Mitigating antimicrobial resistance with aspirin (acetylsalicylic acid) and paracetamol (acetaminophen): Conversion of doxycycline and minocycline resistant bacteria into sensitive in presence of aspirin and paracetamol

The emergence of antimicrobial resistance (AMR) stimulated research for alternatives antimicrobials, repurposing of other drugs, antibiotic adjuvants and alternative therapies for infections. Antimicrobial activity of NSAIDs is often reported and this study evaluated the antimicrobial potential of the two most common NSAIDs, aspirin (acetylsalicylic acid) and paracetamol (acetaminophen), against 293 clinical strains of bacteria. The ability of aspirin and paracetamol to convert minocycline and doxycyclin-resistant bacteria into sensitivity was also tested using micro-broth dilution assays used for determining minimum inhibitory concentration (MIC). Aspirin inhibited all 293 bacterial strains at ≤10.24 mg/ mL concentration. Except for one strain each of Serratia grimaceae and S, aureus paracetamol inhibited none of the 293 strains at 10.24 mg/ mL. Of the 293 strains 116 (39.59%) were sensitive (MIC ≤4 μg/mL) to doxycycline and 127 (43.34%) to minocycline. Of the selected 57 minocycline-resistant (MIC >4 μg/mL) strains aspirin converted 32 (56.14%) to minocycline-sensitive. Of the 49 doxycycline-resistant (MIC >4 μg/mL) strains tested in presence of aspirin 30 (61.22%) turned sensitive. Of the 34 doxycycline-resistant strains tested in presence of paracetamol 11 (32.35%) become sensitive. The study concluded that most of the bacterial strains were not susceptible to aspirin and paracetamol at their concentrations often available in plasma at maximum therapeutic dose levels and had no significant change in their susceptibility to doxycycline and minocycline. The study indicated the potential of aspirin and its combination with antibiotics in the development of therapeutically useful topical antimicrobial formulations.