2020 Volume 69 Issue 2 Pages 205-208
The rapid identification of Streptococcus spp. using Streptococcus-positive blood culture medium is important in patients with sepsis and bloodstream infection (BSI) because these are serious conditions. In this study, we examined whether Streptococcus spp. could be rapidly differentiated by the Lancefield grouping test, pyrrolidonyl arylaminidase (PYR) test, and pneumococcal antigen test using 57 samples of blood culture medium in which Streptococcus was detected. The Lancefield grouping test was performed on 12 isolates from blood culture medium suspected of having β-hemolytic gram-positive Streptococcus. Among the 12 isolates, six were classified into group B, two into group F, and four into group G. These groups B, F, and G were identified as Streptococcus agalactiae, Streptococcus constellatus, and Streptococcus dysgalactiae, respectively, using MALDI Biotyper. Among 45 isolates from the culture medium suspected of having non-β-hemolytic gram-positive Streptococcus, 41 were confirmed to be streptococci by the PYR test and four by the pneumococcal antigen test. Among the 41 isolates that were subjected to the PYR test, 18 were identified as Enterococcus faecalis and 23 as Enterococcus faecium. Similarly, the four isolates that were subjected to the pneumococcal antigen test were identified as Streptococcus pneumoniae. In conclusion, a rapid differentiation of Streptococcus spp. using Streptococcus-positive blood culture medium may be useful for predicting β-hemolytic Streptococcus, S. pneumoniae, and Enterococcus spp. in sepsis and BSI.
