Ceftolozane/Tazobactam Plus Metronidazole for Complicated Intra-abdominal Infections in an Era of Multidrug Resistance: Results From a Randomized, Double-Blind, Phase 3 Trial (ASPECT-cIAI)

Treatment of infections caused by multidrug-resistant Gram-negative bacilli: A practical approach by the Italian (SIMIT) and French (SPILF) Societies of Infectious Diseases

INTRODUCTION

The emergence of multidrug-resistant Gram-negative bacilli and the development of new antibiotics have complicated the selection of optimal regimens. International guidelines are valuable tools, but are limited by the scarcity of high-quality randomized trials in many situations.

METHODS

A panel of experts from the French and Italian Societies of Infectious Diseases aimed to address unresolved issues in clinical practice based on their experience, an updated literature review and open discussions.

RESULTS

The panel reached consensus for the following 'first choices': (i) cefepime for ventilator-acquired pneumonia due to AmpC β-lactamase-producing Enterobacterales; (ii) the β-lactam/β-lactamase inhibitor combination most active in vitro, or cefiderocol combined with fosfomycin, and aerosolized colistin or aminoglycosides, for severe pneumonia due to Pseudomonas aeruginosa resistant to ceftolozane-tazobactam; (iii) high-dose piperacillin-tazobactam (including loading dose and continuous infusion) for complicated urinary tract infections (cUTIs) caused by extended-spectrum β-lactamase-producing Enterobacterales with piperacillin-tazobactam minimum inhibitory concentration (MIC) ≤8 mg/L; (iv) high-dose cefepime for cUTIs due to AmpC β-lactamase-producing Enterobacterales other than Enterobacter spp. if cefepime MIC ≤2 mg/L; (v) ceftolozane-tazobactam or ceftazidime-avibactam plus metronidazole for intra-abdominal infections (IAIs) due to third-generation cephalosporin-resistant Enterobacterales; (vi) ceftazidime-avibactam plus aztreonam plus metronidazole for IAIs due to metallo-β-lactamase-producing Enterobacterales; (vii) ampicillin-sulbactam plus colistin for bloodstream infections (BSIs) caused by carbapenem-resistant Acinetobacter baumannii; (viii) meropenem-vaborbactam for BSIs caused by Klebsiella pneumoniae carbapenemase-producing Enterobacterales; and (ix) ceftazidime-avibactam plus fosfomycin for neurological infections caused by carbapenem-resistant P. aeruginosa.

CONCLUSIONS

These expert choices were based on the necessary balance between antimicrobial stewardship principles and the need to provide optimal treatment for individual patients in each situation.

Intra-abdominal infections survival guide: a position statement by the Global Alliance For Infections In Surgery

Intra-abdominal infections (IAIs) are an important cause of morbidity and mortality in hospital settings worldwide. The cornerstones of IAI management include rapid, accurate diagnostics; timely, adequate source control; appropriate, short-duration antimicrobial therapy administered according to the principles of pharmacokinetics/pharmacodynamics and antimicrobial stewardship; and hemodynamic and organ functional support with intravenous fluid and adjunctive vasopressor agents for critical illness (sepsis/organ dysfunction or septic shock after correction of hypovolemia). In patients with IAIs, a personalized approach is crucial to optimize outcomes and should be based on multiple aspects that require careful clinical assessment. The anatomic extent of infection, the presumed pathogens involved and risk factors for antimicrobial resistance, the origin and extent of the infection, the patient's clinical condition, and the host's immune status should be assessed continuously to optimize the management of patients with complicated IAIs.

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.

The use of new antibacterial drugs against infections caused by multidrug-resistant Gram-negative bacteria: an Italian real-world evidence study in a Lombardy hospital

Infections caused by multidrug-resistant (MDR) bacteria are typically associated with high morbidity and mortality, especially in vulnerable individuals such as patients with prolonged hospitalizations, immunocompromised individuals, and the elderly. This study aimed to provide post-marketing surveillance results concerning the prevalence of antibiotic resistance against Gram-negative bacteria through the collaboration of a multidisciplinary team. Patients involved have been treated with new antibacterial drugs, in particular ceftazidime/avibactam (C/A), meropenem/vaborbactam (M/V), cefiderocol, and ceftolozane/tazobactam (C/T). The most resistant bacterial species were Klebsiella spp., Pseudomonas aeruginosa, and Acinetobacter baumannii. Italian Drug Agency (AIFA) monitoring records for inpatients have been collected and analyzed, assessing the characteristics of the patients involved. Adverse drug reactions (ADRs) and drugs involved have been reported using a descriptive analytical approach. All data have been collected retrospectively from patient's medical records and entered into an electronic case report form (CRF). Among the 104 treated patients, Klebsiella spp. accounted for 50.1% of infections, Pseudomonas aeruginosa for 32.7%, Acinetobacter baumannii for 3%, and other bacterial species for 1.92% configuring polymicrobial infections. Regarding treatment outcomes, healing was achieved in 61 (58.6%) patients, 23 (22.1%) patients died, 8 (7.7%) patients discontinued empirical therapy, and 3 (2.9%) patients were lost to follow-up. Despite the introduction of new antibacterial drugs active against Gram-negative bacteria is improving the clinical scenario, it is crucial that the use of new antibacterial drugs be implemented by appropriate antimicrobial stewardship, surveillance programs, and monitoring efforts to prevent further spread of resistance. This study showed that the new antibiotics have good efficacy against MDR bacteria and cause negligible side effects.

Managing Antimicrobial Resistance in the Emergency Department

(Basic awareness and understanding of antimicrobial resistance and prevailing mechanisms can aid emergency physicians in providing appropriate care to patients with infections due to a multidrug-resistant organism (MDRO). Empiric treatment of MDRO infections should be approached with caution and guided by the most likely pathogens based on differential diagnosis, severity of the illness, suspected source of infection, patient-specific factors, and local antibiotic susceptibility patterns. Newer broad-spectrum antibiotics should be reserved for critically ill patients where there is a high likelihood of infection with an MDRO.).

Efficacy and safety of a structured de-escalation from antipseudomonal β-lactams in bloodstream infections due to Enterobacterales (SIMPLIFY): an open-label, multicentre, randomised trial

BACKGROUND

De-escalation from broad-spectrum to narrow-spectrum antibiotics is considered an important measure to reduce the selective pressure of antibiotics, but a scarcity of adequate evidence is a barrier to its implementation. We aimed to determine whether de-escalation from an antipseudomonal β-lactam to a narrower-spectrum drug was non-inferior to continuing the antipseudomonal drug in patients with Enterobacterales bacteraemia.

