Antimicrobial and synergistic activity of thiazoline derivatives in combination with conventional antibiotics against multidrug resistant Staphylococcus aureus isolated from abscess drainage samples

Abstract

Emergence and spread of multidrug resistant (MDR) Staphylococcus aureus strains is becoming major challenge in treatment of soft tissue infections. This study aimed to explore antimicrobial and synergistic antimicrobial potential of three commercially available thiazoline derivatives (2-amino-2-thiazoline, 2-thiazoline-2-thiol and 2-acetyl2-thiazoline) against MDR Staphylococcus aureus strains isolated from abscess drainage samples (n=20). MDR Staphylococcus aureus isolates were identified by Kirby-Bauer disk diffusion assay and were further subjected to molecular identification by 16srRNA amplification and DNA sequencing. Minimum Inhibitory Concentration (MIC) values of test compounds and antibiotics (0.25-512μg/mL) were measured and subsequently, synergism assay was performed to calculate Fractional Inhibitory Concentration (FIC) index. Out of twenty Staphylococcus aureus isolates, sixteen (80%) were found to be MDR whereas four (20%) were Non-MDR. Moxifloxacin and vancomycine were found most effective antibiotics, inhibiting 100% (n=20) and 95% (n=19) strains respectively. Antimicrobial activity of 2amino-2-thiazoline (MIC: 32μg/mL), 2-thiazoline-2-thiol (MIC: 64μg/mL) and 2-acetyl-2-thiazoline (MIC: 32μg/mL) was found significant against all ten tested MDR strains. Synergistic combinations of thiazoline derivatives with test antibiotics reduced MIC values significantly. Therefore, combination of tested thiazoline derivatives with antibiotics could be used as alternative therapeutic approach to treat soft tissue infections caused by MDR Staphylococcus aureus after further pre-clinical and clinical studies.