What is the most common opportunistic infection found in HIV patients?

Pneumocystis jiroveci pneumonia (PCP) is indeed the most common opportunistic infection in patients with HIV, particularly in those with a CD4 count below 200 cells/mm³. This organism is a fungus that can cause severe pneumonia in immunocompromised individuals, making it a hallmark infection associated with advanced HIV disease.

The risk factors for developing PCP in HIV patients include low CD4 counts, particularly when they fall below the threshold of 200 cells/mm³, which diminishes the body's immune response and allows opportunistic pathogens to take hold. Prophylaxis with medications such as trimethoprim-sulfamethoxazole is often recommended for patients with HIV who have such low CD4 counts to prevent this infection.

While other infections, such as Cytomegalovirus, Toxoplasmosis, and Mycobacterium avium complex, are also significant concerns in the context of HIV, they do not occur as frequently as PCP does in the same population. Cytomegalovirus is often associated with retinal infection, Toxoplasmosis is more related to CNS involvement, and Mycobacterium avium complex typically manifests later in the disease progression when the immune system is severely compromised. Thus, PCP