Ceftolozane-tazobactam and Fosfomycin for rescue treatment of otogenous meningitis caused by XDR Pseudomonas aeruginosa: Case report and review of the literature

Intravenous Fosfomycin as Adjunctive Therapy for Gram-Negative Bacteria Bloodstream Infections: A Propensity Score Adjusted Retrospective Cohort Study

BACKGROUND

The role of intravenous fosfomycin (iv-FOS) as a part of combination therapy for Gram-negative bacteria bloodstream infections (GNB-BSI) needs to be evaluated in clinical practice, as in vitro data show potential efficacy.

METHODS

All consecutive patients with a GNB-BSI from 01 January 2021 to 01 April 2023 were included. Primary outcome was 30-day mortality. A Cox regression analysis was used to identify predictors of mortality; an inverse-probability of treatment-weighting (IPTW) analysis was also performed.

RESULTS

Overall, 363 patients were enrolled: 211 (58%) males, with a median (q1-q3) age of 68 (57-78) years, and a median Charlson comorbidity index of 5 (3-7). At GNB-BSI onset, the median SOFA score was 5 (2-7) and 122 patients (34%) presented with septic shock. Pathogens were principally Klebsiella pneumoniae (42%), Escherichia coli (28%) and Pseudomonas aeruginosa (17%); of them, 36% were carbapenem-resistant. The therapy included carbapenems (40%), cephalosporins (37%) and beta-lactams/beta-lactamases-inhibitors (19%); a combination with iv-FOS was used in 98 (27%) cases at a median dosage of 16 (16-18) g/daily. The use of iv-FOS was not associated with reduced crude mortality (21% vs 29%, P = 0.147). However, on multivariable Cox-regression, combination therapy with iv-FOS resulted in protection for mortality (aHR 0.51, 95% CI 0.28-0.92), but not other combo-therapies (HR 0.69, 95% CI 0.44-1.16). This result was also confirmed with the IPTW-adjusted Cox model (aHR 0.52, 95% CI 0.31-0.91). Subgroup analysis suggested a benefit in severe infections (SOFA > 6, PITT ≥ 4) and when iv-FOS was initiated within 24 hours of GNB-BSI onset.

CONCLUSIONS

Fosfomycin in combination therapy for GNB-BSI may have a role in improving survival. These results justify the development of further clinical trials.

Intravenous Fosfomycin for Systemic Multidrug-Resistant Pseudomonas aeruginosa Infections

Human Pseudomonas infections have high morbidity and mortality rates. Pseudomonas bacteria can cause sepsis or septic shock; they produce biofilm and commonly exhibit a multidrug-resistant phenotype. The choice of antimicrobial therapy in many cases is challenging, and deep knowledge of clinical, microbiological, and pharmacological issues is required. Intravenous fosfomycin is being repurposed in a combination given its favorable pharmacokinetic/pharmacodynamic properties (a small molecule with favorable kinetic both in bloodstream infection and in deep-seated infections), antibiofilm activity, and its interesting synergistic effects with other antimicrobials. Recent literature on epidemiological, microbiological, pharmacological, and clinical data on intravenous fosfomycin therapy against Pseudomonas is herein reviewed and discussed.

Age of Antibiotic Resistance in MDR/XDR Clinical Pathogen of Pseudomonas aeruginosa

Antibiotic resistance in Pseudomonas aeruginosa remains one of the most challenging phenomena of everyday medical science. The universal spread of high-risk clones of multidrug-resistant/extensively drug-resistant (MDR/XDR) clinical P. aeruginosa has become a public health threat. The P. aeruginosa bacteria exhibits remarkable genome plasticity that utilizes highly acquired and intrinsic resistance mechanisms to counter most antibiotic challenges. In addition, the adaptive antibiotic resistance of P. aeruginosa, including biofilm-mediated resistance and the formation of multidrug-tolerant persisted cells, are accountable for recalcitrance and relapse of infections. We highlighted the AMR mechanism considering the most common pathogen P. aeruginosa, its clinical impact, epidemiology, and save our souls (SOS)-mediated resistance. We further discussed the current therapeutic options against MDR/XDR P. aeruginosa infections, and described those treatment options in clinical practice. Finally, other therapeutic strategies, such as bacteriophage-based therapy and antimicrobial peptides, were described with clinical relevance.

