Zerbaxa (ceftolozane /tazobactam) / Merck (MSD) - LARVOL DELTA

Current Management Strategies of Difficult-to-Treat Resistant Pseudomonas aeruginosa Infections. (PubMed, Infect Dis Clin North Am) - "Although new active therapeutic options such as ceftolozane-tazobactam, ceftazidime-avibactam, imipenem-relebactam and cefiderocol are currently available, lack of randomized control trials, drug access limitations, and emerging resistance have a negative impact on the management of these infections. This review discusses the mechanisms of resistance, molecular epidemiology, clinical management, and current and future therapeutic strategies for DTR P aeruginosa infections."

Journal • Review • Infectious Disease

Deciphering the emergence of mutations in Pseudomonas aeruginosa after ceftolozane/tazobactam treatment and evaluating therapeutic alternatives. (PubMed, BMC Microbiol) - "Ceftolozane/tazobactam resistance development was associated mainly with chromosomal mutations in the ampC gene but also with mutations in its regulatory genes. Knowledge about these mutations and gene polymorphisms is essential for interpreting resistance phenotypes from genomic data."

Journal

One-year surveillance of last-resort antimicrobial resistance patterns in carbapenemase-producing Klebsiella pneumoniae strains isolated in a Romanian tertiary care hospital: a prospective study. (PubMed, Germs) - "Strains presenting a minimum inhibitory concentration to meropenem of >0.125 μg/mL underwent phenotypic enzyme production testing, followed by synergistic testing to identify antimicrobial salvage therapy options...Forty-six strains were resistant to cefiderocol (35.7%), 108 (83.7%) to ceftazidime/avibactam, 127 (98.4%) to ceftolozane/tazobactam, 116 (90.0%) to imipenem/relebactam and 127 (98.4%) to aztreonam. The association of aztreonam with ceftazidime/avibactam demonstrated a synergistic effect in 127 (98.5%) strains, while aztreonam with imipenem/relebactam was efficient in vitro against 103 (79.8%) strains. Antimicrobial resistance remains a concerning phenomenon among Enterobacterales, especially when considering the increasing resistance rates even against salvage therapy antimicrobials."

Journal • Infectious Disease • Pneumonia

Clinical performance of the VITEK REVEAL fast antimicrobial susceptibility test within a real-world workflow for gram-negative bacteremia: comparison with QMAC-dRAST and conventional methods. (PubMed, Microbiol Spectr) - "For ceftazidime/avibactam and ceftolozane/tazobactam, REVEAL showed 100% and 98.6% CA, respectively, compared to ETEST. The volatile organic compounds-based system demonstrated high concordance, shorter time-to-results, and reliable performance for newer antimicrobial agents. By directly comparing its performance with established clinical diagnostic tools, this study provides relevant support for the potential integration of this approach into real-world laboratory workflows, with implications for improved patient management and antimicrobial stewardship."

Journal • Real-world evidence • Infectious Disease

Antimicrobial Activity of Aztreonam-Avibactam and Other β-Lactamase Inhibitor Combinations Tested Against Enterobacterales Isolates from Pediatric Patients from United States Medical Centers (2019-2023). (PubMed, Antibiotics (Basel)) - "Susceptibility to imipenem-relebactam varied from 97.1% (ceftriaxone-nonsusceptible) to 100.0% (ESBL producers). Ceftolozane-tazobactam showed good activity against ESBL producers (91.8% susceptible), but limited activity against ceftriaxone-nonsusceptible (75.8% susceptible) and MDR isolates (80.9% susceptible)...ESBL-producing Enterobacterales, mainly CTX-M, remain an important cause of infection in children. Aztreonam-avibactam, ceftazidime-avibactam, and meropenem-vaborbactam were highly active against isolates from both pediatric and adult population."

Journal • Infectious Disease • Nephrology • Pediatrics • Pneumonia • Respiratory Diseases

β-Lactam/β-Lactamase Inhibitor Combinations in Sepsis-Associated Acute Kidney Injury and Renal Replacement Therapy. (PubMed, Antibiotics (Basel)) - "This review summarizes PK/PD features, extracorporeal clearance, and practical dosing considerations about ceftolozane-tazobactam, ceftazidime-avibactam, aztreonam-avibactam, cefiderocol, meropenem-vaborbactam, imipenem-relebactam, and newer agents including sulbactam-durlobactam, cefepime-enmetazobactam, and cefepime-taniborbactam. Full-dose initiation during the first 24-48 h, followed by careful adjustment, appears prudent. Therapeutic drug monitoring should be used when available, and institution-specific protocols should be integrated into stewardship programs to improve efficacy and minimize resistance."

