Ciprofloxacin is an antimicrobial that is commonly used to treat several types of infections. It exerts its antimicrobial activity through interfering with bacterial DNA replication and transcription, leading to increase oxidative stress and eventually bacterial death. Vitamin D, on the other hand, has been found to have DNA protective and antioxidant effects. In the current study, the possible interactive effect of vitamin D on ciprofloxacin-induced cytotoxicity was investigated in various standard bacterial strains.

Results revealed the possible reduction in the activity of ciprofloxacin when used in combination with vitamin D. This could be explained by the ability of vitamin D to reduce oxidative stress in the bacterial cells.

The bacterial strains that were used include Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis, Acinetobacter baumannii, Proteus mirabilis, and Klebsiella pneumoniae. The antibacterial effect of ciprofloxacin with and without vitamin D treatment of the bacteria was assessed using disc diffusion method and by measuring the minimum inhibitory concentration (MIC) and zones of inhibition of bacterial growth. Moreover, reactive oxygen species (ROS) generation after pretreatment of E. Coli cells with ciprofloxacin and/or vitamin D was measured as a function of as a function of hydrogen peroxide generation.

Ciprofloxacin demonstrated a potent antibacterial effect against the tested strains of bacteria. Moreover, pretreatment with vitamin D resulted in protecting the bacteria from the cytotoxicity of ciprofloxacin, this was indicated by the significantly smaller zones of inhibition and higher MIC values compared to ciprofloxacin alone as well as reduced ciprofloxacin-induced ROS generation after treatment with vitamin D.