Multimodal silver-chitosan-acylase nanoparticles inhibit bacterial growth and biofilm formation by Gram-negative Pseudomonas aeruginosa bacterium

Pseudomonas aeruginosa bacteria originate severe infections in hospitalized patients and those with chronic debilitating diseases leading to increased morbidity and mortality, longer hospitalization and huge financial burden to the healthcare system. The clinical relevance of P. aeruginosa infections is increased by the capability of this bacterium to grow in biofilms and develop multidrug resistant mechanisms that preclude conventional antibiotic treatments. Herein, we engineered novel multimodal nanocomposites that integrate in the same entity antimicrobial silver nanoparticles (NPs), the intrinsically antimicrobial, but biocompatible biopolymer chitosan, and the anti-infective quorum quenching enzyme acylase I. Acylase present in the NPs specifically degraded the signal molecules governing bacterial cell-to-cell communication and inhibited by ∼ 55 % P. aeruginosa biofilm formation, while the silver/chitosan template altered the integrity of bacterial membrane, leading to complete eradication of planktonic bacteria. The innovative combination of multiple bacteria targeting modalities resulted in 100-fold synergistic enhancement of the antimicrobial efficacy of the nanocomposite at lower and non-hazardous towards human skin cells concentrations, compared to the silver/chitosan NPs alone.

The efficacy and safety of ceftolozane-tazobactam in the treatment of GNB infections: a systematic review and meta-analysis of clinical studies

BACKGROUND

Ceftolozane-tazobactam is a novel cephalosporin/β-lactamase inhibitor combination with activity against Gram-negative bacteria (GNB). We aimed to comprehensively evaluate the clinical efficacy and safety of ceftolozane-tazobactam in treating GNB infections in adult patients.

RESEARCH DESIGN AND METHODS

PubMed, Embase, and Cochrane databases were retrieved until August 2022. Randomized trials and non-randomized controlled studies evaluating ceftolozane-tazobactam and its comparators in adult patients with GNB infections were included.

RESULTS

A total of 13 studies were included. Overall, patients receiving ceftolozane-tazobactam had significant advantages in clinical cure (odds ratio [OR], 1.62; 95% CI, 1.05-2.51) and microbiological eradication (OR, 1.43; 95% CI, 1.19-1.71), especially in Pseudomonas aeruginosa-infected patients. Ceftolozane-tazobactam had a significant advantage in clinical success or microbial eradication compared with polymyxin/aminoglycosides (PL/AG) or levofloxacin. There were no significant differences in adverse events (AEs), Clostridium difficile infection (CDI), and mortality between ceftolozane-tazobactam and comparators. Notably, ceftolozane-tazobactam showed a significantly lower risk of acute kidney injury compared with PL/AG.

CONCLUSIONS

Ceftolozane-tazobactam showed excellent clinical and microbiological efficacy in treating GNB, especially P. aeruginosa-induced infections. The overall safety profile of ceftolozane-tazobactam was comparable to other antimicrobials, with no increased risk of CDI and obvious advantage over antibacterial agents with high nephrotoxicity.

The Blood-Brain Barrier and Pharmacokinetic/Pharmacodynamic Optimization of Antibiotics for the Treatment of Central Nervous System Infections in Adults

Bacterial central nervous system (CNS) infections are serious and carry significant morbidity and mortality. They encompass many syndromes, the most common being meningitis, which may occur spontaneously or as a consequence of neurosurgical procedures. Many classes of antimicrobials are in clinical use for therapy of CNS infections, some with established roles and indications, others with experimental reporting based on case studies or small series. This review delves into the specifics of the commonly utilized antibacterial agents, updating their therapeutic use in CNS infections from the pharmacokinetic and pharmacodynamic perspectives, with a focus on the optimization of dosing and route of administration that have been described to achieve good clinical outcomes. We also provide a concise synopsis regarding the most focused, clinically relevant information as pertains to each class and subclass of antimicrobial therapeutics. CNS infection morbidity and mortality remain high, and aggressive management is critical in ensuring favorable patient outcomes while averting toxicity and upholding patient safety.

