A randomised, double-blind, phase 3 study comparing the efficacy and safety of ceftazidime/avibactam plus metronidazole versus meropenem for complicated intra-abdominal infections in hospitalised adults in Asia

The Surgical Infection Society Guidelines on the Management of Intra-Abdominal Infection: 2024 Update

Background: The Surgical Infection Society (SIS) published evidence-based guidelines for the management of intra-abdominal infection (IAI) in 1992, 2002, 2010, and 2017. Here, we present the most recent guideline update based on a systematic review of current literature. Methods: The writing group, including current and former members of the SIS Therapeutics and Guidelines Committee and other individuals with content or guideline expertise within the SIS, working with a professional librarian, performed a systematic review using PubMed/Medline, the Cochrane Library, Embase, and Web of Science from 2016 until February 2024. Keyword descriptors combined "surgical site infections" or "intra-abdominal infections" in adults limited to randomized controlled trials, systematic reviews, and meta-analyses. Additional relevant publications not in the initial search but identified during literature review were included. The Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) system was utilized to evaluate the evidence. The strength of each recommendation was rated strong (1) or weak (2). The quality of the evidence was rated high (A), moderate (B), or weak (C). The guideline contains new recommendations and updates to recommendations from previous IAI guideline versions. Final recommendations were developed by an iterative process. All writing group members voted to accept or reject each recommendation. Results: This updated evidence-based guideline contains recommendations from the SIS for the treatment of adult patients with IAI. Evidence-based recommendations were developed for antimicrobial agent selection, timing, route of administration, duration, and de-escalation; timing of source control; treatment of specific pathogens; treatment of specific intra-abdominal disease processes; and implementation of hospital-based antimicrobial agent stewardship programs. Summary: This document contains the most up-to-date recommendations from the SIS on the prevention and management of IAI in adult patients.

Adequacy of the Dosing and Infusion Time of Ceftazidime/Avibactam for the Treatment of Gram-Negative Bacterial Infections: A PK/PD Simulation Study

Introduction

Recent studies suggested the potential benefits of extended infusion times to optimize the treatment efficacy of ceftazidime/avibactam, which indicated that the current pharmacokinetic/pharmacodynamic (PK/PD) target may not be sufficient, especially for severe infections. The purpose of this study is to assess the adequacy of dosing strategies and infusion durations of ceftazidime/avibactam when applying higher PK/PD targets.

Methods

This study utilized published PK parameters to conduct Monte Carlo simulations. Different dosages including the recommended regimen based on renal function were simulated and evaluated by the probability of target attainment (PTA) and cumulative fraction of response (CFR). Different PK/PD targets were set for ceftazidime and avibactam. MIC distributions from various sources were used to calculate the CFR.

Results

Multiple PK/PD targets have been set in this study, All recommended dosage could easily achieve the target of 50%fT ≥ MIC (ceftazidime) and 50%fT ≥ CT=1.0 mg/L (avibactam). However, for severe infection patients with normal renal function and augmented renal clearance at the recommended dosage (2000 mg/500 mg, every 8 hours), the infusion duration needs to be extended to 3 hours and 4 hours to achieve the targets of 100%fT ≥ MIC and 100%fT ≥ CT=1.0 mg/L. Only continuous infusion at higher dosages achieved 100%fT ≥ 4×MIC and 100%fT ≥ CT=4.0 mg/L targets to all currently recommended regimens. According to the varying MIC distributions, higher concentrations are needed for Pseudomonas aeruginosa, with the attainment rates vary across different regions.

Conclusion

The current recommended dosing regimen of ceftazidime/avibactam is insufficient for severe infection patients, and continuous infusion is suggested.

Effectiveness of novel β-lactams for Pseudomonas aeruginosa infection: A systematic review and meta-analysis

BACKGROUND

Novel β-lactams have in vitro activity against Pseudomonas aeruginosa (PA), but their clinical performances and the selection criteria for practical use are still not clear. We aimed to evaluate the efficacy of novel β-lactams for PA infection in various sites and to compare the efficacy of each agent.

METHODS

We searched PubMed, Embase, Cochrane Library, and Web of Science for randomized controlled trials that used novel β-lactams to treat PA infection. The primary outcomes were clinical cure and favorable microbiological response. Subgroup analyses were performed based on drug type, drug resistance of pathogens, and site of infection. Network meta-analysis was carried out within a Bayesian framework.

RESULTS

In all studies combined (16 randomized controlled trials), novel β-lactams indicated comparable performance to other treatment regimens in both outcome measures (relative risk = 1.04; 95% confidence interval 0.94-1.15; P = .43) (relative risk = 0.97; 95% confidence interval 0.81-1.17; P = .76). Subgroup analyses showed that the efficacy of ceftolozane-tazobactam (TOL-TAZ), ceftazidime-avibactam (CAZ-AVI), imipenem-cilastatin-relebactam, and cefiderocol had no apparent differences compared to control groups among different infection sites, drug types and drug resistance of PA. In network meta-analysis, the results showed no statistically significant differences between TOL-TAZ, CAZ-AVI, and cefiderocol.

CONCLUSIONS

TOL-TAZ, CAZ-AVI, imipenem-cilastatin-relebactam, and cefiderocol are not inferior to other agents in the treatment of PA infection. Their efficacy is also comparable between TOL-TAZ, CAZ-AVI, and cefiderocol.

Finding value in novel antibiotics: How can infectious diseases adopt incremental cost-effectiveness to improve new antibiotic utilization?

Research and development of innovative antimicrobials is paramount to addressing the antimicrobial resistance threat. Although antimicrobial discovery and development has increased, difficulties have emerged in the pharmaceutical industry after market approval. In this minireview, we summarize clinical trial data on recently approved antibiotics, calculate incremental cost-effectiveness ratio (ICER) values, and explore ways to adapt ICER calculations to the limitations of antimicrobial clinical trial design. We provide a systematic review and analysis of randomized, controlled studies of antibiotics approved from 2014 - 2022 and extracted the relevant clinical data. Adapted-ICER (aICER) calculations were conducted using the primary condition-specific outcome that was reported in each study (percent mortality or percent cure rate). The literature search identified 18 studies for the 8 total antibiotics which met inclusion criteria and contained data required for aICER calculation. aICER values ranged from -$17,374 to $4,966 per percent mortality and -$43,931 to $2,529 per percent cure rate. With regards to mortality, ceftolozane/tazobactam and imipenem/cilastatin/relebactam proved cost efficacious, with aICER values of $4,965 per percent mortality and $1,955 per percent mortality respectively. Finding value in novel antibiotic agents is imperative to further justifying their development, and aICER values are the most common method of determining value in healthcare. The current outcomes of clinical trials are difficult to translate to aICER, which most effectively use Quality-Adjusted Life Years (QALY) as the quality standard in other fields such as oncology. Future antimicrobial trials should consider introducing methods of assessing measures of health gain such as QALY to better translate the value of novel antimicrobials in healthcare.

Ceftazidime-avibactam combination therapy versus monotherapy for treating carbapenem-resistant gram-negative infection: a systemic review and meta-analysis

BACKGROUND

This meta-analysis was conducted to compare the efficacy of ceftazidime-avibactam combination therapy with that of monotherapy in the treatment of carbapenem-resistant Gram-negative bacterial (CR-GNB).

METHODS

A literature search of PubMed, Embase, the Cochrane Library, and ClinicalTrials.gov was conducted until September 1, 2023. Only studies that compared CZA combination therapy with monotherapy for CR-GNB infections were included.

RESULTS

A total of 25 studies (23 retrospective observational studies and 2 prospective studies) involving 2676 patients were included. There was no significant difference in 30-day mortality between the study group receiving combination therapy and the control group receiving monotherapy (risk ratio [RR] 0.91; 95% confidence interval [CI] 0.71-1.18). In addition, no significant differences were observed between the study and the control group in terms of in-hospital mortality (RR 1.00; 95% CI 0.79-1.27), 14-day mortality (RR 1.54; 95% CI 0.24-9.91), 90-day mortality (RR 1.18; 95% CI 0.62-2.22), and clinical cure rate (RR 0.95; 95% CI 0.84-1.08). However, the combination group had a borderline higher microbiological eradication rate than the control group (RR 1.15; 95% CI 1.00-1.32).

CONCLUSIONS

Compared to monotherapy, CZA combination therapy did not yield additional clinical benefits. However, combination therapy may be associated with favorable microbiological outcomes.

Friends or foes? Novel antimicrobials tackling MDR/XDR Gram-negative bacteria: a systematic review

Gram-negative bacteria have been one of the most studied classes in the field of microbiology, especially in the context of globally alarming antimicrobial resistance levels to these pathogens over the course of the past decades. With high numbers of these microorganisms being described as multidrug-resistant (MDR), or even extended-drug-resistant (XDR) bacteria, specialists in the field have been struggling to keep up with higher prevalence of difficult-to-treat infections caused by such superbugs. The FDA approval of novel antimicrobials, such as cefiderocol (FDC), ceftolozane/tazobactam (C/T), ceftazidime/avibactam (CZA), imipenem/relebactam (IMR), sulbactam/durlobactam (SUL-DUR) and phase 3 clinical trials' results of aztreonam/avibactam (ATM-AVI) has proven that, while all these substances provide encouraging efficacy rates, antibiotic resistance keeps up with the pace of drug development. Microorganisms have developed more extensive mechanisms of resistance in order to target the threat posed by these novel antimicrobials, thus equiring researchers to be on a constant lookout for other potential drug candidates and molecule development. However, these strategies require a proper understanding of bacterial resistance mechanisms to gain a comprehensive outlook on the issue. The present review aims to highlight these six antibiotic agents, which have brought hope to clinicians during the past decade, discussing general properties of these substances, as well as mechanisms and patterns of resistance, while also providing a short overview on further directions in the field.

