HIV & AIDS Health Center

HIV, AIDS, and Mycobacterium Avium Complex

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.

How Mycobacterium Avium Complex Develops

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:

• High fever or chills
• Night sweats
• Abdominal pain
• Diarrhea
• Weight loss
• Fatigue
• Swollen glands
• Low numbers of red blood cells (called anemia)

You may develop other problems as well, such as:

• Blood infections
• Hepatitis
• Pneumonia

Diagnosing Mycobacterium Avium Complex

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:

• Blood
• Urine
• Bone marrow
• Tissue

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).