Fact Sheet Number 509
(Mycobacterium Avium Complex)
- WHAT IS MAC?
- HOW DO I KNOW IF I HAVE MAC?
- HOW IS MAC TREATED?
- CAN MAC BE PREVENTED?
- DRUG INTERACTION PROBLEMS
- THE BOTTOM LINE
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PrintMycobacterium Avium Complex (MAC) is a serious illness caused
by common bacteria. MAC is also known as MAI (Mycobacterium Avium
Intracellulare). MAC infection can be localized (limited to one
part of your body) or disseminated (spread through your whole
body, sometimes called DMAC). MAC infection often occurs in the
lungs, intestines, bone marrow, liver and spleen.
The bacteria that cause MAC are very common. They are found
in water, soil, dust and food. Almost everyone has them in their
body. A healthy immune system will control MAC, but people with
weakened immune systems can develop MAC disease.
Up to 50% of people with AIDS may develop MAC, especially if
their T-cell count is below
50. MAC almost never causes disease in people with more than 100
T-cells.
IF I HAVE MAC?
The symptoms of MAC can include high fevers, chills, diarrhea,
weight loss, stomach aches, fatigue, and anemia (low numbers of
red blood cells). When MAC spreads in the body, it can cause blood
infections, hepatitis, pneumonia, and other serious problems.
Many different opportunistic infections can cause these symptoms.
Therefore, your doctor will probably check your blood, urine,
or saliva to look for the bacteria that causes MAC. The sample
will be tested to see what bacteria are growing in it. This process,
called culturing, can take several weeks. Even if you are infected
with MAC, it can be hard to find the MAC bacteria.
If your T-cell count is less than 50, your doctor might treat
you for MAC, even without a definite diagnosis. This is because
MAC infection is very common but can be difficult to diagnose.
The MAC bacteria can mutate and develop resistance to some of
the drugs used to fight it. So doctors use a combination of antibacterial
drugs (antibiotics) to treat MAC. At least two drugs are used:
usually azithromycin or clarithromycin plus up to three other
drugs. MAC treatment must continue for life, or else the disease
will return.
People react differently to anti-MAC drugs. You and your doctor
may have to try different combinations before you find one that
works for you with the fewest side effects.
The most common MAC drugs and their side effects are:
- Amikacin (Amkin®): kidney and ear problems; taken as
an injection.
- Azithromycin (Zithromax®): nausea, headaches, vomiting,
diarrhea; taken as capsules or intravenously.
- Ciprofloxacin (Cipro® or Ciloxan®): nausea, vomiting,
diarrhea; taken as tablets or intravenously.
- Clarithromycin (Biaxin®): nausea, headaches, vomiting,
diarrhea; taken as capsules or intravenously. Note: The maximum
dose of Biaxin is 500 milligrams twice a day.
- Clofazimine (Lamprene®): pain or tingling in hands and
feet, nausea, vomiting, can turn skin orange; taken as capsules.
- Ethambutol (Myambutol®): nausea, vomiting, vision problems.
- Rifabutin (Mycobutin®): rashes, nausea, anemia.
The bacteria that cause MAC are very common. It is not possible
to avoid being exposed. However, there are drugs that can stop
MAC disease from developing in up to 50% of people.
The antibiotic drugs azithromycin and clarithromycin have been
used to prevent MAC. These drugs are usually prescribed for people
with less than 75 T-cells.
Combination antiviral therapy can make your T-cell count go
up. If it goes over 100 and stays there for 3 to 6 months, it
might be safe to stop taking medications to prevent MAC. Be
sure to talk with your doctor before you stop taking any of your
prescribed medications.
DRUG INTERACTION PROBLEMS
Most of the drugs used to treat MAC interact with many other
drugs, including antiviral drugs, antifungal drugs, and birth
control pills. Be sure your doctor knows about all the medications
that you are taking so that all possible interactions can be considered.
MAC is a serious disease caused by common bacteria. MAC can cause
serious weight loss, diarrhea, and other symptoms.
If you develop MAC, you will probably be treated with azithromycin
or clarithromycin plus one to three other antibiotics. You will
have to continue taking these drugs for life to avoid a recurrence
of MAC.
People with 75 T-cells or less should talk with their doctors
about taking drugs to prevent MAC.
Revised November 22, 2000
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