Which of the following is a common viral pathogen responsible for upper respiratory infections?

• A. Streptococcus pneumoniae
• B. Rhinovirus
• C. Mycobacterium tuberculosis
• D. Escherichia coli

Answer: (B)

The main idea is that upper respiratory infections are most often caused by viruses, and rhinovirus is the most common viral pathogen behind the common cold. This small, non-enveloped RNA virus in the picornavirus family has many serotypes, which is why people can get colds repeatedly. It thrives in the cooler temperatures of the nasal passages, helping it target the upper airway and produce typical URI symptoms like runny nose, congestion, and sore throat. The other organisms are bacteria or are associated with different diseases (for example, Streptococcus pneumoniae with sinusitis or pneumonia, Mycobacterium tuberculosis with tuberculosis, Escherichia coli as a gut-associated bacterium), not the typical viral cause of common URIs.