a matter of considerable concern due to its probable spread to E. faecalis and have necessitated the search of new guidelines with the combination of daptomycin, fosfomycin or tigecycline. Some of them have scarce clinical experience and others are still under investigation and will be analyzed in this review. In addition, the need for prolonged treatment (6–8 weeks) to avoid relapses has forced to the consideration of other viable options as outpatient parenteral strategies, long-acting administrations with the new lipoglycopeptides (dalbavancin or oritavancin), and sequential oral treatments, which will also be discussed.

Vancomycin Resistance in Enterococcus and Staphylococcus aureus

Enterococcus faecalis, Enterococcus faecium and Staphylococcus aureus are both common commensals and major opportunistic human pathogens. In recent decades, these bacteria have acquired broad resistance to several major classes of antibiotics, including commonly employed glycopeptides. Exemplified by resistance to vancomycin, glycopeptide resistance is mediated through intrinsic gene mutations, and/or transferrable van resistance gene cassette-carrying mobile genetic elements. Here, this review will discuss the epidemiology of vancomycin-resistant Enterococcus and S. aureus in healthcare, community, and agricultural settings, explore vancomycin resistance in the context of van and non-van mediated resistance development and provide insights into alternative therapeutic approaches aimed at treating drug-resistant Enterococcus and S. aureus infections.

Impact of PBP4 Alterations on β-Lactam Resistance and Ceftobiprole Non-Susceptibility Among Enterococcus faecalis Clinical Isolates

Penicillin-resistance among Enterococcus faecalis clinical isolates has been recently associated with overexpression or aminoacidic substitutions in low-affinity PBP4. Ceftobiprole (BPR), a new-generation cephalosporin, is a therapeutic option against E. faecalis. Here, we present evidence that pbp4 gene sequence alterations may influence the expression level of the gene and ceftobiprole binding to PBP4 in E. faecalis clinical isolates showing remarkable MDR-phenotypes, and how this could interfere with BPR in vitro antibacterial and bactericidal activity. Seven E. faecalis strains from bloodstream infections were analyzed for their antibiotic and β-lactam resistance. BPR bactericidal activity was assessed by time-kill analysis; pbp4 genes were sequenced and pbp4 relative expression levels of transcription were performed by RT-qPCR. Five penicillin-resistant ampicillin-susceptible (PRAS) isolates were detected, 4 of which were also BPR non-susceptible (BPR-NS). In the time-kill experiments, BPR exposure resulted in a potent bactericidal activity (3-5 log10 reduction) at the different concentrations tested. pbp4 gene sequence analysis revealed some mutations that may account for the changes in PBP4 affinity and MIC increase in the 4 BPR-NS strains (MICs 4-16 mg/L): the deletion of an adenine (delA) in the promoter region in all PRAS/BPR-NS strains; 12 different amino acid substitutions, 7 of which were next to the PBP catalytic-sites. The most significant were: T418A, located 6 amino acids (aa) upstream of the catalytic-serine included in the 424STFK427motif I; L475Q, 7 aa upstream of the 482SDN484motif II; V606A and the novel Y605H, 13/14 aa upstream of the 619KTGT622motif III. Taken together, our data showed that elevated BPR MICs were attributable to increased transcription of pbp4 - associated with a single upstream adenine deletion and PBP4 alterations in the catalytic-site motifs - which might interfere with the formation of the BPR/PBP4 complex. pbp4 molecular alterations may account for the changes in PBP4 affinity and MIC increase, without affecting BPR cidal activity. Indeed, our in vitro dynamic analysis by time-kill assays showed that BPR exerted a bactericidal activity against E. faecalis clinical isolates, despite their MDR phenotypes.

Efficacy of Omadacycline against Multidrug-Resistant Enterococcus faecium Strains in a Mouse Peritonitis Model

Omadacycline (OMC) showed better in vitro potency than daptomycin (DAP) or vancomycin (VAN) against Van^r, Amp^r, DAP-nonsusceptible, linezolid-resistant, cfr(B)⁺ Enterococcus faecium strains. In a mouse peritonitis model, OMC also showed significantly better animal survival during the study and at its end than DAP or VAN with these E. faecium strains. However, OMC, DAP, and VAN showed comparable in vitro and in vivo efficacies against a non-vancomycin-resistant, tetracycline-resistant, DAP-susceptible E. faecium strain.

