Ceftolozane/tazobactam for pulmonary exacerbation in a 63-year-old cystic fibrosis patient with renal insufficiency and an elevated MIC to Pseudomonas aeruginosa

Novel Approaches to Multidrug-Resistant Infections in Cystic Fibrosis

Patients with cystic fibrosis (CF) often develop respiratory tract infections with pathogenic multidrug-resistant organisms (MDROs) such as methicillin-resistant Staphylococcus aureus, and a variety of gram-negative organisms that include Pseudomonas aeruginosa, Burkholderia sp., Stenotrophomonas maltophilia, Achromobacter xylosoxidans, and nontuberculous mycobacteria (NTM). Despite the introduction of new therapies to address underlying cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction, MDRO infections remain a problem and novel antimicrobial interventions are still needed. Therapeutic approaches include improving the efficacy of existing drugs by adjusting the dose based on differences in CF patient pharmacokinetics/pharmacodynamics, the development of inhaled formulations to reduce systemic adverse events, and the use of newer beta-lactam/beta-lactamase combinations. Alternative innovative therapeutic approaches include the use of gallium and bacteriophages to treat MDRO pulmonary infections including those with extreme antibiotic resistance. However, additional clinical trials are required to determine the optimal dosing and efficacy of these different strategies and to identify patients with CF most likely to benefit from these new treatment options.

Ceftolozane/tazobactam plus tobramycin against free-floating and biofilm bacteria of hypermutable Pseudomonas aeruginosa epidemic strains: Resistance mechanisms and synergistic activity

OBJECTIVE

Acute exacerbations of biofilm-associated Pseudomonas aeruginosa infections in cystic fibrosis (CF) have limited treatment options. Ceftolozane/tazobactam (alone and with a second antibiotic) has not yet been investigated against hypermutable clinical P. aeruginosa isolates in biofilm growth. This study aimed to evaluate, using an in vitro dynamic biofilm model, ceftolozane/tazobactam alone and in combination with tobramycin at simulated representative lung fluid pharmacokinetics against free-floating (planktonic) and biofilm states of two hypermutable P. aeruginosa epidemic strains (LES-1 and CC274) from adolescents with CF.

METHODS

Regimens were intravenous ceftolozane/tazobactam 4.5 g/day continuous infusion, inhaled tobramycin 300 mg 12-hourly, intravenous tobramycin 10 mg/kg 24-hourly, and both ceftolozane/tazobactam-tobramycin combinations. The isolates were susceptible to both antibiotics. Total and less-susceptible free-floating and biofilm bacteria were quantified over 120-168 h. Ceftolozane/tazobactam resistance mechanisms were investigated by whole-genome sequencing. Mechanism-based modelling of bacterial viable counts was performed.

RESULTS

Monotherapies of ceftolozane/tazobactam and tobramycin did not sufficiently suppress emergence of less-susceptible subpopulations, although inhaled tobramycin was more effective than intravenous tobramycin. Ceftolozane/tazobactam resistance development was associated with classical (AmpC overexpression plus structural modification) and novel (CpxR mutations) mechanisms depending on the strain. Against both isolates, combination regimens demonstrated synergy and completely suppressed the emergence of ceftolozane/tazobactam and tobramycin less-susceptible free-floating and biofilm bacterial subpopulations.

CONCLUSION

Mechanism-based modelling incorporating subpopulation and mechanistic synergy well described the antibacterial effects of all regimens against free-floating and biofilm bacterial states. These findings support further investigation of ceftolozane/tazobactam in combination with tobramycin against biofilm-associated P. aeruginosa infections in adolescents with CF.

