A 2-year-old presents in winter with the first episode of wheeze, preceded by 2 days of rhinorrhea and low-grade fever. Auscultation reveals widespread fine crackles and wheeze. SpO2 is 93% on room air. The most likely pathogen is:
- A Streptococcus pneumoniae
- B Respiratory syncytial virus (RSV) ✓
- C Parainfluenza virus
- D Mycoplasma pneumoniae
Correct answer: B. Respiratory syncytial virus (RSV)
Explanation
Bronchiolitis is predominantly caused by RSV (60–80% of cases), occurring in epidemic winter outbreaks, affecting children under 2 years with the first episode of viral wheeze, and characterized by the clinical picture of rhinorrhea progressing to wheeze and fine crepitations. SpO2 <94% and feeding difficulty are indications for hospitalization. Parainfluenza causes croup (barking cough, stridor) predominantly. Mycoplasma pneumoniae causes atypical pneumonia in older children. S. pneumoniae causes lobar/segmental consolidation.
Reference: Ghai Essential Pediatrics, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.