Study on Antimicrobial Potential of Selected Non-antibiotics and its Interaction with Conventional Antibiotics

Abstract

The escalating levels of antimicrobial drug resistance render it indispensable to explore newer drugs with lesser degrees of toxicity and with fewer chances of developing resistance. Various studies on the discovery of novel antimicrobials have found different degrees of antimicrobial activity in commonly used medicines with diverse pharmacological actions i.e., non-antibiotics. The present work aimed to describe qualitatively and quantitatively in vitro antimicrobial activity of selected non-antibiotic drugs i.e., Acetyl salicylic acid, Methyldopa, Propranolol and Fluoxetine alone and in combination with three conventional antimicrobial drugs i.e., Ciprofloxacin, Benzyl penicillin, and Fluconazole against three standard test microorganisms, i.e., E. coli, S. aureus and C. albicans. Agar well diffusion method was used for testing antimicrobial sensitivity, while the drug interaction was estimated using fractional inhibitory concentration index (FIC index) obtained from checkerboard broth dilution method. All the four non-antibiotics tested for antimicrobial activity showed activity against at least one tested microorganism, whereas fluoxetine showed antimicrobial activity against all tested organisms. Combined effect of fluconazole + fluoxetine and fluconazole + propranolol against C. albicans showed synergistic activity based on the FICindex value obtained i.e., 0.25 and 0.1875, respectively. Based on the results, study suggests that fluoxetine among the other non-antibiotics has a potential for being developed into an effective antimicrobial agent. However, the study needs to be extended in the future to determine the in vivo antimicrobial activity.