Systematic review registration

https://www.crd.york.ac.uk/prospero/#searchadvanced, Identifier CRD42024505832.

Off-label Use of Ceftazidime/Avibactam in Neonatal Intensive Care Unit: A Real-life Experience and Literature Review

BACKGROUND

Multi/extensively drug-resistant bacterial infections have recently increased and new antimicrobial options are needed for difficult-to-treat infections. Ceftazidime/avibactam (CZA) has been approved for patients 3 months to 18 years of age, but real-life data on its off-label use in neonates and young infants are still scarce.

MATERIALS

We report demographic, clinical and microbiologic data as well as outcome and safety of all cases of infants treated with CZA between January 1, 2021 and September 30, 2022 in a tertiary neonatal intensive care unit. We also review all neonatal cases previously reported.

RESULTS

Twenty-one patients [17 males, with median gestational age 29 +2 (IQR 6 +6 ) weeks] received 31 CZA courses at a dose of 20-50 mg/kg/dose of ceftazidime q8h for suspected or proved multi/extensively drug-resistant infections. Median postnatal age at the onset of treatment was 44 days (IQR: 94 days). Twelve bacteremias, 2 urinary tract infections and 1 ventilator-acquired pneumonia were recorded. Twelve (39%) treatments were targeted, while 19 (61%) were empirically started due to known colonization with Klebsiella pneumoniae carbapenemase-producing Gram-negative bacteria. All patients had received multiple antibiotics prior and concomitantly with CZA. The most common pathogen identified at targeted administrations was carbapenem-resistant Klebsiella pneumoniae (83%). No serious adverse events attributed to the drug were detected. Twenty-one courses of CZA administration to 20 neonates with a median gestational age of 28.5 (IQR 3.5) weeks were previously reported without significant related adverse events.

CONCLUSIONS

Favorable clinical and microbiologic responses in neonatal intensive care unit patients treated with CZA off-label were observed without significant and unexpected adverse events in critically ill neonates.

Ceftazidime-avibactam induced renal disorders: past and present

With the increasing prevalence of multidrug-resistant Gram-negative bacterial pathogens worldwide, antimicrobial resistance has become a significant public health concern. Ceftazidime-avibactam (CAZ-AVI) exhibited excellent in vitro activity against many carbapenemase-producing pathogens, and was widely used for the treatment of various complicated infections. CAZ-AVI is well tolerated across all dosing regimens, and its associated acute kidney injury (AKI) in phase II/III clinical trials is rare. However, recent real-world studies have demonstrated that CAZ-AVI associated AKI was more frequent in real-world than in phase II and III clinical trials, particularly in patients receiving concomitant nephrotoxic agents, with critically ill patients being at a higher risk. Herein, we reviewed the safety data related to renal impairment of CAZ-AVI, and discussed its pharmacokinetic/pharmacodynamic targets and dosage adjustment in patients with impaired renal function. This review aimed to emphasize the importance for healthcare professionals to be aware of this adverse event of CAZ-AVI and provide practical insights into the dosage optimization in critically ill patients with renal dysfunction.

Effectiveness and safety of cefotaxime combined with avibactam for treating multidrug-resistant E coli infections: A systematic review and meta-analysis

BACKGROUND

Multidrug-resistant Escherichia coli infections are a global health challenge, notably in North America, Europe, Asia, and Africa. This systematic review and meta-analysis evaluates the effectiveness and safety of cefotaxime combined with avibactam, aiming to mitigate these infections' impact and lessen their burden on healthcare systems worldwide.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and PICO frameworks, we conducted a comprehensive literature search across 4 primary databases on May 6, 2023. Studies evaluating the efficacy and safety of cefotaxime and avibactam were included. Key outcomes included treatment success, adverse effects, and microbiological eradication. Quality assessment utilized the Cochrane Collaboration Risk of Bias instrument. Heterogeneity was analyzed using chi-square statistics and the I2 index. Both fixed- and random-effects models were applied as appropriate. Publication bias was rigorously evaluated using Egger linear regression test and funnel plot analysis, ensuring the study's integrity and reliability.

RESULTS

The clinical cure rate derived from 8 studies showed no significant difference between the treatment groups (odds ratio [OR] = 1.97, 95% CI: 0.69 to 1.36, P = .86). Analysis of the bacterial clearance rate from the 5 studies also indicated no significant difference (OR = 0.97, 95% CI: 0.42 to 2.25, P = .36). Notably, a reduced mortality rate favoring the experimental group was observed in 6 studies (OR = 0.64, 95% CI: 0.44 to 0.92, P = .012). Comprehensive sensitivity analyses and the assessment of publication bias strengthened the reliability of the results.

CONCLUSIONS

Ceftazidime combined with avibactam significantly reduced mortality among patients with multidrug-resistant Escherichia coli infections, indicating its potential as a therapeutic option, especially for carbapenem-resistant Enterobacteriaceae. However, extensive large-scale clinical trials are required to validate these findings.

Capturing Value Attributes in the Economic Evaluation of Ceftazidime with Avibactam for Treating Severe Aerobic Gram-Negative Bacterial Infections in the United Kingdom

INTRODUCTION

Antimicrobial resistance remains a serious and growing threat to public health, both globally and in the UK, leading to diminishing effectiveness of antimicrobials. Despite a clear need for new antimicrobials, the clinical pipeline is insufficient, driven by high research and development costs and limited expected returns on investment. To counteract this, National Institute for Health and Care Excellence (NICE) and National Health Service (NHS) England have launched a reimbursement mechanism, de-linked from volume of sales, that aims to reduce economic risk by recognising the broader population-level value of antimicrobials. The objective of this study was to quantify the value of ceftazidime-avibactam for treating gram-negative infections in the UK considering some of these broader value elements unique to antimicrobials.

METHODS

A previously developed dynamic disease transmission and cost-effectiveness model was applied to assess the value of introducing ceftazidime-avibactam to UK treatment practice in the management of gram-negative hospital-acquired infections in line with the licenced indications for ceftazidime-avibactam. Model inputs were parameterised using sources aligned to the UK perspective.

RESULTS

The introduction of ceftazidime-avibactam into a two-line treatment sequence saved over 2300 lives, leading to a gain of 27,600 life years and 22,000 quality-adjusted life years (QALY) at an additional cost of £17 million, over a ten-year transmission period. Ceftazidime-avibactam was associated with a net monetary benefit of £642 million at willingness to pay threshold of £30,000 per QALY; even at a lower threshold of £20,000 per QALY, the net monetary benefit is £422 million.

DISCUSSION

Increasing the diversity of antimicrobial treatments through the introduction of an additional antimicrobial, in this instance ceftazidime-avibactam, was associated with substantial clinical and economic benefits, when considering broader population-level value. Despite revealing considerable benefits, the value of ceftazidime-avibactam is only partially reflected in this analysis. Further efforts are required to fully operationalise the spectrum, transmission, enablement, diversity and insurance (STEDI) value framework and accurately reflect the population-level value of antimicrobials.

Clinical Efficacy and Safety Evaluation of Ceftazidime-Avibactam in the Treatment of Klebsiella pneumoniae Infection: A Retrospective Analysis from a Hospital in China

Background

Ceftazidime-avibactam (CAZ-AVI) is a new cephalosporin/β-lactamase inhibitor combination that received clinical approval in China in 2019. This study aims to investigate the efficacy and safety of CAZ-AVI in the treatment of Klebsiella pneumoniae (KP) infection in a hospital, and differences in efficacy among various infection sites and between monotherapy and combination therapy, providing valuable insights for its further application.

Methods

Patients who used CAZ-AVI between January 2019 and April 2023 were identified through the hospital information system. Demographic information, details of the infection site, KP strain's drug sensitivity report, treatment duration, combination therapies, adverse drug reactions (ADR), and 28-day survival were recorded. Clinical and microbiological efficacies were analyzed using SPSS 23.0 software to compare different infection sites and combination therapies.

Results

The overall effective clinical response (CR) rate of CAZ-AVI against KP infection was 62.13%, with a favorable microbial response (MR) rate was 65.68% and a 28-day survival rate was 63.91%. No significant difference occurred in effective CR and 28-day survival rate among different infection sites (P = 0.709 and 0.862, respectively). The favorable MR rate for abdominal infections was slightly lower than that for other sites of infection (P = 0.021). No significant differences in effective CR, favorable MR, and 28-day survival between monotherapy and combination therapy were present (P values were 0.649, 0.123, and 0.280, respectively). The incidence of ADR was 1.78%, including increased creatinine, elevated transaminase, hematuria, and thrombocytopenia.

