By Tim Horn Microbiological Tests Microbiological tests are often recommended by a doctor when an HIV-infected patient has symptoms of a specific opportunistic infection. For example, a doctor might order a Mycobacterium avium microbiology test for a patient experiencing unexplained fever, weight loss, and anemia.
Some microbiological tests require body fluids other than blood.
Patients who are thought to have an infection in their brain may need to have microbiological tests of their spinal fluid, which requires a procedure called a lumbar puncture or spinal tap. Unlike microbiological tests, which look for the presence of a disease-causing microorganism, serologic tests most often look for specific antibodies produced by the immune system. Also unlike microbiology tests, serology tests are extremely useful to determine if someone has been exposed to an infection before they begin showing signs of disease. HIV antibody testing also allows patients to find out their status many years before they get sick, thus allowing them to start medications to treat HIV and prevent opportunistic infections early. Between 15 to 40 percent of people living with HIV have antibodies to Toxoplasma gondii, the protozoan responsible for causing toxoplasmosis.