METHODS

An open-label, pragmatic, randomised trial was performed in 21 Spanish hospitals. Patients with bacteraemia caused by Enterobacterales susceptible to one of the de-escalation options and treated empirically with an antipseudomonal β-lactam were eligible. Patients were randomly assigned (1:1; stratified by urinary source) to de-escalate to ampicillin, trimethoprim-sulfamethoxazole (urinary tract infections only), cefuroxime, cefotaxime or ceftriaxone, amoxicillin-clavulanic acid, ciprofloxacin, or ertapenem in that order according to susceptibility (de-escalation group), or to continue with the empiric antipseudomonal β-lactam (control group). Oral switching was allowed in both groups. The primary outcome was clinical cure 3-5 days after end of treatment in the modified intention-to-treat (mITT) population, formed of patients who received at least one dose of study drug. Safety was assessed in all participants. Non-inferiority was declared when the lower bound of the 95% CI of the absolute difference in cure rate was above the -10% non-inferiority margin. This trial is registered with EudraCT (2015-004219-19) and ClinicalTrials.gov (NCT02795949) and is complete.

FINDINGS

2030 patients were screened between Oct 5, 2016, and Jan 23, 2020, of whom 171 were randomly assigned to the de-escalation group and 173 to the control group. 164 (50%) patients in the de-escalation group and 167 (50%) in the control group were included in the mITT population. 148 (90%) patients in the de-escalation group and 148 (89%) in the control group had clinical cure (risk difference 1·6 percentage points, 95% CI -5·0 to 8·2). The number of adverse events reported was 219 in the de-escalation group and 175 in the control group, of these, 53 (24%) in the de-escalation group and 56 (32%) in the control group were considered severe. Seven (5%) of 164 patients in the de-escalation group and nine (6%) of 167 patients in the control group died during the 60-day follow-up. There were no treatment-related deaths.

INTERPRETATION

De-escalation from an antipseudomonal β-lactam in Enterobacterales bacteraemia following a predefined rule was non-inferior to continuing the empiric antipseudomonal drug. These results support de-escalation in this setting.

FUNDING

Plan Nacional de I+D+i 2013-2016 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Ciencia, Innovación y Universidades, Spanish Network for Research in Infectious Diseases; Spanish Clinical Research and Clinical Trials Platform, co-financed by the EU; European Development Regional Fund "A way to achieve Europe", Operative Program Intelligence Growth 2014-2020.

Cost-effectiveness analysis of CTZ/TAZ for the treatment of ventilated hospital-acquired bacterial pneumonia and ventilator-associated bacterial pneumonia in Japan

BACKGROUND

Resistant bacterial infections, particularly those caused by gram-negative pathogens, are associated with high mortality and economic burdens. Ceftolozane/tazobactam demonstrated efficacy comparable to meropenem in patients with ventilated hospital-acquired bacterial pneumonia in the ASPECT-NP study. One cost-effectiveness analysis in the United States revealed that ceftolozane/tazobactam was cost effective, but no Japanese studies have been conducted. Therefore, the objective of this study was to assess the cost-effectiveness of ceftolozane/tazobactam compared to meropenem for patients with ventilated hospital-acquired bacterial pneumonia/ventilator-associated bacterial pneumonia from a health care payer perspective.

METHODS

A hybrid decision-tree Markov decision-analytic model with a 5-year time horizon were developed to estimate costs and quality-adjusted life-years and to calculate the incremental cost-effectiveness ratio associated with ceftolozane/tazobactam and meropenem in the treatment of patients with ventilated hospital-acquired bacterial pneumonia/ventilator-associated bacterial pneumonia. Clinical outcomes were based on the ASPECT-NP study, costs were based on the national fee schedule of 2022, and utilities were based on published data. One-way sensitivity analysis and probabilistic sensitivity analysis were also conducted to assess the robustness of our modeled estimates.

RESULTS

According to our base-case analysis, compared with meropenem, ceftolozane/tazobactam increased the total costs by 424,731.22 yen (£2,626.96) and increased the quality-adjusted life-years by 0.17, resulting in an incremental cost-effectiveness ratio of 2,548,738 yen (£15,763.94) per quality-adjusted life-year gained for ceftolozane/tazobactam compared with meropenem. One-way sensitivity analysis showed that although the incremental cost-effectiveness ratio remained below 5,000,000 yen (£30,925) for most of the parameters, the incremental net monetary benefit may have been less than 0 depending on the treatment efficacy outcome, especially the cure rate and mortality rate for MEPM and mortality rate for CTZ/TAZ. 53.4% of the PSA simulations demonstrated that CTZ/TAZ was more cost-effective than MEPM was.

CONCLUSION

Although incremental cost-effectiveness ratio was below ￥5,000,000 in base-case analysis, whether ceftolozane/tazobactam is a cost-effective alternative to meropenem for ventilated hospital-acquired bacterial pneumonia/ventilator-associated bacterial pneumonia in Japan remains uncertain. Future research should examine the unobserved heterogeneity across patient subgroups and decision-making settings, to characterise decision uncertainty and its consequences so as to assess whether additional research is required.

Ceftolozane/Tazobactam for the Treatment of Complicated Infections in Hospital Settings-A French Real-world Study

Background

This study describes the conditions of use of ceftolozane/tazobactam (C/T) and associated outcomes in French hospital settings.

Methods

This was a prospective, multicenter, French observational study. Patients who received at least 1 dose of C/T were included and followed up as per routine clinical practice, until stop of C/T.

Results

A total of 260 patients were enrolled between October 2018 and December 2019 in 30 centers across France. Of these, 177 (68.0%) received C/T as per indication of usage following the results of the antibiogram (documented cases). Among documented patients, the mean age was 61.8 years, 73.4% were males, and 93.8% presented with multidrug-resistant (MDR) bacteria at inclusion. C/T was most frequently prescribed for pneumonia (48.6%), bacteremia (14.7%), complicated intra-abdominal infections (13.0%), or complicated urinary tract infections (9.6%). Pseudomonas aeruginosa was the species most frequently isolated with 212 strains from 155 patients, and 96.2% of these strains were susceptible to C/T. The median duration of C/T treatment was 16.1 days (1-115, n = 176). Complete or partial cure was achieved in 71.7% of patients, C/T was discontinued upon adaptation to microbiology results in 11.3% of patients for the following reasons: treatment failure in 2.8%, death in 4.0%, adverse events in 1.7%, and other in 8.5%.

Conclusions

This is the first prospective observational study of C/T utilization in a health care setting enrolling many patients in France. C/T demonstrated a high rate of clinical effectiveness in MDR infections, confirming it as an effective treatment option for complicated infections in a high-risk population.

New Antibiotics Against Multidrug-Resistant Gram-Negative Bacteria in Liver Transplantation: Clinical Perspectives, Toxicity, and PK/PD Properties

Antimicrobial resistance is a growing global health problem, and it is especially relevant among liver transplant recipients where infections, particularly when caused by microorganisms with a difficult-to-treat profile, are a significant cause of morbidity and mortality. We provide here a complete dissection of the antibiotics active against multidrug-resistant Gram-negative bacteria approved over the last years, focusing on their activity spectrum, toxicity profile and PK/PD properties, including therapeutic drug monitoring, in the setting of liver transplantation. Specifically, the following drugs are presented: ceftolozane/tazobactam, ceftazidime/avibactam, meropenem/vaborbactam, imipenem/relebactam, cefiderocol, and eravacycline. Overall, studies on the safety and optimal employment of these drugs in liver transplant recipients are limited and especially needed. Nevertheless, these pharmaceuticals have undeniably enhanced therapeutic options for infected liver transplant recipients.