Off-Label Use of Ceftolozane/Tazobactam for the Successful Treatment of Healthcare-Associated Meningitis Caused by Extensively Drug-Resistant Pseudomonas aeruginosa in a Polytraumatized Patient—A Case Report

Background: Hospital-acquired infections with extensively drug-resistant (XDR) Pseudomonas aeruginosa (PA) have become a worrisome concern because of unfavorable outcomes and limited antimicrobial treatment options. Studies with new antimicrobial substances against XDR-PA show very promising results in different infection types, but the data for central nervous system (CNS) infections are scarce. Case presentation: Here, we report the case of a young patient with healthcare-associated meningitis caused by XDR-PA following severe craniocerebral injury. An off-label use of high-dose ceftolozane/tazobactam (C/T) monotherapy was administered for 10 days in parallel with source-controlling measures. Clinical and microbial recovery could be accomplished promptly. Conclusion: In patients with hospital-acquired CNS infections due to XDR-PA, C/T might be a new, safe and effective alternative with fewer adverse effects compared to older polymyxin- or aminoglycoside-based regimens.

Real-world use of ceftolozane/tazobactam: a systematic literature review

Background

Antibacterial-resistant gram-negative infections are a serious risk to global public health. Resistant Enterobacterales and Pseudomonas aeruginosa are highly prevalent, particularly in healthcare settings, and there are limited effective treatment options. Patients with infections caused by resistant pathogens have considerably worse outcomes, and incur significantly higher costs, relative to patients with susceptible infections. Ceftolozane/tazobactam (C/T) has established efficacy in clinical trials. This review aimed to collate data on C/T use in clinical practice.

Methods

This systematic literature review searched online biomedical databases for real-world studies of C/T for gram-negative infections up to June 2020. Relevant study, patient, and treatment characteristics, microbiology, and efficacy outcomes were captured.

Results

There were 83 studies comprising 3,701 patients were identified. The most common infections were respiratory infections (52.9% of reported infections), urinary tract infections (UTIs; 14.9%), and intra-abdominal infections (IAIs; 10.1%). Most patients included were seriously ill and had multiple comorbidities. The majority of patients had infections caused by P.aeruginosa (90.7%), of which 86.0% were antimicrobial-resistant. C/T was used as both a 1.5 g q8h and 3 g q8h dose, for a median duration of 7–56 days (varying between studies). Outcome rates were comparable between studies: clinical success rates ranged from 45.7 to 100.0%, with 27 studies (69%) reporting clinical success rates of > 70%; microbiological success rates ranged from 31 to 100%, with 14 studies (74%) reporting microbiological success rates of > 70%. Mortality rates ranged from 0 to 50%, with 31 studies (69%) reporting mortality rates of ≤ 20%. In comparative studies, C/T was as effective as aminoglycoside- or polymyxin-based regimens, and in some instances, significantly more effective.

Conclusions

The studies identified in this review demonstrate that C/T is effective in clinical practice, despite the diverse group of seriously ill patients, different levels of resistance of the pathogens treated, and varying dosing regimens used. Furthermore, comparative studies suggest that C/T offers a successful alternative to standard of care (SoC).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-021-00933-8.

Cerebrospinal Fluid Penetration of Ceftolozane-Tazobactam in Critically Ill Patients with an Indwelling External Ventricular Drain

The aim of this study was to describe the pharmacokinetics of ceftolozane-tazobactam in plasma and cerebrospinal fluid (CSF) of infected critically ill patients. In a prospective observational study, critically ill patients (≥18 years) with an indwelling external ventricular drain received a single intravenous dose of 3.0 g ceftolozane-tazobactam. Serial plasma and CSF samples were collected for measurement of unbound ceftolozane and tazobactam concentration by liquid chromatography.

