[Investigation on the identification accuracy for group B Streptococcus by automated identification system RAISUS]

Since we had experienced a case of misidentification for group B Streptococcus (GBS) (Streptococcus agalactiae) by automated identification system RAISUS, we have investigated the identification accuracy for GBS by automated identification system RAISUS system using our stock isolated of GBS. Among 31 strains including standard strain ATCC13813 of GBS, 30 strains were identified as GBS, while only 1 strain was misidentified as Streptococcus constellatus. We have needed 3 hours to identify 29 true GBS strains, while it has taken 6 hours for misidentified strain as S. constellatus. Since we have needed more than 4 hours for our misidentified strain of GBS, the tendency for identification time to become long has been recognized. Longer identification time might be associated with the misidentification. The improvement for galactose and glycerol tests of RAISUS by the manufacturer has resulted in better identification. As for the strains to be identified as S. constellatus by RAISUS, we might re-check it with other identification kits when there is higher clinical necessity.