Perspectives on the use of ceftolozane/tazobactam: a review of clinical trial data and real-world evidence

Hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP) are common healthcare-associated infections linked to high morbidity and mortality. Gram-negative pathogens, such as Pseudomonas aeruginosa, exhibit multidrug resistance and are recognized as major public health concerns, particularly among critically ill patients with HABP/VABP. Ceftolozane/tazobactam is a novel combination antibacterial agent comprising ceftolozane (a potent antipseudomonal cephalosporin) and tazobactam (a β-lactamase inhibitor). Phase III trials have demonstrated non-inferiority of ceftolozane/tazobactam to comparators, leading to the approval of ceftolozane/tazobactam for the treatment of complicated urinary tract infections, complicated intra-abdominal infections, and nosocomial pneumonia. In this article, we review the clinical trial evidence and key real-world effectiveness data of ceftolozane/tazobactam for the treatment of serious healthcare-associated Gram-negative infections, focusing on patients with HABP/VABP.

Worldwide trend discovery of structural and functional relationship of metallo-β-lactamase for structure-based drug design: A bibliometric evaluation and patent analysis

Metallo-β-lactamase (MBL) is an enzyme produced by clinically important bacteria that can inactivate many commonly used antibiotics, making them a significant concern in treating bacterial infections and the risk of having high antibiotic resistance issues among the community. This review presents a bibliometric and patent analysis of MBL worldwide research trend based on the Scopus and World Intellectual Property Organization databases in 2013-2022. Based on the keywords related to MBL in the article title, abstract, and keywords, 592 research articles were retrieved for further analysis using various tools such as Microsoft Excel to determine the frequency analysis, VOSviewer for bibliometric networks visualization, and Harzing's Publish or Perish for citation metrics analysis. Standard bibliometric parameters were analysed to evaluate the field's research trend, such as the growth of publications, topographical distribution, top subject area, most relevant journal, top cited documents, most relevant authors, and keyword trend analysis. Within 10 years, MBL discovery has shown a steady and continuous growth of interest among the community of researchers. United States of America, China, and the United Kingdom are the top 3 countries contribute high productivity to the field. The patent analysis also shows several impactful filed patents, indicating the significance of development research on the structural and functional relationship of MBL for an effective structure-based drug design (SBDD). Developing new MBL inhibitors using SBDD could help address the research gap and provide new successful therapeutic options for treating MBL-producing bacterial infections.

Antimicrobial approach of abdominal post-surgical infections

Abdominal surgical site infections (SSIs) are infections that occur after abdominal surgery. They can be superficial, involving the skin tissue only, or more profound, involving deeper skin tissues including organs and implanted materials. Currently, SSIs are large global health problem with an incidence that varies significantly depending on the United Nations' Human Development Index. The purpose of this review is to provide a practical update on the latest available literature on SSIs, focusing on causative pathogens and treatment with an overview of the ongoing studies of new therapeutic strategies.

Optimized Treatment of Nosocomial Peritonitis

This comprehensive review aims to provide a practical guide for intensivists, focusing on enhancing patient care associated with nosocomial peritonitis (NP). It explores the epidemiology, diagnosis, and management of NP, a significant contributor to the mortality of surgical patients worldwide. NP is, per definition, a hospital-acquired condition and a consequence of gastrointestinal surgery or a complication of other diseases. NP, one of the most prevalent causes of sepsis in surgical Intensive Care Units (ICUs), is often associated with multi-drug resistant (MDR) bacteria and high mortality rates. Early clinical suspicion and the utilization of various diagnostic tools like biomarkers and imaging are of great importance. Microbiology is often complex, with antimicrobial resistance escalating in many parts of the world. Fungal peritonitis and its risk factors, diagnostic hurdles, and effective management approaches are particularly relevant in patients with NP. Contemporary antimicrobial strategies for treating NP are discussed, including drug resistance challenges and empirical antibiotic regimens. The importance of source control in intra-abdominal infection management, including surgical and non-surgical interventions, is also emphasized. A deeper exploration into the role of open abdomen treatment as a potential option for selected patients is proposed, indicating an area for further investigation. This review underscores the need for more research to advance the best treatment strategies for NP.

Management strategies for severe Pseudomonas aeruginosa infections

PURPOSE OF REVIEW

This review focuses on the management of severe Pseudomonas aeruginosa infections in critically ill patients.

RECENT FINDINGS

Pseudomonas aeruginosa is the most common pathogen in intensive care; the main related infections are nosocomial pneumonias, then bloodstream infections. Antimicrobial resistance is common; despite new antibiotics, it is associated with increased mortality, and can lead to a therapeutic deadlock.

SUMMARY

Carbapenem resistance in difficult-to-treat P. aeruginosa (DTR-PA) strains is primarily mediated by loss or reduction of the OprD porin, overexpression of the cephalosporinase AmpC, and/or overexpression of efflux pumps. However, the role of carbapenemases, particularly metallo-β-lactamases, has become more important. Ceftolozane-tazobactam, ceftazidime-avibactam and imipenem-relebactam are useful against DTR phenotypes (noncarbapenemase producers). Other new agents, such as aztreonam-ceftazidime-avibactam or cefiderocol, or colistin, might be effective for carbapenemase producers. Regarding nonantibiotic agents, only phages might be considered, pending further clinical trials. Combination therapy does not reduce mortality, but may be necessary for empirical treatment. Short-term treatment of severe P. aeruginosa infections should be preferred when it is expected that the clinical situation resolves rapidly.

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

Background

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

Methods

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

Results

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

Conclusions

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

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.

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

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

Physicochemical Characteristics of Antimicrobials and Practical Recommendations for Intravenous Administration: A Systematic Review

Most antimicrobial drugs need an intravenous (IV) administration to achieve maximum efficacy against target pathogens. IV administration is related to complications, such as tissue infiltration and thrombo-phlebitis. This systematic review aims to provide practical recommendations about diluent, pH, osmolarity, dosage, infusion rate, vesicant properties, and phlebitis rate of the most commonly used antimicrobial drugs evaluated in randomized controlled studies (RCT) till 31 March 2023. The authors searched for available IV antimicrobial drugs in RCT in PUBMED EMBASE®, EBSCO® CINAHL®, and the Cochrane Controlled Clinical trials. Drugs' chemical features were searched online, in drug data sheets, and in scientific papers, establishing that the drugs with a pH of <5 or >9, osmolarity >600 mOsm/L, high incidence of phlebitis reported in the literature, and vesicant drugs need the adoption of utmost caution during administration. We evaluated 931 papers; 232 studies were included. A total of 82 antimicrobials were identified. Regarding antibiotics, 37 reach the "caution" criterion, as well as seven antivirals, 10 antifungals, and three antiprotozoals. In this subgroup of antimicrobials, the correct vascular access device (VAD) selection is essential to avoid complications due to the administration through a peripheral vein. Knowing the physicochemical characteristics of antimicrobials is crucial to improve the patient's safety significantly, thus avoiding administration errors and local side effects.