The aim of this study was to describe the pharmacokinetics of ceftolozane-tazobactam in plasma and cerebrospinal fluid (CSF) of infected critically ill patients. In a prospective observational study, critically ill patients (≥18 years) with an indwelling external ventricular drain received a single intravenous dose of 3.0 g ceftolozane-tazobactam. Serial plasma and CSF samples were collected for measurement of unbound ceftolozane and tazobactam concentration by liquid chromatography. Unbound concentration-time data were modeled in R using Pmetrics. Dosing simulations were performed using the final model. A three-compartment model adequately described the data from 10 patients. For ceftolozane, the median (interquartile range [IQR]) area under the unbound concentration-time curve from time zero to infinity (fAUC_0-inf) in the CSF and plasma were 30 (19 to 128) h·mg/liter and 323 (183 to 414) h·mg/liter, respectively. For tazobactam, these values were 5.6 (2 to 24) h·mg/liter and 52 (36 to 80) h·mg/liter, respectively. Mean ± standard deviation (SD) CSF penetration ratios were 0.2 ± 0.2 and 0.2 ± 0.26 for ceftolozane and tazobactam, respectively. With the regimen of 3.0 g every 8 h, a probability of target attainment (PTA) of ≥0.9 for 40% fT_>MIC in the CSF was possible only when MICs were ≤0.25 mg/liter. The CSF cumulative fractional response for Pseudomonas aeruginosa-susceptible MIC distribution was 73%. The tazobactam PTA for the minimal suggested exposure of 20% fT_{>1 mg/liter} was 12%. The current maximal dose of ceftolozane-tazobactam (3.0 g every 8 h) does not provide adequate CSF exposure for treatment of Gram-negative meningitis or ventriculitis unless the MIC for the causative pathogen is very low (≤0.25 mg/liter).

Plasma and Cerebrospinal Fluid Therapeutic Drug Monitoring of Ceftolozane and Tazobactam During Treatment of Multidrug-Resistant Pseudomonas aeruginosa Meningitis

We report a case of multidrug-resistant Pseudomonas aeruginosa meningitis treated with ceftolozane-tazobactam with concomitant therapeutic drug monitoring of plasma and cerebral spinal fluid. The data suggest that ceftolozane-tazobactam may be an option for select central nervous system infections; however, treatment decisions should be interpreted on a case-by-case basis.

Continuous infusion of ceftolozane-tazobactam resulted in high cerebrospinal fluid concentrations of ceftolozane in a patient with multidrug-resistant Pseudomonas aeruginosa meningitis

Multidrug-resistant Pseudomonas aeruginosa has limited treatment options. Treatment of healthcare-associated meningitis requires agents active against the organism in vitro and able to penetrate the cerebrospinal fluid adequately. Ceftolozane-tazobactam has been recently approved to treat various Gram-negative organisms, including Pseudomonas aeruginosa; however, ceftolozane's penetration into human cerebrospinal fluid is unknown. Here, we present a case of a patient with multidrug-resistant Pseudomonas aeruginosa meningitis treated with a continuous infusion of ceftolozane-tazobactam. Samples of both serum and cerebrospinal fluid were analyzed for ceftolozane concentration on continuous infusion. Cerebrospinal fluid concentrations of ceftolozane were 83% of that in serum. Treatment with ceftolozane-tazobactam, along with combinations of other antibiotics, resulted in clearance of organism from the patient's cerebrospinal fluid and marked decrease in inflammatory cells. Studies are warranted to determine the efficacy of ceftolozane-tazobactam for patients with healthcare-associated meningitis.

