Randomized Trial of Ceftazidime-Avibactam vs Meropenem for Treatment of Hospital-Acquired and Ventilator-Associated Bacterial Pneumonia (REPROVE): Analyses per US FDA-Specified End Points

Novel Siderophore Cephalosporin and Combinations of Cephalosporins with β-Lactamase Inhibitors as an Advancement in Treatment of Ventilator-Associated Pneumonia

In an era of increasing antibiotic resistance among pathogens, the treatment options for infectious diseases are diminishing. One of the clinical groups especially vulnerable to this threat are patients who are hospitalized in intensive care units due to ventilator-associated pneumonia caused by multidrug-resistant/extensively drug-resistant Gram-negative bacteria. In order to prevent the exhaustion of therapeutic options for this life-threatening condition, there is an urgent need for new pharmaceuticals. Novel β-lactam antibiotics, including combinations of cephalosporins with β-lactamase inhibitors, are proposed as a solution to this escalating problem. The unique mechanism of action, distinctive to this new group of siderophore cephalosporins, can overcome multidrug resistance, which is raising high expectations. In this review, we present the summarized results of clinical trials, in vitro studies, and case studies on the therapeutic efficacy of cefoperazone-sulbactam, ceftolozane-tazobactam, ceftazidime-avibactam, and cefiderocol in the treatment of ventilator-associated pneumonia. We demonstrate that treatment strategies based on siderophore cephalosporins and combinations of β-lactams with β-lactamases inhibitors show comparable or higher clinical efficacy than those used with classic pharmaceuticals, like carbapenems, colistin, or tigecycline, and are often associated with a lower risk of adverse events.

Effectiveness of Ceftazidime-Avibactam in Gram-Negative Nosocomial Pneumonia: A Real-World Study in India

BACKGROUND AND OBJECTIVE

The incidences of nosocomial pneumonia in intensive care units (ICUs) in India have been reported to range from 9% to 58% and are associated with a mortality rate of 30-70%. Ceftazidime-avibactam has activity against OXA-48-like carbapenem-resistant Enterobacterales (CRE) and has a safer adverse effect profile as compared to the nephrotoxic colistin. The current study aimed to assess the effectiveness and usage pattern of ceftazidime-avibactam in gram-negative hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) in real-world settings in India.

METHODS

Electronic medical records of hospitalized patients in three prominent medical centers in India (Fortis Memorial Research Centre, Gurugram, S L Raheja Hospital, Mumbai, and Fortis Hospital, Anandapur, Kolkata) with nosocomial pneumonia and documented gram-negative Klebsiella pneumoniae (KP)-confirmed infection were collected. This study assessed the effectiveness, usage pattern of ceftazidime-avibactam, and clinical and microbiological cure rates.

RESULTS

Among the 116 patients included, 78.45% (91/116) showed clinical cure. Microbiological cure was observed in nine out of 13 (69.23%) patients. In the subset analysis, a clinical cure rate of 84.85% (28/33) and microbiological recovery rate of 62.50% (5/8) were observed when ceftazidime-avibactam was initiated within 72 hours of diagnosis. Ceftazidime-avibactam was administered for a mean (±SD) duration of 7.79 ± 4.43 days, with improvement in signs and symptoms reported among 91.38% (106/116). Ceftazidime-avibactam showed a susceptibility of 56% (28/56) in the study.

CONCLUSION

The current study showed a better clinical and microbiological cure rate with a safer tolerability profile of ceftazidime-avibactam in carbapenem-resistant KP nosocomial pneumonia and VAP. This study has further demonstrated that ceftazidime-avibactam may be used as one of the viable treatment choices in carbapenem-resistant KP with favorable clinical outcomes.

Weighing the Odds: Novel β-Lactam/β-Lactamase Inhibitor Use in Hospital-Acquired and Ventilator-Associated Pseudomonas aeruginosa Pneumonia for Patients Who Are Morbidly Obese

Background

Pseudomonas aeruginosa is a leading cause of hospital-acquired and ventilator-associated bacterial pneumonia (HABP/VABP). Novel β-lactam/β-lactamase inhibitor (BL/BLI) combinations are often used for these infections; however, limited data exist to guide the dosing of BL/BLI in patients who are morbidly obese. Thus, we sought to evaluate the clinical and safety endpoints of patients who are morbidly obese (body mass index ≥35 kg/m2) and non-morbidly obese (<35 kg/m2) and receiving BL/BLI for P aeruginosa HABP/VABP.

Methods

This retrospective study was based on a cohort of patients hospitalized at 2 urban academic medical centers in Detroit, Michigan, from August 2014 through February 2021 with P aeruginosa HABP/VABP who were receiving BL/BLI (ceftazidime/avibactam, ceftolozane/tazobactam, or meropenem/vaborbactam) for ≥72 continuous hours. The primary endpoint was presumed treatment failure, defined as the presence of all-cause in-hospital mortality or the continuation of infectious symptoms. Analyses were adjusted for possible confounding with inverse probability of treatment weighting. Multivariable regression was used to identify predictors of treatment failure.

Results

In total, 285 patients with HABP (61.4%) and/or VABP (56.1%) were enrolled (morbidly obese, n = 95; non-morbidly obese, n = 190). The median Acute Physiology and Chronic Health Evaluation II score was 23 (IQR, 13-26), and 60% of patients were admitted to the intensive care unit at index culture collection. Patients who were morbidly obese demonstrated significantly greater odds of presumed treatment failure vs those who were non-morbidly obese (58.9% vs 37.9%, respectively; adjusted odds ratio, 1.675 [95% CI, 1.465-1.979]). In multivariable analysis, morbid obesity (1.06; 95% CI, 1.02-1.79), prolonged time to BL/BLI initiation (1.47; 95% CI, 1.28-2.66), renal dose-adjusted BL/BLI in the first 48 hours of therapy (1.12; 95% CI, 1.09-1.75), and continuous renal replacement therapy during BL/BLI therapy (1.35; 95% CI, 1.06-1.68) were independently associated with increased odds of presumed treatment failure.