Journal • Review • Acute Kidney Injury • Infectious Disease • Nephrology • Pediatrics • Renal Disease • Septic Shock

How to use novel antimicrobials beyond official indications: an expert consensus. (PubMed, JAC Antimicrob Resist) - "The process comprised three survey rounds evaluating off-label uses of eight drugs: ceftazidime-avibactam, ceftolozane-tazobactam, cefiderocol, ceftaroline, ceftobiprole, dalbavancin, tedizolid, and isavuconazole. The guidance prioritizes targeted treatment over empirical use, aligning with international ASP principles and WHO recommendations. These results provide a regional reference to optimize ASP initiatives focus on new antibiotic use while minimizing ecological impact and resistance development."

Journal • Cardiovascular • Critical care • Infectious Disease

New Drugs, Old Problems: A Narrative Review of Antibiotic Stewardship Program in the era of novel Gram-negative antibiotics. (PubMed, Clin Microbiol Infect) - "Effective stewardship of new Gram-negative antibiotics requires combining enablement, personalized pharmacology, and selective restriction within multidisciplinary ASPs. Strengthening real-world evidence, digital infrastructure, and standardized outcome measures is essential to guide equitable and sustainable implementation."

Journal • Review • Infectious Disease

Evaluation of phenotypic and genotypic susceptibility testing methods for newer β-lactam/β-lactamase inhibitor combinations in multidrug resistant Pseudomonas aeruginosa. (PubMed, J Infect Dis) - "The Sensititre panel met standard acceptance criteria while the Phoenix panel had low CA for all tested BL/BLIs compared to BMD. Acquired β-lactamases were a rare cause of BL/BLI resistance. Further understanding of resistance mechanisms is required before phenotypic BL/BLI resistance can be reliably predicted from genotype, especially in settings where prevalence of acquired β-lactamases is low."

Journal

Effectiveness of imipenem-relebactam for multidrug-resistant Pseudomonas aeruginosa in pneumonia and bloodstream infections in the United States (MIRAGE). (PubMed, Antimicrob Agents Chemother) - "Forty percent of index isolates that were tested displayed non-susceptibility to both ceftolozane-tazobactam and ceftazidime-avibactam. Clinical outcomes following imipenem-relebactam for treatment of MDR P. aeruginosa were comparable to those reported in real-world studies for other novel β-lactam agents. Our data suggests that imipenem-relebactam has a role in the treatment of patients infected with MDR P. aeruginosa."

Journal • Critical care • Infectious Disease • Pneumonia • Respiratory Diseases

First nationwide survey on Pseudomonas aeruginosa in Bolivia: susceptibility profiles, resistome, and genomic epidemiology. (PubMed, Antimicrob Agents Chemother) - "The most active antipseudomonal agents were colistin (98.2% intermediate, MIC50/90=1/2 mg/L) and cefiderocol (92.7% susceptible, MIC50/90=0.25/4 mg/L) according to the Clinical and Laboratory Standards Institute (CLSI). High resistance rates to ceftazidime/avibactam (79.3%), ceftolozane/tazobactam (82.9%), and imipenem/relebactam (71.2%) were documented...The high resistance rates for novel beta-lactams linked to an alarming spread of high-risk clones ST277 and ST235 and the very high prevalence of MBLs and ESBLs raise significant concern. This underscores the urgent need for establishing epidemiological surveillance and infection control strategies."

Journal • Infectious Disease • PER1

Revitalizing cephalosporins: The promise of β-lactamase inhibitor combinations. (PubMed, GMS Hyg Infect Control) - "It examines β-lactam resistance mechanisms, established combinations (e.g., ticarcillin/clavulanic acid, piperacillin/tazobactam), and the clinical efficacy of newer therapies like ceftazidime/avibactam (CAZ-AVI) for carbapenem-resistant Klebsiella pneumoniae (CRKP) and ceftolozane/tazobactam (TOL-TAZ) for MDR Pseudomonas aeruginosa. Additionally, novel combinations (e.g., cefepime-enmetazobactam, cefepime-taniborbactam) are discussed for tackling extensively drug-resistant (XDR) bacteria. Through comparative analyses, this review provides key insights into efficacy, resistance, pharmacokinetics, and safety, guiding researchers in optimizing antimicrobial strategies and clinicians in managing MDR infections, while supporting antibiotic management and future research."