Drug repurposing: Antimicrobial and antibiofilm effects of penfluridol against Enterococcus faecalis

The bacterium Enterococcus faecalis has increasingly attracted global attention as an important opportunistic pathogen due to its ability to form biofilms that are known to increase drug resistance. However, there are still no effective antibiofilm drugs in clinical settings. Here, by drug repurposing, we investigated the antibacterial activity of penfluridol (PF), an oral long‐acting antipsychotic approved by the FDA, against E. faecalis type strain and its clinical isolates. It was found that PF inhibited the growth of E. faecalis planktonic cells with the MIC and MBC of 7.81 µg/ml and 15.63 ~ 62.50 µg/ml, respectively. Moreover, PF could significantly prevent the biofilm formation of E. faecalis at the concentration of 1 × MIC. Furthermore, PF significantly eradicated 24 h pre‐formed biofilms of E. faecalis in a dose‐dependent manner, with a concentration range of 1 × MIC to 8 × MIC. Here, through the checkerboard method with other tested conventional antibiotics, we also determined that gentamycin, penicillin G, and amikacin showed partial synergistic antibacterial effects with PF. Also, PF showed almost no hemolysis on human erythrocytes. In a mouse peritonitis model, a single dose of 20 mg/kg of PF treatment could significantly reduce the bacterial colonization in the liver (~5‐fold reduction) and spleen (~3‐fold reduction). In conclusion, these findings indicated that after structural optimization, PF has the potential as a new antibacterial agent against E. faecalis.

Disrupting Membrane Adaptation Restores In Vivo Efficacy of Antibiotics Against Multidrug-Resistant Enterococci and Potentiates Killing by Human Neutrophils

Daptomycin resistance in enterococci is often mediated by the LiaFSR system, which orchestrates the cell membrane stress response. Activation of LiaFSR through the response regulator LiaR generates major changes in cell membrane function and architecture (membrane adaptive response), permitting the organism to survive the antibiotic attack. Here, using a laboratory strain of Enterococcus faecalis, we developed a novel Caenorhabditis elegans model of daptomycin therapy and showed that disrupting LiaR-mediated cell membrane adaptation restores the in vivo activity of daptomycin. The LiaR effect was also seen in a clinical strain of daptomycin-resistant Enterococcus faecium, using a murine model of peritonitis. Furthermore, alteration of the cell membrane response increased the ability of human polymorphonuclear neutrophils to readily clear both E. faecalis and multidrug-resistant E. faecium. Our results provide proof of concept that targeting the cell membrane adaptive response restores the in vivo activity of antibiotics, prevents resistance, and enhances the ability of the innate immune system to kill infecting bacteria.

In vitro bactericidal activity of amoxicillin combined with different cephalosporins against endocarditis-associated Enterococcus faecalis clinical isolates

Background

The combination of amoxicillin with cefazolin could be an interesting regimen for the empirical therapy of severe infective endocarditis, but its activity against enterococci is unknown.

Objectives

To evaluate in vitro the bactericidal activity of the combination of amoxicillin with different cephalosporins including cefazolin.

Methods

Combinations of amoxicillin (at MIC×¼) with cefazolin, cefotaxime, ceftriaxone, cefepime, ceftaroline or ceftobiprole (at the mean free plasma concentration) were studied using time–kill experiments for 10 endocarditis-associated Enterococcus faecalis strains and 2 reference strains.

Results

The combinations amoxicillin/cefazolin, amoxicillin/cefotaxime, amoxicillin/ceftriaxone and amoxicillin/cefepime were synergistic at 12 and 24 h against 12/12 strains and amoxicillin/ceftobiprole and amoxicillin/ceftaroline against 10/12 strains. The combination amoxicillin/cefepime was bactericidal at 24 h against 9/12 strains, the combination amoxicillin/cefazolin against 8/12 strains, the combinations amoxicillin/ceftaroline, amoxicillin/cefotaxime and amoxicillin/ceftobiprole against 7/12 strains and the combination amoxicillin/ceftriaxone against 6/12 strains.

Conclusions

The combination amoxicillin/cefazolin is as synergistic and bactericidal in vitro as amoxicillin/cefotaxime or amoxicillin/ceftriaxone against E. faecalis.