Conclusions

Among hospitalized patients receiving BL/BLI for P aeruginosa HABP/VABP, those who were morbidly obese had significantly greater odds of presumed treatment failure when compared with those who were non-morbidly obese.

The place of new antibiotics for Gram-negative bacterial infections in intensive care: report of a consensus conference

INTRODUCTION

New beta-lactams, associated or not with beta-lactamase inhibitors (NBs/BIs), can respond to the spread of carbapenemase-producing enterobacteriales and nonfermenting carbapenem-resistant bacteria. The risk of emergence of resistance to these NBs/BIs makes guidelines necessary. The SRLF organized a consensus conference in December 2022.

METHODS

An ad hoc committee without any conflict of interest (CoI) with the subject identified the molecules (ceftolozane-tazobactam, ceftazidime-avibactam, imipenem-cilastatin-relebactam, meropenem-vaborbactam and cefiderocol); defined 6 generic questions; drew up a list of subquestions according to the population, intervention, comparison and outcomes (PICO) model; and reviewed the literature using predefined keywords. The quality of the data was assessed using the GRADE methodology. Seven experts in the field proposed their own answers to the questions in a public session and answered questions from the jury (a panel of 10 critical-care physicians without any CoI) and the public. The jury then met alone for 48 h to write its recommendations. Due to the frequent lack of powerful studies that have used clinically important criteria of judgment, the recommendations were formulated as expert opinions as often as necessary.

RESULTS

The jury provided 17 statements answering 6 questions: (1) Is there a place in the ICU for the probabilistic use of new NBs/IBs active against Gram-negative bacteria? (2) In the context of documented infections with sensitivity to several of these molecules, are there pharmacokinetic, pharmacodynamic, ecological or medico-economic elements for prioritization? (3) What are the possible combinations with these molecules and in what context? (4) Should we integrate these new molecules into a carbapenem-sparing strategy? (5) What pharmacokinetic and pharmacodynamic data are available to optimize their mode of administration in critically ill patients? (6) What are the dosage adaptations in cases of renal insufficiency, hepatocellular insufficiency or obesity?

CONCLUSION

These recommendations should optimize the use of NBs/BIs in ICU patients.

Efficacy and safety of ceftazidime-avibactam compared to other antimicrobials for the treatment of infections caused by carbapenem-resistant Klebsiella pneumoniae strains, a systematic review and meta-analysis

INTRODUCTION

Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections are a significant public health issue. CRKP infections can increase the mortality of severely ill hospitalised patients and elevate the financial burden of their hospitalisation globally. Colistin and tigecycline are the main antimicrobials which have been widely used for the treatment of CRKP infections. However, novel antimicrobials have been recently launched. Ceftazidime-avibactam (CAZ-AVI) seems one of the most efficient ones.

AIM

The aim of the current systematic literature review and meta-analysis is to assess the efficacy and safety of CAZ-AVI compared to other antimicrobials in adult patients (aged >18) with CRKP infection.

METHODS

All data were retrieved using PubMed/Medline, the Web of Science and Cochrane library. The main outcome was the effective treatment of CRKP infection or the microbiological eradication of CRKP in the culture of biological samples. Secondary outcomes included the impact on 28- or 30-day mortality and adverse effects, if available. Pooled analysis was conducted using Review Manager v. 5.4.1 software (RevMan). The level of statistical significance was set at p < 0.05.

RESULTS

CAZ-AVI was proved more effective than other antimicrobials against CRKP infections and CRKP bloodstream infections (p < 0.00001 and p < 0.0001, respectively). Patients in the CAZ-AVI arm displayed statistically lower 28- and 30-day mortality rates (p = 0.002 and p < 0.00001, respectively). Concerning the microbiological eradication, no meta-analysis was feasible due to high heterogeneity.

CONCLUSION

The promotion of CAZ-AVI for treating CRKP infections over other antimicrobials seems favourable. However, there is a long way ahead to reveal additional scientific findings to further strengthen this statement.

[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.

Carbapenem-Resistant Klebsiella pneumoniae: Virulence Factors, Molecular Epidemiology and Latest Updates in Treatment Options

Klebsiella pneumoniae is a Gram-negative opportunistic pathogen responsible for a variety of community and hospital infections. Infections caused by carbapenem-resistant K. pneumoniae (CRKP) constitute a major threat for public health and are strongly associated with high rates of mortality, especially in immunocompromised and critically ill patients. Adhesive fimbriae, capsule, lipopolysaccharide (LPS), and siderophores or iron carriers constitute the main virulence factors which contribute to the pathogenicity of K. pneumoniae. Colistin and tigecycline constitute some of the last resorts for the treatment of CRKP infections. Carbapenemase production, especially K. pneumoniae carbapenemase (KPC) and metallo-β-lactamase (MBL), constitutes the basic molecular mechanism of CRKP emergence. Knowledge of the mechanism of CRKP appearance is crucial, as it can determine the selection of the most suitable antimicrobial agent among those most recently launched. Plazomicin, eravacycline, cefiderocol, temocillin, ceftolozane-tazobactam, imipenem-cilastatin/relebactam, meropenem-vaborbactam, ceftazidime-avibactam and aztreonam-avibactam constitute potent alternatives for treating CRKP infections. The aim of the current review is to highlight the virulence factors and molecular pathogenesis of CRKP and provide recent updates on the molecular epidemiology and antimicrobial treatment options.

