Effect Of Gentamicin On Staphylococcus Aureus Adherence To The Titanium Plate

ObjectiveThe infection is one of the determinants of success or failure in the process of orthopedics surgery,and always plagued the doctors.Microorganisms can form obvious resistance to various antibacterial agent due to the biofilm.Many domestic and foreign scholars devote to the study about infection treatment,hope to make out a more profound understanding on the characteristics of all infection stage and a more effective method to control the infection.Recently,some scholars dedicated to the study of how to reduce bacterial early adhesion on the surface of the material.It has been found that various antibiotic have various effect on bacterial adhesion by the research.Based on the theory of local antibiotic application concept,this article aims to study the effect of gentamicin which commonly used in orthopedics on sensitive and resistant bacterial adhesion to implant in different concentration and provide the basic external experimental data for the strategy of prevent and control infection in clinical.MethodsThe experimental content is divided into two parts according to the experiment,and the two parts of content subdivided into two groups according to the bacteria whether sensitive or resistance,each group include six sensitive bacteria(MSSA)or drug-resistant bacteria(MRSA).The first part is the adhesion inhibition test: Firstly,prepare a mixed liquid contain different final concentration of gentamicin(20 mg/ml,1 mg/ml,100 ?g/ml;10 ?g/ml)and sensitive/resistant s.aureus(106CFU/ml).Then the titanium plate was placed separately in the 24 test holes containing 2 ml mixture.After titanium plates were incubated at 37 ? for 1 hour,all the titanium plate was rinsed and sonicated,and the result was performed by plate counting method.The second part is adhesion relive test :All titanium plate werefirstly incubated in 2ml bacterial suspension of 106CFU/ml for 1h.The lenses were removed from each culture and rinsed 3 times in phosphate-buffered solution(PBS)to remove the non-adhered bacteria.Then,the lenses were treated with different concentrations(the same as the first part of the final concentration)of gentamicin for5 minutes.Finally,all the titanium plate was rinsed and sonicated,and the result was performed by plate counting method.Results1)When gentamicin and MSSA contact titanium plate at the same time,only the group which the gentamicin concentration greater than MIC can inhibit the adhesion effectively,and the influence is concentration-dependent;the concentration higher,the influence more obvious;2)When gentamicin and MRSA contact plate at the same time,no matter which group that gentamicin had no effect on bacteria adhesion.3)There is no effect to immerse the titanium plate in gentamicin for 5min after incubated in two kind of bacteria suspension for 1h.4)There is no bacteria adherence when the amount of bacterial lower than 104 CFU.ConclusionIt can be conclude that there are some limitation about the significance of local application of gentamicin in clinical.Only when the gentamicin concentration is more than MIC can it inhibit the MRSA adherence in early effection,but there is no obvious effect of resistant bacteria.Besides,there is no influence of short-time soaking in gentamycin on bacterial adhesion when the bacteria bave contaminated the wound for an hour,however,bacterial adhesion is a very complex process,it is essential to do more studies about the mechanism of effect of antibiotics on bacterial adhesion.