Combination of Caffeine with Fluoroquinolones to Explore its Potential Role as Adjuvant to Combat Antibiotic Resistance

Salmonella typhimurium, Klebsilla pneumoniae, and Staphylococcus aureus have acquired resistance against various antibiotics including the fluoroquinolones such as levofloxacin, ciprofloxacin and moxifloxacin. The objective of this study was to explore the role of caffeine as an adjuvants to combat antibiotics resistance against various antibiotics including the fluoroquinolones such as levofloxacin, ciprofloxacin and moxifloxacin. Minimum inhibitory concentration (MIC) of all the antibiotics alone and in combinations with caffeine was determined using agar dilution method. Afterward, zone of inhibition (ZoI) of all the selected antibiotics against the chosen antibiotics was studied using disc diffusion method. T-test was applied to compare the findings. For the calculation of MIC, the antibiotics were combined with caffeine in 1 mL × 1 mL concentration. The MIC of levofloxacin, ciprofloxacin and moxifloxacin was noted as 16, 256 and 128 µg/mL and with caffeine was 64 µg/mL for each. According to results, there was a decrease in the MIC of ciprofloxacin and moxifloxacin with caffeine against S. typhi, while MIC of levofloxacin was increased. It indicated that caffeine enhanced the efficacy of ciprofloxacin and moxifloxacin. These findings were further supported by the results of ZoI. There was a significant (p < 0.05) increase in the ZoI of ciprofloxacin (from 12.33 ± 1.16 to 18.33 ± 0.58) and moxifloxacin (from 12.33 ± 1.53 to 19.33 ± 0.58) with caffeine against S. typhi. On the other hand, ZoI of levofloxacin was non-significantly (p > 0.05) increased from 19 ± 0 to 19.00 ± 1.00. The findings reveal that caffeine could be used in combination with ciprofloxacin and moxifloxacin to improve their efficacy; however, the use of caffeine with levofloxacin could reduce its antibacterial efficacy.