Ceftolozane/tazobactam for the treatment of multidrug resistant Pseudomonas aeruginosa: experience from the Balearic Islands

Ceftolozane/tazobactam for the treatment of Pseudomonas aeruginosa infections: A multicenter case series analysis

INTRODUCTION

Pseudomonas aeruginosa displays resistance to several available antibiotics. Infections caused by this pathogen are associated with a high mortality, morbidity, and considerable healthcare resource utilization and costs. This study was aimed at describing the use of ceftolozane/tazobactam (C/T) for the treatment of patients with P. aeruginosa infections.

METHODS

Case series analysis of hospitalized patients treated with C/T for P. aeruginosa infections in five public Portuguese hospitals. Patients presenting with infections caused by this pathogen and receiving C/T for at least 72h during hospitalization were eligible.

RESULTS

Sixty-four hospitalized patients with P. aeruginosa infections treated with C/T were evaluated between December 2016 and July 2019. Most patients were aged between 60 and 79 years (53.9%). Patients presented a total of 68 P. aeruginosa infections, with respiratory infections being the most common (28.1%, 18 out of 64). Most P. aeruginosa strains (85.9%, 55 out of 64) were extensively drug-resistant (XDR). C/T was mostly used as targeted therapy (98.4%, 63 out of 64 patients) and as monotherapy (72.7%, 47 out of 64 patients). Combination therapy was used in 47.4% (9 out of 19) of patients with bacteriemia. Most patients had successful microbiological (79.2%, 42 out of 53) and clinical (78.7%, 48 out of 61) outcomes. All-cause in-hospital mortality rate was 34.4%.

CONCLUSION

The present case series contributes to the body of evidence suggesting that C/T is an effective and safe option for treating P. aeruginosa infections, namely those caused by XDR strains, both when used as mono- or combination therapy.

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.

The safety of ceftolozane/tazobactam for the treatment of complicated urinary tract infections

INTRODUCTION

Ceftolozane is a cephalosporin similar to ceftazidime in its structure, which is marketed in combination with tazobactam, a well-known β-lactamase inhibitor.

AREAS COVERED

After a brief introduction on the drug characteristics and efficacy, we focused on available data from randomized controlled trials and post-marketing observational studies pertaining to the safety of ceftolozane/tazobactam (C/T) for the treatment of complicated urinary tract infections (cUTI). A search was conducted in PubMed from January 2010 to February 2023.

EXPERT OPINION

The use of C/T for the treatment of cUTI is supported by solid efficacy and safety data, especially for the treatment of those pathogens where it can represent a first-line approach due to some peculiar characteristics: (i) treatment of cUTI caused by multidrug-resistant Pseudomonas aeruginosa, in view of its frequent activity against carbapenem-resistant isolates when resistance mechanisms other than production of carbapenemases are concerned; (ii) treatment of cUTI caused by extended-spectrum β-lactamase (ESBL)-producing Enterobacterales in those settings where the selective pressure for carbapenem resistance needs to be relieved, as a suitable and effective carbapenem-sparing option. Although development of resistance to C/T during or after treatment has been reported, this has been reported very rarely in patients receiving C/T for the treatment of cUTI.

Susceptibility profile and β-lactamase content of global Pseudomonas aeruginosa isolates resistant to ceftolozane/tazobactam and/or imipenem/relebactam-SMART 2016-21

Objectives

To determine susceptibility profiles and β-lactamase content for ceftolozane/tazobactam-resistant and imipenem/relebactam-resistant Pseudomonas aeruginosa isolates collected in eight global regions during 2016-21.

Methods

Broth microdilution MICs were interpreted using CLSI breakpoints. PCR to identify β-lactamase genes or WGS was performed on selected isolate subsets.

Results

Ceftolozane/tazobactam-resistant [from 0.6% (Australia/New Zealand) to 16.7% (Eastern Europe)] and imipenem/relebactam-resistant [from 1.3% (Australia/New Zealand) to 13.6% (Latin America)] P. aeruginosa varied by geographical region. Globally, 5.9% of isolates were both ceftolozane/tazobactam resistant and imipenem/relebactam resistant; 76% of these isolates carried MBLs. Most ceftolozane/tazobactam-resistant/imipenem/relebactam-susceptible isolates carried ESBLs (44%) or did not carry non-intrinsic (acquired) β-lactamases (49%); 95% of imipenem/relebactam-resistant/ceftolozane/tazobactam-susceptible isolates did not carry non-intrinsic β-lactamases. Isolates that carried indicators of strong PDC (Pseudomonas-derived cephalosporinase) up-regulation without a mutation known to expand the spectrum of PDC, or non-intrinsic β-lactamases, showed an 8-fold increase in ceftolozane/tazobactam modal MIC; however, this rarely (3%) resulted in ceftolozane/tazobactam resistance. Isolates with a PDC mutation and an indicator for PDC upregulation were ceftolozane/tazobactam non-susceptible (MIC,  ≥ 8 mg/L). MICs ranged widely (1 to >32 mg/L) for isolates with a PDC mutation and no positively identified indicator for PDC up-regulation. Imipenem/relebactam-resistant/ceftolozane/tazobactam-susceptible isolates without non-intrinsic β-lactamases frequently (91%) harboured genetic lesions implying OprD loss of function; however, this finding alone did not account for this phenotype. Among imipenem-non-susceptible isolates without non-intrinsic β-lactamases, implied OprD loss only shifted the distribution of imipenem/relebactam MICs up by 1-2 doubling dilutions, resulting in ∼10% imipenem/relebactam-resistant isolates.

Conclusions

P. aeruginosa with ceftolozane/tazobactam-resistant/imipenem/relebactam-susceptible and imipenem/relebactam-resistant/ceftolozane/tazobactam-susceptible phenotypes were uncommon and harboured diverse resistance determinants.

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.

Ceftolozane/tazobactam for the treatment of bacteremia: a systematic literature review (SLR)

Background

Bloodstream infections (BSIs), or bacteremia, are responsible for considerable disease burden. Increasing rates of antibiotic resistance and delays in selection of appropriate treatment lead to increased morbidity, mortality, and costs. Due to limitations of current standard treatments, especially for bacteremia caused by resistant pathogens, a systematic literature review (SLR) was conducted to understand the utilization of ceftolozane/tazobactam (C/T) in bacteremia.

Methods

Electronic database searches of EMBASE^®, MEDLINE^®, CCTR and Northern Lights, as well as hand searches of conference proceedings from the last two annual meetings (i.e., 2018, 2019) of the European Congress of Clinical Microbiological and Infectious Diseases (ECCMID) and the Infectious Diseases Society of America’s annual meeting (IDWeek) were conducted. A total of 23 studies reporting on patients with bacteremia receiving C/T were included in the review.

Results

Most studies were observational (k = 20 studies), though few interventional studies were also identified (k = 3). Heterogeneity was ubiquitous with respect to source of bacteremia (i.e., primary or secondary), source of infection (for secondary bacteremia), pathogen type, antibiotic resistance, C/T dose, and outcome definitions. This heterogeneity, along with limited data, and small sample sizes (n = 1 to 31) made it difficult to draw any substantial conclusions, though overall results were favorable to C/T with respect to the outcomes of interest. Nineteen studies reported clinical cure or success (primary bacteremia: k = 6, reported range: 33.3% to 100%; secondary bacteremia: k = 8, 60% to 100%; mixed/unspecified bacteremia: k = 10, 50% to 91.7%). Eight studies reported microbiological cure or eradication rates (primary: k = 3, all reporting 100%; secondary: k = 4, 68% to 80%; mixed/unspecified: k = 5, 60% to 80%). Thirteen studies reported mortality (primary: k = 4, 0% to 14%; secondary: k = 7, 0% to 100%; or mixed/unspecified bacteremia: k = 7, 0% to 51.6%). One study each also reported composite clinical response, relapse, hospital re-admission, and hospital length of stay.