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.

Safety and Efficacy of Ceftolozane/Tazobactam Plus Metronidazole Versus Meropenem From a Phase 2, Randomized Clinical Trial in Pediatric Participants With Complicated Intra-abdominal Infection

BACKGROUND

Ceftolozane/tazobactam, a cephalosporin-β-lactamase inhibitor combination, is approved for the treatment of complicated urinary tract infections and complicated intra-abdominal infections (cIAI). The safety and efficacy of ceftolozane/tazobactam in pediatric participants with cIAI were assessed.

METHODS

This phase 2 study (NCT03217136) randomized participants to either ceftolozane/tazobactam+metronidazole or meropenem for treatment of cIAI in pediatric participants (<18 years). The primary objective was to assess the safety and tolerability of intravenous ceftolozane/tazobactam+metronidazole. Clinical cure at end of treatment (EOT) and test of cure (TOC) visits were secondary end points.

RESULTS

The modified intent-to-treat (MITT) population included 91 participants (ceftolozane/tazobactam+metronidazole, n = 70; meropenem, n = 21). Complicated appendicitis was the most common diagnosis (93.4%); Escherichia coli was the most common pathogen (65.9%). Adverse events (AEs) occurred in 80.0% and 61.9% of participants receiving ceftolozane/tazobactam+metronidazole and meropenem, drug-related AEs occurred in 18.6% and 14.3% and serious AEs occurred in 11.4% and 0% of participants receiving ceftolozane/tazobactam+metronidazole and meropenem, respectively. No drug-related serious AEs or discontinuations due to drug-related AEs occurred. Rates of the clinical cure for ceftolozane/tazobactam+metronidazole and meropenem at EOT were 80.0% and 95.2% (difference: -14.3; 95% confidence interval: -26.67 to 4.93) and at TOC were 80.0% and 100.0% (difference: -19.1; 95% confidence interval: -30.18 to -2.89), respectively; 6 of the 14 clinical failures for ceftolozane/tazobactam+metronidazole at TOC were indeterminate responses imputed as failures per protocol.

CONCLUSION

Ceftolozane/tazobactam+metronidazole was well tolerated in pediatric participants with cIAI and had a safety profile similar to the established safety profile in adults. In this descriptive efficacy analysis, ceftolozane/tazobactam+metronidazole appeared efficacious.

Efficacy and safety of tazobactam/ceftolozane in combination with metronidazole for intraabdominal infection in a hepato-biliary-pancreatic field in clinical practice

INTRODUCTION

This single-center study evaluated the efficacy and safety of tazobactam/ceftolozane (TAZ/CTLZ) in combination with metronidazole for intraabdominal infection in a hepato-biliary-pancreatic field in clinical practice.

METHODS

This study included 50 patients, including 35 with intraabdominal abscess or peritonitis, 5 with liver abscess, 4 with cholecystitis, and 6 with cholangitis with sepsis. Of the 50 patients, 29 received TAZ/CTLZ and metronidazole after a prior antibacterial therapy failure, including tazobactam/piperacillin, cefmetazole, and levofloxacin. Source control was performed in 36 patients.

RESULTS

The clinical response could be evaluated in 49 patients. The clinical cure rate at end-of-therapy was 91.8% (45 of 49 patients) and that at test-of-cure was 89.6% (43 of 48 patients). Of 5 patients in whom clinical response at test-of-cure was a failure, 1 developed infectious disease during chemoradiotherapy for recurrent cancer and 4 after liver resection or pancreatoduodenectomy. Three of the 4 patients were associated with pancreatic juice leakage. Isolated pathogens were eradicated or presumably eradicated in 27 of 31 (87.1%) patients in whom microbiological response at test-of-cure could be evaluated. The response rate for AmpC-producing Enterobacteriaceae was 87.5%. Nausea was observed in two patients. Aspartate and alanine aminotransferase activities were increased in 3 of the 50 (6.0%) patients. The activities improved after the antibiotic discontinuation.

CONCLUSIONS

This observational study demonstrated that TAZ/CTLZ in combination with metronidazole has a favorable effect without major drug-related adverse events for intraabdominal infection in the hepato-biliary-pancreatic field in clinical practice although the efficacy of TAZ/CTLZ may decrease in compromised 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.

New Antimicrobials for the Treatment of Neonatal Sepsis Caused by Multi-Drug-Resistant Bacteria: A Systematic Review

BACKGROUND

Infections by multi-drug-resistant (MDR) organisms are sharply increasing in newborns worldwide. In low and middle-income countries, a disproportionate amount of neonatal sepsis caused by MDR Gram negatives was recently reported. Newborns with infections by MDR organisms with limited treatment options may benefit from novel antimicrobials.

METHODS

We performed a literature search investigating the use in newborns, infants and children of novel antimicrobials for the treatment of MDR Gram negatives, namely ceftazidime/avibactam, ceftolozane/tazobactam, cefiderocol, meropenem/vaborbactam, imipenem/relebactam, and Gram positives with resistance of concern, namely ceftaroline and dalbavancin. PubMed, EMBASE, and Web of Science were searched.

RESULTS

A total of 50 records fulfilled the inclusion criteria. Most articles were case reports or case series, and ceftazidime/avibactam was the most studied agent. All studies showed favorable efficacy and safety profile in newborns and across different age cohorts.

CONCLUSIONS

novel antibiotics may be considered in newborns for the treatment of MDR Gram negatives with limited treatment options and for Gram positives with resistance concerns. Further studies are needed to address their effectiveness and safety in newborns.

Antimicrobial susceptibility of ceftolozane-tazobactam against multidrug-resistant Pseudomonas aeruginosa isolates from Melbourne, Australia

We collected 163 clinical Pseudomonas aeruginosa isolates at a tertiary hospital specialising in adult cystic fibrosis (CF) and lung transplantation (LTx) in Melbourne, Australia, to explore the activity of ceftolozane-tazobactam (C/T) in populations at high-risk for antimicrobial resistance. Of these, 144 (88.3%) were collected from sputum, and 19 (11.7%) from bronchoalveolar lavage. Most (85.3%) were derived from patients with cystic fibrosis and included a subset of patients that had undergone LTx. These isolates were tested against 11 antibiotics, including C/T, using Sensititre plates for broth microdilution (BMD) testing. Sixty (36.8%) isolates were classified as multidrug resistant (MDR) and 32 (19.6%) were extensively drug resistant (XDR). Overall, 133/163 (81.6%) isolates were susceptible to C/T. For MDR and XDR isolates, 88.3% and 28.1% were C/T susceptible, respectively. Among the non-MDR/XDR isolates, 100% remained susceptible to C/T. Comparisons of C/T susceptibility were made using BioMérieux Etests and Liofilchem MIC test strips (MTS). Categorical agreement to BMD was >93% for both test strips, but essential agreement to BMD was slightly higher with Etest (89.0%) compared to Liofilchem (74.8%). In conclusion, C/T retained activity against most MDR and over a quarter of XDR P. aeruginosa isolates from complex patients with CF and post-LTx.