Journal • Infectious Disease • Pneumonia

Pharmacokinetics of Ceftolozane/Tazobactam in Patients With Partial- and Full-Thickness Skin Burns. (PubMed, Pharmacotherapy) - "We did not find sufficient deviations in the concentrations of ceftolozane/tazobactam to recommend an empiric dose adjustment for patients with burns. However, this finding is limited by our small sample size and lack of clinical outcome data. Therefore, we also provide a conditional recommendation to conduct therapeutic drug monitoring to adjust ceftolozane/tazobactam dosing or to switch to a continuous infusion approach in cases of a suboptimal clinical response."

Journal • PK/PD data • Thermal Injury

Suspected Tazobactam Allergy in A Case of Anaphylaxis in Multiple Drug Allergy (ACAAI 2025) - "The patient's listed allergies included: penicillin, piperacillin-tazobactam, and multiple cephalosporin. Penicillin resulted in anaphylaxis 9 years prior, as well as anaphylaxis to ceftriaxone and cefepime. Penicillin skin testing was negative and he passed 2-step amoxicillin challenge. He subsequently tolerated Ampicillin-sulbactam. Based off susceptibilities, the primary team requested to change therapy to ceftolozane-tazobactam...He was treated for anaphylaxis with intramuscular epinephrine. Tryptase during event was 13.4μg/L. Discussion This case highlights the importance of history in drug allergy evaluation, as well as consideration of tazobactam as a separate allergenic agent."

Clinical • Allergy • Asthma • Immunology • Inflammation • Pruritus • Respiratory Diseases

Continuous infusion OPAT via elastomeric pumps: effectiveness, safety, and cost-saving potential in a real-world Italian cohort. (PubMed, Infection) - "Elastomeric pump-based OPAT is a clinically effective, well-tolerated, and economically advantageous option for selected infections. Its integration into stewardship programs supports broader implementation within modern, sustainable infectious disease care models."

HEOR • Journal • Real-world evidence • Infectious Disease • Nephrology

Multidrug-resistant Pseudomonas aeruginosa: Pathogenesis, resistance mechanisms, and novel therapeutic strategies. (PubMed, Virulence) - "Innovative therapeutic approaches, including ceftolozane-tazobactam and small molecules with enhanced membrane permeability, are under investigation to circumvent resistance...Future strategies must integrate Immunotherapeutics with antivirulence compounds targeting quorum sensing, iron acquisition, and biofilm disruption. A multidisciplinary approach involving translational research and clinical validation is imperative to combat multidrug-resistant P. aeruginosa and improve patient outcomes."

IO biomarker • Journal • Review • Gene Therapies • Infectious Disease

An update on antimicrobial selection and duration for intra-abdominal infections. (PubMed, Expert Rev Anti Infect Ther) - "Novel antibiotics such as ceftolozane-tazobactam, ceftazidime-avibactam, imipenem-relebactam, eravacycline, and cefiderocol have broadened treatment options for MDR pathogens. Shorter antibiotic courses, guided by source control and biomarkers, have shown to be as effective as traditional longer regimens. Future research should focus on understanding of global resistance patterns, expanding real-world evidence for novel antibiotics, refining biomarker-guided strategies, enhancing rapid diagnostics, and applying artificial intelligence for more personalized and precise management of IAIs."

Journal • Review • Infectious Disease

Keeping the horse with the cart: are we underdosing tazobactam even when using continuous-infusion ceftolozane/tazobactam for effectively preventing resistance development by ESBL-producing Enterobacterales? (PubMed, Antimicrob Agents Chemother) - "Current ceftolozane/tazobactam dosing, even with CI, is often subtherapeutic for tazobactam. These findings challenge fixed-ratio formulations and support individualized, component-guided dosing to preserve efficacy and suppress resistance."

Journal • Infectious Disease • Pneumonia • Respiratory Diseases

SEVERE ACUTE NECROTIZING COLITIS DUE TO ENTAMOEBA HISTOLYTICA IN A PATIENT WITH NEWLY DIAGNOSED ACUTE PROMYELOCYTIC LEUKEMIA: THE IMPORTANCE OF A PROMPT DIAGNOSIS (SIE 2025) - "Initial therapy with ATRA and idarubicin led to differentiation syndrome, with ATRA discontinuation...Under broad-spectrum antibiotics (piperacillin/tazobactam, amikacin, daptomycin), symptoms worsened, with ESBL K. pneumoniae isolation...Molecular analysis confirmed E. histolytica infection, requiring metronidazole, paromomycin, and ceftolozane/tazobactam therapy...This case highlights the importance of considering also parasitic infestations in immunocompromised hematological patients with gastrointestinal symptoms. Rapid molecular and bioptic procedures have to be timely considered, in order to prevent life-threatening complications."