Efficacy of Tedizolid against Enterococci and Staphylococci, Including cfr + Strains, in a Mouse Peritonitis Model

In a mouse peritonitis model, tedizolid was comparable to linezolid and daptomycin against an Enterococcus faecium strain (VAN^r, AMP^r), an Enterococcus faecalis strain, and a methicillin-resistant Staphylococcus aureus (MRSA) strain with and without cfr Against a cfr(B)⁺ E. faecium, tedizolid was inferior in vivo to linezolid and daptomycin, despite an ∼4-fold lower MIC.

Ceftobiprole medocaril for the treatment of community-acquired pneumonia

INTRODUCTION

Ceftobiprole is a novel broad-spectrum cephalosporin with excellent activity against a broad range of pathogens that are important in community-acquired pneumonia (CAP), including drug-resistant pneumococci, methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa. Areas covered: This article reviews the spectrum of activity, the main pharmacological and pharmacodynamic characteristics of ceftobiprole as well its clinical efficacy and safety in the treatment of CAP in adult patients. Expert opinion: Taking into account that the current treatment guidelines for CAP recommend the use of an adequate empirical therapy to improve its prognosis, ceftobiprole shows a profile of antimicrobial activity that would cover most etiological agents in patients with risk factors for infection caused by multidrug resistant organisms. The results of the pivotal clinical trial of patients hospitalized with CAP treated with ceftobiprole showed a high rate of clinical cure. The clinical tolerance of ceftobiprole in clinical trials was generally very good. These findings make ceftobiprole a good parenteral therapeutic alternative for the empirical treatment of CAP that requires hospitalization, especially in patients with risk factors for CAP caused by resistant microorganisms.

In Vivo and In Vitro Effects of a ClpP-Activating Antibiotic against Vancomycin-Resistant Enterococci

Antibiotics with novel bactericidal mechanisms of action are urgently needed. The antibiotic acyldepsipeptide 4 (ADEP4) activates the ClpP protease and causes cells to self-digest. The effects of ADEP4 and ClpP activation have not been characterized sufficiently for the enterococci, which are important pathogens known for high levels of acquired and intrinsic antibiotic resistance. In the present study, ADEP4 was found to be potently active against both Enterococcus faecalis and Enterococcus faecium, with MIC₉₀s of 0.016 μg/ml and 0.031 μg/ml, respectively. ClpP purified from E. faecium was found to bind ADEP4 in a surface plasmon resonance analysis, and ClpP activation by ADEP4 was demonstrated biochemically with a β-casein digestion assay. In addition, E. faecium ClpP was crystallized in the presence of ADEP4, revealing ADEP4 binding to ClpP in the activated state. These results confirm that the anti-enterococcal activity of ADEP4 occurs through ClpP activation. In killing curve assays, ADEP4 was found to be bactericidal against stationary-phase vancomycin-resistant E. faecalis (VRE) strain V583, and resistance development was prevented when ADEP4 was combined with multiple classes of approved antibiotics. ADEP4 in combination with partnering antibiotics also eradicated mature VRE biofilms within 72 h of treatment. Biofilm killing with ADEP4 antibiotic combinations was superior to that with the clinically used combinations ampicillin-gentamicin and ampicillin-daptomycin. In a murine peritoneal septicemia model, ADEP4 alone was as effective as ampicillin. ADEP4 coadministered with ampicillin was significantly more effective than either drug alone. These data suggest that ClpP-activating antibiotics may be useful for treating enterococcal infections.

Combined bacteriophages and antibiotics as an efficient therapy against VRE Enterococcus faecalis in a mouse model

Clinical applications of bacteriophage therapy have been recently gathering significant attention worldwide, used mostly as rescue therapy in cases of near-fatal antibiotic failure. Thus, clinically relevant in-vivo models presenting both short- and long-term implications of phage therapy given as rescue treatment for fulminant infections are of highest importance. In this study, a cocktail consisting of two lytic bacteriophages was used to evaluate the therapeutic efficacy of phage therapy as a rescue treatment for severe septic peritonitis in a mouse model. We established that a single injection of the bacteriophage cocktail was sufficient to completely reverse a 100% mortality trend caused by Vancomycin-Resistant Enterococcus faecalis, with significant improvement in both the clinical state and laboratory test results, and without harmful effects on the microbiome. The combination of bacteriophages with a suboptimal antibiotic regimen imparts an additional beneficial effect on the treatment success.

