Effect Of Scutellaria Aqueous-extracts On Pseudomonas Aeruginosa Biofilm In Vitro

Objectives 1.To study the inhibitory effect of Scutellaria aqueous extracts on biofilm synthesis of P. aeruginosa in vitro. 2.To investigate the destructive effect of Scutellaria aqueous extracts on the biofilm of P. aeruginosa in vitro. 3. To observe the synergism of actericidal effect between Scutellaria aqueous extracts and ceftazidime(CAZ) / Levofloxacin(LFX) on P. aeruginosa within the biofilm. Methods Completely random design was employed. 1.The biofilm models of P. aeruginosa in vitro were divided into 3 groups: control group, erythromycin(EM) group, and Scutellaria group. The drugs being studied were added at the beginning of making biofilm models. 7 days later, the biofilm was examined by scanning electron microscopy(SEM) and silver nitrate staining. The viable bacterial counts within biofilm were determined by serial dilution. 2. The biofilm models of P. aeruginosa in vitro were divided into 9 groups: Control group, EM group, Scutellaria group, CAZ group, EM + CAZ group , Scutellaria + CAZ group, LFX group, EM+LFX group and Scutellaria + LFX group. When the biofilm has developed for 3 days or 7 days , the drugs were added,then the viable bacterial counts within biofilm were determined at 0 hour,4th hour,8th hour and 24th hour, respectively. The biofilm was examined by SEM and silver nitrate staining at 24th. Results 1. In the study of the inhibitory effect of Scutellaria water aqueous on biofilm, the bacterial survival in control group was significantly improved compared with EM group or Scutellaria group (P<0.01), while a statistically significant difference was not detected between EM group and Scutellaria group (P>0.05). Under the SEM , there is a lot of biofilm observed in control group,but seldom was observed in EM group or Scutellaria group. 2. In the study of the destructive effect of Scutellaria on biofilm, the differences of viable bacterial counts among EM group, Scutellaria group and control group was not statistically significant (P>0.05),while the bacterial survival in CAZ group and LFX group were significantly decrease (p<0.01), and in EM combined with CAZ / LFX group or Scutellaria combined with CAZ / LFX group was decrease further (p<0.01). the difference of viable bacterial counts between Scutellaria combined with CAZ / LFX group and EM combined with CAZ / LFX group was not statistically significant (P>0.05). The bacterial survival in Scutellaria combined with LFX group was significantly decrease compared with Scutellaria combined with CAZ group (p<0.01). The inhibition or destruction of biofilm formation by Scutellaria aqueous extracts was also observed by SEM and silver nitrate staining. Conclusions Scutellaria aqueous-extracts can inhibit the adherence of P. aeruginosa and block the formation of biofilm. It can also destruct the biofilm of P. aeruginosa in vitro. It is considered that scutellaria aqueous-extracts can enhance antibacterial activities of CAZ / LFX by enhancing permeability of CAZ / LFX into biofilms. The combination of Scutellaria with LFX is more effective than Scutellaria with CAZ.