The rapid molecular identification of 16 common coagulase negative Staphylococcus
Objective To establish the rapid molecular diagnosis of 16 common coagulase negative Staphylococcus(CNS).Methods DNA sequencing of 16 CNS would be obtained with gap gene.After the alignment gap gene sequences which were available in the GenBank,the bacteria were identified with homological alignment and phylogenetic tree,and compared with the 16S rRNA gene.Results The sequence similarity of the gap sequences ranged from 39% to 98% in 16 CNS.There were the highest similarity (98%) between S.hominis and S.hominis subsp,and the lowest(39% ) between S.saprophyticus and S.xylosus.The sequence similarity of the 16S rRNA sequences ranged from 96 to 98%,at least two species of bacteria similar rate of 99% and the most four species similar rate of 99%.Phylogenetic homology analysis showed that it was a high confidence(99% ) in the detection ofS.xylosus and S.lentus,S.chromogenes and S.intermedius,S.hominis and S.hominis subsp,but for 10 other species of bacteria,gap homology analysis has less unreliable confidence(49%,56% ) and 16S rRNA has more unreliable confidence(43%,43%,50%,56%,63%,65%,76% ).Conclusion Analysis of gap sequence could identify 16 CNS timely and accurately,with higher confidence than 16S rRNA. 
 
Key words: 
Coagulase negative Staphylococcus;  Homology analysis;  16S rRNA ; gap gene