Ceftolozane-Tazobactam against Pseudomonas aeruginosa Cystic Fibrosis Clinical Isolates in the Hollow-Fiber Infection Model: Challenges Imposed by Hypermutability and Heteroresistance

Pseudomonas aeruginosa remains a challenge in chronic respiratory infections in cystic fibrosis (CF). Ceftolozane-tazobactam has not yet been evaluated against multidrug-resistant hypermutable P. aeruginosa isolates in the hollow-fiber infection model (HFIM). Isolates CW41, CW35, and CW44 (ceftolozane-tazobactam MICs of 4, 4, and 2 mg/L, respectively) from adults with CF were exposed to simulated representative epithelial lining fluid pharmacokinetics of ceftolozane-tazobactam in the HFIM. Regimens were continuous infusion (CI; 4.5 g/day to 9 g/day, all isolates) and 1-h infusions (1.5 g every 8 hours and 3 g every 8 hours, CW41). Whole-genome sequencing and mechanism-based modeling were performed for CW41. CW41 (in four of five biological replicates) and CW44 harbored preexisting resistant subpopulations; CW35 did not. For replicates 1 to 4 of CW41 and CW44, 9 g/day CI decreased bacterial counts to <3 log10 CFU/mL for 24 to 48 h, followed by regrowth and resistance amplification. Replicate 5 of CW41 had no preexisting subpopulations and was suppressed below ~3 log10 CFU/mL for 120 h by 9 g/day CI, followed by resistant regrowth. Both CI regimens reduced CW35 bacterial counts to <1 log10 CFU/mL by 120 h without regrowth. These results corresponded with the presence or absence of preexisting resistant subpopulations and resistance-associated mutations at baseline. Mutations in ampC, algO, and mexY were identified following CW41 exposure to ceftolozane-tazobactam at 167 to 215 h. Mechanism-based modeling well described total and resistant bacterial counts. The findings highlight the impact of heteroresistance and baseline mutations on the effect of ceftolozane-tazobactam and limitations of MIC to predict bacterial outcomes. The resistance amplification in two of three isolates supports current guidelines that ceftolozane-tazobactam should be utilized together with another antibiotic against P. aeruginosa in CF.

A systematic review of randomised-controlled trials on deprescribing outcomes in older adults with polypharmacy

BACKGROUND

Mixed findings about deprescribing impact have emerged from varied study designs, interventions, outcome measures and targeting sub-categories of medications or morbidities. This systematic review controls for study design by reviewing randomised-controlled trials (RCTs) of deprescribing interventions using comprehensive medication profiles. The goal is to provide a synthesis of interventions and patient outcomes to inform healthcare providers and policy makers about deprescribing effectiveness.

OBJECTIVES

This systematic review aims to (1) review RCT deprescribing studies focusing on complete medication reviews of older adults with polypharmacy across all health settings, (2) map patients' clinical and economic outcomes against intervention and implementation strategies and (3) inform research agendas based on observed benefits and best practices.

METHODS

The PRISMA framework for systematic reviews was followed. Databases used were EBSCO Medline, PubMed, Cochrane Library, Scopus and Web of Science. Risk of bias was assessed using the Cochrane Risk of Bias tool for randomised trials.

RESULTS

Fourteen articles were included. Interventions varied in setting, preparation, use of interdisciplinary teams, validated guidelines and tools, patient-centredness and implementation strategy. Thirteen studies (92.9%) found deprescribing interventions reduced the number of drugs and/or doses taken. No studies found threats to patient safety in terms of primary outcomes including morbidity, hospitalisations, emergency room use and falls. Four of five studies identifying health quality of life as a primary outcome found significant effects associated with deprescribing. Both studies with cost as their primary outcome found significant effects as did two with cost as a secondary outcome. Studies did not systematically study how intervention components influenced deprescribing impact. To explore this gap, this review mapped studies' primary outcomes to deprescribing intervention components using the Consolidated Framework for Implementation Research. Five studies had significant, positive primary outcomes related to health-related quality of life (HRQOL), cost and/or hospitalisation, with four reporting patient-centred elements in their intervention.

CONCLUSIONS

RCT primary outcomes found deprescribing is safe and reduces drug number or dose. Five RCTs found a significant deprescribing impact on HRQOL, cost or hospitalisation. Important future research agendas include analysing (1) understudied outcomes like cost, and (2) intervention and implementation components that enhance effectiveness, such as patient-centred elements.

