Which of the following is the most common portal of entry for human pathogens?

• A. Respiratory tract
• B. Skin
• C. Gastrointestinal tract
• D. Genitourinary tract

Answer: (A)

Verified step by step guidance

1. Understand the concept of 'portal of entry' in microbiology: it refers to the site through which pathogens enter the host to cause infection.
2. Review the common portals of entry for human pathogens, which include the respiratory tract, skin, gastrointestinal tract, and genitourinary tract.
3. Consider the frequency and ease with which pathogens can enter through each portal. For example, the respiratory tract is constantly exposed to airborne pathogens through breathing.
4. Evaluate the protective barriers present at each portal. The skin is a strong physical barrier, making it less common as a portal of entry unless broken.
5. Conclude that the respiratory tract is the most common portal of entry because it is frequently exposed to pathogens via inhalation and has a large surface area for pathogen contact.