Cefiderocol in Critically Ill Patients with Multi-Drug Resistant Pathogens: Real-Life Data on Pharmacokinetics and Microbiological Surveillance

Rationale and evidence for the use of new beta-lactam/beta-lactamase inhibitor combinations and cefiderocol in critically ill patients

BACKGROUND

Healthcare-associated infections involving Gram-negative bacteria (GNB) with difficult-to-treat resistance (DTR) phenotype are associated with impaired patient-centered outcomes and poses daily therapeutic challenges in most of intensive care units worldwide. Over the recent years, four innovative β-lactam/β-lactamase inhibitor (BL/BLI) combinations (ceftolozane-tazobactam, ceftazidime-avibactam, imipenem-relebactam and meropenem-vaborbactam) and a new siderophore cephalosporin (cefiderocol) have been approved for the treatment of certain DTR-GNB infections. The literature addressing their microbiological spectrum, pharmacokinetics, clinical efficacy and safety was exhaustively audited by our group to support the recent guidelines of the French Intensive Care Society on their utilization in critically ill patients. This narrative review summarizes the available evidence and unanswered questions on these issues.

METHODS

A systematic search for English-language publications in PUBMED and the Cochrane Library database from inception to November 15, 2022.

RESULTS

These drugs have demonstrated relevant clinical success rates and a reduced renal risk in most of severe infections for whom polymyxin- and/or aminoglycoside-based regimen were historically used as last-resort strategies-namely, ceftazidime-avibactam for infections due to Klebsiella pneumoniae carbapenemase (KPC)- or OXA-48-like-producing Enterobacterales, meropenem-vaborbactam for KPC-producing Enterobacterales, ceftazidime-avibactam/aztreonam combination or cefiderocol for metallo-β-lactamase (MBL)-producing Enterobacterales, and ceftolozane-tazobactam, ceftazidime-avibactam and imipenem-relebactam for non-MBL-producing DTR Pseudomonas aeruginosa. However, limited clinical evidence exists in critically ill patients. Extended-infusion scheme (except for imipenem-relebactam) may be indicated for DTR-GNB with high minimal inhibitory concentrations and/or in case of augmented renal clearance. The potential benefit of combining these agents with other antimicrobials remains under-investigated, notably for the most severe presentations. Other important knowledge gaps include pharmacokinetic information in particular situations (e.g., pneumonia, other deep-seated infections, and renal replacement therapy), the hazard of treatment-emergent resistance and possible preventive measures, the safety of high-dose regimen, the potential usefulness of rapid molecular diagnostic tools to rationalize their empirical utilization, and optimal treatment durations. Comparative clinical, ecological, and medico-economic data are needed for infections in whom two or more of these agents exhibit in vitro activity against the causative pathogen.

CONCLUSIONS

New BL/BLI combinations and cefiderocol represent long-awaited options for improving the management of DTR-GNB infections. Several research axes must be explored to better define the positioning and appropriate administration scheme of these drugs in critically ill patients.

Treatment of critically ill patients with cefiderocol for infections caused by multidrug-resistant pathogens: review of the evidence

