MAC is treated using a combination of drugs called antibiotics. As with HIV, in which three drugs are used to help prevent resistance and keep viral load undetectable, MAC must be treated with a combination of drugs to maintain control over the infection.
It can take between two to eight weeks for a patient with MAC to start feeling better upon starting treatment. Because of this, MAC is often treated in a hospital, where resources are readily available to help manage symptoms such as weight loss, fever, and dehydration.
Almost always, MAC combination therapy includes the following drugs:
Clarithromycin (Biaxin): This antibiotic is extremely effective against MAC. An alternative to clarithromycin is azithromycin (Zithromax). Clarithromycin has been studied more extensively than azithromycin and appears to result in more rapid clearance of MAC from the blood. However, azithromycin is considered to be an excellent substitute, when drug interactions or side effects prevent someone from taking or continuing clarithromycin treatment. Both clarithromycin and azithromycin can cause nausea, headaches, vomiting, and diarrhea. Experts recommend testing blood samples from people with MAC to determine whether the bacteria is susceptible to clarithromycin and azithromycin.
Ethambutol (Myambutol): This antibiotic is active against MAC, but not powerful enough to be used on its own. As a result, it is almost always combined with either clarithromycin or azithromycin. Side effects include nausea, vomiting, and vision problems.
To help prevent drug resistance and increase the potency of anti-MAC therapy, a third and sometimes a fourth antibiotic are often recommended by doctors. Rifabutin (Mycobutin) has been shown to be effective, but may cause negative drug interactions with other drugs, particularly the protease inhibitors or non-nucleoside analogues used to treat HIV. Other options include the injectible antibiotics amikacin (Amikin) and streptomycin.
If an HIV-positive person is diagnosed with MAC, he or she may be required to continue therapy for life. This is necessary to prevent MAC from returning. In some cases, anti-HIV therapy can help improve the health of the immune system. If the immune system improves significantly, stopping MAC therapy is possible. In other words, if an HIV-positive person with a history of MAC is able to increase his CD4 cell count to above 100, using anti-HIV treatment, for at least six months, he or she may be able to stop MAC therapy.
Pregnant women should not take clarithromycin as either a prophylaxis or treatment for MAC. Azithromycin is recommended as primary prophylaxis for pregnant women, and pregnant women with disseminated MAC infection should be treated with azithromycin plus ethambutol and continue with this treatment as secondary prophylaxis.
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