(WHS-P33) THE EFFECTS OF N-ACETYL-CYSTEINE, GENTAMICIN, AND CIPROFLOXACIN ON BIOFILM IN VITRO IN THE PRESENCE OR ABSENCE OF OXIDATIVE STRESS
Friday, May 17, 2024
7:30 AM – 5:00 PM East Coast USA Time
Chronic wounds become colonized by pathogens, primarily bacteria, and these infections often result in the development of biofilms. Unfortunately, treatment with antibiotics alone often fails to resolve chronic wound infections, in part because antibiotics are ineffective at killing bacteria in biofilms. Persistent biofilms in chronic wounds significantly delay wound healing. The purpose of this study was to determine the effects of N-acetyl-cysteine (NAC), Ciprofloxacin (Cipro), and Gentamicin (Gent) on Enterobacter cloacae (Ec), Pseudomonas aeruginosa (Pa), and Staphylococcus xylosus (Sx) biofilm, alone and in combination. We also tested the effects of these treatments in presence or absence of oxidative stress. 1x10 6 cfu/200µl of bacteria were cultured in 96-well plates and allowed to form biofilm for 24 hours. The biofilms were then treated with NAC (20 mg/ml) or NAC + Gent (100 µg/ml) + Cipro (10µg/50µl) for another 24 hours. The biofilm was stained with 0.1% crystal violet, distained with 95% ethanol, and analyzed at OD590 to measure the amount of biofilm present after treatment. To create the conditions for oxidative stress, H 2 O 2 at a final concentration of 500µM was used. NAC had a significant effect on Ec, Pa, and Sx individually in decreasing the amount of biofilm, but its effects were significantly lessened when used under oxidative stress conditions. For Ec, Pa, and Sx individually, NAC + Gent + Cipro was less effective than NAC alone at decreasing the amount of biofilm in non-oxidative stress conditions. There was no significant difference for Ec and Sx alone between NAC and NAC + Gent + Cipro under oxidative stress conditions. However, for Pa, NAC + Gent + Cipro was more effective at decreasing the amount of biofilm under oxidative stress conditions. For the combinations Ec+Pa, Ec+Sx, and Pa+Sx, there was no significant difference between the effects of NAC alone versus NAC + Gent + Cipro under conditions without oxidative stress. Under conditions with oxidative stress, NAC + Gent + Cipro was significantly better at decreasing the amount of biofilm for the combinations Ec+Pa, Ec+Sx, and Pa+Sx. For the combination Ec+Pa+Sx, without conditions of oxidative stress, there was a significant difference between NAC alone and NAC + Gent + Cipro, as the latter was more successful at decreasing the amount of biofilm. Under conditions with oxidative stress, there was no significant difference between NAC alone and NAC + Gent + Cipro for Ec+Pa+Sx. In conclusion, NAC, has proven to be able to significantly decrease the amount of biofilm with and without oxidative stress under most conditions. However, under other conditions NAC is aided by Gent and Cipro. Regardless of whether the bacterial strains are alone or in combination with each other, the effect of NAC is significant in decreasing the amount of biofilm, though sometimes it needs the assistance of the antibiotics.