Mycobacterium avium complex (MAC) is a group of bacteria that are related to tuberculosis. These germs are very common in food, water, and soil. Almost everyone has them in their bodies. If you have a strong immune system, they don't cause problems. But they can cause serious illness in people with HIV (human immunodeficiency virus). With the right combination of medications, however, you can prevent or treat MAC. In some cases, you may need lifelong therapy.
With HIV, MAC infection usually happens only after you receive a diagnosis of AIDS (acquired immunodeficiency syndrome) and when CD4 cell counts drop below 50.
MAC is an opportunistic infection that takes advantage of a weakened immune system. It can infect one part of your body, such as your lungs, bones, or intestines. This is called localized infection. It can spread and cause disease throughout your body. This is called disseminated infection.
Symptoms of Mycobacterium Avium Complex
If MAC spreads throughout your body, you may have symptoms such as:
Many opportunistic infections can cause the same symptoms as MAC. It's important to get a diagnosis to know how best to treat it. In addition to performing a physical exam, your doctor may order lab tests to find the MAC bacteria in samples of:
These samples are allowed to grow for several weeks, called a culture. Then a health care provider checks the samples for signs of MAC.
While waiting for the results of the culture, your doctor may conduct other tests, including:
Blood tests to check for problems such as anemia
Serum alkaline phosphatase, a blood test to check for an enzyme that is often high with MAC
Computed tomography (CT) scan of your chest and abdomen to check for problems with lymph nodes or enlargement of the liver or spleen
To diagnose MAC, your doctor may also take a tissue sample and examine it under a microscope (called a biopsy).
Treating Mycobacterium Avium Complex
Even without a confirmed diagnosis, your doctor may treat you for MAC if your CD4 cell count goes below 50. You will likely receive a combination of antibiotics to prevent development of drug resistance. You may receive either clarithromycin or azithromycin and one to three other antibiotics. After the initial treatment to get the condition under control, you'll likely be given maintenance treatment, which typically lasts 12 months.