Which group is least susceptible to infection with Salmonella enteritidis?

• A. Elderly
• B. Infants
• C. Healthy young adults
• D. Immunocompromised individuals

Answer: (C)

Understanding how host defenses affect susceptibility helps explain why healthy young adults are least likely to get infected with Salmonella enteritidis. The body's defenses against Salmonella rely on intact gastric acidity, a healthy gut barrier, and a functioning immune system. Healthy young adults typically have robust immune responses and normal stomach acid, making them better able to limit colonization and control or clear the infection if exposure occurs.

Infants have immature immune systems and less mature gut barriers, which heighten susceptibility. The elderly often experience immunosenescence and sometimes reduced gastric acidity, both of which increase risk. Immunocompromised individuals have impaired immune defenses—whether from HIV, chemotherapy, steroids, or other conditions—greatly increasing both susceptibility and the potential severity of illness.

So, among the groups listed, the healthy young adults are least susceptible to Salmonella enteritidis infection because their immune defenses and digestive barriers are typically strongest.