Multilocus Sequence Typing Of Staphylococcus Epidermidis On Human Skin Surface

Microorganism is the creature existing in the world with various species and large quantity,and the tens and thousands of microorganism are actively existing on and in the human body.It is hardly for people to estimate the quantity and species of bacteria which lived on the skin of human body.And it is easier to leave over on the objects while we touched on it.Thus,the microorganism becomes a new evidence to identify individual.However,there isn’t one set mature methods of forensic microorganism to extract and examine it in domestic and overseas.This paper adopted multilocus sequence typing,and chose Staphylococcus epidermis as the research object,which massively existed in the surface of human skin.First of all,we collected 101 samples from patients of skin diseases,healthy human fingers swabs and cellphone surface swabs.Then we isolated and identified Staphylococcus epidermis so as to extract DNA of bacteria strains.PCR amplified 7 pairs of housekeeping gene(arc C、aro E 、gtr E、mut S、pyr R、tpi A、yqi L)which were selected from alternative 10 housekeeping genes for S.epidermis MLST analysis,and uploaded the alignment results of test results and standard sequence to the MLST database to get the corresponding spectrum composed of 7 of housekeeping gene alleles,and finally confirm the strain allele spectrum sequence type(STs)by uploading the spectrum to the database.A method was preliminarily established for the S.epidermis MLST typing using multilous sequence typing technology,so as to explore whether the S.epidermis MLST from different individual was same or not,and whether S.epidermis could be a forensic tag to identify individual.The experiments’ results show that S.epidermis is widely spread over the surface of human skin and it is relatively stable.Eventually we obtained 53 individual ST type of S.epidermis,including 10 new ST type and 1 new allele sequence.It is proved that this method could effectively differentiate S.epidermis MLST typing from different human skin surface,and preliminarily showed that S.epidermis could be a forensic tag to be used for individual identification.Besides,experiments showed that multilocus sequence typing is an effective method for microorganism typing and the differentiate effect is high,and experiment method can be standardized,and experiment results can be showed in digital.It is very suitable for massive human investigation and comparison from different labs,and it is easy to build database,which could meet the demand of court science application.Due to the research duration is short and sample quantity is limited,it is needed to do further research in the aspect of individual specificity,geography specificity,space-time stability and rule of transfer between objects.