Conclusion

CAZ-AVI demonstrates good clinical efficacy and safety in the treatment of KP infections. The clinical efficacy of CAZ-AVI was similar across different infection sites, and combination therapy did not show an advantage over monotherapy. Further studies are warranted. It should be noted that CAZ-AVI may induce thrombocytopenia and hematuria.

Efficacy and safety of ceftazidime/avibactam in patients with infections caused by β-lactamase-producing Gram-negative pathogens: a pooled analysis from the Phase 3 clinical trial programme

OBJECTIVES

This post hoc pooled analysis evaluated clinical and microbiological outcomes and safety in patients with infections caused by β-lactamase-producing Gram-negative pathogens across five Phase 3, randomized, controlled, multicentre trials of ceftazidime/avibactam in adults with complicated intra-abdominal infection (cIAI), complicated urinary tract infection (cUTI)/pyelonephritis and nosocomial pneumonia (NP), including ventilator-associated pneumonia (VAP).

METHODS

In each trial, RECLAIM/RECLAIM 3 (cIAI), REPRISE (cIAI/cUTI), RECAPTURE (cUTI) and REPROVE (NP, including VAP) patients were randomized 1:1 to IV ceftazidime/avibactam (plus metronidazole for patients with cIAI) or comparators (carbapenems in >97% patients) for 5-21 days. Clinical and microbiological responses at the test-of-cure visit were assessed for patients with ESBLs, and/or plasmidic and/or overexpression of chromosomal AmpC, and/or serine carbapenemases without MBLs identified in baseline Gram-negative isolates by phenotypic screening and molecular characterization in the pooled microbiological modified ITT (mMITT) population.

RESULTS

In total, 813 patients (ceftazidime/avibactam, n = 389; comparator, n = 424) had ≥1 β-lactamase-producing baseline pathogen identified, amongst whom 792 patients (ceftazidime/avibactam, n = 379; comparator, n = 413) had no MBLs. The most frequent β-lactamase-producing pathogens across treatment groups were Escherichia coli (n = 381), Klebsiella pneumoniae (n = 261) and Pseudomonas aeruginosa (n = 53). Clinical cure rates in the pooled non-MBL β-lactamase-producing mMITT population were 88.1% (334/379) for ceftazidime/avibactam and 88.1% (364/413) for comparators; favourable microbiological response rates were 76.5% (290/379) and 68.8% (284/413), respectively. The safety profile of ceftazidime/avibactam was consistent with previous observations.

CONCLUSIONS

This analysis provides supportive evidence of the efficacy and safety of ceftazidime/avibactam in patients with infections caused by ESBLs, AmpC and serine carbapenemase-producing Gram-negative pathogens.

TRIAL REGISTRATION

NCT01499290; NCT01726023; NCT01644643; NCT01595438/NCT01599806; NCT01808092.

Comparative efficacy and safety of non-polymyxin antibiotics against nosocomial pneumonia, complicated intra-abdominal infection, or complicated urinary tract infection: A network meta-analysis of randomised clinical trials

OBJECTIVES

The increasing epidemic of infections caused by drug-resistant Gram-negative bacteria has led to the development of several antibiotic therapies. Owing to the scarcity of head-to-head comparisons of current and emerging antibiotics, the present network meta-analysis aimed to compare the efficacy and safety of antibiotics in patients with nosocomial pneumonia, complicated intra-abdominal infection, or complicated urinary tract infection.

METHODS

Two independent researchers systematically searched databases up to August 2022 and included 26 randomised controlled trials that fulfilled the inclusion criteria. The protocol was registered in the Prospective Register of Systematic Reviews, PROSPERO (CRD42021237798). The frequentist random effects model (R version 3.5.1, netmeta package) was utilized. The DerSimonian-Laird random effects model was used to estimate heterogeneity. The calculated P-score was applied to rank the interventions. Additionally, inconsistencies, publication bias, and subgroup effects were assessed in the present study to avoid bias.

RESULTS

There was no significant difference among included antibiotics in terms of clinical response and mortality, probably because most antibiotic trials were designed to be non-inferior. In terms of P-score ranking, carbapenems may be the recommended choice considering both adverse events and clinical responses. On the other hand, for carbapenem-sparing options, ceftolozane-tazobactam was the preferred antibiotic for nosocomial pneumonia; eravacycline, for complicated intra-abdominal infection; and cefiderocol, for complicated urinary tract infection.

CONCLUSION

Carbapenems may be preferable options in terms of safety and efficacy for the treatment of Gram-negative bacterial complicated infections. However, to preserve the effectiveness of carbapenems, it is important to consider carbapenem-sparing regimens.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Bloodstream Infection and Gram-Negative Resistance: The Role for Newer Antibiotics

Gram-negative resistance remains a major challenge. Rates of in vitro resistance to commonly utilized antibiotics have skyrocketed over the last decade. Clinicians now encounter multidrug-resistant organisms routinely. Fortunately, newer agents, such as ceftazidime-avibactam, ceftolozone-tazobactam, meropenem-vaborbactam, and cefiderocol, have been developed and are now available for use against these pathogens. Clinical trials with these novel therapies have focused on multiple infection types ranging from complicated urinary tract infections to nosocomial pneumonia. Nonetheless, there remains little information about the efficacy of these drugs for bacteremia. To better appreciate the types and limitations of the evidence supporting the role for these unique molecules in bloodstream infection, one requires an appreciation of the initial clinical trials supporting the regulatory approval of these antibiotics. Furthermore, physicians must understand the subsequent case series and reports specifically focusing on outcomes for patients with bacteremia treated with these drugs. Despite the limitations of the data and reports relating to treatment for bacteremia with these antibiotics, each agent appears to be efficacious and can provide good outcomes in bloodstream infections due to resistant pathogens.

Cost-effectiveness of ceftazidime/avibactam plus metronidazole versus meropenem as first-line empiric therapy for the treatment of complicated intra-abdominal infections: A study based on the in-vitro surveillance data in China

BACKGROUND

With the increase in drug resistance rates of pathogens isolated from complicated intra-abdominal infections (cIAIs), ceftazidime/avibactam (CAZ-AVI) is increasingly used clinically. However, given the high drug cost and the fact that not yet covered by the health insurance payment, this study evaluated the cost-effectiveness of CAZ-AVI plus metronidazole versus meropenem as a first-line empiric treatment for cIAIs from the perspective of the Chinese healthcare system.

METHODS

A decision analytic model with a one-year time horizon was constructed to assess the cost-effectiveness based on the entire disease course. Model inputs were mainly obtained from clinical studies, published literature, and publicly available databases. Primary outcomes were cost, quality-adjusted life years (QALYs), life years (Lys), and incremental cost-effectiveness ratio (ICER). One-way sensitivity analysis and probabilistic sensitivity analysis were also performed.

RESULTS

In the base cases, compared to meropenem, CAZ-AVI plus metronidazole had a shorter mean hospital length of stay (-0.77 days per patient) and longer life expectancy (+0.05 LYs and +0.06 QALYs). CAZ-AVI plus metronidazole had an ICER of $25517/QALY, which is well below the threshold of $31509 per QALY in China. The one-way sensitivity analysis showed that the change of the treatment duration of CAZ-AVI plus metronidazole was the parameter that most influenced the results of the ICER. In probabilistic sensitivity analysis, CAZ-AVI plus metronidazole was the optimal strategy in 75% of simulations at $31510/QALY threshold.

CONCLUSIONS

CAZ-AVI plus metronidazole could be considered as a cost-effective option for the empiric treatment of patients with cIAIs in China, and this benefit will be more evident when the price of CAZ-AVI decreases by 23.8%.

Effectiveness of Five Antibiotic Regimens for the Treatment of Intra-Abdominal Infection in Bogotá

Background: Intra-abdominal infection (IAI) results in prolonged in-hospital length-of-stay, critical care unit requirements, and multiple surgical procedures. Several antimicrobial agents are available for treatment of IAI. In Colombia, there are no data on the comparative effectiveness of the different regimens used. Patients and Methods: A multicenter retrospective cohort study was completed in four third-level hospitals by comparing treatment effectiveness of five different antibiotic protocols (ampicillin-sulbactam, clindamycin-amikacin, piperacillin-tazobactam, amikacin-metronidazole, and cefuroxime-metronidazole) in patients with a diagnosis of IAI. Analysis was based on a composed outcome of therapeutic failure (change of antibiotic because of no clinical improvement, requirement of surgical re-intervention, post-operative infection, change of antibiotic because of antimicrobial resistance, and in-hospital mortality). Association of each antibiotic protocol to therapeutic failure was assessed through logistic regression analysis. Results: Five hundred ninety-three individuals were included. Two hundred twenty-nine were prescribed ampicillin-sulbactam; 170, clindamycin-amikacin; 77, amikacin-metronidazole; 83, piperacillin-tazobactam; and 34, cefuroxime-metronidazole. Therapeutic failure rate was 22%. Multivariable analysis showed none of the evaluated antibiotic protocols had an association with the primary outcome. Variables having an association for higher risk were age >70 years old (odds ratio [OR], 2.08; 95% confidence interval [CI], 1.04-4.18); complicated IAI (OR, 3.36; 95% CI, 1.4-8.07); and World Society of Emergency Surgery (WSES) Sepsis Severity Score (OR, 1.31; 95% CI, 1.18-1.45). Adequate source control (OR, 0.16; 95% CI, 0.05-0.45) and hospitalization at Health Center 2 (OR, 0.30; 95% CI, 0.14-0.63) were identified as protective factors. Conclusions: There are no differences between the rate of therapeutic failure among the different antibiotic protocols evaluated. This outcome depends heavily on risk factors related to disease severity when surgical intervention occurs.