Conclusions

Although the available evidence and observed trends for C/T in bacteremia should be interpreted with caution, the direction of effect would support the utilization of C/T for these difficult to treat infections. Future research should supplement the existing evidence by considering the impact of key treatment effect modifiers without contributing to the observed heterogeneity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12941-022-00528-0.

Treatment of multidrug-resistant Pseudomonas aeruginosa bacteremia using ceftolozane-tazobactam-based or colistin-based antibiotic regimens: A multicenter retrospective study

BACKGROUND

Ceftolozane-tazobactam is an emerging ‎treatment for severe infections caused by multidrug-resistant (MDR) Pseudomonas ‎aeruginosa. However, limited ‎data support its use in bacteremia treatment. This study aimed to assess the effectiveness of the treatment of MDR P. aeruginosa bacteremia using ceftolozane-‎tazobactam-based or colistin-based regimens. ‎ PATIENTS AND METHODS: This retrospective, cohort, multicentre study included adult patients with ‎MDR P. aeruginosa bacteremia treated with either ceftolozane-tazobactam or ‎colistin, between September 2018 and August 2021, at four hospitals in Saudi ‎Arabia. The primary endpoint was the 30-day risk-adjusted mortality. Secondary endpoints included the 14-day risk of mortality, bacterial eradication, and clinical ‎success. Cox proportional hazards ‎regression and relative risk estimation were used for analysis, as appropriate. ‎ RESULTS: In total, 46 patients were included; 17 patients received ceftolozane-‎tazobactam-based regimen, and 29 received a colistin-based regimen. There was no association with the use of ‎ceftolozane-tazobactam compared to colistin and the 30-day risk-adjusted mortality ‎‎(hazard ratio [HR] ‎0.58, 95% confidence interval [CI] 0.16-2.13, P = 0.42). Also, the ‎‎14-day risk of mortality and bacterial eradication were not different between the ‎ceftolozane-tazobactam and colistin regimens, HR 2.1, 95% CI 0.42-10.48; P = 0.36; and ‎relative risk (RR) 0.65; 95% CI 0.28-1.52; P = 0.30; respectively. On the other hand, ‎ceftolozane-tazobactam use was associated with higher clinical success than colistin ‎‎(RR 1.84, 95% CI 1.11-3.06: P = 0.021).‎ CONCLUSION: The risk of mortality of MDR P.aeruginosa bacteremia was ‎similar when treated with ceftolozane-tazobactam-based or colistin-based antimicrobial regimens. A higher clinical success was observed with the ceftolozane-‎tazobactam-based regimen compared to the colistin-based regimen. ‎.

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.

Comparison of Ceftolozane/Tazobactam Infusion Regimens in a Hollow-Fiber Infection Model against Extensively Drug-Resistant Pseudomonas aeruginosa Isolates

The aim of this study was to compare the efficacy of intermittent (1-h), extended (4-h), and continuous ceftolozane-tazobactam (C/T) infusion against three extensively drug-resistant (XDR) sequence type (ST) 175 P. aeruginosa isolates with different susceptibilities to C/T (MIC = 2 to 16 mg/L) in a 7-day hollow-fiber infection model (HFIM). C/T in continuous infusion achieved the largest reduction in total number of bacterial colonies in the overall treatment arms for both C/T-susceptible and -resistant isolates. It was also the only regimen with bactericidal activity against all three isolates. These data suggest that continuous C/T infusion should be considered a potential treatment for infections caused by XDR P. aeruginosa isolates, including nonsusceptible ones. Proper use of C/T dosing regimens may lead to better clinical management of XDR P. aeruginosa infections.

IMPORTANCE Ceftolozane-tazobactam (C/T) is an antipseudomonal antibiotic with a high clinical impact in treating infection caused by extensively drug-resistant (XDR) Pseudomonas aeruginosa isolates, but resistance is emerging. Given its time-dependent behavior, C/T continuous infusion can improve exposure and therefore the pharmacokinetic/pharmacodynamic target attainment. We compared the efficacy of intermittent, extended, and continuous C/T infusion against three XDR ST175 P. aeruginosa isolates with different C/T MICs by means of an in vitro dynamic hollow-fiber model. We demonstrated that C/T in continuous infusion achieved the largest reduction in bacterial density in the overall treatment arms for both susceptible and resistant isolates. It was also the only regimen with bactericidal activity against all three isolates. Through this study, we want to demonstrate that developing individually tailored antimicrobial treatments is becoming essential. Our results support the role of C/T level monitoring and of dose adjustments for better clinical management and outcomes.

Infectious Diseases Society of America 2022 Guidance on the Treatment of Extended-Spectrum β-lactamase Producing Enterobacterales (ESBL-E), Carbapenem-Resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with Difficult-to-Treat Resistance (DTR-P. aeruginosa)

BACKGROUND

The Infectious Diseases Society of America (IDSA) is committed to providing up-to-date guidance on the treatment of antimicrobial-resistant infections. The initial guidance document on infections caused by extended-spectrum β-lactamase producing Enterobacterales (ESBL-E), carbapenem-resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with difficult-to-treat resistance (DTR-P. aeruginosa) was published on 17 September 2020. Over the past year, there have been a number of important publications furthering our understanding of the management of ESBL-E, CRE, and DTR-P. aeruginosa infections, prompting a rereview of the literature and this updated guidance document.

METHODS

A panel of 6 infectious diseases specialists with expertise in managing antimicrobial-resistant infections reviewed, updated, and expanded previously developed questions and recommendations about the treatment of ESBL-E, CRE, and DTR-P. aeruginosa infections. Because of differences in the epidemiology of resistance and availability of specific anti-infectives internationally, this document focuses on the treatment of infections in the United States.

RESULTS

Preferred and alternative treatment recommendations are provided with accompanying rationales, assuming the causative organism has been identified and antibiotic susceptibility results are known. Approaches to empiric treatment, duration of therapy, and other management considerations are also discussed briefly. Recommendations apply for both adult and pediatric populations.

CONCLUSIONS

The field of antimicrobial resistance is highly dynamic. Consultation with an infectious diseases specialist is recommended for the treatment of antimicrobial-resistant infections. This document is current as of 24 October 2021. The most current versions of IDSA documents, including dates of publication, are available at www.idsociety.org/practice-guideline/amr-guidance/.

Ceftolozane/tazobactam for difficult-to-treat Gram-negative infections: A real-world tertiary hospital experience

OBJECTIVE

To evaluate the real-world clinical efficacy of ceftolozane/tazobactam (C/T) in difficult-to-treat infections caused by multi-drug resistant Gram-negative microorganisms, including carbapenem-resistant Pseudomonas aeruginosa.

METHODS

Retrospective cohort study of adult patients treated with C/T for at least 48 hours for infections caused by multi-drug resistant Gram-negative bacteria in a tertiary hospital from May 2016 until August 2019. The primary outcome analysed was clinical failure, defined as a composite of symptomatology persistence after 7 days of C/T treatment, infection recurrence, and/or all-cause mortality within 30 days of follow-up.

RESULTS AND DISCUSSION

96 episodes of C/T treatment were included, mostly consisting of targeted treatments (83.9%) for the following sources of infection: intra-abdominal (22.6%), urinary tract (25.8%), skin and soft tissue (19.4%), hospital-acquired pneumonia (14%), and other (6.4%). The most frequently isolated bacteria were carbapenem-resistant (88, 94.6%). Clinical failure rate was 30.1%, due to persistent infection at day 7 (4.3%), recurrence of the initial infection (16.1%), or 30-day all-cause mortality (8.6%). Adverse events most frequently reported were Clostridium difficile infection (9%) and cholestasis (8%).

