Abstract:

Objective To compare the sensitivity and specificity in identifying coagulase negative staphylococcus(CNS) between Vitek32 microbic system and 16S rRNA sequence analysis. Methods 70 strains of CNS isolated from Intensive Care Unit(ICU) the time period from during December 2004 through November 2006 were chosen to perform convention bacilliculture, then they were classified as Vitek32 microbic system and 16S rRNA sequence analysis, and the superiority and shortage of these two identification methods were compared. Results The identifying results were divided into three groups according to Vitek32 system standard. Group Ⅰ,'unacceptable group' %id<80, had 25 strains; Group Ⅱ,'acceptable group'%id 80～90, had 35 strains; and Group Ⅲ,'Good group'%id 90～98, had 10 strains. The standard strain was the Staphylococcus aureus(ATCC29213). All these strains were carried out 16S rRNA gene sequencing respectively. The coincidence rates of group Ⅰ, group Ⅱ and group Ⅲ using these two methods were 64%, 74.3% and 100%, respectively. The overall coincidence rate was 74.4%. Conclusion 16S rRNA sequence analysis could make up the limitation of Vitek32 system in identifying CNS. It will play an important role in identifying the microorganisms that are difficult to culture or those could not be cultured.

Key words: the automatic microorganism analyzer, sequence analysis, coagulase negative staphylococcus(CNS)