New antimicrobial treatment options for severe Gram-negative infections

PURPOSE OF REVIEW

This review will provide rationale for the development of new antibiotics to treat severe or multidrug-resistant (MDR) Gram-negative infections. It will also provide an overview of recently approved and pipeline antibiotics for severe/MDR Gram-negative infections.

RECENT FINDINGS

MDR Gram-negative infections are recognized as critical threats by global and national organizations and carry a significant morbidity and mortality risk. Increasing antibiotic resistance amongst Gram-negative bacteria, including carbapenem-resistant Acinetobacter baumannii , extended-spectrum β-lactamase-producing Enterobacterales, carbapenem-resistant Enterobacterales and Pseudomonas aeruginosa , with difficult-to-treat-resistance has made both empiric and definitive treatment of these infections increasingly problematic. In recent years, several antibiotics have been approved for treatment of MDR Gram-negative infections and ongoing clinical trials are poised to provide additional options to clinicians' armamentarium. These agents include various β-lactam/β-lactamase inhibitor combinations, eravacycline, plazomicin and cefiderocol.

SUMMARY

Severe/MDR Gram-negative infections continue to be important infections due to their impact on patient outcomes, especially in critically ill and immunocompromised hosts. The availability of new antibiotics offers an opportunity to improve empiric and definitive treatment of these infections.

The efficacy and safety of eravacycline compared with current clinically common antibiotics in the treatment of adults with complicated intra-abdominal infections: A Bayesian network meta-analysis

Background

Eravacycline is a novel, fully synthetic fluorocycline antibiotic for the treatment of adults with complicated intra-abdominal infections (cIAIs). However, the efficacy and safety of eravacycline compared with current clinically common antibiotics remain unknown.

Objective

This study aims to compare the efficacy and safety of eravacycline and other clinically common antibiotics in China, including tigecycline, meropenem, ertapenem, ceftazidime/avibactam+metronidazole, piperacillin/tazobactam, imipenem/cilastatin, and ceftriaxone+metronidazole, for the treatment of adults with cIAIs and to provide a reference for clinical choice.

Methods

The PubMed, Embase, Cochrane Library, and ClinicalTrials.gov databases were electronically searched to collect clinical randomized controlled studies (RCTs) comparing different antibiotics in the treatment of patients with cIAIs from inception to June 1, 2021. Two reviewers independently screened the literature, extracted data, and evaluated the risk of bias in the included studies.

Results

A total of 4050 articles were initially retrieved, and 25 RCTs were included after screening, involving eight treatment therapies and 9372 patients. The results of network meta-analysis showed that in the intention-to-treat (ITT) population, the clinically evaluable (CE) population, and the microbiologically evaluable (ME) population, the clinical response rate of eravacycline was not significantly different from that of the other 7 therapies (P > 0.05). In terms of microbiological response rate, eravacycline was significantly better than tigecycline [tigecycline vs. eravacycline: RR = 0.82, 95%CI (0.65,0.99)], and there was no significant difference between the other 6 regimens and eravacycline (P > 0.05). In terms of safety, the incidence of serious adverse events, discontinuation rate, and all-cause mortality of eravacycline were not significantly different from those of the other 7 treatment therapies (P > 0.05).

Conclusion

Based on the evidence generated by the current noninferiority clinical trial design, the efficacy and safety of eravacycline for the treatment of adults with cIAIs are not significantly different from those of the other 7 commonly used clinical antibiotics in China. In terms of microbiological response rate, eravacycline was significantly better than tigecycline. In view of the severe multidrug-resistant situation in China, existing drugs have difficulty meeting the needs of clinical treatment, and the new antibacterial drug eravacycline may be one of the preferred options for the treatment of cIAIs in adults.

Microbiota Assessment of Pediatric Simple and Complex Acute Appendicitis

Background and Objectives. The aim of this study is to determine the prevailing microbiota in samples from pediatric patients with acute appendicitis, as well as evaluate the antibacterial sensitivity of the isolated microorganisms, comparing the data obtained with the clinic’s antibacterial therapy guidelines. Materials and Methods. The study group consisted of 93 patients between the ages of 7 and 18. All patients underwent a laparoscopic or conventional appendectomy. The children were hospitalized with signs and symptoms suggestive of acute appendicitis. Microbiological cultures from the appendix and abdominal cavity were collected intraoperatively. Results. E. coli was identified in most cases irrespective of the clinical presentation of acute appendicitis. Most strains were susceptible to ampicillin and amoxicillin/clavulanic acid. Five strains of E. coli produced extended spectrum beta-lactamase (ESBL). Pseudomonas aeruginosa (P. aeruginosa) was the second most commonly isolated causative agent. Furthermore, it was common in cases of acute complex appendicitis. Most strains of P. aeruginosa were resistant to amoxicillin/clavulanic acid, ertapenem, ampicillin and cefotaxime, yet were susceptible to ceftazidime. Regardless of the clinical presentation, the samples yielded mixed isolates. Conclusion. E. coli is the main causative agent of acute appendicitis in the pediatric population displaying susceptibility to various antibiotics. P. aeruginosa was more prevalent in cases of acute complex appendicitis. P. aeruginosa isolates were susceptible to ceftazidime; however, they were resistant to cefotaxime, which should, therefore, be removed from guidelines for empirical antibacterial treatment of acute appendicitis due to phenotypic resistance of P. aeruginosa. We recommend antibiotics with distinct implementation to avoid antibiotic resistance.

Early and Appropriate Use of Ceftazidime-Avibactam in the Management of Multidrug-Resistant Gram-Negative Bacterial Infections in the Indian Scenario

The increasing prevalence of antibiotic-resistant pathogens exerts a substantial burden on the healthcare infrastructure worldwide. The World Health Organization (WHO) has declared that multidrug-resistant (MDR) Gram-negative pathogens, especially, carbapenem-resistant Enterobacterales (CRE), Acinetobacter baumannii, and Pseudomonas aeruginosa as the topmost priority while developing newer antimicrobials. The increasing prevalence of infectious diseases caused by MDR Gram-negative bacteria also poses a challenge when choosing the empiric antimicrobial therapy for seriously ill hospitalized patients. The infections caused by MDR Gram-negative organisms ultimately result in increased mortality, morbidity, prolonged hospital stay, and increased cost of management. To tackle these challenges, newer antimicrobials like ceftazidime-avibactam were explored. The article also discusses the in vitro activity and therapeutic efficacy of ceftazidime-avibactam along with its pharmacokinetic properties and the role it will play in the management of MDR Gram-negative organisms in the Indian setting. Several studies have highlighted the role of early and appropriate antibiotic use in the reduction of mortality in patients with Gram-negative infections. Timely initiation of appropriate antibiotic therapy for serious infections leads to favorable clinical outcomes. Early and appropriate use of ceftazidime-avibactam while treating MDR Gram-negative infections has been associated with improved clinical outcomes. The aim of this review is to highlight the efficacy of ceftazidime-avibactam in the treatment of MDR Gram-negative infections. We have also summarized the information on outcomes achieved by early and appropriate use of ceftazidime-avibactam.

A Phase 3, Multicenter, Double-blind, Randomized Clinical Trial to Evaluate the Efficacy and Safety of Ceftolozane/Tazobactam Plus Metronidazole Versus Meropenem in Chinese Participants With Complicated Intra-abdominal Infections

OBJECTIVE

To evaluate the efficacy and safety of ceftolozane/tazobactam plus metronidazole vs meropenem plus placebo for the treatment of complicated intra-abdominal infection (cIAI) in Chinese adult participants.

METHODS

In this phase 3 clinical trial (NCT03830333), Chinese adult participants with cIAI were randomized 1:1 to receive ceftolozane/tazobactam plus metronidazole or meropenem plus placebo. The primary objective was to assess ceftolozane/tazobactam plus metronidazole for noninferiority vs meropenem for clinical response rate at the test of cure (TOC; 28 ± 2 days after study start) visit in the clinically evaluable (CE) population. Secondary end points included clinical and microbiologic responses at the TOC and end of treatment (EOT; ≤24 hours after last dose) visits and adverse event rates.

RESULTS

Clinical cure at the TOC visit in the CE population was 95.2% and 93.1% for ceftolozane/tazobactam plus metronidazole and meropenem, respectively (between-treatment difference: 2.1% [95% CI: -4.7%, 8.8%); thus, noninferiority was met. Clinical responses at the TOC and EOT visits and microbiologic responses at the TOC visit were consistent with the primary efficacy end point. Safety was comparable between study treatment groups.

CONCLUSION

In Chinese adult participants with cIAI, ceftolozane/tazobactam plus metronidazole was noninferior to meropenem, with comparable safety.

