CAMP is the correct answer because the case is typical of Streptococcus agalactiae(Group B strep). The main presumptive identification test is CAMP. Bile solubility is positive for Streptococcus pneumonia. Coagulase would be positive for Staphylococcus aureus. PYR is positive for Streptococcus pyogenes (Group A strep) which is ruled out by the resistance to bacitracin.

Microbiology

Spinal fluid cultures on a 3-day-old infant revealed beta-hemolytic, Gram-positive cocci occurring in pairs and chains. The organism was catalase-negative and bile esculin-negative. Resistance to 0.04 U disk of bacitracin was noted. The other test necessary to identify this organism is a positive test by: