A 2-day-old boy is evaluated in the nursery due to difficulty breathing for the past hour. The patient was born at 40 weeks gestation via spontaneous vaginal delivery to a woman, gravida 1 para 1. The mother labored for 6 hours at home. Rupture of membranes occurred 2 hours prior to delivery, and the fluid was clear. The patient was born in triage just after the parents arrived at the hospital. No medications were given prior to delivery. The pregnancy was complicated by urinary tract infection due to Streptococcus agalactiae in the second trimester. The patient was initially well-appearing and roomed in with his parents, but over the past hour, he has developed respiratory distress. Temperature is 37.5 C (99.5 F) and respirations are 70/min. Oxygen saturation is 91%. The patient is grunting, and nasal flaring and intercostal and subcostal retractions are seen. Chest auscultation demonstrates diffuse crackles. Heart examination is normal. Chest x-ray reveals bilateral, patchy, alveolar densities with pleural effusions. Which of the following is the most likely diagnosis in this patient?
Neonatal group B Streptococcus infection | |
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GBS = group B Streptococcus. | |
This neonate who developed respiratory distress in the first week of life after being initially well has chest x-ray findings of alveolar densities and pleural effusions. These findings are consistent with bacterial pneumonia.
The most common cause of early-onset (age <7 days) neonatal pneumonia is Streptococcus agalactiae or group B Streptococcus (GBS), a gram-positive bacterium that can colonize the maternal genital tract and infect infants on exposure to their mucosal membranes or lungs. This at-risk mother (eg, GBS urinary tract infection during pregnancy) did not receive intrapartum antibiotic prophylaxis due to the rapid delivery, increasing the risk for neonatal GBS infection.
GBS most commonly causes neonatal sepsis but can present with pneumonia in a minority of cases. Symptoms typically develop within hours to days of birth and include respiratory distress (eg, tachypnea, nasal flaring, retractions) and hypoxia. Temperature instability (ie, hypothermia, fever) may be present. Clinical presentation is nonspecific because neonatal meningitis and sepsis can present similarly, but classic chest x-ray findings (eg, diffuse alveolar densities with pleural effusions) confirm the diagnosis.
Empiric treatment of pneumonia in a newborn is ampicillin and gentamicin. If GBS is isolated from the blood (ie, pneumonia and bacteremia), coverage can be narrowed to penicillin G alone.
(Choice B) Meconium aspiration syndrome presents at birth with respiratory distress. Chest x-ray reveals linear or patchy densities and hyperinflation. This patient was initially well and had clear, rather than meconium-stained, amniotic fluid, making this diagnosis unlikely.
(Choice C) Pulmonary hypoplasia leads to respiratory distress immediately after birth. In addition, it is usually associated with oligohydramnios or congenital diaphragmatic hernia; neither was present in this patient.
(Choice D) Respiratory distress syndrome is caused by surfactant deficiency, and chest x-ray findings may look similar to those of bacterial pneumonia. However, respiratory distress and cyanosis present within hours, not days, after birth and typically affect premature, not term, newborns.
(Choice E) Transient tachypnea of the newborn is a self-limited condition that presents at birth (not age 2 days) with respiratory distress. In addition, chest x-ray reveals fluid in the interlobar fissures and perihilar vascular markings, not alveolar densities.
Educational objective:
Group B Streptococcus (S agalactiae) is the most common pathogen in early-onset (age <7 days) neonatal pneumonia. Symptoms include respiratory distress (eg, retractions, tachypnea) and hypoxia, and chest x-ray reveals diffuse alveolar opacities, often with pleural effusions.