The primary pharmacology of ceftazidime/avibactam: in vivo translational biology and pharmacokinetics/pharmacodynamics (PK/PD)

This review describes the translational in vivo and non-clinical pharmacokinetics/pharmacodynamics (PK/PD) research that supported clinical trialling and subsequently licensing approval of ceftazidime/avibactam, a new β-lactam/β-lactamase inhibitor combination aimed at the treatment of infections by Enterobacterales and Pseudomonas aeruginosa. The review thematically follows on from the co-published article, Nichols et al. (J Antimicrob Chemother 2022; dkac171). Avibactam protected ceftazidime in animal models of infection with ceftazidime-resistant, β-lactamase-producing bacteria. For example, a single subcutaneous dose of ceftazidime at 1024 mg/kg yielded little effect on the growth of ceftazidime-resistant, blaKPC-2-carrying Klebsiella pneumoniae in the thighs of neutropenic mice (final counts of 4 × 108 to 8 × 108 cfu/thigh). In contrast, co-administration of avibactam in a 4:1 ratio (ceftazidime:avibactam) was bactericidal in the same model (final counts of 2 × 104 to 3 × 104 cfu/thigh). In a rat abdominal abscess model, therapy with ceftazidime or ceftazidime/avibactam (4:1 w/w) against blaKPC-2-positive K. pneumoniae resulted in 9.3 versus 3.3 log cfu/abscess, respectively, after 52 h. With respect to PK/PD, in Monte Carlo simulations, attainment of unbound drug exposure targets (ceftazidime fT>8 mg/L and avibactam fT>1 mg/L, each for 50% of the dosing interval) for the labelled dose of ceftazidime/avibactam (2 and 0.5 g, respectively, q8h by 2 h IV infusion), including dose adjustments for patients with impaired renal function, ranged between 94.8% and 99.6% of patients, depending on the infection modelled.

The primary pharmacology of ceftazidime/avibactam: in vitro translational biology

Previous reviews of ceftazidime/avibactam have focused on in vitro molecular enzymology and microbiology or the clinically associated properties of the combination. Here we take a different approach. We initiate a series of linked reviews that analyse research on the combination that built the primary pharmacology data required to support the clinical and business risk decisions to perform randomized controlled Phase 3 clinical trials, and the additional microbiological research that was added to the above, and the safety and chemical manufacturing and controls data, that constituted successful regulatory licensing applications for ceftazidime/avibactam in multiple countries, including the USA and the EU. The aim of the series is to provide both a source of reference for clinicians and microbiologists to be able to use ceftazidime/avibactam to its best advantage for patients, but also a case study of bringing a novel β-lactamase inhibitor (in combination with an established β-lactam) through the microbiological aspects of clinical development and regulatory applications, updated finally with a review of resistance occurring in patients under treatment. This first article reviews the biochemistry, structural biology and basic microbiology of the combination, showing that avibactam inhibits the great majority of serine-dependent β-lactamases in Enterobacterales and Pseudomonas aeruginosa to restore the in vitro antibacterial activity of ceftazidime. Translation to efficacy against infections in vivo is reviewed in the second co-published article, Nichols et al. (J Antimicrob Chemother 2022; dkac172).

Microbiological, Clinical, and PK/PD Features of the New Anti-Gram-Negative Antibiotics: β-Lactam/β-Lactamase Inhibitors in Combination and Cefiderocol—An All-Inclusive Guide for Clinicians

Bacterial resistance mechanisms are continuously and rapidly evolving. This is particularly true for Gram-negative bacteria. Over the last decade, the strategy to develop new β-lactam/β-lactamase inhibitors (BLs/BLIs) combinations has paid off and results from phase 3 and real-world studies are becoming available for several compounds. Cefiderocol warrants a separate discussion for its peculiar mechanism of action. Considering the complexity of summarizing and integrating the emerging literature data of clinical outcomes, microbiological mechanisms, and pharmacokinetic/pharmacodynamic properties of the new BL/BLI and cefiderocol, we aimed to provide an overview of data on the following compounds: aztreonam/avibactam, cefepime/enmetazobactam, cefepime/taniborbactam, cefepime/zidebactam, cefiderocol, ceftaroline/avibactam, ceftolozane/tazobactam, ceftazidime/avibactam, imipenem/relebactam, meropenem/nacubactam and meropenem/vaborbactam. Each compound is described in a dedicated section by experts in infectious diseases, microbiology, and pharmacology, with tables providing at-a-glance information.

Population Pharmacokinetic Modeling and Probability of Pharmacodynamic Target Attainment for Ceftazidime-Avibactam in Pediatric Patients Aged 3 Months and Older

Increasing prevalence of infections caused by antimicrobial-resistant gram-negative bacteria represents a global health crisis, and while several novel therapies that target various aspects of antimicrobial resistance have been introduced in recent years, few are currently approved for children. Ceftazidime-avibactam is a novel β-lactam β-lactamase inhibitor combination approved for adults and children 3 months and older with complicated intra-abdominal infection, and complicated urinary tract infection or hospital-acquired ventilator-associated pneumonia (adults only in the United States) caused by susceptible gram-negative bacteria. Extensive population pharmacokinetic (PK) data sets for ceftazidime and avibactam obtained during the adult clinical development program were used to iteratively select, modify, and validate the approved adult dosage regimen (2,000-500 mg by 2-hour intravenous (IV) infusion every 8 hours (q8h), with adjustments for renal function). Following the completion of one phase I (NCT01893346) and two phase II ceftazidime-avibactam studies (NCT02475733 and NCT02497781) in children, adult PK data sets were updated with pediatric PK data. This paper describes the development of updated combined adult and pediatric population PK models and their application in characterizing the population PK of ceftazidime and avibactam in children, and in dose selection for further pediatric evaluation. The updated models supported the approval of ceftazidime-avibactam pediatric dosage regimens (all by 2-hour IV infusion) of 50-12.5 mg/kg (maximum 2,000-500 mg) q8h for those ≥6 months to 18 years old, and 40-10 mg/kg q8h for those ≥3 to 6 months old with creatinine clearance > 50 mL/min/1.73 m2 .

