Which among the following is the most common cause of early-onset sepsis in neonates?

Early-onset infection (< 3 days) is most often caused by group B beta-hemolytic streptococci (GBS) and gram-negative enteric pathogens (most commonly E coli). Other organisms to consider are non-typeable Haemophilus influenzae, Enterococcus, Staphylococcus aureus, other streptococci and Listeria monocytogenes. Late-onset sepsis (> 3 days of age) is caused by coagulase-negative staphylococci (most common in infants with indwelling central venous lines), S aureus, GBS, Enterococcus, and gram-negative organisms, in addition to Candida species. 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.