Clinical research designs to study treatment effects for multidrug-resistant bacteria

All-cause mortality rates in adults with carbapenem-resistant Gram-negative bacterial infections: a comprehensive review of pathogen-focused, prospective, randomized, interventional clinical studies

INTRODUCTION

Pathogen-focused, randomized, controlled trials (PF-RCT) are important in the fight against carbapenem-resistant (CR) Gram-negative infections. Some recently approved antibiotics and older generic antibiotics with activity against CR Gram-negative bacteria were investigated in PF-RCTs in a variety of infections.

AREAS COVERED

We searched Pubmed, Cochrane database and international clinical trial databases for PF-RCTs for the period between 2005 and 2020 and compared the study designs, patient populations, infection types, pathogens, and Day-28 all-cause mortality (ACM).

EXPERT OPINION

PF-RCTs are particularly challenging to quantitatively assess and compare due to the heterogeneity in infection types, pathogens, CR mechanism, inclusion/exclusion criteria, and endpoints. Data interpretation is further complicated by lack of formal statistical analysis plans and/or non-inferiority design, and limited power across most PF-RCTs. The studies with new antibiotics (i.e. plazomicin, meropenem/vaborbactam, cefiderocol) ranked lower regarding feasibility, with relatively small sample sizes (analyzed: 37-118) versus the comparative effectiveness studies of older generic drugs (analyzed: 94-406). ACM ranged between 11.8% and 40% for CR Enterobacterales, 17.7% and 57.4% for CR Acinetobacter spp., and 20.0% and 30.8% for CR Pseudomonas aeruginosa. The information gathered must be considered carefully alongside the study limitations and caution should be exercised when making direct comparisons across trials.

Antibiotics in the pipeline: a literature review (2017-2020)

Introduction

Antimicrobial resistance (AMR) is an emerging global threat. It increases mortality and morbidity and strains healthcare systems. Health care professionals can counter the rising AMR by promoting antibiotic stewardship and facilitating new drug development. Even with the economic and scientific challenges, it is reassuring that new agents continue to be developed.

Methods

This review addresses new antibiotics in the pipeline. We conducted a review of the literature including Medline, Clinicaltrials.org, and relevant pharmaceutical companies for approved and in pipeline antibiotics in phase 3 or new drug application (NDA).

Results

We found a number of new antibiotics and reviewed their current development status, mode of action, spectra of activity, and indications for which they have been approved. The included studies from phase 3 clinical trials were mainly utilized for the treatment of acute bacterial skin and skin structure infections, community-acquired bacterial pneumonia, and pneumonia acquired in the healthcare settings. The number of these agents is limited against high priority organisms. The identified antibiotics were based mainly on previously known molecules or pre-existing antimicrobial agents.

Conclusion

There are a limited number of antibiotics against high priority organisms such as multi-drug-resistant Pseudomonas aeruginosa, and carbapenem-resistant Enterobacteriaceae. New antimicrobial agents directed against the top priority organisms as classified by the World Health Organization are urgently needed.

The role of combination therapy in the treatment of severe infections caused by carbapenem resistant gram-negatives: a systematic review of clinical studies

BACKGROUND

Effective treatment of sepsis due to carbapenem-resistant Gram-negative bacteria (CR-GNB) remains a challenge for clinicians worldwide. In recent years, the combination of antibiotics has become the preferred treatment strategy for CR-GNB infection. However, robust evidence to support this approach is lacking. This systematic review aimed at critically evaluating all available antibiotic options for CR-GNB sepsis with particular focus on combination.

METHODS

We systematically searched published literature from January 1945 until December 2018 for observational comparative and non-comparative studies and randomized trials examining any antibiotic option for CR-GNB. Studies were included if reporting microbiologically-confirmed infection caused by Acinetobacter baumannii, Enterobacteriaceae/Klebsiella spp., or Pseudomonas aeruginosa, reporting at least one of the study outcomes, and definitive antibiotic treatment. Carbapenem-resistance was defined as phenotypically-detected in vitro resistance to at least one of the following carbapenems: doripenem, ertapenem, imipenem, meropenem. Each antibiotic regimen was classified as "defined" when at least the molecular class(es) composing the regimen was detailed. Primary outcomes were 30-day and attributable mortality. Bayesian network meta-analysis (NMA) approach was selected for quantitative synthesis to explore feasibility of pooling data on antibiotic regimens.

RESULTS

A total of 6306 records were retrieved and 134 studies including 11,546 patients were included: 54 studies were on Acinetobacter, 52 on Enterobacteriaceae/Klebsiella, 21 on mixed Gram-negative, and 7 on Pseudomonas. Nine (7%) were RCTs; 19 prospective cohorts (14%), 89 (66%) retrospective, and 17 (13%) case series. Forty-one studies (31%) were multicentric. Qualitative synthesis showed an heterogeneous and scattered reporting of key-clinical and microbiological variables across studies. Ninety-two distinct antibiotic regimens were identified with 47 of them (51%, 5863 patients) not reporting any details on numbers, type, dosage and in vitro activity of the included antibiotic molecules. The NMAs could not be performed for any of the selected outcome given the presence of too many disconnected components.

CONCLUSION

The existing evidence is insufficient to allowing for the formulation of any evidence-based therapeutic recommendation for CR-GNB sepsis. Future studies must provide a standardized definition of antibiotic regimen to drive recommendations for using combination of antibiotics that can be reliably applied to clinical practice.

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.

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.