WHAT IS NEW AND CONCLUSION

C/T showed a favourable clinical profile for difficult-to-treat multidrug-resistant and carbapenem-resistant Gram-negative infections, regardless of the source of infection.

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.

Therapeutic Strategies for Emerging Multidrug-Resistant Pseudomonas aeruginosa

Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Pseudomonas aeruginosa isolates are frequent causes of serious nosocomial infections that may compromise the selection of antimicrobial therapy. The goal of this review is to summarize recent epidemiologic, microbiologic, and clinical data pertinent to the therapeutic management of patients with infections caused by MDR/XDR-P. aeruginosa. Historically, conventional antipseudomonal β-lactam antibiotics have been used for the empiric treatment of MDR/XDR-P. aeruginosa. Owing to the remarkable capacity of P. aeruginosa to confer resistance via multiple mechanisms, these traditional therapies are often rendered ineffective. To increase the likelihood of administering empiric antipseudomonal therapy with in vitro activity, a second agent from a different antibiotic class is often administered concomitantly with a traditional antipseudomonal β-lactam. However, combination therapy may pose an increased risk of antibiotic toxicity and secondary infection, notably, Clostridioides difficile. Multiple novel agents that demonstrate in vitro activity against MDR-P. aeruginosa (e.g., β-lactam/β-lactamase inhibitor combinations and cefiderocol) have been recently granted US Food and Drug Administration (FDA) approval and are promising additions to the antipseudomonal armamentarium. Even so, comparative clinical data pertaining to these novel agents is sparse, and concerns surrounding the scarcity of antibiotics active against refractory MDR/XDR-P. aeruginosa necessitates continued assessment of alternative therapies. This is particularly important in patients with cystic fibrosis (CF) who may be chronically colonized and suffer from recurrent infections and disease exacerbations due in part to limited efficacious antipseudomonal agents. Bacteriophages represent a promising candidate for combatting recurrent and refractory infections with their ability to target specific host bacteria and circumvent traditional mechanisms of antibiotic resistance seen in MDR/XDR-P. aeruginosa. Future goals for the management of these infections include increased comparator clinical data of novel agents to determine in what scenario certain agents may be preferred over others. Until then, appropriate treatment of these infections requires a thorough evaluation of patient- and infection-specific factors to guide empiric and definitive therapeutic decisions.

Beta-lactam monotherapy or combination therapy for bloodstream infections or pneumonia due to P. aeruginosa: a meta-analysis

OBJECTIVES

. The aim of the present meta-analysis was to compare the clinical and microbiological outcomes of patients treated with beta-lactam monotherapy or combination therapy for Pseudomonas aeruginosa infections.

DATA SOURCES

MEDLINE, Google Scholar and the Cochrane Library STUDY ELIGIBILITY CRITERIA AND INTERVENTIONS: . Experimental and observational studies published as full papers up to December 2020 that compared the efficacy of beta-lactams used in monotherapy or in combination with other active agents as empirical or targeted therapy for bloodstream infections or Hospital-Acquired or Ventilator-Associated Pneumonia (HAP/VAP) due to P. aeruginosa. The outcomes evaluated were hospital-mortality, 14-day- or 30-day-mortality rate, microbiological eradication rate and clinical cure rate.

RESULTS

. Of a total of 8,363 citations screened, 6 Randomized Controlled Trials (RCTs), 6 prospective cohort studies, and 21 retrospective cohort studies were included in the analysis, accounting for a total of 3,861 subjects. Considering the 14 studies evaluating the empirical therapy, no significant difference in mortality rate was observed between the two groups (RR: 1.06; 95% CI 0.86-1.30, p=0.6). Similar findings were obtained among the 18 studies analysing the targeted therapy (RR: 1.04; 95% CI 0.83-1.31, p=0.708); however, grouping the studies according to the design, a higher mortality among patients receiving monotherapy was observed in 5 prospective studies (RR: 1.37; 95% CI 1.06-1.79, p=0.018). Finally, no difference was observed among groups considering the microbiological and the clinical cure.

CONCLUSIONS

. Our meta-analysis demonstrated no difference in the mortality rate, clinical cure and microbiological cure in patients treated with beta-lactam monotherapy or combination for P. aeruginosa infections.

An Evidence-Based Multidisciplinary Approach Focused on Creating Algorithms for Targeted Therapy of Infection-Related Ventilator-Associated Complications (IVACs) Caused by Pseudomonas aeruginosa and Acinetobacter baumannii in Critically Ill Adult Patients

(1) Background: To develop evidence-based algorithms for targeted antibiotic therapy of infection-related ventilator-associated complications (IVACs) caused by non-fermenting Gram-negative pathogens. (2) Methods: A multidisciplinary team of four experts had several rounds of assessments for developing algorithms devoted to targeted antimicrobial therapy of IVACs caused by two non-fermenting Gram-negative pathogens. A literature search was performed on PubMed-MEDLINE (until September 2021) to provide evidence for supporting therapeutic choices. Quality and strength of evidence was established according to a hierarchical scale of the study design. Six different algorithms with associated recommendations in terms of therapeutic choice and dosing optimization were suggested according to the susceptibility pattern of two non-fermenting Gram-negative pathogens: multi-susceptible Pseudomonas aeruginosa (PA), multidrug-resistant (MDR) metallo-beta-lactamase (MBL)-negative-PA, MBL-positive-PA, carbapenem-susceptible Acinetobacter baumannii (AB), and carbapenem-resistant AB. (3) Results: Piperacillin–tazobactam or fourth-generation cephalosporins represent the first therapeutic choice in IVACs caused by multi-susceptible PA. A carbapenem-sparing approach favouring the administration of novel beta-lactam/beta-lactamase inhibitors should be pursued in the management of MDR-MBL-negative PA infections. Cefiderocol should be used as first-line therapy for the management of IVACs caused by MBL-producing-PA or carbapenem-resistant AB. Fosfomycin-based combination therapy, as well as inhaled colistin, could be considered as a reasonable alternative for the management of IVACs due to MDR-PA and carbapenem-resistant AB. (4) Conclusions: The implementation of algorithms focused on prompt revision of antibiotic regimens guided by results of conventional and rapid diagnostic methodologies, 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 is strongly suggested.

European Society of clinical microbiology and infectious diseases (ESCMID) guidelines for the treatment of infections caused by Multidrug-resistant Gram-negative bacilli (endorsed by ESICM -European Society of intensive care Medicine)

SCOPE

These ESCMID guidelines address the targeted antibiotic treatment of 3^rd generation cephalosporin-resistant Enterobacterales (3GCephRE) and carbapenem-resistant Gram-negative bacteria, focusing on the effectiveness of individual antibiotics and on combination vs. monotherapy.

METHODS

An expert panel was convened by ESCMID. A systematic review was performed including randomized controlled trials and observational studies, examining different antibiotic treatment regimens for the targeted treatment of infections caused by the 3GCephRE, carbapenem-resistant Enterobacterales (CRE), carbapenem-resistant Pseudomonas aeruginosa (CRPA) and carbapenem-resistant Acinetobacter baumanni (CRAB). Treatments were classified as head-to-head comparisons between individual antibiotics and monotherapy vs. combination therapy regimens, including defined monotherapy and combination regimens only. The primary outcome was all-cause mortality, preferably at 30 days and secondary outcomes included clinical failure, microbiological failure, development of resistance, relapse/recurrence, adverse events and length of hospital stay. The last search of all databases was conducted in December 2019, followed by a focused search for relevant studies up until ECCMID 2021. Data were summarized narratively. The certainty of the evidence for each comparison between antibiotics and between monotherapy vs. combination therapy regimens was classified by the GRADE recommendations. The strength of the recommendations for or against treatments was classified as strong or conditional (weak).

