Synergistic Activity of 3-Hydrazinoquinoxaline-2-Thiol in Combination with Penicillin Against MRSA

Background: The growing resistance seen in various antibiotics, including those considered as last-resort options, underscores the pressing need for novel approaches and new substances to address MRSA infections. Combining antibiotics as a treatment approach can enhance effectiveness, expand the range of targeted bacteria, and minimize the likelihood of resistance emergence. This approach holds promise in addressing the escalating issue of antibiotic resistance.

Purpose: This study seeks to investigate the potential synergy between 3-hydrazinoquinoxaline-2-thiol and penicillin against a diverse array of MRSA isolates, thereby providing insights into their combined antimicrobial action.

Methods: Twenty-two clinical MRSA isolates subjected to broth microdilution to determine the Minimum Inhibitory Concentrations (MICs) of 3-hydrazinoquinoxaline-2-thiol and penicillin. Subsequently, a checkerboard assay was employed to evaluate the interaction between 3-hydrazinoquinoxaline-2-thiol and penicillin, focusing on the Fractional Inhibitory Concentration Index (FICI).

Results: The MICs of penicillin and 3-hydrazinoquinoxaline-2-thiol were determined for 22 clinical MRSA strains. Penicillin exhibited MICs within a range of 1024 to 128 µg/mL, while 3-hydrazinoquinoxaline-2-thiol displayed MICs varying from 64 to 8 µg/mL. Remarkably, the combination of 3-hydrazinoquinoxaline-2-thiol and penicillin yielded a synergistic effect, resulting in a significant reduction of MICs by up to 64-fold.

Conclusion: The potential of 3-hydrazinoquinoxaline-2-thiol in combination with penicillin as a viable solution against MRSA appears promising. However, to establish its practical utility, further extensive testing and experiments are essential.