Appropriate antibiotic treatment for critically ill patients with serious Gram-negative infections in the intensive care unit is crucial to minimize morbidity and mortality. Several new antibiotics have shown in vitro activity against carbapenem-resistant Enterobacterales (CRE) and difficult-to-treat resistant Pseudomonas aeruginosa. Cefiderocol is the first approved siderophore beta-lactam antibiotic with potent activity against multidrug-resistant, carbapenem-resistant, difficult-to-treat or extensively drug-resistant Gram-negative pathogens, which have limited treatment options. The spectrum of activity of cefiderocol includes drug-resistant strains of Acinetobacter baumannii, P. aeruginosa, Stenotrophomonas maltophilia, Achromobacter spp. and Burkholderia spp. and CRE that produce serine- and/or metallo-carbapenemases. Phase 1 studies established that cefiderocol achieves adequate concentration in the epithelial lining fluid in the lung and requires dosing adjustment for renal function, including patients with augmented renal clearance and continuous renal-replacement therapy (CRRT); no clinically significant drug-drug interactions are expected. The non-inferiority of cefiderocol versus high-dose, extended-infusion meropenem in all-cause mortality (ACM) rates at day 14 was demonstrated in the randomized, double-blind APEKS-NP Phase 3 clinical study in patients with nosocomial pneumonia caused by suspected or confirmed Gram-negative bacteria. Furthermore, the efficacy of cefiderocol was investigated in the randomized, open-label, pathogen-focused, descriptive CREDIBLE-CR Phase 3 clinical study in its target patient population with serious carbapenem-resistant Gram-negative infections, including hospitalized patients with nosocomial pneumonia, bloodstream infection/sepsis, or complicated urinary tract infections. However, a numerically greater ACM rate with cefiderocol compared with BAT led to the inclusion of a warning in US and European prescribing information. Cefiderocol susceptibility results obtained with commercial tests should be carefully evaluated due to current issues regarding their accuracy and reliability. Since its approval, real-world evidence in patients with multidrug-resistant and carbapenem-resistant Gram-negative bacterial infections suggests that cefiderocol can be efficacious in certain critically ill patient groups, such as those requiring mechanical ventilation for COVID-19 pneumonia with subsequently acquired Gram-negative bacterial superinfection, and patients with CRRT and/or extracorporeal membrane oxygenation. In this article, we review the microbiological spectrum, pharmacokinetics/pharmacodynamics, efficacy and safety profiles and real-world evidence for cefiderocol, and look at future considerations for its role in the treatment of critically ill patients with challenging Gram-negative bacterial infections.

Ventilator-associated pneumonia (VAP) and pleural empyema caused by multidrug-resistant Acinetobacter baumannii in HIV and COVID 19 infected patient: A case report

We analyzed the case of a 49-year-old woman with HIV infection off-therapy with poor viro-immunological compensation, not vaccinated for SARS-COV-2, hospitalized for lobar pneumonia and severe COVID19-related respiratory failure in intensive care unit (ICU). The hospitalization was complicated by bacteraemic ventilator-associated pneumonia (VAP) caused by multidrug-resistant Acinetobacter baumannii (MDR-AB) isolated on pleural fluid culture, treated with colistin and cefiderocol for about 3 weeks. The molecular research of MDR-AB on transtracheal aspirate was negative following this therapy. The aim is to show the safety, efficacy and tolerability of colistin-based combination therapy with cefiderocol for Acinetobacter baumannii infection in HIV-infected patient.

Cefiderocol Efficacy in a Real-Life Setting: Single-Centre Retrospective Study

The current carbapenem-resistant gram-negative bacteria (CR-GN) treatment guidelines lack strong evidence about cefiderocol (CFD) efficacy against CR-GN, especially CRAB. The study's purpose is to evaluate the effectiveness of CFD in a real-life setting. We made a single-center retrospective study of 41 patients who received CFD in our hospital for several CR-GN infections. Bloodstream infections (BSI) affected 43.9% (18/41) of patients, while CRAB affected 75.6% (31/41) of isolated CR-GN patients. Thirty-days (30-D) all-causes mortality affected 36.6% (15/41) of patients, while end-of-treatment (EOT) clinical cure affected 56.1% (23/41). Finally, microbiological eradication at EOT affected 56.1% (23/41) of patients. Univariate and multivariate analysis showed that septic shock is an independent factor associated with mortality. Subgroup analyses showed no difference in CFD effectiveness between monotherapy and combination therapy.

Real-Life Data on the Effectiveness and Safety of Cefiderocol in Severely Infected Patients: A Case Series

INTRODUCTION

Real-life data about cefiderocol use to treat extensively drug-resistant bacteria are scarce. We aim to report our early experience in patients with difficult-to-treat infections and limited therapeutic options.

METHODS

Patients treated with cefiderocol from March 2018 to April 2022 in a tertiary-care hospital in Spain were included. Demographic, clinical, and microbiological data were collected up to 90 days after the end of treatment or until death. Survival status was recorded at 30 and 90 days.