Ceftazidime/Avibactam in Ventilator-Associated Pneumonia Due to Difficult-to-Treat Non-Fermenter Gram-Negative Bacteria in COVID-19 Patients: A Case Series and Review of the Literature

Ventilator-associated pneumonia (VAP) in critically ill patients with COVID-19 represents a very huge global threat due to a higher incidence rate compared to non-COVID-19 patients and almost 50% of the 30-day mortality rate. Pseudomonas aeruginosa was the first pathogen involved but uncommon non-fermenter gram-negative organisms such as Burkholderia cepacea and Stenotrophomonas maltophilia have emerged as other potential etiological causes. Against carbapenem-resistant gram-negative microorganisms, Ceftazidime/avibactam (CZA) is considered a first-line option, even more so in case of a ceftolozane/tazobactam resistance or shortage. The aim of this report was to describe our experience with CZA in a case series of COVID-19 patients hospitalized in the ICU with VAP due to difficult-to-treat (DTT) P. aeruginosa, Burkholderia cepacea, and Stenotrophomonas maltophilia and to compare it with data published in the literature. A total of 23 patients were treated from February 2020 to March 2022: 19/23 (82%) VAPs were caused by Pseudomonas spp. (16/19 DTT), 2 by Burkholderia cepacea, and 6 by Stenotrophomonas maltophilia; 12/23 (52.1%) were polymicrobial. Septic shock was diagnosed in 65.2% of the patients and VAP occurred after a median of 29 days from ICU admission. CZA was prescribed as a combination regimen in 86% of the cases, with either fosfomycin or inhaled amikacin or cotrimoxazole. Microbiological eradication was achieved in 52.3% of the cases and the 30-day overall mortality rate was 14/23 (60.8%). Despite the high mortality of critically ill COVID-19 patients, CZA, especially in combination therapy, could represent a valid treatment option for VAP due to DTT non-fermenter gram-negative bacteria, including uncommon pathogens such as Burkholderia cepacea and Stenotrophomonas maltophilia.

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.

Are there differences between ceftolozane/tazobactam and ceftazidime/avibactam in treating patients with complicated abdominal infections? Evidence from clinical trials

Ceftolozane/tazobactam (C/T) and ceftazidime/avibactam (CZA) are new possibilities of antimicrobial treatment that combined a β-lactam with a β-lactamase inhibitor. The United States (US) and European regulatory agencies approved their clinical use in adults with complicated intra-abdominal infections. This study aims to know if one of the two antibiotics obtain better efficacy in adults with complicated intra-abdominal infections and by specific pathogens such as P. aeruginosa or E. coli. A search of all trials in MEDLINE, Scopus, and Web of Science comparing a C/T or CZA based antimicrobial regimen with other treatments in patients with intraabdominal infections until August 2021 was performed. To make indirect comparisons, we used a frequentist approach using the R package netmeta.The effects have been expressed through the relative risk (RR) with its confidence interval. Considering the clinical cure and failure rates between the different trial populations (mMITT, CE, ME) and the mortality at the end of the study, we have not found significant differences between CZA and C/T. In the case of Pseudomonas, the RR of treatment failure between these two antibiotics is 1 (95% CI 0.55-1.18). In the case of E. Coli, although it seems that CZA would have a worse result than C/T, differences did not reach statistical significance (RR1.06; 95% CI 0.9-1.14). In conclusion, we have not found statistically significant differences between ceftolozane-tazobactam and ceftazidime-avibactam in treating cIAI. In regards to E. Coli, our results do not reach significance, but it would be possible that C/T and meropenem had better results than CZA. Perhaps new trials would allow a better profile of the role in different types of patients or infections caused by specific microorganisms in the future.

New Drugs for the Treatment of Pseudomonas aeruginosa Infections with Limited Treatment Options: A Narrative Review

P. aeruginosa is still one of the most threatening pathogens responsible for serious hospital-acquired infections. It is intrinsically resistant to many antimicrobial agents and additional acquired resistance further complicates the management of such infections. High rates of combined antimicrobial resistance persist in many countries, especially in the eastern and south-eastern parts of Europe. The aim of this narrative review is to provide a comprehensive assessment of the epidemiology, latest data, and clinical evidence on the current and new available drugs active against P. aeruginosa isolates with limited treatment options. The latest evidence and recommendations supporting the use of ceftolozane-tazobactam and ceftazidime-avibactam, characterized by targeted clinical activity against a significant proportion of P. aeruginosa strains with limited treatment options, are described based on a review of the latest microbiological and clinical studies. Cefiderocol, with excellent in vitro activity against P. aeruginosa isolates, good stability to all β-lactamases and against porin and efflux pumps mutations, is also examined. New carbapenem combinations are explored, reviewing the latest experimental and initial clinical evidence. One section is devoted to a review of new anti-pseudomonal antibiotics in the pipeline, such as cefepime-taniborbactam and cefepime-zidebactam. Finally, other “old” antimicrobials, mainly fosfomycin, that can be used as combination strategies, are described.

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 .

The Efficacy of Using Combination Therapy against Multi-Drug and Extensively Drug-Resistant Pseudomonas aeruginosa in Clinical Settings

Pseudomonas aeruginosa is a Gram-negative bacterium which is capable of developing a high level of antibiotic resistance. It has been placed on the WHO's critical priority pathogen list and it is commonly found in ventilator-associated pneumonia infections, blood stream infections and other largely hospital-acquired illnesses. These infections are difficult to effectively treat due to their increasing antibiotic resistance and as such patients are often treated with antibiotic combination regimens.

METHODS

We conducted a systematic search with screening criteria using the Ovid search engine and the Embase, Ovid Medline, and APA PsycInfo databases.

RESULTS

It was found that in many cases the combination therapies were able to match or outperform the monotherapies and none performed noticeably worse than the monotherapies. However, the clinical studies were mostly small, only a few were prospective randomized clinical trials and statistical significance was lacking.

CONCLUSIONS

It was concluded that combination therapies have a place in the treatment of these highly resistant bacteria and, in some cases, there is some evidence to suggest that they provide a more effective treatment than monotherapies.

The Role of Colistin in the Era of New β-Lactam/β-Lactamase Inhibitor Combinations

With the current crisis related to the emergence of carbapenem-resistant Gram-negative bacteria (CR-GNB), classical treatment approaches with so-called “old-fashion antibiotics” are generally unsatisfactory. Newly approved β-lactam/β-lactamase inhibitors (BLBLIs) should be considered as the first-line treatment options for carbapenem-resistant Enterobacterales (CRE) and carbapenem-resistant Pseudomonas aeruginosa (CRPA) infections. However, colistin can be prescribed for uncomplicated lower urinary tract infections caused by CR-GNB by relying on its pharmacokinetic and pharmacodynamic properties. Similarly, colistin can still be regarded as an alternative therapy for infections caused by carbapenem-resistant Acinetobacter baumannii (CRAB) until new and effective agents are approved. Using colistin in combination regimens (i.e., including at least two in vitro active agents) can be considered in CRAB infections, and CRE infections with high risk of mortality. In conclusion, new BLBLIs have largely replaced colistin for the treatment of CR-GNB infections. Nevertheless, colistin may be needed for the treatment of CRAB infections and in the setting where the new BLBLIs are currently unavailable. In addition, with the advent of rapid diagnostic methods and novel antimicrobials, the application of personalized medicine has gained significant importance in the treatment of CRE infections.

In vitro susceptibility of Burkholderia pseudomallei isolates from Thai patients to ceftolozane/tazobactam and ceftazidime/avibactam

Treatment options are limited for melioidosis patients who develop nosocomial infection from extensively drug-resistant (XDR) gram-negative bacilli. Ceftolozane/tazobactam (C/T) and ceftazidime/avibactam (CZA), which have activity against XDR gram-negative bacteria, are two potential options. Data regarding the susceptibility of B. pseudomallei to these agents are limited, especially from Thailand, which is an endemic area for melioidosis. A total of 28 B. pseudomallei isolates from melioidosis patients in northeast Thailand were tested for susceptibility to C/T and CZA using the E-test and disk diffusion test. Minimal inhibitory concentrations (MICs) for other antibiotics commonly used in melioidosis, including trimethoprim/sulfamethoxazole (SXT), ceftazidime (CAZ), imipenem (IPM), and meropenem, were also ascertained. The MIC of C/T was very low in all isolates, ranging from 0.75 to 1.0 µg/mL. For CZA, wide inhibitory zones ranging from 34 to 35 mm and MICs at 0.5 µg/mL were found. All isolates were also susceptible to SXT, CAZ, and IPM based on CLSI breakpoints. C/T and CZA exhibited excellent in vitro activity against B. pseudomallei. Further studies are required to prove efficacy in human subjects.

Ceftazidime-Avibactam for the Treatment of Serious Gram-Negative Infections with Limited Treatment Options: A Systematic Literature Review

INTRODUCTION

A systematic literature review was undertaken to evaluate real-world use of ceftazidime-avibactam for infections due to aerobic Gram-negative organisms in adults with limited treatment options.

