Abstract：Objective To investigate the antibacterial effect of iodophor on Staphylococcus aureus biofilm (BBF). Methods Staphylococcus aureus were cultured in vitro and 480 pieces of titanium alloy plates were selected. On the surface of titanium plates, in vitro models of Staphylococcus aureus biofilms were established at days 7, 14, 21 and 28 respectively with 120 pieces of titanium plates at each time points. The biofilms at each time point were assigned to no iodophor immersion (PBS group), 5 g/L iodophor immersion for 5 minutes (5 min group) and 5 g/L iodophor immersion for 10 minutes (10 min group), according to the random number table method. FITCConA, propidium iodide (PI) and SYT09 were used to dye Staphylococcus aureus in PBS group. After dyeing, confocal laser scanning microscopy and scanning electron microscopy were used to observe the morphological structure of bacterial biofilms, and the Colony forming unit (CFU) was counted by the viable count method. In the other two groups, PI and SYT09 were applied to dye Staphylococcus aureus, and then confocal laser scanning microscopy and scanning electron microscopy were used to observe the changes of biofilms and bacterial viability after iodophor immersion. The antibacterial effect of iodophor was evaluated by the viable count method. Results After dyeing Staphylococcus aureus with FITC-ConA and PI in PBS group, confocal laser scanning microscopy showed that the extracellular polymers of the bacteria increased gradually with the extension of culture time. The space structure of biofilm was gradually mature, changed significantly at day 21 and became mature at day 28. After staining Staphylococcus aureus with PI and SYT09 in PBS group, confocal laser scanning microscopy showed that the number of bacteria increased, and had a mountain-like shape. Scanning electron microscopy showed that the number of bacterial extracellular polymers increased gradually with the extension of culture time and a structured microenvironment was formed and gradually matured. In 5 min and 10 min groups, all bacteria were killed at days 7 and 14 ［0(0, 0)CFU/ml］, the antibacterial effect was weakened at 21 days, but the antibacterial effect of iodophor immersion in 10 min group ［100 (100, 125)CFU/ml］ was better than that in 5min group ［300 (275, 425)CFU/ml］(P<0.05). There was no significant difference in iodophor immersion in 5 min group ［500 (375, 700)CFU/ml］ and 10 min group ［250 (175, 400)CFU/ml］ at 28 days (P>0.05). Conclusions The maturation of biofilm is the overall maturation of bacteria and bacterial extracellular polymers and the formation of a spatialized microenvironment. Bounded by the 21st day, biofilms are divided into young biofilms and mature biofilms. The main difference between them lies in the maturation of extracellular polymers and microenvironment. For the bacterial biofilm with culture time less than 21 days, the antibacterial effect of the iodophor immersion for 10 min is better than that of 5 min. However, for the bacterial biofilm with culture time greater than 21 days, there is no significant difference in the antibacterial effect of the bacterial biofilm of prolonged iodophor immersion time.