Enterococcal endocarditis revisited

The Enterococcus species is the third main cause of infective endocarditis (IE) worldwide, and it is gaining relevance, especially among healthcare-associated cases. Patients with enterococcal IE are older and have more comorbidities than other types of IE. Classical treatment options are limited due to the emergence of high-level aminoglycosides resistance (HLAR), vancomycin resistance and multidrug resistance in some cases. Besides, few new antimicrobial alternatives have shown real efficacy, despite some of them being recommended by major guidelines (including linezolid and daptomycin). Ampicillin plus ceftriaxone 2 g iv./12 h is a good option for Enterococcus faecalis IE caused by HLAR strains, but randomized clinical trials are essential to demonstrate its efficacy for non-HLAR EFIE and to compare it with ampicillin plus short-course gentamicin. The main mechanisms of resistance and treatment options are also reviewed for other enterococcal species.

An optimized mouse thigh infection model for enterococci and its impact on antimicrobial pharmacodynamics

Negligible in vivo growth of enterococci and high-level dispersion of data have led to inaccurate estimations of antibiotic pharmacodynamics (PD). Here we improved an in vivo model apt for PD studies by optimizing the in vitro culture conditions for enterococci. The PD of vancomycin (VAN), ampicillin-sulbactam (SAM), and piperacillin-tazobactam (TZP) against enterococci were determined in vivo, comparing the following different conditions of inoculum preparation: aerobiosis, aerobiosis plus mucin, and anaerobiosis plus mucin. Drug exposure was expressed as the ratio of the area under the concentration-time curve for the free, unbound fraction of the drug to the MIC (fAUC/MIC) (VAN) or the time in a 24-h period that the drug concentration for the free, unbound fraction exceeded the MIC under steady-state pharmacokinetic conditions (fT(>MIC)) (SAM and TZP) and linked to the change in log10 CFU/thigh. Only anaerobiosis plus mucin enhanced the in vivo growth, yielding significant PD parameters with all antibiotics. In conclusion, robust in vivo growth of enterococci was crucial for better determining the PD of tested antibacterial agents, and this was achieved by optimizing the procedure for preparing the inoculum.

A phase 3 randomized double-blind comparison of ceftobiprole medocaril versus ceftazidime plus linezolid for the treatment of hospital-acquired pneumonia

BACKGROUND

Ceftobiprole, the active moiety of ceftobiprole medocaril, is a novel broad-spectrum cephalosporin, with bactericidal activity against a wide range of gram-positive bacteria, including Staphylococcus aureus (including methicillin-resistant strains) and penicillin- and ceftriaxone-resistant pneumococci, and gram-negative bacteria, including Enterobacteriaceae and Pseudomonas aeruginosa.

METHODS

This was a double-blind, randomized, multicenter study of 781 patients with hospital-acquired pneumonia (HAP), including 210 with ventilator-associated pneumonia (VAP). Treatment was intravenous ceftobiprole 500 mg every 8 hours, or ceftazidime 2 g every 8 hours plus linezolid 600 mg every 12 hours; primary outcome was clinical cure at the test-of-cure visit.

RESULTS

Overall cure rates for ceftobiprole vs ceftazidime/linezolid were 49.9% vs 52.8% (intent-to-treat [ITT], 95% confidence interval [CI] for the difference, -10.0 to 4.1) and 69.3% vs 71.3% (clinically evaluable [CE], 95% CI, -10.0 to 6.1). Cure rates in HAP (excluding VAP) patients were 59.6% vs 58.8% (ITT, 95% CI, -7.3 to 8.8), and 77.8% vs 76.2% (CE, 95% CI, -6.9 to 10.0). Cure rates in VAP patients were 23.1% vs 36.8% (ITT, 95% CI, -26.0 to -1.5) and 37.7% vs 55.9% (CE, 95% CI, -36.4 to 0). Microbiological eradication rates in HAP (excluding VAP) patients were, respectively, 62.9% vs 67.5% (microbiologically evaluable [ME], 95% CI, -16.7 to 7.6), and in VAP patients 30.4% vs 50.0% (ME, 95% CI, -38.8 to -0.4). Treatment-related adverse events were comparable for ceftobiprole (24.9%) and ceftazidime/linezolid (25.4%).

