Figure 6 : Representative microscopic images of Alcian blue staining and comparison of RGB ratio of samples stained with Alcian blue. Error bars were produced from the standard deviation of six replicates. (n=8, mean ± SEM) **** P<0.0001 (using unpaired t-tests).
Antibiotic Treatment Test
The effect of antibiotic treatment on biofilms grown in different interfaces was evaluated to understand the differences in biofilm susceptibility and to validate our model as a more realistic screening tool in biofilm management. The results of the antibiotic susceptibility test in the range of 50-1600μg/mL for the ALI and LLI interfaces are depicted in Fig. 7. Data is presented using the number of detached, attached and total CFUs. CIP induced a concentration-dependent decrease for the biofilm, detached bacteria, and total counts for both interfaces. Statistical differences were only observed for concentrations from 800μg/mL, and biofilms were not eradicated at the highest concentration tested (1600μg/mL). This is probably due to the biofilm’s complex structure and the presence of EPS, which creates an antibiotic gradient in the biofilm community [5-8].
The antibiotic effect on the biofilms was further corroborated by the SEM images (Fig. 8), showing the differences in biofilm density across the membranes when compared to the control (without antibiotic).