This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Pediatrics
The MC organism causing congenital pneumonia is: 
Select and explain. 
A. Group B haemolytic Streptococcus, B. E. coli, C. Staphylococcus aureus, D. Salmonella spp
A: Group B haemolytic Streptococcus
Answer: A: Group B haemolytic Streptococcus 
Explanation: Ans. A. Group B haemolytic StreptococcusPneumonia that becomes clinically evident within 24 hours of birth may originate at 3 different times. The 3 categories of congenital pneumonia are as follows:* True congenital pneumonia* Intrapartum pneumonia* Postnatal pneumoniaTrue congenital pneumonia is already established at birth. It may become established long before birth or relatively shortly before birth. Transmission of congenital pneumonia usually occurs via 1 of 3 routes:Hematogenous, Ascending and Aspiration. Group B Streptococcus (GBS) was the most common bacterial isolate. Other isolates include Nontypable Haemophilus influenzaeOther gram-negative bacilli, Listeria monocytogenes, EnterococciAnd Occasionally, Staphylococcus aureus and rarely, Mycoplasma pneumoniae