First Report of Klebsiella pneumoniae Clinical Isolates Carrying pAmpc Gene ACT-5 with Reduced Sensitivity to Cefepime from Brazil.

Antimicrobial resistance remains a major threat to global public health, with increasing reports of the spread of β-lactamase genes posing significant risks. The number of Enterobacteriaceae harboring plasmid-mediated AmpC enzymes has been rising worldwide, with prevalence rates varying across regions. These β-lactamases are of particular epidemiological concern because they confer resistance to several β-lactam antibiotics, including penicillins, second and third-generation cephalosporins, and monobactams, while isolates typically remain susceptible to cefepime and carbapenems. This study reports, for the first time in Brazil, the detection of the blaACT-5 gene in a Klebsiella pneumoniae isolate recovered from a community-acquired infection clinical sample in Rio de Janeiro, which notably exhibited resistance to both cefepime and carbapenems.