Glutamine Potentiates Cefoperazone-Sulbactam against Klebsiella pneumoniae by Enhancing Cellular Uptake and ROS Production.

Antibiotic-resistant Klebsiella pneumoniae poses a serious global challenge to clinical practice and public health, highlighting an urgent need for effective therapeutic strategies. This study systematically evaluated the preclinical pharmacodynamics of cefoperazone-sulbactam (SCF) in combination with glutamine against K. pneumoniae. Clinically isolated strains were classified into three groups: 56 sensitive (S-KP), 62 multidrug-resistant but carbapenem-sensitive (MDR-KP), and 195 multidrug-resistant and carbapenem-resistant (CR-KP) isolates. Compared with SCF alone, the combination with glutamine enhanced bacterial killing in 95.85% of the tested isolates. This potentiation was further confirmed by time-kill kinetic assays and a murine infection model, with results showing consistent efficacy independent of pH and calcium levels but dependent on bacterial inoculum. Moreover, glutamine delayed the increase in the minimum inhibitory concentration of SCF, extended its postantibiotic effect, and reduced the mutation frequency. Mechanistically, glutamine overcomes antibiotic resistance by reprogramming bacterial metabolism to promote cefoperazone uptake and elevate reactive oxygen species (ROS) production. Increased intracellular drug levels counteract efflux- and hydrolysis-mediated defenses, while elevated ROS acts synergistically with the antibiotic, together resulting in enhanced bactericidal activity. This study demonstrates that glutamine enhances the activity of SCF against a broad range of K. pneumoniae pathogens, supporting its potential development as an adjuvant therapy for resistant infections.