ABSTRACT
Objective To observe the inhibitory effects of sub-MIC matrine alone and in combination with erythromycin on Staphylococcus epidermidis biofilms and their influences on morphological changes of the biofilms.Methods Minimum inhibitory concentrations (MIC) of matrine and erythromycin against Staphylococcus epidermidis were determined by the serial dilution method,antibacterial activity of matrine combined with erythromycin against planktonic S.epidermidis was evaluated by the checkerboard method.S.epidermidis biofilms were constructed in vitro,XTT reduction assay was used to evaluate influences of sub-MIC matrine alone and in combination with erythromycin on metabolism and adhesion of S.epidermidis biofilms,and scanning electronic microscope(SEM) was applied to observe the morphological and the structural changes of the biofilms.Results The MIC of erythromycin to S.epidermidis was 7.8125 μg/ml,while the MIC of matrine was greater than 1000 μg/ml,besides,a synergistic effect between erythronmycin and matrine on planktonic S.epidermidis was shown (FIC＜0.5).The sub-MIC matrine had no significant inhibitory effect on adhesion of S.epidermidis,and also the combination of the two agents was better than was used alone.However,the sub-MIC matrine had inhibitory effects on metabolism and morphology of S.epidermidis biofilms,and the combination of the two agents was weaker than was used alone.Conclusion Both the sub-MIC matrine and erythromycin had a significant inhibitory effect on S.epidermidis biofilm formation.Combination of the two agents showed synergistic effects on plankton and adhesion of S.epidermidis,but showed no synergistic effect on metabolism and morphology of the biofilms.
ABSTRACT
<p><b>OBJECTIVE</b>To provide a new therapeutic approach for Staphylococcus epidermidis biofilm-associated infections by the study of inhibitory effect of andrographolide (AG) on S. epidermidis biofilm.</p><p><b>METHOD</b>S. epidermidis biofilms were set up in vitro, erythromycin was acted as the positive control agent, XTT reduction assay was used to evaluate AG on the initial adhesion of S. epidermidis and bacterial metabolism within biofilm, microscope was applied to observe biofilm morphology, and Congo red assay was used to detect polysacchatide interc-ellular adhesion (PIA)formation when exposed to AG.</p><p><b>RESULT</b>AG showed inhibitory effects against the initial adhesion of S. epidermidis at concentrations of 1 000,100, 10 mg x L(-1), respectively,and inhibited metabolism of biofilm bacteria at the concentration of 31.25 mg x L(-1), and exhibited significantly inhibition against the biofilm morphology at the concentration of 250 mg x L(-1), while did not display inhibition against PIA formation at the concentration of 10 mg x L(-1).</p><p><b>CONCLUSION</b>AG could remarkably inhibit biofilm formation of S. epidermidis, although it was less potent than erythromycin.</p>