Microplate technique to determine hemolytic activity for routine typing of Listeria strains

Because the hemolysis produced by Listeria monocytogenes and Listeria seeligeri on blood agar is frequently difficult to interpret, we developed a microplate technique for the routine determination of hemolytic activity with erythrocyte suspensions. This microtechnique is a simple and reliable test for distinguishing clearly between hemolytic and nonhemolytic strains and could be used instead of the CAMP (Christie-Atkins-Munch-Petersen) test with Staphylococcus aureus in the routine typing of Listeria strains. Furthermore, our results suggest that the quantitation of the hemolytic activity of the Listeria strains, along with the D-xylose, L-rhamnose, and alpha-methyl-D-mannoside acidification tests, allows the differentiation of L. monocytogenes, L. seeligeri, and Listeria ivanovii. We also observed that the treatment of erythrocytes with crude exosubstances of rhodococcus equi, Pseudomonas fluorescens, Acinetobacter calcoaceticus, and S. aureus enhanced the hemolytic activity of all Listeria strains with this characteristic

Role of potassium tellurite and brain heart infusion in expression of the hemolytic phenotype of Listeria spp. on agar plates.

The influence of potassium tellurite (PT) and brain heart infusion agar (Difco), two components of modified Listeria selective agar medium (LSAMm), on the hemolytic phenotype of Listeria spp. was studied. L. monocytogenes and L. ivanovii displayed bigger zones of hemolysis on brain heart intusion agar compared with on Columbia agar base. The addition of PT increased the sizes of zones of hemolysis displayed by L. monocytogenes. This effect seemed to be produced by the enhancement of the cytolytic effect of listeriolysin O. PT decreased the hemolysis produced by L. ivanovii, and this effect seemed to be due to an inhibition of the sphingomyelinase C produced by this species

Neonatal mortality in puppies due to bacteremia by Streptococcus dysgalactiae subsp dysgalactiae

We report a case of bacteremia in puppies caused by Streptococcus dysgalactiae subsp. dysgalactiae. Identification was achieved by phenotypic and molecular genetic methods. This is the first report of the recovery of S. dysgalactiae subsp. dysgalactiae from dogs

Genome Sequence of Lactococcus garvieae 21881, Isolated in a Case of Human Septicemia ▿

Lactococcus garvieae is a Gram-positive bacterium considered an important opportunistic emerging human pathogen and also a well-recognized fish pathogen. Here, we present the draft genome sequence of Lactococcus garvieae strain 21881 (2,164,557 bp, with a G+C content of 37.9%), which represents the first report of a genome sequence on Lactococcus garvieae