Resistance to oxyimino-cephalosporins conferred by an alternative mechanism of hydrolysis by the <i>Acinetobacter</i>-derived cephalosporinase-33 (ADC-33), a class C β-lactamase present in carbapenem-resistant <i>Acinetobacter baumannii</i> (CR<i>Ab</i>).

ABSTRACT: Antimicrobial resistance in Acinetobacter baumannii is partly mediated by chromosomal class C β-lactamases, the Acinetobacter-derived cephalosporinases (ADCs). Recently, a growing number of emerging variants were described, expanding this threat. Consistent with other β-lactamases, one of the main areas of variance exists in the Ω-loop region near the site of cephalosporin binding. Interestingly, a common alanine duplication (Adup) is found in this region. Herein, we studied specific Adup variants expressed in a uniform Escherichia coli genetic background that demonstrated high-level resistance to multiple oxyimino-cephalosporins. For ceftolozane and ceftazidime, the Adup ADCs significantly increased levels of resistance (minimum inhibitory concentration [MIC] ≥ 512 µg

SUBMITTER: Powers RA 

PROVIDER: S-EPMC12153338 | biostudies-literature | 2025 Jun

REPOSITORIES: biostudies-literature