Use of cholesterol as an antibiotic activity modifier agent in Salmonella bacteria

In this study, the effect of cholesterol on Salmonella Typhimurium to different antibiotics and concentrations was investigated. When Salmonella Typhimurium antibiotic resistance profile was examined, it was observed that it is susceptible to ampicillin, streptomycin, sulfamethoxazole/trimethoprim, ciprofloxacin, tetracycline, chloramphenicol and gentamicin and resistant to penicillin and vancomycin. The minimum inhibitory concentrations (MIC) for ampicillin, streptomycin, ciprofloxazine and sulfamethoxazole/ trimethoprim powder antibiotics were found as 16, 128, 0.25 and 16 mg/L, respectively. When the effect of cholesterol on MIC values was examined, it was found that MIC values increased in cholesterol medium than in non-cholesterol medium. There was also a decrease in inhibition zone diameters. The increase in MIC and decrement in inhibition zone diameters were considered as the cholesterol may cause a decrease in the sensitivity of Salmonella Typhimurium to antibiotics. The effect of cholesterol on Salmonella Typhimurium interaction with antibiotics were also determined by Fourier transformed infrared (FT-IR) spectroscopy. When cholesterol was added to the medium, changes were identified in the functional groups compared to non-cholesterol environment and new functional groups were observed at different wavelengths. Antibiotics generally caused changes in peaks at wavelengths which were interpreted as polysaccharide regions of bacteria. Unlike other antibiotics, ampicillin caused changes in the wavelengths observed in the amide region of the bacteria.