Newborns with pneumonia commonly present with poor feeding and irritability, as well as tachypnea, retractions, grunting, and hypoxemia. Infections with group B Streptococcus, Listeria monocytogenes, or gram-negative rods (eg, Escherichia coli, Klebsiella pneumoniae) are common causes of bacterial pneumonia. Group B streptococci infections are most often transmitted to the fetus in utero. The most commonly isolated virus is respiratory syncytial virus (RSV).