RESULTS

Ten patients were included, seven of them critically ill. Ventilator-associated pneumonia (40%) and bacteremia (40%) were the main infections. Multidrug-resistant or extensively drug-resistant P. aeruginosa was the most frequently isolated pathogen (70%, of which six patients were infected with bacteria with difficult-to-treat resistance), followed by A. baumannii, E. coli, and A. xylosoxidans (10% each). Seven patients received combination therapy. Clinical and microbiological cures were achieved in 90% and 80% of patients, respectively. Two previously susceptible strains (20%) developed resistance to cefiderocol. Overall, 30-day and 90-day mortality rates were 10% and 50%, respectively, although two out of five patients died due to the infection. No serious adverse events were reported, except for one patient who developed thrombocytopenia.

CONCLUSION

Cefiderocol seems to be an effective and safe rescue therapy for patients infected with difficult-to-treat pathogens, although there is a definite risk of the emergence of resistance.

Clinical Appraisal of Cefiderocol in the Treatment of Non-fermenting Gram-Negative Bacilli

Purpose of Review

Cefiderocol has a potential role in the treatment of infections caused by increasingly resistant non-fermenting Gram-negative organisms.

Recent Findings

Non-fermenting Gram-negative organisms pose a unique threat to public health given their arsenal of inherent resistance mechanisms. High rates of intrinsic resistance to a wide array of agents, inducible adaptive resistance, and the ability to acquire resistance through horizontal transfer of resistance genes limit the utility of conventional antimicrobial treatment options against non-fermenting Gram-negative infections. Beta-lactams, one of the most reliable classes of antimicrobials, are often rendered inactive by the acquisition of beta-lactamases, with activity potentially restored by beta-lactamase inhibitors. Alteration of intrinsic mechanisms of resistance, porin channels, and efflux pumps reduce the ability of beta-lactamase inhibitors to protect the activity of beta-lactams. This multifactorial nature of resistance exhibited by non-fermenting Gram-negative organisms is difficult to overcome and novel agents are needed to combat this growing threat.

Summary

Cefiderocol is a novel siderophore cephalosporin that utilizes the active transport of ferric iron to gain access to the periplasmic space of Gram-negative organisms. Cefiderocol also has additional modifications that confer some stability in the presence of beta-lactamases, which can be particularly beneficial for infections caused by non-fermenters. Herein, we discuss the potential role of cefiderocol therapy in the management of infections caused by non-fermenting Gram-negative bacilli, with an intentional focus on carbapenem-resistant Acinetobacter baumannii (CRAB), Pseudomonas aeruginosa, and Stenotrophomonas spp.

[Clinical experience using cefiderocol]

BACKGROUND

Infections due to antibiotic-resistant bacteria are threatening modern healthcare, and antibacterial resistance has become one of the greatest threats to public health. In Germany 54,500 patients become infected with antibiotic-resistant bacteria per year, causing about 2400 attributable deaths. Rising resistance in Gram-negative bacteria especially carbapenem-resistant pathogens is of particular concern due to the lack of effective and safe alternative treatment options.

OBJECTIVE

The results from trials and compassionate-use programs with the new antibiotic cefiderocol, which was approved by the European Medicines Agency (EMA) in April 2020 for the treatment of adults with infections caused by aerobic Gram-negative bacteria, are summarized.

RESULTS

The new β‑lactam antibiotic cefiderocol is the first siderophore cephalosporin indicated for the treatment of infections due to aerobic Gram-negative organisms in adults with limited treatment options. Its chemical structure and its unique mechanism of action confer enhanced stability against β‑lactamases including all classes of clinically relevant carbapenemases. In vitro data show high antibacterial activity against multidrug resistant Gram-negative bacteria, Enterobacterales and nonfermenters, including carbapenem-resistant strains. In clinical trials, cefiderocol showed superiority in complicated urinary tract infection in comparison to imipenem and non-inferiority versus meropenem in hospital-acquired/ventilator-associated pneumonia patients and severe infections caused by carbapenem-resistant pathogens.

