Fig. 2
Analysis of percent growth of invasive vs. clinical isolates of Group B Streptococcus (GBS) when cultured under increasing concentrations of zinc. GBS strains isolated from colonized patients, or patients experiencing invasive disease were grown in medium alone (Medium Alone) or increasing concentrations of zinc chloride (125 μM, 250 μM, 500 μM, 750 μM, 1000 μM, 2500 μM). Bacterial growth was measured at 24 h post-inoculation as an optical density at 600 nm absorbance (OD600). At 250, 500, 1000, and 2500 μM concentrations of zinc, invasive strains of GBS (circles) showed significantly higher percent growth compared to medium alone (as calculated by mean percent growth of three biological replicates for each strain, comparing OD600 values in each zinc concentration compared to OD600 values for each strain in medium alone). Statistical significance was determined by paired Student’s t test (n = 3 biological replicates)