| Mycobacterium Avium Complex
(MAC)
What is MAC?
MAC, formerly known as MAI, stands for Mycobacterium Avium Complex.
MAC is a group of mycobacteria (the two most common being M. avium
and M. intracellulare), that cause a serious disease in people with
advanced AIDS. MAC most often causes a disseminated illness (bacteria
is spread though the blood stream) and can cause many symptoms throughout
the body.
MAC bacteria are found in air, water, soil, foods, some tobacco
products, and in many animals. It is impossible to avoid contact
with MAC bacteria. A recent study showed that person-to-person transmission
of MAC bacteria is unlikely.
Who is at risk of developing MAC?
Risk factors for developing MAC include having fewer than 50 CD4
cells, a high viral load (greater than 90,000 copies per/ml), and
having had another opportunistic infection such as CMV (cytomegalovirus).
Before HAART (Highly Active Antiretroviral Therapy), also known
as the "cocktail," the number of people with AIDS who developed
MAC reached as high as 40 percent. Since HAART, the number of people
getting MAC has greatly declined.
What are the signs and symptoms of MAC?
MAC can infect a person's entire body. The signs and symptoms of
MAC can be the same signs of other diseases. They include high fever,
drenching sweats, diarrhea, weight loss, abdominal pain, fatigue,
weakness, anemia (low levels of red blood cells), neutropenia (low
levels of white blood cells) or thrombocytopenia (low levels of
platelets), and elevated liver function tests. The liver or spleen
may be enlarged. Blood infections, hepatitis, skin lesions, and
pneumonia may also occur.
How is MAC diagnosed?
A doctor will usually give you a blood test to see if you have MAC.
Although the blood test is the best test at this time, sometimes
other tests are needed. Other tests may include stool samples and
biopsies of the liver, digestive tract (gut), bone marrow, or other
organs. Biopsies involve taking a sample of an organ using a big
needle. Biopsies can be painful but are more reliable than stool
samples.
Can MAC be prevented?
Yes, there are medications available that can help reduce one's
risk of developing MAC. Preventive medication, also called prophylaxis,
is recommended for anyone who is HIV-positive and has 50 CD4 cells
or less. While rifabutin, clarithromycin, and azithromycin are all
approved drugs for prophylaxis of MAC, clarithromycin and azithromycin
are the preferred choices. You should talk with your doctor to see
which one of these medications is best for you.
Can MAC be Treated?
Treatment for MAC involves taking a combination of antibiotics.
MAC treatment must include at least two drugs, one of which should
be either clarithromycin or azithromycin. Ethambutol is the recommended
second drug. Rifabutin, ciprofloxacin, or amikacin may be added
for people with more severe MAC. All of the drugs are pills except
amikacin, which is given intravenously (IV).
In cases where people with MAC either do not respond to treatment
at all or relapse after first responding to treatment, many doctors
recommend a type of drug test that checks to see if the medications
will work on the type of MAC a person has. This is called a drug
susceptibility test. Susceptible means that the drugs will likely
work, while resistant means that the drugs probably will not work.
Susceptibility testing is recommended mainly for clarithromycin,
azithromycin, and rifabutin, though other drugs might be tested
as well.
|
| Drug |
|
Side Effects |
|
Amikacin
(Amikin®) |
kidney problems, hearing problems, joint pain,
fever, and skin rash |
|
Azithromycin
(Zithromax®) |
headaches, nausea, vomiting, diarrhea, abdominal
pain, skin rash, and raised liver-function tests |
|
Clarithromycin
(Biaxin®) |
headaches, nausea, vomiting, diarrhea, and raised
liver-function tests |
|
Ciprofloxacin
(Cipro®) |
nausea, vomiting, diarrhea, abdominal pain, metallic
taste, and raised liver-function tests |
|
Ethambutol
(Myambutol®) |
vision problems, skin rash, headache, and general
feeling of being unwell |
|
Rifabutin
(Mycobutin®) |
skin rash, nausea, low white blood cells, low
platelets, irritation of the eye, brown/orange color change
in body fluids, and raised liver-function tests |
MAC and the drugs used for treatment are hard on the body. You
might consider visiting a nutritionist when you are first diagnosed
with MAC so you can keep your weight up and prevent wasting. There
are also medications available to help ease common MAC symptoms
such pain, nausea, vomiting, and diarrhea, so do not be shy in asking
for them.
Doctors recommend that you stay on your HAART combination while
being treated for MAC. HAART keeps HIV suppressed so that the immune
system can better control MAC.
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