You are a third year medical student working in the pediatric emergency room when you are asked to see a 10 day old infant with a fever. 

You arrive to meet Carole and her new daughter Lucy. Carole explains that for the last couple of days, Lucy has been very sleepy and hasn’t been breast-feeding as much. This morning, Lucy woke with a fever of 39.3°C at which point, Carole got concerned and brought Lucy to the emergency room.

You have a look at Lucy’s most recent vitals which are as follows:

HR-120bpm

BP-70/45

RR-30

SpO2-98% on room air

Temperature-38.7°C

Which of the following are most likely in your differential diagnosis for a fever in a 10-day old neonate?