A 5-month-old infant presents in the winter months with wheezing, rapid respirations (>45 breaths/min), and chest retractions. The patient has a 2-day history of rhinorrhea and low-grade fever. Breath sounds are normal, and there is no cyanosis.
Question
What test can confirm the most likely diagnosis?
1 Chest X-ray
2 Immunofluorescence of nasal secretion
3 Gram stain of the sputum
4 Blood gas analysis
5 Complete blood count with differential