OI

abbreviation,  opportunistic infection

an illness caused by a microorganism that usually does not cause disease in persons with healthy immune systems, but which may cause serious illness when the immune system is suppressed. Common OI in HIV positive people include Pneumocystis carinii pneumonia (PCP), Mycobacterium avium complex (MAC) and cytomegalovirus (CMV) infection.

Infections that are caused by agents that are frequently present in the body or environment, and can cause an infection in an immune-compromised person by an organism that does not usually cause disease in healthy people. When an individual's immune system becomes weak, these organisms may cause serious or even life-threatening illnesses.

Opportunistic Infection