Clinicians often treat gram-negative infections with older antibiotics despite the availability of next-generation, gram-negative antibiotics, according to a study published in the Annals of Internal Medicine. Jeffrey R. Strich, MD, and colleagues examined use patterns of recently approved gram-negative antibiotics and identified factors associated with their use over traditional generic agents in gram-negative infections due to pathogens with difficult-to-treat resistance (DTR) at 619 hospitals. Ceftolozane-tazobactam and ceftazidime-avibactam predominated new antibiotic use between quarter 1 of 2016 and quarter 2 of 2021, while researchers observed relatively low uptake of subsequently approved gram-negative antibiotics. Overall, 0.7% of the gram-negative infections displayed DTR pathogens. In 41.5% of DTR episodes, patients were treated exclusively with traditional agents, including polymyxins, aminoglycosides, and tigecycline. The adjusted probability of receiving newer versus traditional antibiotics for DTR infections was greater for patients with bacteremia and chronic diseases and lower for those with do-not-resuscitate status, acute liver failure, and Acinetobacter baumannii complex and other nonpseudomonal, nonfermenter pathogens. “There is a stark imbalance between available new antibiotics and unmet pathogen targets,” Dr. Strich and colleagues wrote.