METHODS

Literature searches retrieved peer-reviewed publications and abstracts from major international infectious disease congresses from January 2015 to February 2021. Results were screened using pre-defined criteria to limit the dataset to relevant publications (notable exclusions were paediatric data and outcomes data for bacteria intrinsically resistant to ceftazidime-avibactam). Data for included publications were subjected to qualitative synthesis.

RESULTS

Seventy-three relevant publications (62 peer-reviewed articles; 10 abstracts) comprising 1926 patients treated with ceftazidime-avibactam (either alone or combined with other antimicrobials) and 1114 comparator/control patients were identified. All patients were hospitalised for serious illness and most had multiple comorbidities. The most common infections were pneumonia, bacteraemia, and skin/soft tissue, urinary tract, or abdominal infections; smaller numbers of patients with meningitis, febrile neutropenia, osteomyelitis, and cystic fibrosis were also included. Carbapenem-resistant or carbapenemase-producing Enterobacterales (CRE; n = 1718) and carbapenem-resistant, multidrug-resistant (MDR), and extensively drug-resistant Pseudomonas aeruginosa (n = 150) were the most common pathogens. Most publications reported positive outcomes for ceftazidime-avibactam treatment (clinical success rates ranged from 45 to 100% and reported 30-day mortality from 0 to 63%), which were statistically superior versus comparators in some studies. ceftazidime-avibactam resistance emergence occurred infrequently and mostly in Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae strains.

CONCLUSION

This review provides qualitative evidence of successful use of ceftazidime-avibactam for the treatment of hospitalised patients with CRE and MDR P. aeruginosa infections with limited treatment options.

Novel β-Lactam/β-Lactamase Inhibitor Combinations versus Alternative Antibiotics in Adults with Hospital-Acquired Pneumonia or Ventilator-Associated Pneumonia: An Integrated Analysis of 3 Randomized Controlled Trials

OBJECTIVES

This study assessed the efficacy and safety of novel β-lactam/β-lactamase inhibitor combinations in adult patients with hospital-acquired pneumonia (HAP) or ventilator-associated pneumonia (VAP).

METHODS

PubMed, Web of Science, the Cochrane Library, Ovid MEDLINE, Embase and EBSCO databases were searched for randomized controlled trials (RCTs) published before September 13, 2020. Only RCTs comparing the treatment efficacy of novel β-lactam/β-lactamase inhibitor combinations with other antibiotics for HAP/VAP in adult patients were included in this integrated analysis.

RESULTS

Three RCTs were included, and no significant difference in clinical cure rate of the test of cure (TOC) was observed between the novel β-lactam/β-lactamase inhibitor combination and comparators (odds ratio [OR], 1.01; 95% CI, 0.81-1.27; I² = 35%). The 28-day all-cause mortality was 16.2% and 17.6% for patients receiving the novel β-lactam/β-lactamase inhibitor combination and those receiving comparators, respectively, and no significant difference was noted (OR, 0.90; 95% CI, 0.69-1.16; I² = 11%). Compared with the comparators, the novel β-lactam/β-lactamase inhibitor combination was associated with a similar microbiological response (OR, 1.06; 95% CI, 0.73-1.54; I² = 64%) and a similar risk of AEs (treatment-emergent AEs [TEAEs]: OR, 1.04; 95% CI, 0.83-1.30; I² = 0%; serious AEs: OR, 1.14; 95% CI, 0.79-1.63; I² = 68%; treatment discontinuation for TEAE: OR, 0.90; 95% CI, 0.62-1.31; I² = 11%).

CONCLUSIONS

The clinical and microbiological responses of novel β-lactam/β-lactamase inhibitor combinations in the treatment of HAP/VAP were similar to those of other available antibiotics. These combinations also shared a similar safety profile to that of comparators.

Review of Ceftazidime-Avibactam, Meropenem-Vaborbactam, and Imipenem/Cilastatin-Relebactam to Target Klebsiella pneumoniae Carbapenemase-Producing Enterobacterales

Objective: To provide a review of 3 novel antimicrobial agents-ceftazidime-avibactam, meropenem-vaborbactam, and imipenem/cilastatin-relebactam-regarding treatment of Klebsiella pneumoniae carbapenemase-producing Enterobacterales (KPC). Data Sources: A literature search of PubMed and OVID (MEDLINE) was performed up to March 2020 using the following search terms: Vabomere, meropenem-vaborbactam, vaborbactam, RPX7009, Klebsiella pneumoniae carbapenemase, KPC, carbapenem-resistant Enterobacteriaceae, CRE, relebactam, imipenem-relebactam, MK-7655, ceftazidime-avibactam. Abstracts from conferences, article bibliographies, and product information were also reviewed. Study Selection and Data Extraction: Articles were first screened by English language, then title, then abstract, and finally by review of the full article. Fifty-five clinical and preclinical studies were included. Data Synthesis: These 3 novel β-lactam/β-lactamase inhibitor combinations have shown considerable improvement in safety and efficacy as compared with traditional polymyxin-based combination therapy for the treatment of KPC infections. While meropenem-vaborbactam has not shown improved activity against Pseudomonas aeruginosa, it has shown decreased rates of resistance to KPC versus ceftazidime-avibactam. Conclusions: With increasing incidence of KPC infections on a global scale, pharmacists should be aware of the notable similarities and differences between these 3 agents, and the current data supporting their use. Pharmacists may want to consider meropenem-vaborbactam over ceftazidime-avibactam for KPC infections due to decreased likelihood of resistance.

Review of Ceftazidime-Avibactam for the Treatment of Infections Caused by Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen that causes a range of serious infections that are often challenging to treat, as this pathogen can express multiple resistance mechanisms, including multidrug-resistant (MDR) and extensively drug-resistant (XDR) phenotypes. Ceftazidime–avibactam is a combination antimicrobial agent comprising ceftazidime, a third-generation semisynthetic cephalosporin, and avibactam, a novel non-β-lactam β-lactamase inhibitor. This review explores the potential role of ceftazidime–avibactam for the treatment of P. aeruginosa infections. Ceftazidime–avibactam has good in vitro activity against P. aeruginosa relative to comparator β-lactam agents and fluoroquinolones, comparable to amikacin and ceftolozane–tazobactam. In Phase 3 clinical trials, ceftazidime–avibactam has generally demonstrated similar clinical and microbiological outcomes to comparators in patients with complicated intra-abdominal infections, complicated urinary tract infections or hospital-acquired/ventilator-associated pneumonia caused by P. aeruginosa. Although real-world data are limited, favourable outcomes with ceftazidime–avibactam treatment have been reported in some patients with MDR and XDR P. aeruginosa infections. Thus, ceftazidime–avibactam may have a potentially important role in the management of serious and complicated P. aeruginosa infections, including those caused by MDR and XDR strains.

Clinical and Microbiological Outcomes of Ceftazidime-Avibactam Treatment in Adults with Gram-Negative Bacteremia: A Subset Analysis from the Phase 3 Clinical Trial Program

Introduction

This exploratory analysis assessed efficacy and safety outcomes in patients with Gram-negative bacteremia treated with ceftazidime-avibactam or comparator across five phase 3, randomized, controlled, multi-center trials in adults with complicated intra-abdominal infection (cIAI), complicated urinary tract infection (cUTI)/pyelonephritis, hospital-acquired pneumonia (HAP), and ventilator-associated pneumonia (VAP).

Methods

In each trial, RECLAIM and RECLAIM 3 (cIAI; NCT01499290/NCT01726023), REPRISE (cIAI/cUTI; NCT01644643), RECAPTURE (cUTI; NCT01595438/NCT01599806), and REPROVE (HAP/VAP; NCT01808092), patients were randomized 1:1 to intravenous ceftazidime-avibactam (plus metronidazole for those with cIAI) or comparators (carbapenems in > 97% patients) for 5–21 days. Efficacy assessments included clinical and microbiological responses at the test-of-cure visit in the pooled Gram-negative extended microbiologically evaluable (GNeME) population (bacteremia subset). Safety outcomes were summarized for patients with positive bacterial blood culture(s) at baseline who received ≥ 1 dose of study treatment.

Results

The overall safety population included 4050 patients (ceftazidime-avibactam, n = 2024; comparator, n = 2026). The GNeME population (bacteremia subset) comprised 101 patients (ceftazidime-avibactam, n = 54; comparator, n = 47). Clinical cure rates (all indications combined) were 47/54 (87.0%) for ceftazidime-avibactam and 39/47 (83.0%) for comparators; favorable microbiological response rates were 43/54 (79.6%) and 32/47 (68.1%), respectively. Clinical and microbiological responses in the bacteremia subset were generally similar to those in the overall set. The pattern of adverse events in patients with bacteremia was similar between treatment groups and was consistent with the known safety profile of ceftazidime-avibactam.

Conclusion

This analysis provides supportive evidence of the efficacy and safety of ceftazidime-avibactam in patients with Gram-negative bacteremia associated with cIAI, cUTI/pyelonephritis, or HAP/VAP.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00506-7.

Safety Profile of Ceftazidime-Avibactam: Pooled Data from the Adult Phase II and Phase III Clinical Trial Programme

INTRODUCTION

Ceftazidime-avibactam combines the established anti-pseudomonal cephalosporin, ceftazidime, with the novel non-β-lactam β-lactamase inhibitor, avibactam.

