Inhibitory And Destructive Effect Of Honeysuckle Aqueous Extracts On Biofilm Formation By Pseudomonas Aeruginosa In Vitro

Objectives 1.To study the inhibitory effect of honeysuckle aqueous extracts on biofilm synthesis of Pseudomonas aeruginosa in vitro. 2.To investigate the destructive effect of honeysuckle aqueous extracts on the biofilm of P. aeruginosa in vitro. 3. To observe the synergism of actericidal effect between honeysuckle aqueous extracts and ceftazidime(CAZ) 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 honeysuckle 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 the viable bacterial counts within biofilm were determined. 2. The biofilm models of P. aeruginosa in vitro were divided into 6 groups: control group, EM group, honeysuckle group, CAZ group, EM combined with CAZ group and honeysuckle combined with CAZ 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 at 24th hour.Results 1.In the study of the inhibitory effect of honeysuckle water aqueous on biofilm, the bacterial survival in control group was significantly improved compared with EM group or honeysuckle group (P<0.01), while a statistically significant difference was not detected between EM group and honeysuckle group (P>0.05). Under the SEM , there is a lot of biofilm was observed in control group,but seldom was observed in EM group or honeysuckle group. 2. In the study of the destructive effect of honeysuckle on biofilm, the differences of viable bacterial counts among EM group, honeysuckle group and control group was not statisticallysignificant (P>0.05) , while the bacterial survival in CAZ group was significantly decrease (p<0.01), and in EM combined with CAZ group or honeysuckle combined with CAZ group was decrease further (p<0.01). In 3 days biofilm, the difference of viable bacterial counts between honeysuckle combined with CAZ group and EM combined with CAZ group was not statistically significant (P>0.05), while in 7 days biofilm, the bacterial survival in honeysuckle combined with CAZ group was significantly decrease compared with EM combined with CAZ group (p<0.05). The inhibition or destruction of biofilm formation by honeysuckle aqueous extracts was also observed by SEM. Conclusions　⑴ Our findings suggest that honeysuckle aqueous extracts inhibit biofilm formation by P. aeruginosa in vitro. ⑵ Our data also demonstrate that honeysuckle aqueous extracts destruct the biofilm of P. aeruginosa in vitro. ⑶ We consider that honeysuckle aqueous extracts can enhance the bactericidal effect of CAZ on PA within the biofilm.