A Real-world Multicenter Outpatient Experience of Ceftolozane/Tazobactam

Background

Ceftolozane/tazobactam (C/T) is indicated for the treatment of complicated intra-abdominal infection (IAI), complicated urinary tract infection (UTI), and hospital-acquired/ventilator-associated bacterial pneumonia caused by susceptible bacteria. As real-world data are limited, we report utilization and associated outcomes of C/T use in the outpatient setting.

Methods

This is a multicenter, retrospective study of patients who received C/T between May 2015 and December 2020. Demographics, infection types, C/T utilization characteristics, microbiology, and health care resource utilization were collected. Clinical success was defined as complete or partial symptom resolution at completion of C/T. Persistent infection and discontinuation of C/T were deemed nonsuccess. Logistic regression analysis was used to identify predictors associated with clinical outcomes.

Results

A total of 126 patients (median age, 59 years; 59% male; median Charlson index, 5) from 33 office infusion centers were identified. Infection types included 27% bone and joint infection (BJI), 23% UTI, 18% respiratory tract infection (RTI), 16% IAI, 13% complicated skin and soft tissue infection (cSSTI), and 3% bacteremia. The median daily dose of C/T was 4.5 g, primarily administered via elastomeric pumps as intermittent infusion. The most common gram-negative pathogen was P. aeruginosa (63%), 66% of which was multidrug-resistant and 45% carbapenem-resistant. Enterobacterales was identified in 26% of isolates, of which 44% were extended-spectrum beta-lactamase producers. The overall clinical success rate of C/T was 84.7%. Nonsuccessful outcomes were due to persistent infections (9.7%) and drug discontinuations (5.6%).

Conclusions

C/T was successfully used in the outpatient setting to treat a variety of serious infections with a high prevalence of resistant pathogens.

What to Do with the New Antibiotics?

Multidrug-resistant Gram-negative bacteria-related infections have become a real public health problem and have exposed the risk of a therapeutic impasse. In recent years, many new antibiotics have been introduced to enrich the therapeutic armamentarium. Among these new molecules, some are mainly of interest for the treatment of the multidrug-resistant infections associated with Pseudomonas aeruginosa (ceftolozane/tazobactam and imipenem/relebactam); others are for carbapenem-resistant infections associated with Enterobacterales (ceftazidime/avibactam, meropenem/vaborbactam); and finally, there are others that are effective on the majority of multidrug-resistant Gram-negative bacilli (cefiderocol). Most international guidelines recommend these new antibiotics in the treatment of microbiologically documented infections. However, given the significant morbidity and mortality of these infections, particularly in the case of inadequate therapy, it is important to consider the place of these antibiotics in probabilistic treatment. Knowledge of the risk factors for multidrug-resistant Gram-negative bacilli (local ecology, prior colonization, failure of prior antibiotic therapy, and source of infection) seems necessary in order to optimize antibiotic prescriptions. In this review, we will assess these different antibiotics according to the epidemiological data.

Satisfactory In Vitro Activity of Ceftolozane–Tazobactam against Carbapenem-Resistant Pseudomonas aeruginosa But Not against Klebsiella pneumoniae Isolates

Background: Gram-negative rods are one of the most commonly isolated bacteria within human infections. These microorganisms are typically opportunistic pathogens that pose a serious threat to public health due to the possibility of transmission in the human population. Resistance to carbapenems is one of the most important antimicrobial resistance mechanisms amongst them. The aim of this study was to evaluate ceftolozane–tazobactam in vitro activity against carbapenem-resistant Pseudomonas aeruginosa and Klebsiella pneumoniae clinical strains. Information on the antimicrobial activity of this antimicrobial against Gram-negative rods was also supplemented with a brief review of the relevant literature. Methods: The research involved 316 strains of Gram-negative rods: P. aeruginosa—206 and K. pneumoniae—110. Results: Of the tested strains, 86.0% P. aeruginosa and 30.0% K. pneumoniae remained susceptible to ceftolozane–tazobactam. Conclusions: Therefore, ceftolozane–tazobactam might be a good option in the treatment of infections caused by carbapenem-resistant P. aeruginosa strains, including those in ICU patients. Meanwhile, due to dissemination of ESBLs among K. pneumoniae strains, infections with this etiology should not be treated with the ceftolozane–tazobactam combination.

A single- and multiple-dose study to characterize the pharmacokinetics, safety, and tolerability of ceftolozane/tazobactam in healthy Chinese participants

Ceftolozane/tazobactam (C/T) is approved in several countries to treat complicated urinary tract infections, complicated intra-abdominal infections, and nosocomial pneumonia. There is a paucity of pharmacokinetics and safety data for C/T in Chinese participants. This study evaluated the pharmacokinetics, safety, and tolerability of C/T in 12 healthy Chinese participants after three single administrations of increasing doses (0.75 g, 1.5 g, and 3 g) and multiple administrations of 1.5 g C/T every 8 h for 3 days. After single doses, maximum concentrations of ceftolozane and tazobactam were reached by the end of the 1-h infusion and declined in a biphasic manner thereafter, with mean half-lives of 1.9-2.2 h and 0.74-0.95 h, respectively. Volume of distribution (V_d) and renal clearance (CL) were consistent across the three single-dose levels for ceftolozane (V_d, 15.8-19.5 L; CL, 5.68-6.09 L/h) and tazobactam (V_d, 23.3-28.6 L; CL, 20.8-23.5 L/h). Area under the concentration-time curve (AUC) extrapolated to infinity (ceftolozane, 88.1-328 h∙μg/mL; tazobactam, 10.7-48.0 h∙μg/mL) increased in a dose-dependent manner. After multiple doses over 3 days, AUC from time 0 to 8 h, and concentration at the end of infusion were similar to single-dose measurements (geometric mean ratios, 0.87-1.01 for both drugs). C/T was well tolerated, with no serious adverse events or discontinuations reported; all adverse events were mild. The pharmacokinetics and safety/tolerability of C/T in healthy Chinese participants was comparable to that in previous studies in other populations, supporting the use of C/T for the treatment of Chinese patients.

