Ceftolozane/Tazobactam vs. Piperacillin/Tazobactam for the Treatment of Bacteremia Due to Enterobacteriaceae and Pseudomonas Aeruginosa in Hemato-oncological Patients With Severe Neutropenia and Fever: Non-inferiority Study

At a global level, a very significant increase in multidrug-resistant (MDR) Gram-negative microorganisms has been described during the last decade, particularly Enterobacteriaceae producing extended-spectrum beta-lactamases (ESBL) and MDR Pseudomonas aeruginosa. This is directly related to the use of broad-spectrum antimicrobials, particularly carbapenems. Among the strategies to reduce bacterial resistance, using ceftolozane/tazobactam (C/T) as a "carbapenem-sparing" antibiotic is proposed. C/T has been administered in hemato-oncological patients with severe neutropenia, colonized by resistant strains in centers with a high prevalence of Enterobacteriaceae-ESBL and P. aeruginosa MDR.

The study's purpose is to demonstrate non-inferiority between ceftolozane/tazobactam vs. piperacillin/tazobactam for patients with hematological malignancies who present severe neutropenia and fever, including those patients who have bacteremia due to Enterobacteriaceae and Pseudomonas aeruginosa. C/T is a combination antibiotic with a new cephalosporin, structurally similar to ceftazidime, plus tazobactam. The FDA approved This known beta-lactamase inhibitor in 2018 to treat intra-abdominal and complicated urinary infections. In 2019, its indication was expanded to nosocomial pneumonia and those associated with mechanical ventilation. In Mexico, it was approved for marketing in June 2019. C/T has broad-spectrum activity since it has action against ESBL-producing Enterobacteria and MDR P. aeruginosa. Studies carried out in the real world using this antibiotic in patients with hematological malignancies have demonstrated clinical success in reports and case series, considered a therapeutic option in patients with Enterobacteriaceae and P. aeruginosa infections, particularly in MDR pathogens.

At the National Cancer Institute, Gram-negative bacilli have been identified for more than 20 years as the pathogens most frequently associated with bacteremia, with Escherichia coli occupying first place at 25% (41% ESBL), followed by Klebsiella sp. in 5.6% (11.2% ESBL), and P. aeruginosa in 5.6% (11.2% MDR). The protocol for approaching and treating hemato-oncological patients with severe neutropenia and fever is to initiate an antimicrobial regimen with piperacillin/tazobactam (P/T) if they are hemodynamically stable. In patients who persist with fever after 48 to 72 hours of starting antibiotics, who present with clinical deterioration, or in whom P/T-resistant bacteria are identified, this is escalated to a carbapenem (usually meropenem).

A randomized, open, non-inferiority clinical trial comparing 1:1 two antibiotics, P/T vs. C/T, for the treatment of severe neutropenia and fever and/or developing Enterobacteriaceae or P. aeruginosa bacteremia in patients with hematologic malignancies

Methodological strategies All patients who come to the National Cancer Institute with signs of severe neutropenia (polymorphonuclear cells <500 cells/mm3) and fever (≥38.3 degrees Celsius in one measure or ≥38 degrees Celsius in at least two measures) will be considered for inclusion. Blood cultures will be taken upon admission (catheter and peripheral in those with the same), or two peripherals with a difference of 15 minutes between each one. Blood cultures will be requested before signing the informed consent since they are part of the initial approach to these patients, regardless of whether they enter the study. They will be taken before the administration of antimicrobials.