Novel Approaches to Multidrug-Resistant Infections in Cystic Fibrosis

Patients with cystic fibrosis (CF) often develop respiratory tract infections with pathogenic multidrug-resistant organisms (MDROs) such as methicillin-resistant Staphylococcus aureus, and a variety of gram-negative organisms that include Pseudomonas aeruginosa, Burkholderia sp., Stenotrophomonas maltophilia, Achromobacter xylosoxidans, and nontuberculous mycobacteria (NTM). Despite the introduction of new therapies to address underlying cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction, MDRO infections remain a problem and novel antimicrobial interventions are still needed. Therapeutic approaches include improving the efficacy of existing drugs by adjusting the dose based on differences in CF patient pharmacokinetics/pharmacodynamics, the development of inhaled formulations to reduce systemic adverse events, and the use of newer beta-lactam/beta-lactamase combinations. Alternative innovative therapeutic approaches include the use of gallium and bacteriophages to treat MDRO pulmonary infections including those with extreme antibiotic resistance. However, additional clinical trials are required to determine the optimal dosing and efficacy of these different strategies and to identify patients with CF most likely to benefit from these new treatment options.

Systematic Literature Review of Real-world Evidence of Ceftolozane/Tazobactam for the Treatment of Respiratory Infections

Introduction

Gram-negative nosocomial pneumonia (NP), including hospital-acquired bacterial pneumonia (HABP), ventilated HABP (vHABP), and ventilator-associated bacterial pneumonia (VABP), is a significant cause of morbidity and mortality. Common pathogens, including Enterobacterales and Pseudomonas aeruginosa, are prevalent in healthcare settings and have few effective treatment options due to high rates of antibacterial resistance. Resistant pathogens are associated with significantly worse outcomes, relative to patients with susceptible infections. Ceftolozane/tazobactam (C/T) has established efficacy in clinical trials of patients with NP. This review aims to collate data on C/T use for HABP/vHABP/VABP infections in real-world clinical practice.

Methods

This systematic literature review searched online biomedical databases for real-world studies of C/T used to treat Gram-negative respiratory tract infections (RTIs) between January 2009 and June 2020.

Results

Thirty-three studies comprising 658 patients were identified. Pneumonia was the most common infection treated with C/T (85%), with a smaller number of unspecified RTIs (9%) and tracheobronchitis (5%) reported. The majority of patients had respiratory infections caused by P. aeruginosa (92.8%), of which 88.1% were multidrug-resistant. Examination of these studies demonstrated an increase in the percentage of patients receiving the recommended dose of C/T for respiratory infections (3 g q8h or renal impairment-adjusted) over time (36.8% of patients in 2017 to 71.5% in 2020). Clinical success rates ranged from 51.4 to 100%, with 10 studies (55.6% of studies reporting clinical success) reporting clinical success rates of > 70%; microbiological success rates ranged from 57.0 to 100.0%, with three studies (60.0% of studies reporting microbiological success) reporting microbiological success rates of > 70%. Thirty-day mortality ranged from 0.0 to 33.0%, with nine studies (90% of studies reporting mortality) reporting 30-day mortality of < 30%.

Conclusions

The studies identified in this review demonstrate that C/T shows similar outcomes as those seen in clinical trials, despite the higher frequency of multidrug-resistant pathogens, and comorbidities that may have been excluded from the trials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00491-x.

Ceftolozane/Tazobactam for Resistant Drugs Pseudomonas aeruginosa Respiratory Infections: A Systematic Literature Review of the Real-World Evidence

Background: Ceftolozane/tazobactam (C/T) is a β-lactam/β-lactamase inhibitor combination that mainly targets Gram-negative bacteria. The current international guidelines recommend including C/T treatment in the empirical therapy for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP). Pseudomonas aeruginosa (PA) is one of the most challenging Gram-negative bacteria. We conducted a systematic review of all cases reported in the literature to summarize the existing evidence. Methods: The main electronic databases were screened to identify case reports of patients with drug-resistant PA respiratory infections treated with C/T. Results: A total of 22 publications were included for a total of 84 infective episodes. The clinical success rate was 72.6% across a wide range of comorbidities. The 45.8% of patients treated with C/T presented colonization by PA. C/T was well tolerated. Only six patients presented adverse events, but none had to stop treatment. The most common therapeutic regimens were 1.5 g every 8 h and 3 g every 8 h. Conclusion: C/T may be a valid therapeutic option to treat multidrug-resistant (MDR), extensively drug-resistant (XDR), pandrug-resistant (PDR), and carbapenem-resistant (CR) PA infections. However, further data are necessary to define the optimal treatment dosage and duration.