OBJECTIVES

The aim of this study was to evaluate the safety of ceftazidime-avibactam in adults using pooled data from two phase II (NCT00690378, NCT00752219) and five phase III (NCT01499290, NCT01726023, NCT01644643, NCT01808093 and NCT01595438/NCT01599806) clinical studies.

METHODS

Safety data from seven multicentre, randomised, active-comparator studies were pooled by study group at the patient level for descriptive analyses, comprising patients with complicated urinary tract infection (cUTI), including pyelonephritis, complicated intra-abdominal infection (cIAI), or nosocomial pneumonia (NP), including ventilator-associated pneumonia (VAP), treated with ceftazidime-avibactam ± metronidazole or comparator.

RESULTS

In total, 4050 patients (ceftazidime-avibactam ± metronidazole, n = 2024; comparator, n = 2026) were included in the pooled analysis. Adverse events (AEs) up to the last study visit occurred in 996 (49.2%) and 965 (47.6%) patients treated with ceftazidime-avibactam ± metronidazole and comparator, respectively. The most common AEs across treatment groups were diarrhoea, nausea, headache, vomiting and pyrexia. There were few discontinuations due to AEs (2.5% and 1.7% for ceftazidime-avibactam ± metronidazole and comparators, respectively). Overall rates of serious AEs were 8.7% for ceftazidime-avibactam ± metronidazole and 7.2% for comparators; respective rates of AEs with an outcome of death were 2.0% and 1.8%. AEs considered causally related to the study drug or procedures occurred in 10.7% and 9.6% of patients treated with ceftazidime-avibactam ± metronidazole and comparators; the most common drug-related AEs in both groups were diarrhoea, headache, nausea and increased alanine aminotransferase. No impact to the safety profile of ceftazidime-avibactam ± metronidazole was found with regard to intrinsic factors, such as age or renal function at baseline, or extrinsic factors, such as geographical origin. Potentially clinically significant changes in laboratory parameters were infrequent with no trends or safety concerns identified.

CONCLUSION

The observed safety profile of ceftazidime-avibactam across infection types is consistent with the established safety profile of ceftazidime monotherapy and no new safety findings were identified. This analysis supports the use of ceftazidime-avibactam as a treatment option in adults with cUTI, cIAI and NP, including VAP.

An Evidence-Based Multidisciplinary Approach Focused at Creating Algorithms for Targeted Therapy of BSIs, cUTIs, and cIAIs Caused by Enterobacterales in Critically Ill Adult Patients

Prompt implementation of appropriate targeted antibiotic therapy represents a valuable approach in improving clinical and ecological outcome in critically septic patients. This multidisciplinary opinion article focused at developing evidence-based algorithms for targeted antibiotic therapy of bloodstream (BSIs), complicated urinary tract (cUTIs), and complicated intrabdominal infections (cIAIs) caused by Enterobacterales. The aim was to provide a guidance for intensive care physicians either in appropriately placing novel antibiotics or in considering strategies for sparing the broadest-spectrum antibiotics. A multidisciplinary team of experts (one intensive care physician, one infectious disease consultant, one clinical microbiologist and one MD clinical pharmacologist), performed several rounds of assessment to reach agreement in developing six different algorithms according to the susceptibility pattern (one each for multi-susceptible, extended-spectrum beta-lactamase-producing, AmpC beta-lactamase-producing, Klebsiella pneumoniae carbapenemase (KPC)-producing, OXA-48-producing, and Metallo-beta-lactamase (MBL)-producing Enterobacterales). Whenever multiple therapeutic options were feasible, a hierarchical scale was established. Recommendations on antibiotic dosing optimization were also provided. In order to retrieve evidence-based support for the therapeutic choices proposed in the algorithms, a comprehensive literature search was performed by a researcher on PubMed-MEDLINE from inception until March 2021. Quality and strength of evidence was established according to a hierarchical scale of the study design. Only articles published in English were included. It is expected that these algorithms, by allowing prompt revision of antibiotic regimens whenever feasible, appropriate place in therapy of novel beta-lactams, implementation of strategies for sparing the broadest-spectrum antibiotics, and pharmacokinetic/pharmacodynamic optimization of antibiotic dosing regimens, may be helpful either in improving clinical outcome or in containing the spread of antimicrobial resistance.

Choosing Optimal Antibiotics for the Treatment of Patients Infected With Enterobacteriaceae: A Network Meta-analysis and Cost-Effectiveness Analysis

Overuse of carbapenems has led to the increasing carbapenem-resistant Enterobacteriaceae. It is still unknown whether other antibiotics [especially novel β-lactam/β-lactamase inhibitor combinations (BL/BLIs)] are better than carbapenems in the treatment of Enterobacteriaceae. A systematic literature search was performed to identify randomized controlled trials (RCTs) assessing the efficacy and safety of any antibiotics on Enterobacteriaceae infections. We carried out a traditional paired meta-analysis to compare ceftazidime/avibactam to comparators. Network meta-analysis (NMA) was conducted to integrate direct and indirect evidence of all interventions. Moreover, cost-effectiveness analysis using a combined decision analytical Markov model was completed for the treatment of patients with complex urinary tract infection (cUTI). A total of 25 relevant RCTs were identified, comprising 15 different interventions. Ceftazidime/avibactam exhibited comparable efficacy and safety with comparators (carbapenems) in the paired meta-analysis. In the NMA, the surface under the cumulative ranking curve probabilities showed that in terms of efficacy, the interventions with the highest-ranking were meropenem/vaborbactam, meropenem, imipenem/cilastatin, ceftriaxone, ceftazidime/avibactam, and ceftolozane/tazobactam [but no significant difference between any two antibiotics (p > 0.05)]. Regarding safety, ceftazidime/avibactam had a higher incidence of adverse events than that of piperacillin/tazobactam (relative risk = 0.74, 95% confidence interval = 0.59–0.94). Based on drug and hospitalization costs in China, the incremental cost-effectiveness ratio per quality-adjusted life-year gained in the patients with cUTI for meropenem, ceftazidime/avibactam, and ceftolozane/tazobactam compared to imipenem/cilastatin were US$579, US$24569, and US$29040, respectively. The role of these BL/BLIs to serve as alternatives to carbapenems requires large-scale and high-quality studies to validate.

Carbapenemase producing Klebsiella pneumoniae: implication on future therapeutic strategies

Introduction: The emergence of carbapenemase resistant Gram-negative is designated as an 'urgent' priority of public health. Carbapenemase producing Klebsiella pneumoniae (CPKP) is linked with significant mortality. Conventionally used antibiotics (polymyxins, tigecycline, aminoglycosides, etc.) are associated with poor efficacy and toxicity profiles are quite worrisome.Areas covered: This article reviews mechanism of resistance and evidence regarding novel treatments of infections caused by CPKP, focusing mainly on currently approved new therapies and implications on future therapeutic strategies. A review of novel β-lactam/β-lactamase inhibitors (BLI) recently approved and in clinical development as well as cefiderocol, eravacycline and apramycin are discussed.Expert opinion: Newly approved and forthcoming antimicrobial agents are promising to combat infections caused by CPKP. Ceftazidime-avibactam, meropenem-vaborbactam, and imipenem-cilastatin-relebactam are novel agents with favorable outcome and associated with improved mortality in KPC-producing K. pneumoniae infections. However, are inactive against metallo-β-lactamases (MBL). Novel BLI in later stage of development, i.e. aztreonam-avibactam, cefepime-zidebactam, cefepime-taniborbactam, and meropenem-nacubactam as well as cefiderocol are active in vitro against both KPC and MBL. Potential expectations of future therapeutic strategies are improved potency against CPKP, more tolerable safety profile, and capability of overcoming current resistance mechanism of multidrug-resistant K. pneumoniae.

Diagnosis and Management of Intraabdominal Infection: Guidelines by the Chinese Society of Surgical Infection and Intensive Care and the Chinese College of Gastrointestinal Fistula Surgeons

The Chinese guidelines for IAI presented here were developed by a panel that included experts from the fields of surgery, critical care, microbiology, infection control, pharmacology, and evidence-based medicine. All questions were structured in population, intervention, comparison, and outcomes format, and evidence profiles were generated. Recommendations were generated following the principles of the Grading of Recommendations Assessment, Development, and Evaluation system or Best Practice Statement (BPS), when applicable. The final guidelines include 45 graded recommendations and 17 BPSs, including the classification of disease severity, diagnosis, source control, antimicrobial therapy, microbiologic evaluation, nutritional therapy, other supportive therapies, diagnosis and management of specific IAIs, and recognition and management of source control failure. Recommendations on fluid resuscitation and organ support therapy could not be formulated and thus were not included. Accordingly, additional high-quality clinical studies should be performed in the future to address the clinicians' concerns.

A systematic review of antimicrobial susceptibility testing as a tool in clinical trials assessing antimicrobials against infections due to gram-negative pathogens

BACKGROUND

Antimicrobial susceptibility testing (AST) is the standard of care for treating bacterial infections. In randomized clinical trials of new antimicrobials, AST might not be performed or reported in real time.

OBJECTIVES

To determine local, real-time laboratory AST performance, its usage in the trial flow, quality control (QC) of the local testing, central AST performance and the effect of using AST categorization on the trials' primary outcomes.