Clinical • Acute Promyelocytic Leukemia • Crohn's disease • Gastroenterology • Gastrointestinal Disorder • Genetic Disorders • Hematological Malignancies • Immunology • Infectious Disease • Inflammatory Bowel Disease • Leukemia • Obesity • Pneumonia • Solid Tumor • Thyroid Gland Carcinoma • Ulcerative Colitis

CERTAIN Study: Ceftolozane/tazobactam continuous infusion for outpatient treatment of exacerbations of Cystic Fibrosis and Bronchiectasis (WBC 2025) - "Thus far, ceftolozane/tazobactam has been demonstrated to be a safe, well-tolerated and effective alternative to other antimicrobial agents used to treat infectious exacerbations of CF and bronchiectasis associated with these difficult pathogens."

Clinical • Bronchiectasis • Cystic Fibrosis • Genetic Disorders • Immunology • Infectious Disease • Non‐Cystic Fibrosis Bronchiectasis • Pulmonary Disease • Respiratory Diseases

Antimicrobial resistance among agents of hospital-acquired lower respiratory tract infection in the UK and Ireland: trends from 2008/2009 to 2018/2019. (PubMed, J Antimicrob Chemother) - "From 2008/09 to 2018/19, there were no major rises in resistance among the principal agents of HA-LRTI; for several important organisms/resistance combinations there were notable declines."

Journal • Infectious Disease • Pneumonia • Respiratory Diseases

Population diversity and antimicrobial resistance profiling of Pseudomonas aeruginosa isolated from Australians with bronchiectasis (WBC 2025) - "Ciprofloxacin resistance was most common (33% of strains), followed by ceftazidime (25%), aztreonam (25%), cefepime (17.9%), meropenem (16.7%), piperacillin/tazobactam (14.3%), imipenem (13.1%), ceftolozane/tazobactam (12.2%), and amikacin (6%) resistance...Similarly, no AMR was so observed towards the last-line antibiotic, colistin, despite several participants in our cohort receiving long term nebulised colistin...This discovery opens up new personalised treatment avenues (qPCR, genomics, metagenomics) for rapid molecular-based AMR diagnosis. Finally, our findings highlight the importance of infection control to prevent patient-to-patient spread of AMR and MDR clones, and the need for accurate AST or genomic of P. aeruginosa to effectively eradicate infections, prevent persistence, and reduce patient morbidity and mortality."

Clinical • Bronchiectasis • Cystic Fibrosis • Genetic Disorders • Immunology • Infectious Disease • Pulmonary Disease • Respiratory Diseases

Trends in Pseudomonas aeruginosa In Vitro Susceptibility to Ceftolozane/Tazobactam in Latin America: SMART Surveillance Program, 2016-2024. (PubMed, Antibiotics (Basel)) - "Among individual countries that participated each year, P. aeruginosa isolates from all except Guatemala displayed stable or increasing rates of susceptibility to ceftolozane/tazobactam. Since it was first tested by the SMART program in 2016, and for 8 years thereafter, the in vitro activity of ceftolozane/tazobactam has remained consistent against clinical isolates of P. aeruginosa from the Latin American region (overall, 86.3% susceptible), with limited resistance development restricted to specific clinical sites."

Journal • Preclinical • Pediatrics

Stability of Two Reserve Antibiotics in Elastomeric Pumps: Ceftazidime-Avibactam and Ceftolozane-Tazobactam. (PubMed, Antibiotics (Basel)) - "In the ceftolozane-tazobactam pumps, the ceftolozane concentration was stable for 24 h incubation, but tazobactam concentrations decreased below 90% within 12 h in the two higher dosages. Accordingly, stability cannot be guaranteed for both tested preparations and their use for OPAT should be thoroughly considered."

Journal • Infectious Disease

β-Lactamase inhibitors, cefiderocol and delafloxacin: evaluating promising antibiotics options for Pseudomonas aeruginosa in adults with cystic fibrosis. (PubMed, New Microbiol) - "High in vitro activity was observed for newer antibiotics such as ceftolozane-tazobactam (83% susceptibility), ceftazidime-avibactam (85% susceptibility), and cefiderocol (89% susceptibility). Delafloxacin also showed promising activity, with 93% of the isolates exhibiting MICs below the EUCAST epidemiological cut-off value. Results emphasize the potential utility of these agents."

Journal • Cystic Fibrosis • Genetic Disorders • Immunology • Infectious Disease • Pulmonary Disease • Respiratory Diseases