Key Findings

The study identifies ADC-33, a class C beta-lactamase from Acinetobacter baumannii, as a key mediator of resistance to oxyimino-cephalosporins such as ceftazidime, ceftolozane, and cefiderocol. The resistance mechanism involves an alternative hydrolysis pathway, with structural and kinetic analyses revealing unique features of ADC-33 that enhance its catalytic efficiency towards these antibiotics.