American Board of Internal Medicine (ABIM) Certification Practice Exam

Which organism are immunocompromised patients at increased risk of becoming infected with?

1. Escherichia coli

2. Staphylococcus aureus

3. Vibrio vulnificus

4. Salmonella enterica

The correct answer is: Vibrio vulnificus

Immunocompromised patients are at increased risk of infection with Vibrio vulnificus primarily due to their altered immune responses. This organism is a halophilic bacterium found in warm coastal waters, and it is associated with infections that can occur from consuming raw or undercooked shellfish or through wounds exposed to seawater. For immunocompromised individuals, such as those with liver disease, diabetes, or those undergoing chemotherapy or on immunosuppressive therapy, the ability to fend off infections is significantly decreased. Vibrio vulnificus can cause severe and rapidly progressing infections, especially in those with preexisting health conditions that affect immune function. In contrast, while Escherichia coli, Staphylococcus aureus, and Salmonella enterica can also cause infections in immunocompromised patients, they are not as specifically associated with the unique risk factors presented by Vibrio vulnificus, especially in the context of seafood consumption or exposure to marine environments. Thus, the heightened risk of Vibrio vulnificus infections in these vulnerable populations makes it the correct choice in this context.