Which of the following is NOT a respiratory infection?

• A. Influenza
• B. Pneumonia
• C. Tetanus
• D. Bronchitis

Answer: (C)

The concept being tested is distinguishing infections of the respiratory tract from conditions that do not involve the respiratory system. Respiratory infections directly affect the airways or lungs and are usually caused by viruses or bacteria that invade the respiratory tract. Influenza involves the respiratory tract, bronchitis inflames the airways, and pneumonia is an infection of the lungs. Tetanus, on the other hand, is caused by a toxin from Clostridium tetani and primarily affects the nervous system and muscles rather than the respiratory tract. It can impact breathing only if muscle tension or spasms alter breathing, but it is not an infection of the respiratory tract itself. That’s why tetanus is not a respiratory infection.