Ceftazidime-Avibactam in Combination With Fosfomycin: A Novel Therapeutic Strategy Against Multidrug-Resistant Pseudomonas aeruginosa

Previously, by targeting penicillin-binding protein 3, Pseudomonas-derived cephalosporinase (PDC), and MurA with ceftazidime-avibactam-fosfomycin, antimicrobial susceptibility was restored among multidrug-resistant (MDR) Pseudomonas aeruginosa. Herein, ceftazidime-avibactam-fosfomycin combination therapy against MDR P. aeruginosa clinical isolate CL232 was further evaluated. Checkerboard susceptibility analysis revealed synergy between ceftazidime-avibactam and fosfomycin. Accordingly, the resistance elements present and expressed in P. aeruginosa were analyzed using whole-genome sequencing and transcriptome profiling. Mutations in genes that are known to contribute to β-lactam resistance were identified. Moreover, expression of blaPDC, the mexAB-oprM efflux pump, and murA were upregulated. When fosfomycin was administered alone, the frequency of mutations conferring resistance was high; however, coadministration of fosfomycin with ceftazidime-avibactam yielded a lower frequency of resistance mutations. In a murine infection model using a high bacterial burden, ceftazidime-avibactam-fosfomycin significantly reduced the P. aeruginosa colony-forming units (CFUs), by approximately 2 and 5 logs, compared with stasis and in the vehicle-treated control, respectively. Administration of ceftazidime-avibactam and fosfomycin separately significantly increased CFUs, by approximately 3 logs and 1 log, respectively, compared with the number at stasis, and only reduced CFUs by approximately 1 log and 2 logs, respectively, compared with the number in the vehicle-treated control. Thus, the combination of ceftazidime-avibactam-fosfomycin was superior to either drug alone. By employing a "mechanism-based approach" to combination chemotherapy, we show that ceftazidime-avibactam-fosfomycin has the potential to offer infected patients with high bacterial burdens a therapeutic hope against infection with MDR P. aeruginosa that lack metallo-β-lactamases.

Real-World Experience with Ceftolozane-Tazobactam for Multidrug-Resistant Gram-Negative Bacterial Infections

Our objective was to describe the prescribing practices, clinical characteristics, and outcomes of patients treated with ceftolozane-tazobactam (C/T) for multidrug-resistant (MDR) Gram-negative infections. This was a multicenter, retrospective, cohort study at eight U.S. medical centers (2015 to 2019). Inclusion criteria were age ≥18 years and receipt of C/T (≥72 hours) for suspected or confirmed MDR Gram-negative infection. The primary efficacy outcome, evaluated among patients with MDR Pseudomonas aeruginosa infections, was composite clinical failure, namely, 30-day all-cause mortality, 30-day recurrence, and/or failure to resolve or improve infection signs or symptoms after C/T treatment. In total, 259 patients were included, and P. aeruginosa was isolated in 236 (91.1%). The MDR and extremely drug-resistant phenotypes were detected in 95.8% and 37.7% of P. aeruginosa isolates, respectively. The most common infection source was the respiratory tract (62.9%). High-dose C/T was used in 71.2% of patients with a respiratory tract infection (RTI) overall but in only 39.6% of patients with an RTI who required C/T renal dose adjustment. In the primary efficacy population (n = 226), clinical failure and 30-day mortality occurred in 85 (37.6%) and 39 (17.3%) patients, respectively. New C/T MDR P. aeruginosa resistance was detected in 3 of 31 patients (9.7%) with follow-up cultures. Hospital-acquired infection and Acute Physiological and Chronic Health Evaluation II (APACHE II) score were independently associated with clinical failure (adjusted odds ratio [aOR], 2.472 and 95% confidence interval [CI], 1.322 to 4.625; and aOR, 1.068 and 95% CI, 1.031 to 1.106, respectively). Twenty-five (9.7%) patients experienced ≥1 adverse effect (9 acute kidney injury, 13 Clostridioides difficile infection, 1 hepatotoxicity, 2 encephalopathy, and 2 gastrointestinal intolerance). C/T addresses an unmet medical need in patients with MDR Gram-negative infections.

Efficacy and safety of ceftolozane/tazobactam as therapeutic option for complicated skin and soft tissue infections by MDR/XDR Pseudomonas aeruginosa in patients with impaired renal function: a case series from a single-center experience

INTRODUCTION

Pseudomonas aeruginosa (PA) is a known cause of skin and soft tissue infections (SSTIs). Therapeutic options against multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of PA are limited, especially in patients with impaired renal function. Ceftolozane/tazobactam (C/T) is a novel beta-lactam/beta-lactamase inhibitor with powerful anti-PA activity. Thanks to its characteristics, it appears to be the best available anti-pseudomonal drug in many clinical scenarios. A case series of four adult patients followed between January 2018 and May 2019 is reported. All subjects presented complicated SSTIs by MDR- or XDR-PA and were affected by chronic kidney disease.