Management of pneumonia in critically ill patients

Severe pneumonia is associated with high mortality (short and long term), as well as pulmonary and extrapulmonary complications. Appropriate diagnosis and early initiation of adequate antimicrobial treatment for severe pneumonia are crucial in improving survival among critically ill patients. Identifying the underlying causative pathogen is also critical for antimicrobial stewardship. However, establishing an etiological diagnosis is challenging in most patients, especially in those with chronic underlying disease; those who received previous antibiotic treatment; and those treated with mechanical ventilation. Furthermore, as antimicrobial therapy must be empiric, national and international guidelines recommend initial antimicrobial treatment according to the location's epidemiology; for patients admitted to the intensive care unit, specific recommendations on disease management are available. Adherence to pneumonia guidelines is associated with better outcomes in severe pneumonia. Yet, the continuing and necessary research on severe pneumonia is expansive, inviting different perspectives on host immunological responses, assessment of illness severity, microbial causes, risk factors for multidrug resistant pathogens, diagnostic tests, and therapeutic options.

Is there a role of faecal microbiota transplantation in reducing antibiotic resistance burden in gut? A systematic review and Meta-analysis

OBJECTIVES

The aim of current systematic review and meta-analysis is to provide insight into the therapeutic efficacy of fecal microbiota transplantation (FMT) for the decolonization of antimicrobial-resistant (AMR) bacteria from the gut.

METHODS

The protocol for this Systematic Review was prospectively registered with PROSPERO (CRD42020203634). Four databases (EMBASE, MEDLINE, SCOPUS, and WEB of SCIENCE) were consulted up until September 2020. A total of fourteen studies [in vivo (n = 2), case reports (n = 7), case series without control arm (n = 3), randomized clinical trials (RCT, n = 2)], were reviewed. Data were synthesized narratively for the case reports, along with a proportion meta-analysis for the case series studies (n = 102 subjects) without a control arm followed by another meta-analysis for case series studies with a defined control arm (n = 111 subjects) for their primary outcomes.

RESULTS

Overall, seven non-duplicate case reports (n = 9 participants) were narratively reviewed and found to have broad AMR remission events at the 1-month time point. Proportion meta-analysis of case series studies showed an overall 0.58 (95% CI: 0.42-0.74) AMR remission. Additionally, a significant difference in AMR remission was observed in FMT vs treatment naïve (RR = 0.44; 95% CI: 0.20-0.99) and moderate heterogeneity (I2=65%). A subgroup analysis of RCTs (n = 2) revealed FMT with further benefits of AMR remission with low statistical heterogeneity (RR = 0.37; 95% CI: 0.18-0.79; I2 =23%).

CONCLUSION

More rigorous RCTs with larger sample size and standardized protocols on FMTs for gut decolonization of AMR organisms are warranted.KEY MESSAGEExisting studies in this subject are limited and of low quality with moderate heterogeneity, and do not allow definitive conclusions to be drawn.More rigorous RCTs with larger sample size and standardized protocols on FMTs for gut decolonization of AMR organisms are warranted.

Advances in novel antibiotics to treat multidrug-resistant gram-negative bacterial infections

Antimicrobial resistance is a growing threat to public health and an increasingly common problem for acute care physicians to confront. Several novel antibiotics have been approved in the past decade to combat these infections; however, physicians may be unfamiliar with how to appropriately utilize them. The purpose of this review is to evaluate novel antibiotics active against resistant gram-negative bacteria and highlight clinical information regarding their use in the acute care setting. This review focuses on novel antibiotics useful in the treatment of infections caused by resistant gram-negative organisms that may be seen in the acute care setting. These novel antibiotics include ceftolozane/tazobactam, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/cilistatin/relebactam, cefiderocol, plazomicin, eravacycline, and omadacycline. Acute care physicians should be familiar with these novel antibiotics so they can utilize them appropriately.

Epidemiology, risk factors, and prediction score of carbapenem resistance among inpatients colonized or infected with 3rd generation cephalosporin resistant Enterobacterales

In this study, we determined the incidence and risk factors of Carbapenem-resistant Enterobacterales (CRE) acquisition in inpatients with 3rd generation cephalosporin-resistant (3GCR) Enterobacterales at a tertiary-care hospital in Lebanon, and suggested a risk prediction score for it. This is a retrospective matched case–control study of inpatients with 3GCR Enterobacterales that are carbapenem resistant (cases) versus those with carbapenem-sensitive isolates (controls). Data analysis was performed on IBM SPSS program, version 23.0 (Armonk, NY, USA: IBM Corp.). Categorical variables were compared between cases and controls through bivariate analysis and those with statistical significance (P < 0.05) were included in the forward stepwise multiple logistic regression analysis. To develop the CRE acquisition risk score, variables that maintained statistical significance in the multivariate model were assigned a point value corresponding to the odds ratio (OR) divided by the smallest OR identified in the regression model, and the resulting quotient was multiplied by two and rounded to the nearest whole number. Summation of the points generated by the calculated risk factors resulted in a quantitative score that was assigned to each patient in the database. Predictive performance was determined by assessing discrimination and calibration. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated for different cutoffs of the score. The incidence of CRE acquisition significantly increased with time from 0.21 cases/1000 patient-days (PD) in 2015 to 1.89 cases/1000PD in 2019 (r² = 0.789, P = 0.041). Multivariate analysis of matched data revealed that the history of cerebrovascular disease (OR 1.96; 95% CI 1.04–3.70; P = 0.039), hematopoietic cells transplantation (OR 7.75; 95% CI 1.52–39.36; P = 0.014), presence of a chronic wound (OR 3.38; 95% CI 1.73–6.50; P < 0.001), endoscopy done during the 3 months preceding the index hospitalization (OR 2.96; 95% CI 1.51–4.73; P = 0.01), nosocomial site of acquisition of the organism in question (OR 2.68; 95% CI 1.51–4.73; P = 0.001), and the prior use of meropenem within 3 months of CRE acquisition (OR 5.70; 95% CI 2.61–12.43; P < 0.001) were independent risk factors for CRE acquisition. A risk score ranging from 0 to 25 was developed based on these independent variables. At a cut-off of ≥ 5 points, the model exhibited a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 64.5%, 85.8%, 82%, 70.7% and 75%, respectively. We also showed that only meropenem consumption intensity and CRE acquisition incidence density showed a strong positive correlation(r = 0.798, P = 0.106), unlike imipenem (r = − 0.868, P = 0.056) and ertapenem (r = 0.385, P = 0.522). Patients with a score of ≥ 5 points in our model were likely to acquire CRE. Only meropenem was associated with CRE carriage. Our proposed risk prediction score would help target surveillance screening for CRE amongst inpatients at the time of hospital admission and properly guide clinicians on using anti-CRE therapy.