Trends of Antimicrobial Resistance and Combination Susceptibility Testing of Multidrug-Resistant Pseudomonas aeruginosa Isolates from Cystic Fibrosis Patients: a 10-Year Update

Antimicrobial combination therapy is a time/resource-intensive procedure commonly employed in the treatment of cystic fibrosis (CF) pulmonary exacerbations caused by Pseudomonas aeruginosa Ten years ago, the most promising antimicrobial combinations were proposed, but there has since been the introduction of new β-lactam plus β-lactamase inhibitor antimicrobial combinations. The aims of this study were to (i) compare in vitro activity of these new antimicrobials with other antipseudomonal agents and suggest their most synergistic antimicrobial combinations and (ii) determine antimicrobial resistance rates and study inherent trends of antimicrobials over 10 years. A total of 721 multidrug-resistant P. aeruginosa isolates from 183 patients were collated over the study period. Antimicrobial susceptibility and combination testing were carried out using the Etest method. The results were further assessed using the fractional inhibitory concentration index (FICI) and the susceptible breakpoint index (SBPI). Resistance to almost all antimicrobial agents maintained a similar level during the studied period. Colistin (P < 0.001) and tobramycin (P = 0.001) were the only antimicrobials with significant increasing isolate susceptibility, while an increasing resistance trend was observed for levofloxacin. The most active antimicrobials were colistin, ceftolozane-tazobactam, ceftazidime-avibactam, and gentamicin. All combinations with β-lactam plus β-lactamase inhibitors produced some synergistic results. Ciprofloxacin plus ceftolozane-tazobactam (40%) and amikacin plus ceftazidime (36.7%) were the most synergistic combinations, while colistin combinations gave the best median SBPI (50.11). This study suggests that effective fluoroquinolone stewardship should be employed for CF patients. It also presents in vitro data to support the efficacy of novel combinations for use in the treatment of chronic P. aeruginosa infections.

Real-life experience with ceftolozane/tazobactam in Canada: results from the CLEAR (Canadian LEadership on Antimicrobial Real-life usage) registry

OBJECTIVES

Ceftolozane/tazobactam is a cephalosporin/β-lactamase inhibitor combination with activity against Gram-negative bacilli. Here we report the use of ceftolozane/tazobactam in Canada using a national registry.

METHODS

The CLEAR registry uses a REDCap^TM online survey to capture details associated with clinical use of ceftolozane/tazobactam.

RESULTS

Data from 51 patients treated in 2020 with ceftolozane/tazobactam are available. Infections treated included hospital-acquired bacterial pneumonia (37.3% of patients), ventilator-associated bacterial pneumonia (15.7%), bone and joint infection (11.8%), complicated intra-abdominal infection (7.8%) and complicated skin and skin-structure infection (7.8%). Moreover, 17.6% of patients had bacteraemia and 47.1% were in intensive care. Ceftolozane/tazobactam was primarily used as directed therapy for Pseudomonas aeruginosa infections (92.2% of patients). Ceftolozane/tazobactam was used because of resistance to (86.3%), failure of (11.8%) or adverse effects from (2.0%) previously prescribed antimicrobials. Ceftolozane/tazobactam susceptibility testing was performed on isolates from 88.2% of patients. Ceftolozane/tazobactam was used in combination with another antimicrobial active against Gram-negative bacilli in 39.2% of patients [aminoglycosides (15.7%), fluoroquinolones (9.8%) and colistin/polymyxin B (7.8%)]. The dosage regimen was customised in all patients based on creatinine clearance. The treatment duration was primarily >10 days (60.8% of patients), with microbiological success in 60.5% and clinical success in 64.4% of patients. Moreover, 7.8% of patients had adverse effects not requiring drug discontinuation.

