microbiology research (newborn complications)

In my study this child was born with left diaphragmmatic hernia.after surgery required intubation  and continuos respiratory support. 24hr period  bulgin anterior  fontanelles,increased resp. and heart rate.flucuation of b/p and difficulties maintaining adequate tissue perfusion and (WBC) increased from 6,000 to 13,700/ul. the child had a focal seizureas as well. (CSF)examination showed 3,900 WBC/ul w/ 92% neutrophils,glucose of 2 mg/dl and protein of 350 mg/dl. Gram stain of the childs CSF revealed Gram-positive cocci.

I trying to fiqure out what is the most likely organism causing this infection?