RECOMMENDATIONS

The guideline panel reviewed the evidence per pathogen, preferably per site of infection, critically appraising the existing studies. Many of the comparisons were addressed in small observational studies at high risk of bias only. Notably, there was very little evidence on the effects of the new, recently approved, beta-lactam beta-lactamase inhibitors on infections caused by carbapenem-resistant Gram-negative bacteria. Most recommendations are based on very-low and low certainty evidence. A high value was placed on antibiotic stewardship considerations in all recommendations, searching for carbapenem-sparing options for 3GCephRE and limiting the recommendations of the new antibiotics for severe infections, as defined by the sepsis-3 criteria. Research needs are addressed.

New antibiotics for the treatment of nonfermenting Gram-negative bacteria

PURPOSE OF REVIEW

To discuss the current literature on novel agents for the treatment of carbapenem-resistant nonfermenting Gram-negative bacteria (NF-GNB) infections.

RECENT FINDINGS

Some novel agents have recently become available that are expected to replace classical polymyxins as the first-line options for the treatment of carbapenem-resistant NF-GNB infections.

SUMMARY

In this narrative review, we provide a brief overview of the differential activity of various recently approved agents against NF-GNB most encountered in the daily clinical practice, as well as the results from phase-3 randomized clinical trials and large postapproval observational studies, with special focus on NF-GNB. Since resistance to novel agents has already been reported, the use of novel agents needs to be optimized, based on their differential activity (not only in terms of targeted bacteria, but also of resistance determinants), the local microbiological epidemiology, and the most updated pharmacokinetic/pharmacodynamic data. Large real-life experiences remain of crucial importance for further refining the optimal treatment of NF-GNB infections in the daily clinical practice.

Clinical outcomes, molecular epidemiology and resistance mechanisms of multidrug-resistant Pseudomonas aeruginosa isolated from bloodstream infections from Qatar

BACKGROUND

Bloodstream infections (BSIs) caused by multidrug-resistant (MDR)-Pseudomonas aeruginosa are associated with poor clinical outcomes, at least partly due to delayed appropriate antimicrobial therapy. The characteristics of MDR-P. aeruginosa bloodstream isolates have not been evaluated in Qatar. Our study aimed to examine in vitro susceptibility, clinical and molecular characteristics, and mechanisms of resistance of MDR-P. aeruginosa bloodstream isolates from Qatar.

MATERIALS AND METHODS

We included all MDR-P. aeruginosa isolated from blood cultures taken between October 2014 and September 2017. Blood cultures were processed using BD BACTEC™ FX automated system. BD Phoenix™ was used for identification, Liofilchem® MIC Test Strips for MIC determination. Whole-genome sequencing was performed using the Illumina-HiSeq-2000.

RESULTS

Out of 362 P. aeruginosa bloodstream isolates, 16 (4.4%) were MDR. The median patient age was 55 years (range 43-81) and all patients presented with septic shock. Most patients received meropenem (12/16) and/or colistin (10/16). Clinical response was achieved in eight patients, and five patients died within 30-days. MDR-P. aeruginosa isolates belonged to 13 different sequence types. All isolates were non-susceptible to cefepime and ciprofloxacin. The most active agents were colistin (16/16) and aztreonam (10/16). Seven isolates produced bla_VIM, and four possessed genes encoding extended-spectrum β-lactamases. Aminoglycoside modifying enzymes were present in 15/16, transferable qnr-mediated quinolone resistance gene was detected in 3/16, and the novel ciprofloxacin modifying enzyme CrpP-encoding gene in one isolate.

CONCLUSION

MDR-P. aeruginosa BSIs are relatively uncommon in Qatar but are highly resistant, harbour multiple resistance genes, and are commonly associated with unfavourable clinical outcomes. Colistin was the only agent with consistent activity against the study isolates.Key messagesMDR-P. aeruginosa constituted <5% of P. aeruginosa blood isolates over three years.Typical risk factors for MDR infections were highly prevalent in the study population and overall clinical outcomes are consistent with those previously reported.Colistin was the only agent with consistent antibacterial activity against the study isolates.

Impact of ceftolozane/tazobactam concentrations in continuous infusion against extensively drug-resistant Pseudomonas aeruginosa isolates in a hollow-fiber infection model

Ceftolozane/tazobactam (C/T) has emerged as a potential agent for the treatment of extensively drug-resistant (XDR) Pseudomonas aeruginosa infections. As it is a time-dependent antimicrobial, prolonged infusion may help achieve pharmacokinetic/pharmacodynamic (PK/PD) targets. To compare alternative steady-state concentrations (Css) of C/T in continuous infusion (CI) against three XDR P. aeruginosa ST175 isolates with C/T minimum inhibitory concentration (MIC) values of 2 to 16 mg/L in a hollow-fiber infection model (HFIM). Duplicate 10-day HFIM assays were performed to evaluate Css of C/T in CI: one compared 20 and 45 mg/L against the C/T-susceptible isolate while the other compared 45 and 80 mg/L against the two C/T-non-susceptible isolates. C/T resistance emerged when C/T-susceptible isolate was treated with C/T in CI at a Css of 20 mg/L; which showed a deletion in the gene encoding AmpC β-lactamase. The higher dosing regimen (80 mg/L) showed a slight advantage in effectiveness. The higher dosing regimen has the greatest bactericidal effect, regardless of C/T MIC. Exposure to the suboptimal Css of 20 mg/L led to the emergence of C/T resistance in the susceptible isolate. Antimicrobial regimens should be optimized through C/T levels monitoring and dose adjustments to improve clinical management.

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

Introduction

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

Methods

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

Results

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

Conclusions

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

Supplementary Information

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

New Perspectives on Antimicrobial Agents: Ceftolozane-Tazobactam

Ceftolozane-tazobactam (C/T) is a new fifth-generation cephalosporin/beta-lactamase inhibitor combination approved by the Food and Drug Administration and the European Medicines Agency for treatment of complicated intraabdominal infections, complicated urinary tract infections, and hospital-acquired pneumonia in adult patients. This review will briefly describe the pharmacology of C/T and focus on the emerging clinical trial and real-world data supporting its current utilization. Additionally, our synthesis of these data over time has set our current usage of C/T at Barnes-Jewish Hospital (BJH). C/T is primarily employed as directed monotherapy at BJH when Pseudomonas aeruginosa isolates are identified with resistance to other beta-lactams. C/T can also be used empirically in specific clinical situations at BJH prior to microbiological detection of an antibiotic-resistant P. aeruginosa isolate. These situations include critically ill patients in the intensive care unit (ICU) setting, where there is a high likelihood of infection with multidrug-resistant (MDR) P. aeruginosa; patients failing therapy with a carbapenem; specific patient populations known to be at high risk for infection with MDR P. aeruginosa (e.g., lung transplant and cystic fibrosis patients); and patients know to have previous infection or colonization with MDR P. aeruginosa.

Risk Factors Associated with Carbapenemase Producing Carbapenem-Resistant Enterobacteriaceae (CP-CRE) Positive Cultures in a Cohort of U.S. Veterans

INTRODUCTION

Carbapenem-resistant Enterobacterales (CRE) cause approximately 13,100 infections with 8% mortality in the United States annually. The subset of carbapenemase-producing CRE (CP-CRE) infections have much higher mortality rates (40% -50%). There has been little research on characteristics unique to CP-CRE. The goal of this study was to assess differences between those with nonCP-CRE and CP-CRE cultures in U.S. Veterans.

