This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'When neonatal meningitis is caused by streptococci, they usually are: \nSelect and explain. \nA. Streptococcus pyogenes (Group A), B. Streptococcus Agalactiae (Group B), C. Streptococcus Sanguis (Viridans), D. Streptococcus pneumoniae (Serotype B)', 'role': 'user'}, {'content': "Answer: B \nExplanation: Neonatal sepsis and meningitis is usually caused by Group B streptococci (Streptococcus agalactiae). The organism infects the neonate from the mother's vaginal flora (about 20% of women carry group B streptococci) during vaginal delivery. Group B streptococci give a positive reaction in the cAMP test, where there is a zone of complete hydrolysis when it is inoculated perpendicular to the streak of S. aureus. Ref: Thilo E.H., Rosenberg A.A. (2012). Chapter 2. The Newborn Infant. In W.W. Hay, Jr., M.J. Levin, R.R. Deterding, J.J. Ross, J.M. Sondheimer (Eds), CURRENT Diagnosis & Treatment: Pediatrics, 21e.", 'role': 'assistant'}]