CONCLUSION

Clinical trial data and case reports identified in the literature search show that cefiderocol is a promising treatment option for severe infections caused by drug-resistant Gram-negative bacteria, particularly carbapenem-resistant bacteria.

Pharmacokinetic of Cefiderocol in Critically Ill Patients Receiving Renal Replacement Therapy: A Case Series

Background: Cefiderocol is a novel parenteral siderophore cephalosporin, demonstrating enhanced activity against multidrug-resistant (MDR) Gram-negative bacteria and difficult-to-treat Acinetobacter baumannii (DTR-AB). Plasma-free trough concentration (fCtrough) over the minimum inhibitory concentration (MIC) was reported as the best pharmacokinetic parameter to describe the microbiological efficacy of cefiderocol. Materials and methods: We retrospectively described the pharmacokinetic and pharmacodynamic profile of three critically ill patients admitted to the intensive care unit, receiving cefiderocol under compassionate use to treat severe DTR-AB infections while undergoing continuous venovenous haemofiltration. Cefiderocol was administrated at a dosage of 2 g every 8 h infused over 3 h. Therapeutic drug monitoring (TDM) was assessed at the steady state. Cthrough was evaluated by assuming a plasma protein binding of 58.0%. The fCmin/MIC was calculated assuming a cefiderocol MIC equal to the PK-PD breakpoint of susceptibility ≤ 2. The association between the PK/PD parameters and microbiological outcome was assessed. Results: fCtrough/MIC were >12 in 2 patients and 2.9 in the 1 who rapidly recovered from renal failure. Microbiological cure occurred in 3/3 of patients. None of the 3 patients died within 30 days. Conclusions: A cefiderocol dosage of 2 g q8 h in critically ill patients with AKI undergoing CVVH may bring about a very high plasma concentration, corresponding to essentially 100% free time over the MIC for DTR-AB.

Pharmacokinetics, Pharmacodynamics, and Dosing Considerations of Novel β-Lactams and β-Lactam/β-Lactamase Inhibitors in Critically Ill Adult Patients: Focus on Obesity, Augmented Renal Clearance, Renal Replacement Therapies, and Extracorporeal Membrane Oxygenation

OBJECTIVE

Dose optimization of novel β-lactam antibiotics (NBLA) has become necessary given the increased prevalence of multidrug-resistant infections in intensive care units coupled with the limited number of available treatment options. Unfortunately, recommended dose regimens of NBLA based on PK/PD indices are not well-defined for critically ill patients presenting with special situations (i.e., obesity, extracorporeal membrane oxygenation (ECMO), augmented renal clearance (ARC), and renal replacement therapies (RRT)). This review aimed to discuss and summarize the available literature on the PK/PD attained indices of NBLA among critically ill patients with special circumstances.

DATA SOURCES

PubMed, MEDLINE, Scopus, Google Scholar, and Embase databases were searched for studies published between January 2011 and May 2022.

STUDY SELECTION AND DATA EXTRACTION

Articles relevant to NBLA (i.e., ceftolozane/tazobactam, ceftazidime/avibactam, cefiderocol, ceftobiprole, imipenem/relebactam, and meropenem/vaborbactam) were selected. The MeSH terms of "obesity", "augmented renal clearance", "renal replacement therapy", "extracorporeal membrane oxygenation", "pharmacokinetic", "pharmacodynamic" "critically ill", and "intensive care" were used for identification of articles. The search was limited to adult humans' studies that were published in English. A narrative synthesis of included studies was then conducted accordingly.

DATA SYNTHESIS

Available evidence surrounding the use of NBLA among critically ill patients presenting with special situations was limited by the small sample size of the included studies coupled with high heterogeneity. The PK/PD target attainments of NBLA were reported to be minimally affected by obesity and/or ECMO, whereas the effect of renal functionality (in the form of either ARC or RRT) was more substantial.

CONCLUSION

Critically ill patients presenting with special circumstances might be at risk of altered NBLA pharmacokinetics, particularly in the settings of ARC and RRT. More robust, well-designed trials are still required to define effective dose regimens able to attain therapeutic PK/PD indices of NBLA when utilized in those special scenarios, and thus aid in improving the patients' outcomes.

