UC Riverside Undergraduate Research Journal

The purpose of this study was to determine whether Enterobacter cloacae, Pseudomonas aeruginosa, and Staphylococcus xylosus can form biofilm in vitro, and the effects of N-acetyl cysteine, ciprofloxacin, and gentamicin on biofilm growth, in the presence or absence of oxidative stress and/or high glucose levels. The bacteria were cultured in vitro and formed biofilm within 24 h. Treatments included N-acetyl cysteine at a final concentration of 20mg/ml, gentamicin at 0.1mg/ml, and ciprofloxacin at 0.2mg/ml. For the oxidative stress condition, H₂O₂ was used at a final concentration of 500µM, and for the high glucose levels, d(+)-Glucose was used at 300mg/dL. When used alone, N-acetyl cysteine was able to significantly dismantle the biofilm, even when the bacteria were combined. However, in the presence of oxidative stress or high glucose levels, N-acetyl cysteine was not as effective at dismantling the biofilm, especially when the bacterial strains were combined. Combining glucose and H₂O₂ had no additional impact for most strains. In conclusion, H₂O₂ and glucose diminish the efficacy of our treatments, which have a significantly detrimental effect on biofilm. While N-acetyl cysteine is not as effective at dismantling biofilm under conditions of high oxidative stress and high glucose levels, the addition of antibiotics becomes more helpful in these cases, making the treatment viable overall.