METHODS

A retrospective cohort of Veterans with CRE cultures from 2013-2018 and their demographic, medical, and facility level covariates were collected. Clustered multiple logistic regression models were used to assess independent factors associated with CP-CRE.

RESULTS

3,096 unique patients with cultures positive for either nonCP-CRE or CP-CRE were included. Being African American (Odds Ratio (OR)=1.44 (95% Confidence Interval (CI) 1.15,1.80), diagnosis in 2017 (OR=3.11 (95% CI 2.13,4.54)) or 2018 (OR=3.93 (95%CI 2.64,5.84)), congestive heart failure (OR=1.35 (95%CI 1.11,1.64)), and gastroesophageal reflux disease (OR=1.39 (95%CI 1.03,1.87)) were associated with CP-CRE cultures. 752 (24.3%) patients had no known antibiotic exposure in the year before culture; these individuals had a comparatively increased frequency of prolonged PPI use (17.3% vs 5.6%).

DISCUSSION

Among a cohort of patients with CRE, African Americans, individuals with congestive heart failure, and patients with gastroesophageal reflux disease had greater odds of having a CP-CRE culture. Roughly one in four patients with CP-CRE had no known antibiotic exposure in the year before their positive culture.

6-Halopyridylmethylidene Penicillin-Based Sulfones Efficiently Inactivate the Natural Resistance of Pseudomonas aeruginosa to β-Lactam Antibiotics

Pseudomonas aeruginosa, a major cause of nosocomial infections, is considered a paradigm of antimicrobial resistance, largely due to hyperproduction of chromosomal cephalosporinase AmpC. Here, we explore the ability of 6-pyridylmethylidene penicillin-based sulfones 1-3 to inactivate the AmpC β-lactamase and thus rescue the activity of the antipseudomonal ceftazidime. These compounds increased the susceptibility to ceftazidime in a collection of clinical isolates and PAO1 mutant strains with different ampC expression levels and also improved the inhibition kinetics relative to avibactam, displaying a slow deacylation rate and involving the formation of an indolizine adduct. Bromide 2 was the inhibitor with the lowest K_I (15.6 nM) and the highest inhibitory efficiency (k_inact/K_I). Computational studies using diverse AmpC enzymes revealed that the aromatic moiety in 1-3 targets a tunnel-like site adjacent to the catalytic serine and induces the folding of the H10 helix, indicating the potential value of this not-always-evident pocket in drug design.

Real-world use of ceftolozane/tazobactam: a systematic literature review

Background

Antibacterial-resistant gram-negative infections are a serious risk to global public health. Resistant Enterobacterales and Pseudomonas aeruginosa are highly prevalent, particularly in healthcare settings, and there are limited effective treatment options. Patients with infections caused by resistant pathogens have considerably worse outcomes, and incur significantly higher costs, relative to patients with susceptible infections. Ceftolozane/tazobactam (C/T) has established efficacy in clinical trials. This review aimed to collate data on C/T use in clinical practice.

Methods

This systematic literature review searched online biomedical databases for real-world studies of C/T for gram-negative infections up to June 2020. Relevant study, patient, and treatment characteristics, microbiology, and efficacy outcomes were captured.

Results

There were 83 studies comprising 3,701 patients were identified. The most common infections were respiratory infections (52.9% of reported infections), urinary tract infections (UTIs; 14.9%), and intra-abdominal infections (IAIs; 10.1%). Most patients included were seriously ill and had multiple comorbidities. The majority of patients had infections caused by P.aeruginosa (90.7%), of which 86.0% were antimicrobial-resistant. C/T was used as both a 1.5 g q8h and 3 g q8h dose, for a median duration of 7–56 days (varying between studies). Outcome rates were comparable between studies: clinical success rates ranged from 45.7 to 100.0%, with 27 studies (69%) reporting clinical success rates of > 70%; microbiological success rates ranged from 31 to 100%, with 14 studies (74%) reporting microbiological success rates of > 70%. Mortality rates ranged from 0 to 50%, with 31 studies (69%) reporting mortality rates of ≤ 20%. In comparative studies, C/T was as effective as aminoglycoside- or polymyxin-based regimens, and in some instances, significantly more effective.

Conclusions

The studies identified in this review demonstrate that C/T is effective in clinical practice, despite the diverse group of seriously ill patients, different levels of resistance of the pathogens treated, and varying dosing regimens used. Furthermore, comparative studies suggest that C/T offers a successful alternative to standard of care (SoC).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-021-00933-8.

A Multicenter Evaluation of Ceftolozane/Tazobactam Treatment Outcomes in Immunocompromised Patients With Multidrug-Resistant Pseudomonas aeruginosa Infections

Background

Real-world data assessing outcomes of immunocompromised patients treated with ceftolozane/tazobactam (C/T) are limited. This study evaluated treatment and clinical outcomes of immunocompromised patients receiving C/T for multidrug-resistant (MDR) Pseudomonas aeruginosa.

Methods

This was a 14-center retrospective cohort study of adult immunocompromised inpatients treated for ≥24 hours with C/T for MDR P. aeruginosa infections. Patients were defined as immunocompromised if they had a history of previous solid organ transplant (SOT), disease that increased susceptibility to infection, or received immunosuppressive therapies. The primary outcomes were all-cause 30-day mortality and clinical cure.

Results

Sixty-nine patients were included; 84% received immunosuppressive agents, 68% had a history of SOT, and 29% had diseases increasing susceptibility to infection. The mean patient age was 57 ± 14 years, and the median (interquartile range) patient Acute Physiology and Chronic Health Evaluation II and Charlson Comorbidity Index scores were 18 (13) and 5 (4), respectively, with 46% receiving intensive care unit care at C/T initiation. The most frequent infection sources were respiratory (56%) and wound (11%). All-cause 30-day mortality was 19% (n = 13), with clinical cure achieved in 47 (68%) patients. Clinical cure was numerically higher (75% vs 30%) in pneumonia patients who received 3-g pneumonia regimens vs 1.5-g regimens.

Conclusions

Of 69 immunocompromised patients treated with C/T for MDR P. aeruginosa, clinical cure was achieved in 68% and mortality was 19%, consistent with other reports on a cross-section of patient populations. C/T represents a promising agent for treatment of P. aeruginosa resistant to traditional antipseudomonal agents in this high-risk population.

Meta-analysis of Clinical Outcomes Using Ceftazidime/Avibactam, Ceftolozane/Tazobactam, and Meropenem/Vaborbactam for the Treatment of Multidrug-Resistant Gram-Negative Infections

Ceftolozane-tazobactam (C/T), ceftazidime-avibactam (C/A), and meropenem/vaborbactam (M/V) are new beta-lactam/beta-lactamase combination antibiotics commonly used to treat multidrug-resistant Pseudomonas aeruginosa (MDRPA) and carbapenem-resistant Enterobacteriaceae (CRE) infections. This review reports the clinical success rates for C/T, C/A, and M/V. PubMed and EMBASE were searched from January 1, 2012, through September 2, 2020, for publications detailing the use of C/T, C/A, and M/V. A meta-analysis determined the pooled effectiveness of C/T, C/A, and M/V. The literature search returned 1950 publications; 29 publications representing 1620 patients were retained. Pneumonia was the predominant infection type (49.8%). MDRPA was the major pathogen treated (65.3%). The pooled clinical success rate was 73.3% (95% CI, 68.9%-77.5%). C/T, C/A, or M/V resistance was reported in 8.9% of the population. These antibiotics had a high clinical success rate in patients with complicated infections and limited treatment options. Larger studies comparing C/T, C/A, and M/V against other antibiotic regimens are needed.

