ABSTRACT
Objective To investigate the effect of ica operon on adherence and biofilm formation of Staphylococcus epidermidis(S.epidermidis)at orthopedic implants,and to provide theoretical basis for the use of clinical orthopedic materials.Methods The icaADBC genes of S.epidermidis were amplified by PCR.The expression of ica genes was detected by fluorescence quantitative PCR.The contents of polysaccharide intercellular adhesion (PIA) were determined by phenol-sulfuric acid method.The ability of bacterial adherence was detected by colony counting method and the ability of biofilm formation was measured by crystal violet staining method.Results The icaADBC genes were presented and expressed in eleven S.epidermidis strains.The strains with high icaABDC gene expression had higher PIA product.S.epidermidis isolates had the strongest adherence and biofilm formation ability on bone material,followed by titanium and stainless steel.The expression of icaA gene correlated with the biofilm formation of bacteria on three biomaterials.Conclusion S.epidermidis isolates had the different adherence and biofilm formation on different biomaterial implants.Ica gene regulates the biofilm formation of S.epidermidis by regulating the expression of PIA.
ABSTRACT
Objective To investigate the effects of 3 kinds of broth media,including tryptose soya broth(TSB),LB and M-H,on the biofilm formation of Staphylococcus epidermidis (S.epidermidis).Methods The effects of TSB,LB and M-H broth media on the biofilm formation of S.epidermidis were investigated by the construction of bacterial biofilm in 96-well and 6-well microplates and the crystal violet straining for the semi-quantitative analysis and microscopic observation of the bacterial biofilm.The effects of TSB,LB and M-H broth media on the expression of adhesion-related genes in S.epidermidis were determined by the extraction of bacterial total RNA,reverse transcription and real-time PCR.Results Compared with LB (0.149 ± 0.047) and M-H (0.323 ± 0.003) media,TSB medium (2.954 ± 0.287) could significantly promote the biofilm formation of S.epidermidis (TSB vs LB,t =16.706,P ＜ 0.01;TSB vs M-H,t =15.877,P ＜ 0.01).Compared with LB medium,TSB medium could significantly enhance the expression of icaA gene (t =9.667,P＜0.01) but inhibit icaR gene (t =13.283,P＜0.01).Conclusion Compared with LB and M-H broth media,TSB medium may significantly improve the biofilm formation and the expression of adhesion-related gene icaA of S.epidermidis.
ABSTRACT
Objective To study the biofilm formation ability and related gene distribution of Staphylococcus (S .) aureus iso‐lated from urinary tract infections to provide the theoretical basis for the prevention and treatment of clinical infection .Methods The minimal inhibitory concentration was detected using the agar double dilution method .The bacterial adhesion ability was deter‐mined by flat colony counting method .The biofilm formation ability was analyzed by the 96‐well crystal violet staining method .The biofilm‐associated genes were detected by PCR amplification .Results Eleven clinical strains of S .aureus were high resistant to pen‐icillin and erythromycin ,whereas were all sensitive to vancomycin and nitrofurantoin .All the isolates had a strong ability of adhe‐sion ,but the biofilm formation ability was weak .Among them ,the icaAD and icaBC genes were amplified in 10 S .aureus isolates . Conclusion The adhesion ability and biofilm formation ability of S .aureus isolated from urinary tract infections have the strain differences ,and ica is an important gene of S .aureus biofilm formation .