American Board of Internal Medicine (ABIM) Certification Practice Exam

What prophylaxis should be considered for patients with HIV/AIDS with CD4 cell counts less than 200/µL?

1. Pneumocystis jirovecii

2. Cytomegalovirus

3. Toxoplasma gondii

4. Mycobacterium avium complex

The correct answer is: Pneumocystis jirovecii

For patients with HIV/AIDS who have a CD4 cell count of less than 200/µL, prophylaxis against Pneumocystis jirovecii pneumonia (PCP) is essential due to the significant risk of this opportunistic infection. The immune system is severely compromised at this level of CD4 count, which makes individuals highly susceptible to infections that a healthy immune system would typically control effectively. Pneumocystis jirovecii is a fungus that causes pneumocystis pneumonia, a severe and often life-threatening infection in immunocompromised individuals, particularly those with HIV/AIDS. The initiation of prophylaxis—typically with trimethoprim-sulfamethoxazole (TMP-SMX)—when the CD4 count drops below 200/µL helps reduce the incidence of PCP and improves outcomes in HIV-infected patients. In terms of other conditions mentioned, while patients with CD4 counts below 200/µL are also at risk for diseases caused by Cytomegalovirus, Toxoplasma gondii, and Mycobacterium avium complex, the specific guideline for initiating prophylaxis prioritizes Pneumocystis jirovecii, as it is directly related to the CD4 count category. Pro