CONCLUSIONS

Ceftobiprole is a safe and effective bactericidal antibiotic for the empiric treatment of HAP (excluding VAP). Further investigations are needed before recommending the use of ceftobiprole in VAP patients. Clinical Trials Registration. NCT00210964, NCT00229008.

Intrinsic and acquired resistance mechanisms in enterococcus

Enterococci have the potential for resistance to virtually all clinically useful antibiotics. Their emergence as important nosocomial pathogens has coincided with increased expression of antimicrobial resistance by members of the genus. The mechanisms underlying antibiotic resistance in enterococci may be intrinsic to the species or acquired through mutation of intrinsic genes or horizontal exchange of genetic material encoding resistance determinants. This paper reviews the antibiotic resistance mechanisms in Enterococcus faecium and Enterococcus faecalis and discusses treatment options.

Efficacy of ceftobiprole Medocaril against Enterococcus faecalis in a murine urinary tract infection model

We evaluated ceftobiprole against the well-characterized Enterococcus faecalis strain OG1RF (with and without the β-lactamase [Bla] plasmid pBEM10) in a murine urinary tract infection (UTI) model. Ceftobiprole was equally effective for Bla(+) and Bla(-) OG1 strains, while ampicillin was moderately to markedly (depending on the inoculum) less effective against Bla(+) than Bla(-) OG1 strains. These data illustrate an in vivo effect on ampicillin of Bla production by E. faecalis and the stability and efficacy of ceftobiprole in experimental UTI.

Evaluation of ceftobiprole activity against a variety of gram-negative pathogens, including Escherichia coli, Haemophilus influenzae (β-lactamase positive and β-lactamase negative), and Klebsiella pneumoniae, in a rabbit meningitis model

Ceftobiprole medocaril, a new cephalosporin, is highly active against a broad spectrum of Gram-positive and Gram-negative clinical pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and penicillin-resistant pneumococci. In this study, we tested ceftobiprole against various Gram-negative pathogens in a rabbit meningitis model and determined its penetration into the cerebrospinal fluid (CSF). In this animal model, ceftobiprole produced an antibacterial activity similar to that of cefepime against an Escherichia coli strain, a Klebsiella pneumoniae strain, and a β-lactamase-negative Haemophilus influenzae strain. Against a β-lactamase-positive H. influenzae strain, ceftobiprole was significantly superior. The penetration of ceftobiprole through inflamed meninges reached about 16% of serum levels compared to about 2% of serum levels through uninflamed meninges.

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.

Resistance and the management of complicated skin and skin structure infections: the role of ceftobiprole

Antimicrobial resistant bacteria are an increasing concern due to the resulting increase in morbidity, mortality, and health-care costs associated with the administration of inadequate or delayed antimicrobial therapy. The implications of inadequate antimicrobial therapy in complicated skin and skin structure infections (cSSSIs) have gained more attention recently, most likely due to the recent emergence of community-acquired methicillin resistant Staphylococcus aureus (MRSA) and the already high prevalence of MRSA in the nosocomial setting. Due to the continuous threat of resistance arising and the limitations of currently available agents for the treatment of cSSSIs, it is necessary to develop new antimicrobials for this indication. Ceftobiprole medocaril, the prodrug of ceftobiprole, is a parental investigational cephalosporin for the treatment of cSSSIs displaying a wide-spectrum of activity against both Gram-positive and Gram-negative species, including MRSA. Ceftobiprole displays noncomplex linear pharmacokinetics, is eliminated primarily by glomerular filtration, and distributes to extracellular fluid. Additionally, it has been shown that the extent of distribution to the site of action with regard to cSSSIs, ie, the extracellular space fluid of subcutaneous adipose tissue and skeletal muscle, is expected to be efficacious, as free concentrations meet efficacy targets for most pathogens. Similar to other beta-lactams, it displays an excellent safety and tolerability profile with the primary adverse events being dysgeusia in healthy volunteers, resulting from the conversion of the prodrug to the active, and nausea in patients. Ceftobiprole has demonstrated noninferiority in two large-scale pivotal studies comparing it to vancomycin, clinical cure rates 93.3% vs 93.5%, respectively, or vancomycin plus ceftazidime, clinical cure rates 90.5% vs 90.2%, respectively. Given the pharmacokinetic and pharmacodynamic properties, ceftobiprole is a promising new agent for the treatment of cSSSIs and has the potential to be used as a single agent for empiric treatment.

