MAC stands for Mycobacterium avium complex, which is sometimes also called Mycobacterium avium intracellulare (MAI). It is caused by at least two different bacteria: Mycobacterium avium and Mycobacterium intracellulare. These bacteria can get inside certain cells in your body. Because they hide in your body’s cells, they can be very hard to treat.The bacteria that cause MAC are in the same family as those that cause tuberculosis (TB). MAC can not be passed from one person to another. MAC bacteria can be found in soil and water. Probably most people have been exposed to MAC, but they do not get sick from it. Their immune systems are strong enough to fight it off. But when your immune system is damaged, MAC can cause infection. 
 

   Symptoms

Mac can be found in many parts of the bodies of people who have AIDS. This is called disseminated MAC infection. The most common symptoms of MAC infection are persistent fever and tiredness, accompanied by night sweats, loss of appetite, abdominal pain (belly), and chronic diarrhea. It can also cause serious weight loss, swollen lymph glands, an enlarged spleen and liver, and anaemia.
 

   Diagnosis

   When you visit your doctor, you will be asked if you have any problems or symptoms. If you report symptoms that sound typical of MAC infection, and if your T4 cell count is below 100, your doctor may order some lab tests. There are two blood tests that can be done to check for MAC infection. The first test can show if your blood sample contains bacteria from the family Mycobacteria. But it can not tell the difference between MAC and other Mycobacteria, including the one that causes tuberculosis.The second test used is a blood culture. The lab will put a sample of your blood in a dish and watch to see if MAC will grow. It can take several weeks to get results. Because MAC can be a serious illness, doctors almost always recommend treatment as soon as they think you have it. Your doctor can always change the treatment if the results show that something else is causing your symptoms.
 

   Prevention


   The risk of developing MAC increases if your T4 cell count is below 50. You may be able to reduce the risk of getting MAC by taking special care in preparing foods. Wash and peel all fruit and vegetables carefully. The Food and Drug Administration in the USA says to “boil it, peel it, cook it, or forget it.” These precautions can help you avoid other germs as well. See the sections on water safety and food safety for more information.

The drug rifabutin (Mycobutin) cuts the risk of getting MAC in half for people with T4 counts below 100. If you have fewer than 100 T4 cells, you may want to talk to your doctor about rifabutin.

The most common side effects are nausea, abdominal pain (belly), and skin rash. Very rarely reported side effects are muscle and joint aches. A rare but serious side effect is neutropenia. If you take rifabutin, your doctor will check your white blood cells regularly. The urine (pee), faeces (shit), saliva (spit), sweat, tears, and skin of people who take rifabutin may be coloured orange or brown. Soft contact lenses may be permanently stained.The most common dose of rifabutin is 300 mg per day. When taken at doses of 600 mg per day, rifabutin can cause an eye condition called “uveitis.” Uveitis is not a dangerous condition but is painful and irritating. It is usually treated with eye drops containing anti-inflammatory steroids, and by stopping rifabutin for a week or two.

Once the uveitis is cleared up, if you want to take rifabutin again, your doctor may recommend taking a lower dose.Rifabutin interacts with some other drugs. For example, it can decrease the action of AZT, and ketoconazole (Nizoral, so you may have to increase your dose of these drugs. Fluconazole (Diflucan) can increase or decrease rifabutin levels in your body. Rifabutin also interacts with birth control pills ( they do not work as well), and with methadone (you have to take more methadone or you may go into withdrawal).
 

   Treatment 


   Treatment for MAC infection is lifelong. Once the infection has been brought under control, it requires treatment to permanently keep the bacteria from making you sick again. Combinations of several different antibiotics are the usual treatment for MAC infection. For example, you may be given clarithromycin (Biaxin) or azithromycin (Zithromax),  plus ethambutol, and rifabutin. Other antibiotics that may be used are rifampin, clofazimine, ciprofloxacin, ethambutol, and amikacin. The choice of drugs depends on how well you tolerate them, which drugs are most effective for you, and how expensive they are. Clarithromycin and azithromycin are relatively new drugs, and they are very expensive. Provincial or territorial drug programs and many private drug insurance programs may not pay for these drugs for people with MAC. One month’s supply can cost hundreds of dollars. 

The most commonly reported side effects from the antibiotics used to treat MAC are nausea and vomiting, diarrhea, abdominal pain (belly), and rashes. Because you usually take two or more of these drugs at the same time, it’s hard to tell which is causing which drug side effect. It can take a month or more before you will know if the drugs are clearing up the infection.

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