An overview of cilastatin + imipenem + relebactam as a therapeutic option for hospital-acquired and ventilator-associated bacterial pneumonia: evidence to date

Introduction: Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are prevalent nosocomial infections with a worrisomely increasing prevalence of multidrug-resistant causative organisms, including those with resistance to carbapenems. The addition of relebactam, a β-lactamase inhibitor, to imipenem treatment restores the antimicrobial activity against the most of multidrug-resistant Gram-negative bacteria, including some carrying β-lactamase enzyme-type carbapenemases.Areas covered: The aim of this article is to summarize the current evidence regarding imipenem/relebactam for the treatment of HAP/VAP. The authors discuss its chemistry, pharmacokinetics/pharmacodynamics, microbiology, tolerance and clinical efficacy. The results of clinical trials have demonstrated an efficacy of imipenem/relebactam similar to that of its comparator for the treatment of patients with HAP/VAP. Different studies have also shown its good safety profile, which is better than that of the combination of other β-lactams with other antibiotics.Expert opinion: This drug should be incorporated as a new therapeutic option for the treatment of patients with HAP/VAP, especially as an alternative treatment in patients with confirmed infections caused by multidrug-resistant Gram-negatives.

Novel Cephalosporins in Septic Subjects and Severe Infections: Present Findings and Future Perspective

In past decade, cephalosporins have developed significantly, and data regarding novel cephalosporins (i.e., ceftobiprole, ceftaroline, ceftolozane/tazobactam, ceftazidime/avibactam, and cefiderocol) within septic and bacteremic subjects are rising. These compounds generally offer very promising in vitro microbiological susceptibility, although the variability among gram-negative and -positive strains of different cohorts is noticed in the literature. We require further pharmacological data to measure the best dose in order to prevent sub-therapeutic drug levels in critically ill patients. These new compounds in theory are the sparing solution in the Enterobacteriales infection group for different antimicrobial classes such as aminoglycosides notably within endovascular and GNB-bacteremias, as well as colistin and carbapenem-sparing strategies, favoring good safety profile molecules. Moreover, new cephalosporins are the basis for the actual indications to open up new and exciting prospects for serious infections in the future. In future, patients will be addressed with the desirable approach to sepsis and serious infections in terms of their clinical situation, inherent features of the host, the sensitivity profile, and local epidemiology, for which evidence of the use of new cephalosporin in the treatment of severe infections will fill the remaining gaps.

Cefiderocol versus high-dose, extended-infusion meropenem for the treatment of Gram-negative nosocomial pneumonia (APEKS-NP): a randomised, double-blind, phase 3, non-inferiority trial

BACKGROUND

Nosocomial pneumonia due to multidrug-resistant Gram-negative pathogens poses an increasing challenge. We compared the efficacy and safety of cefiderocol versus high-dose, extended-infusion meropenem for adults with nosocomial pneumonia.

METHODS

We did a randomised, double-blind, parallel-group, phase 3, non-inferiority trial in 76 centres in 17 countries in Asia, Europe, and the USA (APEKS-NP). We enrolled adults aged 18 years and older with hospital-acquired, ventilator-associated, or health-care-associated Gram-negative pneumonia, and randomly assigned them (1:1 by interactive response technology) to 3-h intravenous infusions of either cefiderocol 2 g or meropenem 2 g every 8 h for 7-14 days. All patients also received open-label intravenous linezolid (600 mg every 12 h) for at least 5 days. An unmasked pharmacist prepared the assigned treatments; investigators and patients were masked to treatment assignment. Only the unmasked pharmacist was aware of the study drug assignment for the infusion bags, which were administered in generic infusion bags labelled with patient and study site identification numbers. Participants were stratified at randomisation by infection type and Acute Physiology and Chronic Health Evaluation II (APACHE II) score (≤15 and ≥16). The primary endpoint was all-cause mortality at day 14 in the modified intention-to-treat (ITT) population (ie, all patients receiving at least one dose of study drug, excluding patients with Gram-positive monomicrobial infections). The analysis was done for all patients with known vital status. Non-inferiority was concluded if the upper bound of the 95% CI for the treatment difference between cefiderocol and meropenem groups was less than 12·5%. Safety was investigated to the end of the study in the safety population, which included all patients who received at least one dose of study drug. This trial is registered with ClinicalTrials.gov, NCT03032380, and EudraCT, 2016-003020-23.