Safety and efficacy of cefiderocol for off-label treatment indications: A systematic review

PURPOSE

Cefiderocol is a siderophore cephalosporin recently approved by the United States Food and Drug Administration for the treatment of hospital- and ventilator-acquired bacterial pneumonia and complicated urinary tract infections. However, there is potential for cefiderocol utility for a variety of other infections. The purpose of this systematic review was to identify literature examining the safety and efficacy of cefiderocol for off-label indications.

METHODS

The PRISMA guidelines were utilized for reporting. Databases searched included PubMed, Scopus, and Embase, from inception to September 2021. Manuscripts describing cefiderocol off-label use in clinical settings were included. Exclusion criteria were studies focused on labeled indications, animal studies, pharmacodynamic/pharmacokinetic studies, in vitro or laboratory studies, and manuscripts in languages other than English or Arabic. Each stage of review utilized two independent investigators, with conflicts resolved and critical appraisal performed. Data regarding presentation, clinical course, and infection characteristics were extracted and descriptively analyzed.

RESULTS

The search identified a total of 985 records, narrowed to a final set of 27 studies. Among studies included were 18 (66.7%) case reports, 8 (29.6%) case series, and 1 (3.7%) phase 3 clinical trial. Cefiderocol was most frequently used off-label for bacteremia/sepsis with or without an identified source in 51 (67.1%) out of a total of 76 included patients. Among case series/reports with available data, 43 of 53 patients (81.1%) received combination antibiotic therapy. The most common pathogens identified included multi/extensively drug-resistant Pseudomonas aeruginosa and/or Acinetobacter baumannii. Various clinical end points were reported, while microbiological end points were reported in 18 (66.7%) studies. Cefiderocol-related side effects were uncommon and rarely use-limiting.

CONCLUSIONS

This systematic review depicts relative clinical effectiveness of off-label cefiderocol, most commonly for P. aeruginosa and A. baumannii infections as combination antibiotic therapy. Further study is needed to elucidate the safety and efficacy of cefiderocol across an expanded set of patients and indications.

Cefiderocol Protects against Cytokine- and Endotoxin-Induced Disruption of Vascular Endothelial Cell Integrity in an In Vitro Experimental Model

The severe course of bloodstream infections with Gram-negative bacilli can lead to organ dysfunctions and compromise the integrity of the vascular barrier, which are the hallmarks of sepsis. This study aimed to investigate the potential effect of cefiderocol on the barrier function of vascular endothelial cells (vECs) in an in vitro experimental set-up. Human umbilical vein cells (HUVECs), co-cultured with erythrocyte-depleted whole blood for up to 48 h, were activated with tumor necrosis factor-alpha (TNF-α) or lipopolysaccharide (LPS) to induce endothelial damage in the absence or presence of cefiderocol (concentrations of 10, 40 and 70 mg/L). The endothelial integrity was quantified using transendothelial electrical resistance (TEER) measurement, performed at 0, 3, 24 and 48 h after stimulation. Stimulation with TNF-α and LPS increased the endothelial permeability assessed by TEER at 24 and 48 h of co-culture. Furthermore, cefiderocol reduces interleukin-6 (IL-6), interleukin-1β (IL-1β) and TNF-α release in peripheral blood mononuclear cells (PBMCs) following LPS stimulation in a dose-dependent manner. Collectively, the data suggest that cefiderocol may have an influence on the cellular immune response and might support the maintenance of vEC integrity during inflammation associated with infection with Gram-negative bacteria, which warrants further investigations.

