Seven-week-old infant in respiratory distress

Alexandre, 7 weeks old and born at term, is brought to the emergency department by his parents on a January evening. For three days he has had copious rhinorrhea and a cough; since yesterday he has been drinking less than half his usual bottles and has wet only two diapers in twelve hours. Initial assessment: rectal temperature 38.2 °C, respiratory rate 68/min, heart rate 176/min, SpO2 93% on room air. The nurse notes intercostal and subcostal retractions, nasal flaring and expiratory grunting; auscultation reveals diffuse fine crackles and wheezes. Thirty minutes later the infant is far less agitated, his respiratory rate is 40/min and his heart rate 92/min. The parents are relieved that he is "finally resting" and ask when the antibiotic and the chest X-ray will be ordered.