Epidemiological Characteristics And Pathogenicity Of Surface Protein-encoding Gene Ebh In Staphylococcus Aureus

Objective:In this study,we investigated the distribution of ebh gene in Staphylococcus aureus isolated from Lanzhou,and analyzed the influence of ebh gene on bacterial resistance,production of bacterial biofilm,pathogenicityin and transmission of same strains in Staphylococcus aureus,which provided valuable epidemiological data for further study of ebh gene function.Methods: Staphylococcus aureus isolated from clinical specimens were randomly collected at Gansu provincial Hospital from December 2016 to July 2017.The drug sensitivity were tested by disc diffusion method with 84 Staphylococcus aureus clinical isolates.By using PCR to detect the mecA gene.ebh gene of 48 randomly selected isolates in 84 isolates and general population nasal and skin isolates was were tested by PCR.Meanwhile,the positive amplification products were sequenced and compared with the online database.The detection of Staphylococcus aureus producing biofilm was performed under the same conditions using Congo red medium.Aggregation rate of Staphylococcus aureus strains was detection in human plasma.Establishing the main protein features of ebh gene positive and negative strains by using MALDI-TOF MS,the prevalence and the genetic relationship among strains were determined.Result:Randomly selected 84 strains of Staphylococcus aureus.Susceptibility results showed that all the strains have varying degrees of resistance.Initially,we screened thirty-nine strains that resisted to cefoxitin using disc diffusion method.The detection rate of MRSA with phenotypic method was 46.4%.The detection of mecA gene of 84 isolates by PCR showed that 45 were positive for mecA gene and positive rate was 53.6(45/84).Selecting 24 strains of MRSA and MSSA identified by PCR,which ebh positive strain were 19 and the total positive rate was 39.6%(19/48).Respectively,the positive rate was 45.8%(11/24)in MRSA strains;the positive rate in MSSA strains was 33.3%(8/24).The positive rate of MRSA and MSSA had no significant difference(P> 0.05).Respectively ebh gene-positive MRSA strains and negative strains were cultured in Congo red medium to screen production of biofilm,of which 17 produced biofilm in 19 ebh gene-positive strains;4 produced biofilm in11 ebhgene-negative strains.The biological typing of positive and negative strains of ebh using MALDI-TOF MS showed that the ebh-positive strains had a better genetic relationship.Conclusion: ebh gene producion may be one of virulence factors in Staphylococcus aureus,but there is no significant difference about carrying rate between MRSA and MSSA.Staphylococcus aureus ebh gene maybe not relate to the production of biofilm but closely related to bloodstream infections.The bio-typing of Staphylococcus aureus by MALDI-TOF MS revealed the variation in Lanzhou area,which provided valid data and basic information for further study on the evolution of S.aureus isolates in Gansu Province.which provided valid data and basic information for further study on the evolution of Staphylococcus aureus isolated form Gansu Province.