Mechanisms of Resistance to Ceftolozane/Tazobactam in Pseudomonas aeruginosa: Results of the GERPA Multicenter Study

Resistance mechanisms of Pseudomonas aeruginosa to ceftolozane/tazobactam (C/T) were assessed on a collection of 420 nonredundant strains nonsusceptible to ceftazidime (MIC > 8 μg/ml) and/or imipenem (>4 μg/ml), collected by 36 French hospital laboratories over a one-month period (the GERPA study). Rates of C/T resistance (MIC > 4/4 μg/ml) were equal to 10% in this population (42/420 strains), and 23.2% (26/112) among the isolates resistant to both ceftazidime and imipenem. A first group of 21 strains (50%) was found to harbor various extended-spectrum β-lactamases (1 OXA-14; 2 OXA-19; 1 OXA-35; 1 GES-9; and 3 PER-1), carbapenemases (2 GES-5; 1 IMP-8; and 8 VIM-2), or both (1 VIM-2/OXA-35 and 1 VIM-4/SHV-2a). All the strains of this group belonged to widely distributed epidemic clones (ST111, ST175, CC235, ST244, ST348, and ST654), and were highly resistant to almost all the antibiotics tested except colistin. A second group was composed of 16 (38%) isolates moderately resistant to C/T (MICs from 8/4 to 16/4 μg/ml), of which 7 were related to international clones (ST111, ST253, CC274, ST352, and ST386). As demonstrated by targeted mass spectrometry, cloxacillin-based inhibition tests, and gene bla _PDC deletion experiments, this resistance phenotype was correlated with an extremely high production of cephalosporinase PDC. In part accounting for this strong PDC upregulation, genomic analyses revealed the presence of mutations in the regulator AmpR (D135N/G in 6 strains) and enzymes of the peptidoglycan recycling pathway, such as AmpD, PBP4, and Mpl (9 strains). Finally, all of the 5 (12%) remaining C/T-resistant strains (group 3) appeared to encode PDC variants with mutations known to improve the hydrolytic activity of the β-lactamase toward ceftazidime and C/T (F147L, ΔL223-Y226, E247K, and N373I). Collectively, our results highlight the importance of both intrinsic and transferable mechanisms in C/T-resistant P. aeruginosa Which mutational events lead some clinical strains to massively produce the natural cephalosporinase PDC remains incompletely understood.

Multicenter study of ceftolozane/tazobactam for treatment of Pseudomonas aeruginosa infections in critically ill patients

BACKGROUND

This study aimed to assess the efficacy of ceftolozane-tazobactam (C/T) for treating infections due to Pseudomonas aeruginosa (P. aeruginosa) in critically ill patients.

PATIENTS AND METHODS

A multicenter, retrospective and observational study was conducted in critically ill patients receiving different C/T dosages and antibiotic combinations for P. aeruginosa infections. Demographic data, localisation and severity of infection, clinical and microbiological outcome, and mortality were evaluated.

RESULTS

Ninety-five patients received C/T for P. aeruginosa serious infections. The main infections were nosocomial pneumonia (56.2%), intra-abdominal infection (10.5%), tracheobronchitis (8.4%), and urinary tract infection (6.3%). Most infections were complicated with sepsis (49.5%) or septic shock (45.3%), and bacteraemia (10.5%). Forty-six episodes were treated with high-dose C/T (3 g every 8 hours) and 38 episodes were treated with standard dosage (1.5 g every 8 hours). Almost half (44.2%) of the patients were treated with C/T monotherapy, and the remaining group received combination therapy with other antibiotics. Sixty-eight (71.6%) patients presented a favourable clinical response. Microbiological eradication was documented in 42.1% (40/95) of the episodes. The global ICU mortality was 36.5%. Univariate analysis showed that 30-day mortality was significantly associated (P < 0.05) with Charlson Index at ICU admission and the need of life-supporting therapies.

CONCLUSIONS

C/T appeared to be an effective therapy for severe infections due to P. aeruginosa in critically ill patients. Mortality was mainly related to the severity of the infection. No benefit was observed with high-dose C/T or combination therapy with other antibiotics.

Ceftolozane-Tazobactam Combination Therapy Compared to Ceftolozane-Tazobactam Monotherapy for the Treatment of Severe Infections: A Systematic Review and Meta-Analysis

Ceftolozane-tazobactam (C/T) is a combination of an advanced-generation cephalosporin (ceftolozane) with a β-lactamase inhibitor (tazobactam). It is approved for the treatment of complicated urinary-tract/intra-abdominal infections and hospital-acquired/ventilator-associated pneumonia. This systematic review and meta-analysis (registered prospectively on PROSPERO, no. CRD42019134099, on 20 January 2020) aimed to evaluate the effectiveness of C/T combination therapy compared to C/T monotherapy for the treatment of severe infections and to describe the prevalence of microorganisms in the included studies. We retrieved literature from PubMed, EMBASE, and CENTRAL, until 26 November 2020. Eligible studies were both randomised trials and nonrandomised studies with a control group, published in the English language and peer-reviewed journals. The primary outcome was all-cause mortality; secondary outcomes were (i) clinical improvement and (ii) microbiological cure. Eight nonrandomised studies were included in the qualitative synthesis: Seven retrospective cohort studies and one case-control study. The meta-analysis of the four studies evaluating all-cause mortality (in total 148 patients: 87 patients treated with C/T alone and 61 patients treated with C/T combination therapy) showed a significant reduction of mortality in patients receiving C/T combination therapy, OR: 0.31, 95% CI: 0.10–0.97, p = 0.045. Conversely, the meta-analysis of the studies evaluating clinical improvement and microbiological cure showed no differences in C/T combination therapy compared to C/T monotherapy. The most consistent data come from the analysis of the clinical improvement, n = 391 patients, OR: 0.97, 95% CI: 0.54–1.74, p = 0.909. In 238 of the 391 patients included (60.8%), C/T was used for the treatment of infections caused by Pseudomonas aeruginosa.

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).

Resistance to Novel β-Lactam-β-Lactamase Inhibitor Combinations: The "Price of Progress"

Significant advances were made in antibiotic development during the past 5 years. Novel agents were added to the arsenal that target critical priority pathogens, including multidrug-resistant Pseudomonas aeruginosa and carbapenem-resistant Enterobacterales. Of these, 4 novel β-lactam-β-lactamase inhibitor combinations (ceftolozane-tazobactam, ceftazidime-avibactam, meropenem-vaborbactam, and imipenem-cilastatin-relebactam) reached clinical approval in the United States. With these additions comes a significant responsibility to reduce the possibility of emergence of resistance. Reports in the rise of resistance toward ceftolozane-tazobactam and ceftazidime-avibactam are alarming. Clinicians and scientists must make every attempt to reverse or halt these setbacks.

Multicentre study of the in vitro activity of ceftolozane/tazobactam and other commonly used antibiotics against Pseudomonas aeruginosa isolates from patients in the UK

Objectives

To evaluate the in vitro activity of ceftolozane/tazobactam and other commonly used antipseudomonal antibiotics against geographically spread Pseudomonas aeruginosa isolates in the UK using disc susceptibility testing.

Methods

The in vitro activity of ceftolozane/tazobactam and nine other commonly used antipseudomonal antibiotics was evaluated. Isolates were collected between January 2015 and April 2018. Susceptibility results were interpreted using EUCAST 2018 criteria.