FINDINGS

Between Oct 23, 2017, and April 14, 2019, we randomly assigned 148 participants to cefiderocol and 152 to meropenem. Of 292 patients in the modified ITT population, 251 (86%) had a qualifying baseline Gram-negative pathogen, including Klebsiella pneumoniae (92 [32%]), Pseudomonas aeruginosa (48 [16%]), Acinetobacter baumannii (47 [16%]), and Escherichia coli (41 [14%]). 142 (49%) patients had an APACHE II score of 16 or more, 175 (60%) were mechanically ventilated, and 199 (68%) were in intensive care units at the time of randomisation. All-cause mortality at day 14 was 12·4% with cefiderocol (18 patients of 145) and 11·6% with meropenem (17 patients of 146; adjusted treatment difference 0·8%, 95% CI -6·6 to 8·2; p=0·002 for non-inferiority hypothesis). Treatment-emergent adverse events were reported in 130 (88%) of 148 participants in the cefiderocol group and 129 (86%) of 150 in the meropenem group. The most common treatment-emergent adverse event was urinary tract infection in the cefiderocol group (23 patients [16%] of 148) and hypokalaemia in the meropenem group (23 patients [15%] of 150). Two participants (1%) of 148 in the cefiderocol group and two (1%) of 150 in the meropenem group discontinued the study because of drug-related adverse events.

INTERPRETATION

Cefiderocol was non-inferior to high-dose, extended-infusion meropenem in terms of all-cause mortality on day 14 in patients with Gram-negative nosocomial pneumonia, with similar tolerability. The results suggest that cefiderocol is a potential option for the treatment of patients with nosocomial pneumonia, including those caused by multidrug-resistant Gram-negative bacteria.

FUNDING

Shionogi.

Evaluating the clinical effectiveness of new beta-lactam/beta-lactamase inhibitor combination antibiotics: A systematic literature review and meta-analysis

Background:

Ceftazidime/avibactam (C/A), ceftolozane/tazobactam (C/T), imipenem/relebactam (I/R), and meropenem/vaborbactam (M/V) combine either a cephalosporin (C/T and C/A) or a carbapenem antibiotic (M/V and I/R) with a β-lactamase inhibitor. They are used to treat carbapenem-resistant Enterobacterales (CRE) and/or multidrug-resistant Pseudomonas aeruginosa (MDRPA).

Objective:

We compared the pooled clinical success of these medications to older therapies.

Methods:

PubMed and EMBASE were searched from January 1, 2012, through September 2, 2020, for C/A, C/T, I/R, and M/V studies. The main outcome was clinical success, which was assessed using random-effects models. Stratified analyses were conducted for study drug, sample size, quality, infection source, study design, and multidrug-resistant gram-negative organism (MDRGNO) population. Microbiological success and 28- and 30-day mortality were assessed as secondary outcomes. Heterogeneity was determined using I2 values.

Results:

Overall, 25 articles met the inclusion criteria; 8 observational studies and 17 randomized control trials. We detected no difference in clinical success comparing new combination antibiotics with standard therapies for all included organisms (pooled OR, 1.21; 95% CI, 0.96–1.51). We detected a moderate level of heterogeneity among the included studies I2 = 56%. Studies that focused on patients with CRE or MDRPA infections demonstrated a strong association between treatment with new combination antibiotics and clinical success (pooled OR, 2.20; 95% CI, 1.60–3.57).

Conclusions:

C/T, C/A, I/R, and M/V are not inferior to standard therapies for treating various complicated infections, but they may have greater clinical success for treating MDRPA and CRE infections. More studies that evaluate the use of these antibiotics for drug-resistant infections are needed to determine their effectiveness.

New perspectives in the antibiotic treatment of mechanically ventilated patients with infections from Gram-negatives

Introduction: Ventilator-associated pneumonia (VAP) is a common and potentially fatal complication of mechanical ventilation that is often caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB). Despite the repurposing of older treatments and the novel antimicrobials, many resistance mechanisms cannot be confronted, and novel therapies are needed.Areas covered: We searched the literature for keywords regarding the treatment of GNB infections in mechanically ventilated patients. This narrative review presents new data on antibiotics and non-antibiotic approaches focusing on Phase 3 trials against clinically significant GNB that cause VAP.Expert opinion: Ceftazidime-avibactam, meropenem-vaborbactam, and imipenem-relebactam stand out as new options for infections by Klebsiella pneumoniae carbapenemase-producing bacteria, whereas ceftolozane-tazobactam adds therapeutic flexibility in Pseudomonas aeruginosa infections with multiple resistance mechanisms. Ceftazidime-avibactam and ceftolozane-tazobactam have relevant literature. Aztreonam-avibactam holds promise for the treatment of infections by metallo-β-lactamase (MBL)-producing organisms. Recently approved cefiderocol possesses an extended antibacterial spectrum, including KPC- and MBL-producers. However, recently published data have toned down optimism about treating VAP caused by carbapenem-resistant Acinetobacter baumannii. For the latter, eravacycline may provide additional hope, pending pertinent data. Non-antibiotic treatments currently being considered as adjunct therapeutic approaches are welcome. Nevertheless, they will hopefully substitute current antimicrobials in the future.

