Designing of inhibitors against CTX-M-15 type beta-lactamase: potential drug candidate against -lactamases-producing multi-drug-resistant bacteria

CTX-M-15 are the most prevalent types of beta-lactamases that hydrolyze almost all antibiotics of beta-lactam group lead to multiple-antibiotic resistance in bacteria. Three beta-lactam inhibitors are available for use in combination with different antibiotics of cephalosporine group against the CTX-M-15-producing strains. Therefore, strategies to identify novel anti beta-lactamase agents with specific mechanisms of action are the need of an hour. In this study, we screened three novel non-beta-lactam inhibitors against CTX-M-15 by multi-step virtual screening approach. The potential for virtually screened drugs was estimated through in vitro cell assays. Hence, we proposed a study to understand the binding mode of CTX-M-15 with inhibitors using bioinformatics and experimental approach. We calculated the dissociation constants (K-d), association constant (K-a), stoichiometry (n) and binding energies (Delta G) of compounds with the respective targets. Molecular dynamic simulation carried out for 25ns, revealed that these complexes were found stable throughout the simulation with relative RMSD in acceptable range. Moreover, microbiological and kinetic studies further confirmed high efficacies of these inhibitors by reducing the minimum inhibitory concentration (MIC) and catalysis of antibiotics by -lactamases in the presence of inhibitors. Therefore, we conclude that these potential inhibitors may be used as a lead molecule for future drug candidates against beta-lactamases-producing bacteria.