Ceftobiprole: A novel, broad-spectrum cephalosporin with activity against methicillin-resistant Staphylococcus aureus

PURPOSE

The pharmacology, antimicrobial activity, pharmacokinetics, pharmacodynamics, clinical efficacy, safety, and place in therapy of ceftobiprole are reviewed.

SUMMARY

Ceftobiprole, a novel, broad-spectrum, parenteral cephalosporin, inhibits the cell-wall synthesis of penicillin-binding proteins (PBPs) PBP2a and PBP2x, responsible for the resistance in staphylococci and pneumococci, respectively. Ceftobiprole has good activity against gram-positive aerobes and anaerobes, and its activity against gram-negative aerobes and anaerobes is species dependent. Ceftobiprole is relatively inactive against Acinetobacter species. Its ability to bind relevant PBPs of resistant gram-positive and gram-negative bacteria indicates its potential use in the treatment of hospital-acquired pneumonia and complicated skin and skin-structure infections (cSSSIs). Ceftobiprole is primarily excreted unchanged by the kidneys and exhibits linear pharmacokinetics. The half-life of the drug is approximately 3-4 hours. It exhibits minimal plasma protein binding (16%). Ceftobiprole does not inhibit the cytochrome P-450 isoenzyme system, so the possibility of drug-drug interactions is low. The drug has not been approved for use in the United States but has been approved in Canada and elsewhere. Ceftobiprole is currently undergoing Phase III clinical trials and has demonstrated activity against methicillin-resistant Staphylococcus aureus, penicillin-resistant Streptococcus pneumoniae, and Pseudomonas aeruginosa. Completed Phase III trials used i.v. dosages of 500 mg every 8-12 hours. The most commonly observed adverse effects of ceftobiprole included headache and gastrointestinal upset.

CONCLUSION

Ceftobiprole is a novel, broad-spectrum, parenteral cephalosporin undergoing Phase III clinical trials. Its broad spectrum of activity makes it a candidate for monotherapy of cSSSIs and pneumonias that have required combination therapy in the past.

Emerging agents to combat complicated and resistant infections: focus on ceftobiprole

Antimicrobial resistance is a global concern. Over the past few years, considerable efforts and resources have been expended to detect, monitor, and understand at the basic level the many different facets of emerging and increasing resistance. Development of new antimicrobial agents has been matched by the development of new mechanisms of resistance by bacteria. Current antibiotics act at a variety of sites within the target bacteria, including the cross-linking enzymes in the cell wall, various ribosomal enzymes, nucleic acid polymerases, and folate synthesis. Ceftobiprole is a novel parenteral cephalosporin with high affinity for most penicillin-binding proteins, including the mecA product penicillin-binding protein 2a, rendering it active against methicillin-resistant staphylococci. Its in vitro activity against staphylococci and multiresistant pneumococci, combined with its Gram-negative spectrum comparable to that of other extended-spectrum cephalosporins, its stability against a wide range of beta-lactamases, and its pharmacokinetic and safety profiles make ceftobiprole an attractive and well tolerated new antimicrobial agent. The US Food and Drug Administration granted ceftobiprole medocaril fast-track status in 2003 for the treatment of complicated skin infections and skin structure infections due to methicillin-resistant staphylococci, and subsequently extended this to treatment of hospital-acquired pneumonia, including ventilator-associated pneumonia due to suspected or proven methicillin-resistant Staphylococcus aureus.

Ceftobiprole: a new beta-lactam antibiotic

The increasing threat of antimicrobial resistance in general, and that of methicillin-resistant Staphylococcus aureus (MRSA) in particular, is raising significant medical, economical and public health challenges worldwide, both within hospitals and throughout the community. These considerations, along with the extensive time and costs associated with the development and approval of new therapeutic agents, represent some of the major reasons why understanding the advantages and limitations of new antibiotics, ensuring their judicious use and maximising their active shelf life should become global priorities. On March 18, 2008, the Food and Drug Administration issued an approvable letter for ceftobiprole, a broad-spectrum beta-lactam antibiotic active against MRSA and other clinically relevant Gram-positive and Gram-negative pathogens. Ceftobiprole is currently available only for parenteral administration, and besides its remarkable antimicrobial spectrum, this antibiotic possesses additional desirable characteristics, such as low propensity to select for resistance, efficacy in animal models of disease and good safety profile. Furthermore, in recently completed clinical trials, ceftobiprole demonstrated non-inferiority to comparator compounds such as vancomycin, and emerged as a promising clinical option of monotherapy for the treatment of complicated skin and skin structure infections and community-acquired pneumonia. Here, we discuss some of the most important clinically relevant findings on ceftobiprole obtained from in vitro studies, animal models of disease and recently completed phase III clinical trials.