Is Ceftazidime/Avibactam an Option for Serious Infections Due to Extended-Spectrum-β-Lactamase- and AmpC-Producing Enterobacterales?: a Systematic Review and Meta-analysis

Carbapenem-sparing regimens are needed for the treatment of infections caused by extended-spectrum-β-lactamase (ESBL)- and AmpC-producing members of the Enterobacterales We sought to compare the clinical efficacy of ceftazidime/avibactam and carbapenems against ESBL- and AmpC-producing Enterobacterales species. A systematic review and meta-analysis of randomized controlled trials comparing ceftazidime/avibactam with carbapenems for the treatment of ESBL- and AmpC-producing Enterobacterales was conducted. Five randomized controlled trials (RCTs) with ESBL- and AmpC-specific outcome data were compiled. Of the 246 patients infected with an ESBL-producing microorganism in the ceftazidime/avibactam arm, 224 (91%) had a clinical response at test of cure (TOC), versus 240 of 271 (89%) patients in the carbapenem arm (risk ratio [RR], 1.02; 95% confidence interval [CI], 0.97 to 1.08; P = 0.45; I ² = 0%). Clinical response rates for AmpC producers in the ceftazidime/avibactam and carbapenem arms were 32/40 (80%) and 37/42 (88%), respectively (RR, 0.91; 95% CI, 0.76 to 1.10; P = 0.35; I ² = 0%). Microbiological response and mortality rates were not reported specifically for ESBL/AmpC producers. Ceftazidime/avibactam may be a carbapenem-sparing option for the treatment of mild to moderate complicated urinary tract and intra-abdominal infections caused by ESBL-producing Enterobacterales species, and the data are too limited to provide any conclusive recommendations for the AmpC producers. Care should be taken before extrapolating this to severe infections, given that the representation of this population in the reviewed studies was negligible. Ceftazidime/avibactam is a costly drug active against carbapenem-resistant microorganisms and should be used judiciously to preserve its activity against them.

Microbial Resistance Movements: An Overview of Global Public Health Threats Posed by Antimicrobial Resistance, and How Best to Counter

Antibiotics changed medical practice by significantly decreasing the morbidity and mortality associated with bacterial infection. However, infectious diseases remain the leading cause of death in the world. There is global concern about the rise in antimicrobial resistance (AMR), which affects both developed and developing countries. AMR is a public health challenge with extensive health, economic, and societal implications. This paper sets AMR in context, starting with the history of antibiotics, including the discovery of penicillin and the golden era of antibiotics, before exploring the problems and challenges we now face due to AMR. Among the factors discussed is the low level of development of new antimicrobials and the irrational prescribing of antibiotics in developed and developing countries. A fundamental problem is the knowledge, attitude, and practice (KAP) regarding antibiotics among medical practitioners, and we explore this aspect in some depth, including a discussion on the KAP among medical students. We conclude with suggestions on how to address this public health threat, including recommendations on training medical students about antibiotics, and strategies to overcome the problems of irrational antibiotic prescribing and AMR.

New cephalosporins for the treatment of pneumonia in internal medicine wards

The burden of hospital admission for pneumonia in internal medicine wards may not be underestimated; otherwise, cases of pneumonia are a frequent indication for antimicrobial prescriptions. Community- and hospital-acquired pneumonia are characterized by high healthcare costs, morbidity and non-negligible rates of fatality. The overcoming prevalence of resistant gram-negative and positive bacteria (e.g., methicillin-resistant Staphylococcus aureus, penicillin and ceftriaxone-resistant Streptococcus pneumoniae, extended-spectrum β-lactamases and carbapenemases producing Enterobacteriaceae) has made the most of the first-line agents ineffective for treating lower respiratory tract infections. A broad-spectrum of activity, favourable pulmonary penetration, harmlessness and avoiding in some cases a combination therapy, characterise new cephalosporins such as ceftolozane/tazobactam, ceftobiprole, ceftazidime/avibactam and ceftaroline. We aimed to summarise the role and place in therapy of new cephalosporins in community- and hospital-acquired pneumonia within the setting of internal medicine wards. The “universal pneumonia antibiotic strategy” is no longer acceptable for treating lung infections. Antimicrobial therapy should be individualized considering local antimicrobial resistance and epidemiology, the stage of the illness and potential host factors predisposing to a high risk for specific pathogens.

In Vitro Activity of Ceftazidime-Avibactam against Isolates from Respiratory and Blood Specimens from Patients with Nosocomial Pneumonia, Including Ventilator-Associated Pneumonia, in a Phase 3 Clinical Trial

Nosocomial pneumonia (NP), including ventilator-associated pneumonia (VAP), is increasingly associated with multidrug-resistant Gram-negative pathogens. This study describes the in vitro activity of ceftazidime-avibactam, ceftazidime, and relevant comparator agents against bacterial pathogens isolated from patients with NP, including VAP, enrolled in a ceftazidime-avibactam phase 3 trial. Gram-positive pathogens were included if coisolated with a Gram-negative pathogen. In vitro susceptibility was determined at a central laboratory using Clinical and Laboratory Standards Institute broth microdilution methods. Of 817 randomized patients, 457 (55.9%) had ≥1 Gram-negative bacterial pathogen(s) isolated at baseline, and 149 (18.2%) had ≥1 Gram-positive pathogen(s) coisolated. The most common isolated pathogens were Klebsiella pneumoniae (18.8%), Pseudomonas aeruginosa (15.8%), and Staphylococcus aureus (11.5%). Ceftazidime-avibactam was highly active in vitro against 370 isolates of Enterobacteriaceae, with 98.6% susceptible (MIC₉₀, 0.5 μg/ml) compared with 73.2% susceptible for ceftazidime (MIC₉₀, >64 μg/ml). The percent susceptibility values for ceftazidime-avibactam and ceftazidime against 129 P. aeruginosa isolates were 88.4% and 72.9% (MIC₉₀ values of 16 μg/ml and 64 μg/ml), respectively. Among ceftazidime-nonsusceptible Gram-negative isolates, ceftazidime-avibactam percent susceptibility values were 94.9% for 99 Enterobacteriaceae and 60.0% for 35 P. aeruginosa MIC₉₀ values for linezolid and vancomycin (permitted per protocol for Gram-positive coverage) were within their respective MIC susceptibility breakpoints against the Gram-positive pathogens isolated. This analysis demonstrates that ceftazidime-avibactam was active in vitro against the majority of Enterobacteriaceae and P. aeruginosa isolates from patients with NP, including VAP, in a phase 3 trial. (This study has been registered at ClinicalTrials.gov under identifier NCT01808092.).