Cefiderocol for the Treatment of Multidrug-Resistant Gram-Negative Bacteria: A Systematic Review of Currently Available Evidence

Cefiderocol is a novel synthetic siderophore-conjugated antibiotic that hijacks the bacterial iron transport systems facilitating drug entry into cells, achieving high periplasmic concentrations. This systematic review analyzed the currently available literature on cefiderocol. It summarized in vitro susceptibility data, in vivo antimicrobial activity, pharmacokinetics/pharmacodynamics (PK/PD), clinical efficacy, safety and resistance mechanisms of cefiderocol. Cefiderocol has potent in vitro and in vivo activity against multidrug-resistant (MDR) Gram-negative bacteria, including carbapenem-resistant isolates. But New Delhi Metallo-β-lactamase (NDM)- positive isolates showed significantly higher MICs than other carbapenemase-producing Enterobacterales, with a susceptible rate of 83.4% for cefiderocol. Cefiderocol is well-tolerated, and the PK/PD target values can be achieved using a standard dose regimen or adjusted doses according to renal function. Clinical trials demonstrated that cefiderocol was non-inferiority to the comparator drugs in treating complicated urinary tract infection and nosocomial pneumonia. Case reports and series showed that cefiderocol was a promising therapeutic agent in carbapenem-resistant infections. However, resistant isolates and reduced susceptibility during treatment to cefiderocol have already been reported. In conclusion, cefiderocol is a promising powerful weapon for treating MDR recalcitrant infections.

Human Serum Proteins and Susceptibility of Acinetobacter baumannii to Cefiderocol: Role of Iron Transport

Cefiderocol, a recently introduced antibiotic, has a chemical structure that includes a cephalosporin that targets cell wall synthesis and a chlorocatechol siderophore moiety that facilitates cell penetration by active iron transporters. Analysis of the effect that human serum, human serum albumin, and human pleural fluid had on growing Acinetobacter baumannii showed that genes related to iron uptake were down-regulated. At the same time, β-lactamase genes were expressed at higher levels. The minimum inhibitory concentrations of this antimicrobial in A. baumannii cells growing in the presence of human serum, human serum albumin, or human pleural fluid were higher than those measured when these fluids were absent from the culture medium. These results correlate with increased expression levels of β-lactamase genes and the down-regulation of iron uptake-related genes in cultures containing human serum, human serum albumin, or human pleural fluid. These modifications in gene expression could explain the less-than-ideal clinical response observed in patients with pulmonary or bloodstream A. baumannii infections. The exposure of the infecting cells to the host’s fluids could cause reduced cefiderocol transport capabilities and increased resistance to β-lactams. The regulation of genes that could impact the A. baumannii susceptibility to cefiderocol, or other antibacterials, is an understudied phenomenon that merits further investigation.

Clinical Pharmacokinetics and Pharmacodynamics of Cefiderocol

Cefiderocol is a new broad-spectrum cephalosporin antibiotic with promising activity against various Gram-negative bacteria including carbapenem-resistant strains. A chlorocatechol group in the C-3 side chain provides cefiderocol with a siderophore activity, improving its stability against β-lactamases and facilitating the transportation of cefiderocol across outer bacterial membranes. Cefiderocol shows linear pharmacokinetics over a broad range of clinically relevant doses, with unchanged renal excretion constituting the main route of elimination. Geometric means (coefficient of variation) of the volume of distribution and clearance in individuals with normal kidney function were 15.8 (15%) L and 4.70 (27%) L/h, respectively. In patients with end-stage renal disease, clearance was 1.10 (24%) L/h. Time above the minimum inhibitory concentration is the main predictor of efficacy. There is no evidence for clinically relevant interactions of cefiderocol with other drugs mediated by metabolizing enzymes or drug transporters. Simulations based on population pharmacokinetic modeling suggest that dosing regimens should be adjusted based on kidney function to optimize therapeutic exposure to cefiderocol. Clinical efficacy trials indicated that cefiderocol is non-inferior to imipenem/cilastatin in the treatment of complicated urinary tract infections and acute uncomplicated pyelonephritis, and to meropenem in the treatment of nosocomial pneumonia. In the one study currently available, cefiderocol performed similarly to the best available therapy in the treatment of severe carbapenem-resistant Gram-negative infections regarding clinical and microbiological efficacy. In summary, cefiderocol shows favorable pharmacokinetic/pharmacodynamic properties and an acceptable safety profile, suggesting that cefiderocol might be a viable option to treat infections with bacteria resistant to other antibiotics.