Review of novel β-lactams and β-lactam/β-lactamase inhibitor combinations with implications for pediatric use

Antimicrobial resistance continues to surmount increasing concern globally, and treatment of difficult-to-treat (DTR) Pseudomonas aeruginosa, carbapenem-resistant (CR) Acinetobacter baumannii (CRAB), and CR Enterobacterales (CRE) remains a challenge for clinicians. Although previously rare, the incidence of multidrug-resistant (MDR) and CR infections in pediatric patients has increased drastically in the last decade and is associated with increased morbidity and mortality. To combat this issue, 14 novel antibiotics, including three β-lactam/novel β-lactamase inhibitor combinations (βL-βLIs) and two novel β-lactams (βLs), have received approval from the United States Food and Drug Administration since 2010. Improving clinician understanding of the utility of these novel therapies is imperative to improve judicious decision-making and prevent societal regression to a pre-penicillin era. In this review, we summarize the pharmacokinetic/pharmacodynamic (PK/PD) properties, clinical efficacy and safety data, dosing considerations, and subsequent role in therapy for ceftazidime-avibactam (CAZ-AVI), meropenem-vaborbactam (MER-VAB), imipenem-cilastatin-relebactam (IMI-REL), ceftolozane-tazobactam (TOL-TAZ), and cefiderocol in pediatric patients.

Evidence-Based Treatment of Pseudomonas aeruginosa Infections: A Critical Reappraisal

Multidrug-resistant (MDR)/extensively drug-resistant (XDR) Pseudomonas aeruginosa is emerging as a major threat related to adverse patient outcomes. The goal of this review is to describe evidence-based empiric and targeted treatment regimens that can be exploited when dealing with suspected or confirmed infections due to MDR/XDR P. aeruginosa. P. aeruginosa has inherent resistance to many drug classes, the capacity to form biofilms, and most importantly, the ability to quickly acquire resistance to ongoing treatments. Based on the presence of risk factors for MDR/XDR infections and local epidemiology, where large proportions of strains are resistant to classic beta-lactams, the recommended empirical treatment for suspected P. aeruginosa infections is based on ceftolozane-tazobactam or ceftazidime-avibactam. Where local epidemiology indicates low rates of MDR/XDR and there are no risk factors, a third or fourth generation cephalosporin can be used in the context of a "carbapenem-sparing" strategy. Whenever feasible, antibiotic de-escalation is recommended after antimicrobial susceptibility tests suggest that it is appropriate, and de-escalation is based on different resistance mechanisms. Cefiderocol and imipenem-cilastatin-relebactam withstand most resistance mechanisms and may remain active in cases with resistance to other new antibiotics. Confronting the growing threat of MDR/XDR P. aeruginosa, treatment choices should be wise, sparing newer antibiotics when dealing with a suspected/confirmed susceptible P. aeruginosa strain and choosing the right option for MDR/XDR P. aeruginosa based on specific types and resistance mechanisms.

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

BACKGROUND

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

RESEARCH DESIGN AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Short-course antibiotics for common infections: what do we know and where do we go from here?

BACKGROUND

Over the past 25 years, researchers have performed >120 randomized controlled trials (RCTs) illustrating short courses to be non-inferior to long courses of antibiotics for common bacterial infections.

OBJECTIVE

We sought to determine whether clinical data from RCTs affirm the mantra of 'shorter is better' for antibiotic durations in 7 common infections: pneumonia, urinary tract infection, intra-abdominal infection, bacteraemia, skin and soft tissue infection, bone and joint infections, pharyngitis and sinusitis.

SOURCES

Published RCTs comparing short- versus long-course antibiotic durations were identified through searches of PubMed and clinical guideline documents.

CONTENT

Short-course antibiotic durations consistently result in similar treatment success rates as longer antibiotic courses among patients with community-acquired pneumonia, complicated urinary tract infections in women, gram-negative bacteraemia, and skin and soft tissue infections when the diagnosis is confirmed, appropriate antimicrobials are used, and patients show clinical signs of improvement. For patients with osteomyelitis, 6 weeks of antibiotics is adequate for the treatment of osteomyelitis in the absence of implanted foreign bodies and surgical debridement. Whether durations can be further shortened with debridement is unclear, although small studies are promising.

IMPLICATIONS

With few exceptions, short courses were non-inferior to long courses; future research should focus on appropriately defining the patient population, ensuring the correct choice and dose of antimicrobials and developing meaningful outcomes relevant for frontline clinicians.

Ceftolozane-Tazobactam Pharmacokinetics in the Abdominal Tissue of Patients Undergoing Lower Gastrointestinal Surgery: Dosing Considerations Based on Site-Specific Pharmacodynamic Target Attainment

INTRODUCTION

Recently, complicated intra-abdominal infections (cIAI) have been caused not only by Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa, but also by extended-spectrum β-lactamase-producing Enterobacterales members. Ceftolozane-tazobactam (CTLZ-TAZ) is considered to exhibit therapeutic effects against cIAI. Studies on the concentrations of antibiotics in abdominal tissues directly affected by cIAI are limited. Therefore, in this study, we investigated the pharmacokinetics of CTLZ-TAZ in abdominal tissue and simulated the administration regimen required to achieve the pharmacodynamic target for cIAI-causing bacteria.

METHODS

Patients scheduled for elective lower gastrointestinal surgery were intravenously administered preoperative CTLZ-TAZ (1 g CTLZ and 0.5 g TAZ). Plasma, peritoneal fluid, peritoneum, and subcutaneous adipose tissue samples were collected during the surgery, and CTLZ as well as TAZ concentrations were measured. The noncompartmental and compartmental pharmacokinetic parameters were then estimated. Site-specific pharmacodynamic target attainment analysis using 1.5 g of CTLZ-TAZ was performed.

RESULTS

CTLZ-TAZ was administered to nine patients (once to five patients and twice to four patients). The mean peritoneal fluid-to-plasma ratio (one dose/two doses) for CTLZ was 0.74/1.15, which was slightly higher than the mean peritoneal fluid-to-plasma ratio for TAZ (0.95/1.13). The ratio for subcutaneous adipose was lower than those for peritoneal fluid and peritoneum tissues. We also discovered that the average ratio of CTLZ and TAZ concentrations in all tissues was maintained at or above 2:1. In our investigation of pharmacodynamic target attainment in each tissue, the desired bactericidal effect was attained with all CTLZ-TAZ (1.5 g) administration regimens [q12h (3 g/day), q8h (4.5 g/day), and q6h (6 g/day)].

CONCLUSION

To the best of our knowledge, this is the first study investigating the optimal pharmacodynamic level of CTLZ-TAZ in the abdominal tissue against cIAI-causing bacteria. This study also serves as a guideline for designing an optimal administration regimen based on pharmacodynamic target attainment for cIAI-causing bacteria.

DETAILS OF THE TRIAL REGISTRATION

The institutional review board of Hiroshima University Hospital, CRB6180006. The Japan Registry of Clinical Trials, jRCTs061190025.

