In a small percentage of cases, the initial treatment for tuberculosis does not go as planned. The medication chosen may not work for a particular infection, or the patient's body may not absorb the medications properly. Some patients fail to take the medications as instructed. In these cases, the bacteria that cause TB may become resistant to some or all of the medications. Some people have drug-resistant TB from the start if they were infected by someone whose disease was caused by drug-resistant bacteria. People with HIV or AIDS and persons who have been treated previously are at higher risk of developing drug-resistant TB. While 100 years ago there were no drugs to cure TB, now for every TB drug, there is at least one strain of TB-causing bacteria resistant to it.
Drug-resistant TB is very difficult to treat and, in some cases, cannot be cured. It generally requires more and different medications for a longer period of treatment than drug-susceptible TB. A person with drug-resistant TB should be treated by a specialist with considerable experience in managing the disease. The medications used for drug-resistant tuberculosis include the injectable antibiotics capreomycin, kanamycin, and amikacin. The injectable drugs can cause hearing loss and balance problems. Sometimes, surgery is needed to remove areas of destroyed lung that contain germs that are inaccessible to antibiotics.
There are various levels of drug-resistant tuberculosis. Multidrug-resistant TB (MDR-TB) is resistant to the first-line drugs rifampin and isoniazid, and also may be resistant to some other anti-TB drugs. Extensively drug-resistant tuberculosis (XDR-TB) is a newly described category of TB that is resistant to fluoroquinolone (a strong antibiotic like ciprofloxacin) and capreomycin, kanamycin, or amikacin, drugs currently used for MDR-TB. XDR-TB is extremely difficult to treat. Misusing medications increases the risk of developing MDR-TB or XDR-TB. If drugs cannot be found to treat XDR-TB, it is fatal.
Tuberculosis with HIV/AIDS
Tuberculosis is particularly problematic among people with HIV and AIDS. Because these people have compromised immune systems, they are less likely to be able to keep a latent TB infection in check and more likely to have that infection progress rapidly to active TB disease. Some AIDS drugs reduce the effectiveness of drugs used to treat TB, so people with HIV who are being treated for TB may need to adjust doses, or switch to other drugs. Drug-resistant TB can be deadly in people with HIV.
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