RESULTS

C/T was used as a monotherapy in three cases and in combination regimen in the remaining case. In two cases, C/T was the first-line option, in the remaining ones was the salvage treatment. All patients were successfully treated without worsening of renal function and without any other adverse events.

CONCLUSIONS

C/T may represent a useful option against MDR- and XDR-PA strains responsible of complicated SSTIs in patients affected by impaired renal function.

Ceftolozane/tazobactam for difficult-to-treat Pseudomonas aeruginosa infections: A systematic review of its efficacy and safety for off-label indications

Ceftolozane/tazobactam (C/T) is a novel β-lactam/β-lactamase inhibitor combination targeting Enterobacteriaceae and Pseudomonas aeruginosa (PA). It is approved in adult patients for complicated urinary tract infections (cUTIs) and complicated intra-abdominal infections (cIAIs) as well as for nosocomial pneumonia. It displays excellent activity against PA, even multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains. The aim of this systematic review (PROSPERO protocol no. CRD42019117350) was to summarise the available evidence from observational studies regarding the efficacy and safety of off-label use of C/T when administered to treat MDR- or XDR-PA infections. The MEDLINE and Embase databases were screened from inception up to 30 June 2019. Studies were deemed eligible if they described real-life use of C/T in the case of MDR- or XDR-PA infections for non-approved indications. Exclusion criteria were cIAIs, cUTIs, pneumonia (unless occurring in a paediatric population) and infections by non-MDR/XDR-PA. Thirty articles fulfilled the inclusion criteria. In total, 130 cases of MDR- or XDR-PA infections treated with C/T in 128 patients were described. The most relevant off-label uses were skin and soft-tissue infection (49/30; 37.7%), bone and joint infection (42/130; 32.3%) and bloodstream infection (23/130; 17.7%). Five cases involved paediatric patients. The overall clinical success rate was 76.2%. The most common adverse event was hypokalaemia (4.2%, in 48 evaluable cases). C/T may be a useful therapeutic option for difficult-to-treat infections by PA even outside the framework of approved indications. Further studies are necessary to better define new indications for the drug.

Epidemiology and Treatment of Multidrug-Resistant and Extensively Drug-Resistant Pseudomonas aeruginosa Infections

In recent years, the worldwide spread of the so-called high-risk clones of multidrug-resistant or extensively drug-resistant (MDR/XDR) Pseudomonas aeruginosa has become a public health threat. This article reviews their mechanisms of resistance, epidemiology, and clinical impact and current and upcoming therapeutic options. In vitro and in vivo treatment studies and pharmacokinetic and pharmacodynamic (PK/PD) models are discussed. Polymyxins are reviewed as an important therapeutic option, outlining dosage, pharmacokinetics and pharmacodynamics, and their clinical efficacy against MDR/XDR P. aeruginosa infections. Their narrow therapeutic window and potential for combination therapy are also discussed. Other "old" antimicrobials, such as certain β-lactams, aminoglycosides, and fosfomycin, are reviewed here. New antipseudomonals, as well as those in the pipeline, are also reviewed. Ceftolozane-tazobactam has clinical activity against a significant percentage of MDR/XDR P. aeruginosa strains, and its microbiological and clinical data, as well as recommendations for improving its use against these bacteria, are described, as are those for ceftazidime-avibactam, which has better activity against MDR/XDR P. aeruginosa, especially strains with certain specific mechanisms of resistance. A section is devoted to reviewing upcoming active drugs such as imipenem-relebactam, cefepime-zidebactam, cefiderocol, and murepavadin. Finally, other therapeutic strategies, such as use of vaccines, antibodies, bacteriocins, anti-quorum sensing, and bacteriophages, are described as future options.