Treatment of severe infections caused by ESBL or carbapenemases-producing Enterobacteriaceae

Enterobacteriaceae are the most frequent pathogens in the Intensive Care Unit. Due to their safety and activity, β-Lactams (BL) and carbapenems represented the most common strategy adopted against these germs. The increasing exposure to these molecules led to the development of several types of antimicrobial resistance as the expression of extended-spectrum β-lactamases (ESBLs) and carbapenemases. Great molecular variability exists among these enzymes, with significant clinical impact. To limit morbidity and mortality, old antibiotics were tested and represent viable alternatives for specific types of infections, or once the spectrum of susceptibility of each germ has been determined. Alongside, new molecules have been specifically designed but enzyme molecular variability prevents the existence of one single antibiotic which fits for all. Therefore, a quicker identification of the molecular identity of each germ, together with the knowledge of the activity spectrum of each antibiotic is crucial to tailor the therapy and make it effective.

Ceftolozane/Tazobactam In-Vitro Activity against Clinical Isolates from Complicated Intra-Abdominal Infection Patients in Three Indonesian Referral Hospitals

Complicated intra-abdominal infections (cIAIs) lead to high morbidity and mortality, especially if poorly managed. However, Indonesia's microbial pattern and susceptibility data are limited, especially for new antibiotics. Ceftolozane/tazobactam (C/T) is reported to be a new potent antibiotic against various pathogens. Thus, we aim to investigate C/T in vitro activity against clinical isolates from cIAI patients. This prospective cross-sectional study was conducted in three major referral hospitals in Indonesia, including Dr. Cipto Mangunkusumo Hospital (Jakarta), Dr. Kariadi Hospital (Semarang), and Dr. Soetomo Hospital (Surabaya), enrolling those diagnosed with cIAIs. Blood specimens were collected before or after at least 72 h of the last antibiotic administration. Meanwhile, tissue biopsy/aspirate specimens were collected intraoperatively. These specimens were cultured, followed by a susceptibility test for specific pathogens. The minimum inhibitory concentration (MIC) of isolates was determined according to CLSI M100. Two-hundred-and-eighty-four patients were enrolled from 2019-2021. Blood culture was dominated by Gram-positive bacteria (GPB, n = 25, 52.1%), whereas abdominal tissue culture was dominated by Gram-negative bacteria (GNB, n = 268, 79.5%). The three most common organisms were GNB, including E. coli, K. pneumoniae, and P. aeruginosa. C/T was susceptible in 96.7%, 70.2%, and 94.1% of the E. coli, K. pneumoniae, and P. aeruginosa isolates, respectively. In addition, C/T also remained active against ESBL Enterobacterales and carbapenem-non-susceptible P. aeruginosa. Overall, C/T demonstrates a high potency against GNB isolates and can be considered an agent for carbapenem-sparing strategy for cIAI patients as the susceptibility is proven.

Antimicrobial Treatment of Pseudomonas aeruginosa Severe Sepsis

Pseudomonas aeruginosa is a pathogen often encountered in a healthcare setting. It has consistently ranked among the most frequent pathogens seen in nosocomial infections, particularly bloodstream and respiratory tract infections. Aside from having intrinsic resistance to many antibiotics, it rapidly acquires resistance to novel agents. Given the high mortality of pseudomonal infections generally, and pseudomonal sepsis particularly, and with the rise of resistant strains, treatment can be very challenging for the clinician. In this paper, we will review the latest evidence for the optimal treatment of P. aeruginosa sepsis caused by susceptible as well as multidrug-resistant strains including the difficult to treat pathogens. We will also discuss the mode of drug infusion, indications for combination therapy, along with the proper dosing and duration of treatment for various conditions with a brief discussion of the use of non-antimicrobial agents.

A Proposal for a Classification Guiding the Selection of Appropriate Antibiotic Therapy for Intra-Abdominal Infections

Adequately controlling the source of infection and prescribing appropriately antibiotic therapy are the cornerstones of the management of patients with intra-abdominal infections (IAIs). Correctly classifying patients with IAIs is crucial to assessing the severity of their clinical condition and deciding the strategy of the treatment, including a correct empiric antibiotic therapy. Best practices in prescribing antibiotics may impact patient outcomes and the cost of treatment, as well as the risk of “opportunistic” infections such as Clostridioides difficile infection and the development and spread of antimicrobial resistance. This review aims to identify a correct classification of IAIs, guiding clinicians in the selection of the best antibiotic therapy in patients with IAIs.

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.

Antimicrobial Challenge in Acute Care Surgery

The burden of infections in acute care surgery (ACS) is huge. Surgical emergencies alone account for three million admissions per year in the United States (US) with estimated financial costs of USD 28 billion per year. Acute care facilities and ACS patients represent boost sanctuaries for the emergence, development and transmission of infections and multi-resistant organisms. According to the World Health Organization, healthcare-associated infections affected around 4 million cases in Europe and 1.7 million in the US alone in 2011 with 39,000 and 99,000 directly attributable deaths, respectively. In this scenario, antimicrobial resistance arose as a public-health emergency that worsens patients’ morbidity and mortality and increases healthcare costs. The optimal patient care requires the application of comprehensive evidence-based policies and strategies aiming at minimizing the impact of healthcare associated infections and antimicrobial resistance, while optimizing the treatment of intra-abdominal infections. The present review provides a snapshot of two hot topics, such as antimicrobial resistance and systemic inflammatory response, and three milestones of infection management, such as source control, infection prevention, and control and antimicrobial stewardship.

Epidemiology, Mechanisms of Resistance and Treatment Algorithm for Infections Due to Carbapenem-Resistant Gram-Negative Bacteria: An Expert Panel Opinion

Antimicrobial resistance represents a serious threat for global health, causing an unacceptable burden in terms of morbidity, mortality and healthcare costs. In particular, in 2017, carbapenem-resistant organisms were listed by the WHO among the group of pathogens for which novel treatment strategies are urgently needed. Fortunately, several drugs and combinations have been introduced in recent years to treat multi-drug-resistant (MDR) bacteria. However, a correct use of these molecules is needed to preserve their efficacy. In the present paper, we will provide an overview on the epidemiology and mechanisms of resistance of the most common MDR Gram-negative bacteria, proposing a treatment algorithm for the management of infections due to carbapenem-resistant bacteria based on the most recent clinical evidence.

Treatment of severe multi-drug resistant Pseudomonas aeruginosa infections

Pseudomonas aeruginosa is the microorganism most frequently involved in the main ICU-acquired infections, with special importance in ventilator associated pneumonia. Its importance lies, in addition to its high incidence in critically ill patients, in the severity of the infections it causes and in the difficulty of its antimicrobial treatment, directly related to the high percentage of resistance to antibiotics classically considered first-line. New active antibiotics have recently been developed against Pseudomonas aeruginosa, even against multi-drug resistant strains. This review analyzes both the differential characteristics of Pseudomonas aeruginosa infections and the new therapeutic options, focusing on multi-drug resistant Pseudomonas aeruginosa.

