A 1-day-old male newborn is brought to the emergency department because of fever and poor feeding for 2 hours. He became very fussy the previous evening and cried for most of the night. He was born at 36 weeks' gestation and weighed 2430 g (5 lb 3 oz) to a 21-year-old woman who came to the emergency department in active labor with ruptured membranes; she had not received adequate prenatal careHe appears irritable. His temperature is 38.6°C (101.5°F), pulse is 180/min, and blood pressure is 82/51 mm Hg. Examination shows scleral icterus. He becomes more agitated when picked up.Blood samples are obtained, and empiric antibiotics are initiated for the treatment of sepsis. Cultures on blood agar grow bacterial colonies with a narrow zone of clear hemolysis. When these bacteria are grown in the presence of Staphylococcus aureus, the zone of hemolysis is enhanced around the staphylococcal colonies. Which of the following is the most likely pathogen infecting this patient?

Question

A 1-day-old male newborn is brought to the emergency department because of fever and poor feeding for 2 hours. He became very fussy the previous evening and cried for most of the night. He was born at 36 weeks' gestation and weighed 2430 g (5 lb 3 oz) to a 21-year-old woman who came to the emergency department in active labor with ruptured membranes; she had not received adequate prenatal careHe appears irritable. His temperature is 38.6°C (101.5°F), pulse is 180/min, and blood pressure is 82/51 mm Hg. Examination shows scleral icterus. He becomes more agitated when picked up.Blood samples are obtained, and empiric antibiotics are initiated for the treatment of sepsis.  Cultures on blood agar grow bacterial colonies with a narrow zone of clear hemolysis.  When these bacteria are grown in the presence of Staphylococcus aureus, the zone of hemolysis is enhanced around the staphylococcal colonies.  Which of the following is the most likely pathogen infecting this patient?

Quizplus · Accepted Answer

Eductional Objective: Streptococcus agalactiae (group B Streptococcus), one of the most common causes of early neonatal sepsis, is typically identified by the presence of a narrow zone of beta-hemolysis when plated on blood agar.  It is also identified by the production of CAMP factor, which enhances beta-hemolysis by particular strains of Staphylococcus aureus.

A 1-Day-Old Male Newborn Is Brought to the Emergency Department