Results

Overall, 1326 clinical isolates from 14 centres in the UK were tested. The majority of the isolates were collected from non-cystic fibrosis (non-CF) patients (n = 1123, 85.0%). In addition, 199 cystic fibrosis (CF) isolates were collected from 10 centres. Overall susceptibility to ceftolozane/tazobactam was 89.3% (n = 1181), which included 128 CF and 1053 non-CF isolates. The other antibacterial agents with the highest susceptibility were tobramycin (92.4%, n = 1221) and piperacillin/tazobactam (90.7%, n = 1199). Susceptibility to all antibacterial agents was lower for CF isolates. Piperacillin/tazobactam was the most active of the antibacterial agents tested, followed by ceftolozane/tazobactam (70.4% and 64.3%, respectively), and <60% of CF isolates were susceptible to ceftazidime and the carbapenems. The reason for the higher rates of susceptibility to piperacillin/tazobactam and lower susceptibility to ceftazidime compared with other studies is unclear.

Conclusions

The data presented here support the need to investigate the place of ceftolozane/tazobactam as a treatment option in the management of pseudomonal infections, particularly in patients with CF. The results highlight the importance of routine testing of new antibacterial agents and of making the data available to clinicians to make appropriate and informed treatment choices.

Dissemination of carbapenem-resistant Pseudomonas aeruginosa isolates and their susceptibilities to ceftolozane-tazobactam in Germany

Pseudomonas aeruginosa (PA) is a major cause of healthcare-associated infections. Antipseudomonal carbapenems are among the antimicrobial agents used to treat PA infections, but several mechanisms of resistance, including the production of a carbapenemase (CP), may compromise their clinical efficacy. The objectives of this study were to determine: (i) the dissemination of carbapenem-resistant CP-negative and CP-positive PA isolates; and (ii) the in-vitro activity of ceftolozane-tazobactam (CTT) against carbapenem-susceptible and carbapenem-resistant isolates. Isolates were collected prospectively from January 2016 to April 2017 at 20 German medical laboratories. Each centre was asked to provide 50 consecutive isolates from hospitalized patients. Overall, 985 isolates were collected, of which 34% were obtained from intensive care patients. Seven hundred and thirty-eight (74.9%) isolates were susceptible to both imipenem and meropenem (Subgroup I), and 247 (25.1%) isolates were resistant to carbapenems (Subgroup II): 125 (12.7%) were imipenem-resistant but meropenem-susceptible, 12 (1.2%) were meropenem-resistant but imipenem-susceptible, and 110 (11.2%) were resistant to both carbapenems (Subgroup III). A CP was detected in 28 (2.8%) isolates (predominantly VIM-2). Nine hundred and fifty (96.4%) isolates were CTT-susceptible. Susceptibility to CTT was seen in 99.6% of Subgroup I isolates, 87% of Subgroup II isolates and 74.5% of Subgroup III isolates. Overall, 2.8% of PA produced a CP, while 22.2% were carbapenem-resistant, CP-non-producing isolates. Based on these findings, CTT may be considered for treatment of PA infections, particularly those caused by multi-drug-resistant CP-non-producing isolates.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Activity of Imipenem-Relebactam against a Large Collection of Pseudomonas aeruginosa Clinical Isolates and Isogenic β-Lactam-Resistant Mutants

Imipenem and imipenem-relebactam MICs were determined for 1,445 Pseudomonas aeruginosa clinical isolates and a large panel of isogenic mutants showing the most relevant mutation-driven β-lactam resistance mechanisms. Imipenem-relebactam showed the highest susceptibility rate (97.3%), followed by colistin and ceftolozane-tazobactam (both 94.6%). Imipenem-relebactam MICs remained ≤2 μg/ml in all 16 isogenic PAO1 mutants and in 8 pairs of extensively drug-resistant clinical strains that had developed resistance to ceftolozane-tazobactam and ceftazidime-avibactam due to mutations in OXA-10 or AmpC.

Ceftolozane/tazobactam for difficult-to-treat Pseudomonas aeruginosa infections: A systematic review of its efficacy and safety for off-label indications

Ceftolozane/tazobactam (C/T) is a novel β-lactam/β-lactamase inhibitor combination targeting Enterobacteriaceae and Pseudomonas aeruginosa (PA). It is approved in adult patients for complicated urinary tract infections (cUTIs) and complicated intra-abdominal infections (cIAIs) as well as for nosocomial pneumonia. It displays excellent activity against PA, even multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains. The aim of this systematic review (PROSPERO protocol no. CRD42019117350) was to summarise the available evidence from observational studies regarding the efficacy and safety of off-label use of C/T when administered to treat MDR- or XDR-PA infections. The MEDLINE and Embase databases were screened from inception up to 30 June 2019. Studies were deemed eligible if they described real-life use of C/T in the case of MDR- or XDR-PA infections for non-approved indications. Exclusion criteria were cIAIs, cUTIs, pneumonia (unless occurring in a paediatric population) and infections by non-MDR/XDR-PA. Thirty articles fulfilled the inclusion criteria. In total, 130 cases of MDR- or XDR-PA infections treated with C/T in 128 patients were described. The most relevant off-label uses were skin and soft-tissue infection (49/30; 37.7%), bone and joint infection (42/130; 32.3%) and bloodstream infection (23/130; 17.7%). Five cases involved paediatric patients. The overall clinical success rate was 76.2%. The most common adverse event was hypokalaemia (4.2%, in 48 evaluable cases). C/T may be a useful therapeutic option for difficult-to-treat infections by PA even outside the framework of approved indications. Further studies are necessary to better define new indications for the drug.

Higher MICs (>2 mg/L) Predict 30-Day Mortality in Patients With Lower Respiratory Tract Infections Caused by Multidrug- and Extensively Drug-Resistant Pseudomonas aeruginosa Treated With Ceftolozane/Tazobactam

Background

Ceftolozane/tazobactam (C/T) efficacy and safety in ventilator-associated pneumonia (VAP) is being evaluated at a double dose by several trials. This dosing is based on a pharmacokinetic (PK) model that demonstrated that 3 g q8h achieved ≥90% probability of target attainment (50% ƒT > minimal inhibitory concentration [MIC]) in plasma and epithelial lining fluid against C/T-susceptible P. aeruginosa. The aim of this study was to evaluate the efficacy of different C/T doses in patients with lower respiratory infection (LRI) due to MDR- or XDR-P. aeruginosa considering the C/T MIC.

Methods

This was a multicenter retrospective study of 90 patients with LRI caused by resistant P. aeruginosa who received a standard or high dose (HDo) of C/T. Univariable and multivariable analyses were performed to identify independent predictors of 30-day mortality.

Results

The median age (interquartile range) was 65 (51-74) years. Sixty-three (70%) patients had pneumonia, and 27 (30%) had tracheobronchitis. Thirty-three (36.7%) were ventilator-associated respiratory infections. The median C/T MIC (range) was 2 (0.5-4) mg/L. Fifty-four (60%) patients received HDo. Thirty-day mortality was 27.8% (25/90). Mortality was significantly lower in patients with P. aeruginosa strains with MIC ≤2 mg/L and receiving HDo compared with the groups with the same or higher MIC and dosage (16.2% vs 35.8%; P = .041). Multivariate analysis identified septic shock (P < .001), C/T MIC >2 mg/L (P = .045), and increasing Charlson Comorbidity Index (P = .019) as independent predictors of mortality.

Conclusions

The effectiveness of C/T in P. aeruginosa LRI was associated with an MIC ≤2 mg/L, and the lowest mortality was observed when HDo was administered for strains with C/T MIC ≤2 mg/L. HDo was not statistically associated with a better outcome.