Trends, Epidemiology, and Management of Multi-Drug Resistant Gram-Negative Bacterial Infections in the Hospitalized Setting

The increasing prevalence of antibiotic resistance is a threat to human health, particularly within vulnerable populations in the hospital and acute care settings. This leads to increasing healthcare costs, morbidity, and mortality. Bacteria rapidly evolve novel mechanisms of resistance and methods of antimicrobial evasion. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii have all been identified as pathogens with particularly high rates of resistance to antibiotics, resulting in a reducing pool of available treatments for these organisms. Effectively combating this issue requires both preventative and reactive measures. Reducing the spread of resistant pathogens, as well as reducing the rate of evolution of resistance is complex. Such a task requires a more judicious use of antibiotics through a better understanding of infection epidemiology, resistance patterns, and guidelines for treatment. These goals can best be achieved through the implementation of antimicrobial stewardship programs and the development and introduction of new drugs capable of eradicating multi-drug resistant Gram-negative pathogens (MDR GNB). The purpose of this article is to review current trends in MDR Gram-negative bacterial infections in the hospitalized setting, as well as current guidelines for management. Finally, new and emerging antimicrobials, as well as future considerations for combating antibiotic resistance on a global scale are discussed.

An overview of ceftolozane sulfate + tazobactam for treating hospital acquired pneumonia

INTRODUCTION

Ceftolozane-tazobactam is a combination of a new cephalosporin, with activity similar to that of ceftazidime, and a known inhibitor of beta-lactamases. This compound shows excellent activity against most gram-negative organisms causative of hospital-acquired pneumonia (HAP) or ventilator-acquired pneumonia (VAP), including extended spectrum beta-lactamase (ESBL)-producing Enterobacterales and multidrug-resistant (MDR) Pseudomonas aeruginosa.

AREAS COVERED

This article reviews the spectrum of activity, the main pharmacokinetic and pharmacodynamic characteristics and the clinical efficacy and safety of ceftolozane-tazobactam in the treatment of HAP/VAP in adult patients.

EXPERT OPINION

The results of a randomized clinical trial have demonstrated an efficacy and safety profile of ceftolozane-tazobactam similar to that of its comparator for the treatment of patients with HAP/VAP. Several retrospective studies have shown good efficacy of the drug for the treatment of respiratory infections caused by MDR P. aeruginosa. The use of this drug may be incorporated as a new therapeutic option for the treatment of patients with HAP/VAP in a carbapenem-saving setting or as a therapeutic alternative with a better safety profile than other therapeutic options in patients with infections caused by MDR P. aeruginosa.

Considerations in the Selection of Renal Dosage Adjustments for Patients with Serious Infections and Lessons Learned from the Development of Ceftazidime-Avibactam

An extensive clinical development program (comprising two phase 2 and five phase 3 trials) has demonstrated the efficacy and safety of ceftazidime-avibactam in the treatment of adults with complicated intra-abdominal infection (cIAI), complicated urinary tract infection (cUTI), and hospital-acquired pneumonia (HAP), including ventilator-associated pneumonia (VAP). During the phase 3 clinical program, updated population pharmacokinetic (PK) modeling and Monte Carlo simulations using clinical PK data supported modified ceftazidime-avibactam dosage adjustments for patients with moderate or severe renal impairment (comprising a 50% increase in total daily dose compared with the original dosage adjustments) to reduce the risk of subtherapeutic drug exposures in the event of rapidly improving renal function. The modified dosage adjustments were included in the ceftazidime-avibactam labeling information at the time of initial approval and were subsequently evaluated in the final phase 3 trial (in patients with HAP, including VAP), providing supportive data for the approved U.S. and European ceftazidime-avibactam dosage regimens across renal function categories. This review describes the analyses supporting the ceftazidime-avibactam dosage adjustments for renal impairment and discusses the wider implications and benefits of using modeling and simulation to support dosage regimen optimization based on emerging clinical evidence.

Selecting the dosage of ceftazidime-avibactam in the perfect storm of nosocomial pneumonia

PURPOSE

Ceftazidime-avibactam is a novel β-lactam/β-lactamase inhibitor combination recently approved in Europe and the USA for the treatment of adults with hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), among other indications. In the phase III REPROVE trial (NCT01808092), ceftazidime-avibactam demonstrated non-inferiority to meropenem for the treatment of patients with nosocomial pneumonia (NP), including VAP. As ceftazidime-avibactam was not studied in patients with NP prior to REPROVE, selecting an appropriate dosage regimen in the "perfect storm" of NP required careful consideration of potential determinants and confounders of response specific to the NP patient population.

METHODS

This review describes the series of preclinical studies and pharmacokinetic/pharmacodynamic (PK/PD) analyses that supported ceftazidime-avibactam dosage selection for patients with NP/VAP (2000/500 mg by 2-h intravenous infusion every 8 h, adjusted for renal function). In parallel, important considerations for antibiotic dosage selection in patients with NP are highlighted, including adequate drug penetration into the lungs, the suitability of murine-derived plasma PK/PD targets, evaluation of MIC distributions against clinical bacterial isolates from patients with NP, and consideration of PK in patients with NP, who are often critically ill. These analyses also supported the European approval of ceftazidime-avibactam for adults with HAP, including VAP, before the completion of REPROVE.

CONCLUSIONS

This work serves as a successful practical example of dosage design for a new antibacterial drug therapy in the indication of NP, including VAP, where previous drug therapies have failed, possibly as a result of evaluation of too few variables, thereby limiting the accuracy of pharmacodynamic predictions.