Epidemiological Characteristics, Antimicrobial Susceptibility Profile, and Surgical Outcome of Complicated Intra-Abdominal Infection at a Tertiary Hospital in Somalia

Background

Intra-abdominal infections (IAIs) are common surgical emergencies and one of the leading causes of non-trauma deaths in hospitals worldwide. Because of limited resources, most patients in low-income countries experience delayed diagnosis and treatment. To the best of our knowledge, this is the first study to evaluate the epidemiological characteristics, antimicrobial susceptibility profile, and outcome of patients with complicated IAI at a tertiary hospital in Somalia.

Methods

This study included all patients with confirmed IAIs who underwent laparotomy or percutaneous drainage, either emergency or elective, and whose cultures showed growth. Sociodemographic and clinical characteristics, culture results, antimicrobial susceptibility profile, and the type of source control were reviewed.

Results

The prevalence of CIAI was 5.3%, 144 (70%) were male, and 61 (30%) were female. The mean age was 38.6±8.5 years. Appendicitis was the most common source of infection, accounting for 32%, followed by bowel perforation in 37 (18%). Out of 15 patients with liver abscesses, ten patients had diabetes (67%). E. coli 82 (40%) was the most common isolated organism, followed by Klebsiella pneumonia (n = 44, 21.5%). The prevalence of extended-spectrum beta-lactamase-producing and multidrug-resistant pathogens was 6.8% and 5.9%, respectively. The pathogens revealed a higher antimicrobial resistance against penicillins in 62%, cephalosporins in 54%, and fluoroquinolones in 44%. E. coli showed 2.5–13% antimicrobial resistance against carbapenems, lower than Klebsiella pneumonia in about 4.5%. Tigecycline, teicoplanin, and linezolid revealed the highest sensitivity against pathogens, about 100%. Source control was achieved by laparotomy in 81%, while the 19% were managed in a percutaneous approach. The mortality rate in our study was 9.3%.

Conclusion

The prevalence of CIAI in our study was 5.3%, with an increasing number of MDR microorganisms isolated from cultures. CIAI and intra-abdominal abscess are significant sources of high morbidity and mortality with sepsis and poor clinical outcome; thus, early detection and intervention are crucial.

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.

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

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

Antibiotics for multidrug-resistant gram-negative bacteria

Background: Increase in antimicrobial-resistant bacteria continues to be challenge to physicians. Particularly, multidrug-resistant (MDR) gram-negative bacilli (GNB), such as extended-spectrum beta-lactamase (ESBL)-producers and carbapenem-resistant pathogens, are becoming a major human health problem globally.Current Concepts: Gram-negative bacteria have developed resistance via mechanisms encoding AmpC beta-lactamases, ESBLs, and carbapenemases. The therapeutic options available for these pathogens are extremely limited. Infection by MDR bacteria is associated with ineffective antimicrobial therapy, which poses a major threat to the survival of patients with serious infections. Physicians should be familiar with the local epidemiology of MDR bacterial infections and the available therapeutic options. Carbapenems are considered as the drugs of choice for treating ESBL or AmpC-producers. However, increased use of carbapenems in response to an increased prevalence of MDR pathogens could be associated with the rapid emergence of carbapenem resistance. Therefore, there is an ongoing quest for carbapenem-sparing regimens for the treatment of MDR-GNB. Treatment of MDR-GNB infections need not be limited to carbapenems as novel antimicrobial agents are now available.Discussion and Conclusion: This comprehensive review aims to describe therapeutic options available for MDR-GNB infections in Korea, a country with a high prevalence of MDR pathogens. Recently developed antimicrobial agents that should be urgently introduced in Korea include ceftolozane-tazobactam, ceftazidime-avibactam, meropenem-vaborbactam, imipenem-relebactam, and cefiderocol. These drugs have been shown to be effective against carbapenem-resistant Enterobacterales, carbapenem-resistant Pseudomonas aeruginosa, and Acinetobacter baumannii.

Treatment of carbapenem-resistant Pseudomonas aeruginosa infections: a case for cefiderocol

INTRODUCTION

Carbapenem-resistant (CR) Pseudomonas aeruginosa infections constitute a serious clinical threat globally. Patients are often critically ill and/or immunocompromised. Antibiotic options are limited and are currently centered on beta-lactam-beta-lactamase inhibitor (BL-BLI) combinations and the siderophore cephalosporin cefiderocol.

AREAS COVERED

This article reviews the mechanisms of P. aeruginosa resistance and their potential impact on the activity of current treatment options, along with evidence for the clinical efficacy of BL-BLI combinations in P. aeruginosa infections, some of which specifically target infections due to CR organisms. The preclinical and clinical evidence supporting cefiderocol as a treatment option for P. aeruginosa involving infections is also reviewed.

EXPERT OPINION

Cefiderocol is active against most known P. aeruginosa mechanisms mediating carbapenem resistance. It is stable against different serine- and metallo-beta-lactamases, and, due to its iron channel-dependent uptake mechanism, is not impacted by porin channel loss. Furthermore, the periplasmic level of cefiderocol is not affected by upregulated efflux pumps. The potential for on-treatment resistance development currently appears to be low, although more clinical data are required. Information from surveillance programs, real-world compassionate use, and clinical studies demonstrate that cefiderocol is an important treatment option for CR P. aeruginosa infections.

Clinical data from studies involving novel antibiotics to treat multidrug-resistant Gram-negative bacterial infections

Multidrug-resistant (MDR) Gram-negative bacteria (GNB) are a critical threat to healthcare worldwide, worsening outcomes and increasing mortality among infected patients. Carbapenemase- and extended-spectrum β-lactamase-producing Enterobacterales, as well as carbapenemase-producing Pseudomonas and Acinetobacter spp., are common MDR pathogens. To address this threat, new antibiotics and combinations have been developed. Clinical trial findings support several combinations, notably ceftazidime-avibactam (CZA, a cephalosporin-β-lactamase inhibitor combination) which is effective in treating complicated urinary tract infections (cUTI), complicated intra-abdominal infections and hospital-acquired and ventilator-associated pneumonia caused by GNBs. Other clinically effective combinations include meropenem-vaborbactam (MVB), ceftolozane-tazobactam (C/T) and imipenem- relebactam (I-R). Cefiderocol is a recent siderophore β-lactam antibiotic that is useful against cUTIs caused by carbapenem-resistant Enterobacterales (CRE) and is stable against many β-lactamases. CRE are a genetically heterogeneous group that vary in different world regions and are a substantial cause of infections, among which Klebsiella pneumoniae are the most common. Susceptible CRE infections can be treated with fluoroquinolones, aminoglycosides or fosfomycin, but alternatives include CZA, MVB, I-R, cefiderocol, tigecycline and eravacycline. MDR Acinetobacter baumannii and Pseudomonas aeruginosa are increasingly common pathogens producing a range of different carbapenemases, and infections are challenging to treat, often requiring novel antibiotics or combinations. Currently, no single agent can treat all MDR-GNB infections, but new β-lactam-β-lactamase inhibitor combinations are often effective for different infection sites, and, when used appropriately, have the potential to improve outcomes. This article reviews clinical studies investigating novel β-lactam approaches for treatment of MDR-GNB infections.

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.