CONCLUSION

In Canada, ceftolozane/tazobactam is used as directed therapy to treat a variety of severe infections caused by multidrug-resistant P. aeruginosa. It is commonly used in combination with other antimicrobials with relatively high microbiological/clinical cure rates and an excellent safety profile.

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.

A guide to therapeutic drug monitoring of β-lactam antibiotics

Therapeutic drug monitoring (TDM) opens the door to personalized medicine, yet it is infrequently applied to β-lactam antibiotics, one of the most commonly prescribed drug classes in the hospital setting. As we continue to understand more about β-lactam pharmacodynamics (PD) and wide inter- and intra-patient variability in pharmacokinetics (PK), the utility of TDM has become increasingly apparent. For β-lactams, the time that free concentrations remain above the minimum inhibitory concentration (MIC) as a function of the dosing interval (%fT>MIC) has been shown to best predict antibacterial effect. Many studies have shown that β-lactam %fT>MIC exposures are often suboptimal across a wide variety of disease states and clinical settings. A limitation to implementing this practice is the general lack of understanding on how to best operationalize this intervention and interpret the results. The instrumentation and expertise needed to quantify β-lactams for TDM is rarely available locally, but certain laboratories advertise these services and perform them regularly. Familiarity with the modalities and nuances of antimicrobial susceptibility testing is crucial to establishing β-lactam concentration targets that meet the relevant exposure thresholds. Evaluation of these concentrations is best accomplished using population PK software and Bayesian modeling, for which a multitude of programs are available. While TDM of β-lactams has shown an ability to increase the rate of target attainment, there is currently limited evidence to suggest that it leads to improved clinical outcomes. Although consensus guidelines for β-lactam TDM do not exist in the United States, guidance would help to promote this important practice and better standardize the approach across institutions. Herein, we discuss the basis for β-lactam TDM, review supporting evidence, and provide guidance for implementation in specific patient populations.

Contemporary analysis of ETEST for antibiotic susceptibility and minimum inhibitory concentration agreement against Pseudomonas aeruginosa from patients with cystic fibrosis

Objectives

Cystic fibrosis (CF) acute pulmonary exacerbations are often caused by Pseudomonas aeruginosa, including multi-drug resistant strains. Optimal antibiotic therapy is required to return lung function and should be guided by in vitro susceptibility results. There are sparse data describing ETEST performance for CF isolates using contemporary isolates, methods and interpretation, as well as novel antibiotics, such as ceftazidime–avibactam and ceftolozane–tazobactam.

Methods

Pseudomonas aeruginosa (n = 105) isolated during pulmonary exacerbation from patients with CF were acquired from 3 US hospitals. Minimum inhibitory concentrations (MICs) were assessed by reference broth microdilution (BMD) and ETEST for aztreonam, cefepime, ceftazidime, ceftazidime–avibactam, ceftolozane–tazobactam, ciprofloxacin, levofloxacin, meropenem, piperacillin–tazobactam, and tobramycin. Broth microdilution was conducted in concordance with the Clinical and Laboratory Standards Institute M100. ETEST methodology reflected package insert recommendations. Performance of ETEST strips was evaluated using the Food and Drug Administration (FDA) and Susceptibility Testing Manufacturers Association (STMA) guidance.

Results

Of the 105 P. aeruginosa included, 46% had a mucoid phenotype. ETEST MICs typically read 0–1 dilution higher than BMD for all drugs. Categorical agreement and essential agreement ranged from 64 to 93% and 63 to 86%, respectively. The majority of observed errors were minor. A single very major error occurred with ceftazidime (4.2%). For ceftazidime–vibactam, 2 very major errors were observed and both were within essential agreement. Major errors occurred for aztreonam (3.3%), cefepime (9.4%), ceftazidime–avibactam (5.3%, adjusted 2.1%), ceftolozane–tazobactam (1%), meropenem (3.3%), piperacillin–tazobactam (2.9%), and tobramycin (1.5%).

Conclusions

ETEST methods performed conservatively for most antibiotics against this challenging collection of P. aeruginosa from patients with CF.