DATA SOURCES

We systematically searched PubMed, Embase, PsychINFO and Web of Science.

ELIGIBILITY CRITERIA

We included registered randomized controlled trials published in journals between January 2015 and December 2019.

PARTICIPANTS AND INTERVENTIONS

We included trials comparing different antibiotics for the treatment of infections caused predominantly by Gram-negative bacteria.

METHODS

Primary outcomes for different trial populations were extracted and differences between trial arms were compared for patients with infections caused by susceptible versus non-susceptible bacteria. Results are described narratively.

RESULTS

Of 32 randomized trials, 25 trials reported that local AST was performed, 1312 reported the local laboratory AST methods, no trial reported QC, but post-hoc referral for AST at a reference laboratory was common. Patients' outcomes were superior when patients with infections due to susceptible and non-susceptible pathogens were compared post hoc (median difference 14%, interquartile range 8%-24%) in trials allowing this comparison (seven antimicrobials), except for colistin, where 14-day mortality was 9% higher when patients were treated with colistin for colistin-susceptible versus colistin-resistant carbapenem-resistant Acinetobacter baumannii. When excluding patients with pathogens that were non-susceptible to either antimicrobial in the trials, the difference in the primary outcome between the trial arms was reduced in five out of six trials.

CONCLUSIONS

Trials should perform AST to guide patient inclusion or exclusion from the study and consider the impact of the central laboratory susceptibility results on the study outcomes when using post-hoc reference testing.

Antimicrobial Activity of Ceftazidime-Avibactam Against Contemporary Pathogens From Urinary Tract Infections and Intra-abdominal Infections Collected From US Children During the 2016-2019 INFORM Surveillance Program

BACKGROUND

Antibacterial activity of ceftazidime-avibactam (CAZ-AVI) was evaluated against bacterial isolates from children in the United States with a urinary tract infection (UTI) or intra-abdominal infection (IAI) during the 2016-2019 International Network for Optimal Resistance Monitoring program. Prevalence of isolates and susceptibility to CAZ-AVI in pediatric and adult patients were compared.

METHODS

Bacterial isolates were collected from children with a UTI or IAI at 70 US medical centers from 2016 to 2019. The antimicrobial activity of CAZ-AVI and comparator agents was tested by broth microdilution methods.

RESULTS

The most prevalent Enterobacterales pathogens in children with UTIs were Escherichia coli (62.5%), Klebsiella pneumoniae (12.1%) and Proteus mirabilis (6.2%). Minimum inhibitory concentration 90% values for CAZ-AVI against Enterobacterales (0.25 μg/mL) and Pseudomonas aeruginosa (4 μg/mL) were identical for children and adults. The most prevalent Enterobacterales pathogens in children with IAIs were E. coli (57.4%), K. pneumoniae (11.1%) and Enterobacter cloacae species complex (9.3%). All isolates of Enterobacterales from pediatric patients with UTI and IAI were susceptible to CAZ-AVI, including extended-spectrum β-lactamase phenotypes. Susceptibility of P. aeruginosa isolates to CAZ-AVI was 96.2% in children and 98.4% in adults with a UTI: for IAI it was 100% and 97.2%, respectively.

CONCLUSIONS

Contemporary UTI and IAI pathogens collected from US children from 2016 to 2019 exhibited similar prevalence and susceptibilities as isolates collected from adult patients. CAZ-AVI exhibited potent activity against these pathogens.

An Update on Eight "New" Antibiotics against Multidrug-Resistant Gram-Negative Bacteria

Infections in the ICU are often caused by Gram-negative bacteria. When these microorganisms are resistant to third-generation cephalosporines (due to extended-spectrum (ESBL) or AmpC beta-lactamases) or to carbapenems (for example carbapenem producing Enterobacteriales (CPE)), the treatment options become limited. In the last six years, fortunately, there have been new antibiotics approved by the U.S. Food and Drug Administration (FDA) with predominant activities against Gram-negative bacteria. We aimed to review these antibiotics: plazomicin, eravacycline, temocillin, cefiderocol, ceftazidime/avibactam, ceftolozane/tazobactam, meropenem/vaborbactam, and imipenem/relebactam. Temocillin is an antibiotic that was only approved in Belgium and the UK several decades ago. We reviewed the in vitro activities of these new antibiotics, especially against ESBL and CPE microorganisms, potential side effects, and clinical studies in complicated urinary tract infections (cUTI), intra-abdominal infections (cIAI), and hospital-acquired pneumonia/ventilator-associatedpneumonia (HAP/VAP). All of these new antibiotics are active against ESBL, and almost all of them are active against CPE caused by KPC beta-lactamase, but only some of them are active against CPE due to MBL or OXA beta-lactamases. At present, all of these new antibiotics are approved by the U.S. Food and Drug Administration for cUTI (except eravacycline) and most of them for cIAI (eravacycline, ceftazidime/avibactam, ceftolozane/tazobactam, and imipenem/relebactam) and for HAP or VAP (cefiderocol, ceftazidime/avibactam, ceftolozane/tazobactam, and imipenem/relebactam).

In vitro antagonistic inhibitory effects of palm seed crude oils and their main constituent, lauric acid, with oxacillin in Staphylococcus aureus

Infections caused by Staphylococcus aureus are a serious global threat, and with the emergence of antibiotic resistance, even more difficult to treat. One of the possible complications in antistaphylococcal therapy represents negative interactions of antibiotics with food. In this study, the in vitro interaction between oxacillin and crude palm seed oil from Astrocaryum vulgare, Cocos nucifera, and Elaeis guineensis against nine strains of S. aureus was determined using the checkerboard method. Lauric acid was identified as a major constituent of all tested oils by gas chromatography. The results showed strong concentration dependent antagonistic interactions between palm oils and oxacillin with values of fractional inhibitory concentrations indices ranging from 4.02 to 8.56 at concentrations equal or higher than 1024 µg/mL of the tested oils. Similarly, lauric acid in combination with oxacillin produced antagonistic action with fractional inhibitory concentration indices ranging from 4.01 to 4.28 at 1024 µg/mL. These findings suggest that interference between oxacillin and palm oils and their constituents can negatively affect the treatment of staphylococcal infections in humans and other animals.

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.

Spontaneous bacterial peritonitis due to carbapenemase-producing Enterobacteriaceae: Etiology and antibiotic treatment

Carbapenem antibiotics were first introduced in the 1980s and have long been considered the most active agents for the treatment of multidrug-resistant gram-negative bacteria. Over the last decade, carbapenem-resistant Enterobacteriaceae (CRE) have emerged as organisms causing spontaneous bacterial peritonitis. Infections caused by CRE have shown a higher mortality rate than those caused by bacteria sensitive to carbapenem antibiotics. Current antibiotic guidelines for the treatment of spontaneous bacterial peritonitis are insufficient, and rapid de-escalation of empiric antibiotic treatment is not widely recognized. This review summarizes the molecular characteristics, epidemiology and possible treatment of spontaneous bacterial peritonitis caused by CRE.

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.

New β-Lactam-β-Lactamase Inhibitor Combinations

The limited armamentarium against drug-resistant Gram-negative bacilli has led to the development of several novel β-lactam-β-lactamase inhibitor combinations (BLBLIs). In this review, we summarize their spectrum of in vitro activities, mechanisms of resistance, and pharmacokinetic-pharmacodynamic (PK-PD) characteristics. A summary of available clinical data is provided per drug. Four approved BLBLIs are discussed in detail. All are options for treating multidrug-resistant (MDR) Enterobacterales and Pseudomonas aeruginosa Ceftazidime-avibactam is a potential drug for treating Enterobacterales producing extended-spectrum β-lactamase (ESBL), Klebsiella pneumoniae carbapenemase (KPC), AmpC, and some class D β-lactamases (OXA-48) in addition to carbapenem-resistant Pseudomonas aeruginosa Ceftolozane-tazobactam is a treatment option mainly for carbapenem-resistant P. aeruginosa (non-carbapenemase producing), with some activity against ESBL-producing Enterobacterales Meropenem-vaborbactam has emerged as treatment option for Enterobacterales producing ESBL, KPC, or AmpC, with similar activity as meropenem against P. aeruginosa Imipenem-relebactam has documented activity against Enterobacterales producing ESBL, KPC, and AmpC, with the combination having some additional activity against P. aeruginosa relative to imipenem. None of these drugs present in vitro activity against Enterobacterales or P. aeruginosa producing metallo-β-lactamase (MBL) or against carbapenemase-producing Acinetobacter baumannii Clinical data regarding the use of these drugs to treat MDR bacteria are limited and rely mostly on nonrandomized studies. An overview on eight BLBLIs in development is also provided. These drugs provide various levels of in vitro coverage of carbapenem-resistant Enterobacterales, with several drugs presenting in vitro activity against MBLs (cefepime-zidebactam, aztreonam-avibactam, meropenem-nacubactam, and cefepime-taniborbactam). Among these drugs, some also present in vitro activity against carbapenem-resistant P. aeruginosa (cefepime-zidebactam and cefepime-taniborbactam) and A. baumannii (cefepime-zidebactam and sulbactam-durlobactam).