Having received no prenatal care, a young woman arrives at a hospital after many hours of labor and delivers a baby girl.Three days later the baby girl is listless, nursing poorly, and is running a fever.Blood cultures are done, and after 24 hours, they are Gram stained and show the presence of gram-positive cocci in pairs and short chains.Upon subculture, these form colonies that are beta hemolytic on blood agar.Further tests demonstrate that the isolate is catalase negative, resistant to bacitracin, and is CAMP test positive.What is the identification of this organism?

Question

Quizplus · Accepted Answer

The characteristics described match those of Streptococcus agalactiae, also known as group B streptococcus (GBS). GBS is part of the normal flora of the genital tract in some women, but can cause severe infections in newborns if not identified and treated promptly. The presence of beta hemolysis on blood agar and a positive CAMP test are characteristic of GBS. Resistance to bacitracin and catalase negativity also support the identification of GBS. S. pyogenes and S. pneumoniae are not beta hemolytic on blood agar, and S. aureus is catalase positive. N. meningitidis is a gram-negative diplococcus and is not beta hemolytic on blood agar.

Having Received No Prenatal Care, a Young Woman Arrives at a Hospital