Ceftobiprole: a novel cephalosporin with activity against Gram-positive and Gram-negative pathogens, including methicillin-resistant Staphylococcus aureus (MRSA)

Ceftobiprole is a novel broad-spectrum cephalosporin with activity against a wide range of Gram-positive and Gram-negative bacteria, including several resistant species such as methicillin-resistant Staphylococcus aureus and penicillin-resistant Streptococcus pneumoniae. Ceftobiprole is administered intravenously as the prodrug ceftobiprole medocaril, which is almost immediately converted to the active form. It is currently under review by the US Food and Drug Administration (FDA) and is approved in Canada under the trade name Zeftera. The pharmacokinetics of ceftobiprole are non-complex as it displays a two-compartment model, dose proportionality, linear plasma protein binding and negligible accumulation. The volume of distribution is approximately equal to the extracellular fluid volume and it is cleared primarily by glomerular filtration, resulting in a half-life of approximately 3-4h. Ceftobiprole displays a low plasma protein binding of approximately 22%. The efficacy of ceftobiprole was demonstrated in two pivotal studies in patients with complicated skin and skin-structure infections (cSSSIs) that compared ceftobiprole with vancomycin in Gram-positive infections in one study and ceftobiprole with vancomycin plus ceftazidime in Gram-positive and Gram-negative infections in the other. The clinical cure rates were similar for ceftobiprole vs. comparator treatments: 93.3% vs. 93.5% with vancomycin only and 90.5% vs. 90.2% with vancomycin plus ceftazidime. The pharmacokinetic/pharmacodynamic profile supports the use of ceftobiprole to treat a wide range of cSSSIs.

Ceftobiprole: an extended-spectrum anti-methicillin-resistant Staphylococcus aureus cephalosporin

OBJECTIVE

To summarize and evaluate the literature concerning ceftobiprole.

DATA SOURCES

Literature identification was conducted through MEDLINE (1966-February 2008) and International Pharmaceutical Abstracts (1970-February 2008) using the terms ceftobiprole, medocaril, BAL 5788, RO-5788, BAL 9141, RO 63-9141, pyrrolidinone cephalosporin, MRSA, complicated skin and skin-structure infections (cSSSIs), community-acquired pneumonia, and nosocomial pneumonia. Additional publications were identified through a review of articles and abstracts from infectious disease meetings.

STUDY SELECTION AND DATA EXTRACTION

All articles in English were evaluated and all pertinent information was included.

DATA SYNTHESIS

Ceftobiprole medocaril is an extended-spectrum cephalosporin with activity against methicillin-resistant Staphylococcus spp., vancomycin-resistant Staphylococcus aureus, penicillin-resistant Streptococcus pneumoniae, vancomycin-resistant Enterococcus faecalis, Enterobacteriaceae, and Pseudomonas aeruginosa. Inactivity includes extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae and Enterococcus faecium. Preliminary data suggest that ceftobiprole may be effective with a 1-hour infusion of 500 mg every 12 hours for gram-positive infections and 500 mg every 8 hours with a 2-hour infusion for polymicrobial infections. Two clinical trials support these dosing regimens for cSSSIs. Ceftobiprole was noninferior to vancomycin in suspected gram-positive cSSSIs, with cure rates of 93.3% and 93.5%, respectively. Furthermore, ceftobiprole was noninferior to vancomycin and ceftazidime in polymicrobial cSSSIs (cure rates 90.5% vs 90.2%, respectively). Although the total number of adverse effects was similar to those of the comparator, more patients in the ceftobiprole group experienced nausea, vomiting, and dysgeusia.

CONCLUSIONS

The activity of ceftobiprole and limited clinical data suggest that it may be useful as empiric monotherapy for cSSSI and in combination with other antimicrobials in lower respiratory tract infections for which Phase 3 clinical trials are currently exploring. Although not shown in vitro, ceftobiprole may induce resistance due to its broad spectrum of activity. Approval is expected for the treatment of cSSSI.