Epidemiology and Treatment of Multidrug-Resistant and Extensively Drug-Resistant Pseudomonas aeruginosa Infections

In recent years, the worldwide spread of the so-called high-risk clones of multidrug-resistant or extensively drug-resistant (MDR/XDR) Pseudomonas aeruginosa has become a public health threat. This article reviews their mechanisms of resistance, epidemiology, and clinical impact and current and upcoming therapeutic options. In vitro and in vivo treatment studies and pharmacokinetic and pharmacodynamic (PK/PD) models are discussed. Polymyxins are reviewed as an important therapeutic option, outlining dosage, pharmacokinetics and pharmacodynamics, and their clinical efficacy against MDR/XDR P. aeruginosa infections. Their narrow therapeutic window and potential for combination therapy are also discussed. Other "old" antimicrobials, such as certain β-lactams, aminoglycosides, and fosfomycin, are reviewed here. New antipseudomonals, as well as those in the pipeline, are also reviewed. Ceftolozane-tazobactam has clinical activity against a significant percentage of MDR/XDR P. aeruginosa strains, and its microbiological and clinical data, as well as recommendations for improving its use against these bacteria, are described, as are those for ceftazidime-avibactam, which has better activity against MDR/XDR P. aeruginosa, especially strains with certain specific mechanisms of resistance. A section is devoted to reviewing upcoming active drugs such as imipenem-relebactam, cefepime-zidebactam, cefiderocol, and murepavadin. Finally, other therapeutic strategies, such as use of vaccines, antibodies, bacteriocins, anti-quorum sensing, and bacteriophages, are described as future options.

Ceftolozane/tazobactam for the treatment of complicated intra-abdominal and urinary tract infections: current perspectives and place in therapy

The current prevalence of infections caused by multidrug-resistant (MDR) organisms is a global threat, and thus, the development of new antimicrobial agents with activity against these pathogens is a healthcare priority. Ceftolozane-tazobactam (C/T) is a new combination of a cephalosporin with a β-lactamase inhibitor that shows excellent in vitro activity against a broad spectrum of Enterobacteriaceae and Pseudomonas aeruginosa, including extended spectrum β-lactamase-producing (ESBL) strains and MDR or extensively drug-resistant (XDR) P. aeruginosa. In phase III randomized clinical trials, C/T demonstrated similar efficacy to meropenem for the treatment of complicated intra-abdominal infections (cIAIs) and superior efficacy to levofloxacin for the treatment of complicated urinary tract infections (cUTIs), including pyelonephritis. The drug is generally safe and well tolerated and its PK/PD profile is very favorable. Observational studies with C/T have revealed good efficacy for the treatment of different types of infection caused by MDR or XDR P. aeruginosa, including some that originated from the digestive or urinary tracts. The place of C/T in therapy is not well defined, but its use could be recommended in a carbapenem-sparing approach for the treatment of infections caused by ESBL-producing strains or for the treatment of infections caused by P. aeruginosa if there are no other more favorable therapeutic options. Further clinical experience is needed to position this new antimicrobial drug for the empirical treatment of cIAIs or cUTIs.

Shifting Gears: The Future of Polymyxin Antibiotics

The manuscripts contained in this special edition of Antibiotics represent a current review of the polymyxins as well as highlights from the 3rd International Polymyxin Conference, which was held in Madrid, Spain, April 25 to 26, 2018. The role of the polymyxin antibiotics has evolved over time based on the availability of alternative agents. After high rates of nephrotoxicity caused the drug class to fall out of favor, polymyxins were once against utilized in the 21st century to combat drug-resistant pathogens. However, the introduction of safer agents with activity against drug-resistant organisms has brought the future utility of polymyxins into question. The present review investigates the future niche of polymyxins by evaluating currently available and future treatment options for difficult-to-treat pathogens. The introduction of ceftazidime-avibactam, meropenem-vaborbactam and plazomicin are likely to decrease polymyxin utilization for infections caused by Enterobacteriaceae. Similarly, the availability of ceftolozane-tazobactam will reduce the use of polymyxins to counter multidrug-resistant Pseudomonas aeruginosa. In contrast, polymyxins will likely continue be an important option for combatting carbapenem-resistant Acinetobacter baumannii until better options become commercially available. Measuring polymyxin concentrations in patients and individualizing therapy may be a future strategy to optimize clinical outcomes while minimizing nephrotoxicity. Inhaled polymyxins will continue to be an adjunctive option for pulmonary infections but further clinical trials are needed to clarify the efficacy of inhaled polymyxins. Lastly, safer polymyxin analogs will potentially be an important addition to the antimicrobial armamentarium.

A Case-Control Study of Real-Life Experience with Ceftolozane-Tazobactam in Patients with Hematologic Malignancy and Pseudomonas aeruginosa Infection

We present our experience in patients with hematologic malignancy and Pseudomonas aeruginosa infection treated with ceftolozane-tazobactam. We performed a single-center case-control study comparing patients with hematologic malignancy and P. aeruginosa infection treated with ceftolozane-tazobactam (study group) with similar patients not treated with ceftolozane-tazobactam (control group) to assess safety and efficacy. Nineteen cases and 38 controls were analyzed. Cases were younger (45.6 years versus 57.6 years; P = 0.012) and less frequently had bacteremia (52.6% versus 86.8%; P = 0.008). They also had worse Multinational Association for Supportive Care in Cancer (MASCC) scores (10.2 versus 16.1; P = 0.0001), more hospital-acquired infections (78.9% versus 47.4%; P = 0.013), and more extremely drug-resistant (XDR) P. aeruginosa infections (47.4% versus 21.1%; P = 0.015). Cases received a median of 14 days (7 to 18 days) of ceftolozane-tazobactam (monotherapy in 11 cases [57.9.6%]). Ceftolozane-tazobactam was mostly used as targeted therapy (16 cases; 84.2%) because of resistance (9 cases; 47.4%), failure (4 cases; 21.1%), and toxicity (3 cases; 15.8%). Ten cases had bacteremia (52.6%). The sources were pneumonia (26.3%), catheter-related bacteremia (21.1%), primary bacteremia (21.1%), and perianal/genital (15.7%), urinary (10.5%), and skin/soft tissue (5.3%) infection. No toxicity was attributed to ceftolozane-tazobactam. More than 60% had neutropenia, and 15.8% fulfilled the criteria for sepsis. There were no significant differences in clinical cure at day 14 (89.5% versus 71.1%; P = 0.183) or recurrence (15.8% versus 10.5%; P = 0.675). Thirty-day mortality was lower among cases (5.3% versus 28.9%; P = 0.045). Ceftolozane-tazobactam was well tolerated and at least as effective as other alternatives for P. aeruginosa infection in patients with hematologic malignancy, including neutropenic patients with sepsis caused by XDR strains.

Pseudomonas aeruginosa bacteremia among liver transplant recipients

Pseudomonas aeruginosa bacteremia remains as a life-threatening complication after liver transplantation (LT) and is intractable because of the high rate of drug resistance to commonly used antibiotics. To better understand the characteristics of this postoperative complication, PubMed and Embase searches as well as reference mining was done for relevant literature from the start of the databases through August 2018. Among LT recipients, the incidence of P. aeruginosa bacteremia ranged from 0.5% to 14.4% and mortality rates were up to 40%. Approximately 35% of all episodes of bloodstream infections (BSIs) were P. aeruginosa bacteremia, of which 47% were multidrug resistant and 63% were extensively drug resistant. Several factors are known to affect the mortality of LT recipients with P. aeruginosa bacteremia, including hypotension, mechanical ventilation, and increasing severity of illness. In LT recipients with P. aeruginosa bacteremia, alteration in DNA gyrase A genes and overexpression of proteins involved in efflux systems, namely the expression of KPC-2-type carbapenemase, NDM-1, and VIM-2-type MBL, contribute to the high resistance of P. aeruginosa to a wide variety of antibiotics. Because of complicated mechanisms of drug resistance, P. aeruginosa causes high morbidity and mortality in bacteremic LT patients. Consequently, early detection and treatment with adequate early targeted coverage for P. aeruginosa BSI are of paramount importance in the early posttransplantation period to obtain a better prognosis for LT patients.