Color Plate 26 • shows the Gram stain of a blood culture on a 23-year-old pregnant woman who presented with fever and flulike symptoms in her ninth month. The isolate on blood agar produced small, translucent beta-hemolytic colonies. Which of the following is the most likely etiologic agent in this case?

A) Streptococcus pneumoniae
B) Staphylococcus aureus
C) Escherichia coli
D) Group B Streptococcus
E) Haemophilus influenzae