Captopril potentiated meropenem activity against MBL-producing carbapenem-resistant Klebsiella pneumoniae: in vitro and in vivo study

This study investigated whether captopril can reverse drug resistance in metallo-β-lactamase (MBL)-producing carbapenem-resistant Klebsiella pneumoniae (CRKP) and increase their sensitivity to antimicrobial agents. And also aimed to further characterize the affinity of captopril for imipenemase 4 (IMP-4) to explore the drug resistance treatment of MBL-producing bacteria. Five clinically isolated MBL-producing strains of CRKP were screened and the combined effects of captopril and meropenem were examined in vitro and in vivo to analyze whether captopril can reverse antimicrobial resistance in drug-resistant bacteria. Additionally, enzyme inhibition kinetics was analyzed to characterize the affinity of captopril for IMP-4. In MBL-producing Klebsiella pneumoniae, combined treatment with captopril significantly reduced the minimum inhibitory concentration (MIC) of carbapenems to 1 μg/mL at least, and captopril inhibited New-Delhi metallo-β-lactamase 1 (NDM-1) and IMP-4 in a concentration-dependent manner in vitro. Following the infection of Galleria mellonella by IMP-expressing bacteria, the survival rates were significantly higher in the combination treatment group than in the monotherapy groups. And the bacterial load in the combination treatment group was significantly lower than those in the monotherapy groups and IMP-4-producing bacteria were more sensitive to the combination treatment than NDM-1-producing bacteria. Additionally, enzyme inhibition kinetics firstly illustrated that the half-maximal inhibitory concentration of captopril for IMP-4 was 26.34 μM, and the dissociation constant was 37.14 μM. In brief, captopril potentiated meropenem activity and restored its efficacy against MBL-producing CRKP. Additionally, analysis of enzyme inhibition kinetics confirmed that captopril has good inhibitory effects on IMP-4 activity. Therefore, captopril or its derivatives may have clinical utility for overcoming antibiotic resistance.