Multidrug-resistant TB (MDR-TB) is caused by bacteria that are resistant to at least isoniazid and rifampicin, the most effective anti-TB drugs. MDR-TB results from either primary infection with resistant bacteria or may develop in the course of a patient'streatment.Extensively drug-resistant TB (XDR-TB) is a form of TB caused by bacteria that are resistant to isoniazid and rifampicin (i.e. MDR-TB) as well as any fluoroquinolone and any of the second-line anti-TB injectable drugs (amikacin, kanamycin or capreomycin).
First case of highly drug-resistant TB found in US 2010
The strain - so-called extremely drug-resistant (XXDR) TB - has never before been seen in the U.S., according to Dr. David Ashkin, one of the nation's leading experts on tuberculosis. XXDR tuberculosis is so rare that only a handful of other people in the world are thought to have had it. Simple TB is simple to treat - as cheap as a $10 course of medication for six to nine months. But if treatment is stopped short, the bacteria fight back and mutate into a tougher strain. It can cost $100,000 a year or more to cure drug-resistant TB, which is described as multi-drug-resistant (MDR), extensively drug-resistant (XDR) and extremely drug-resistant (XXDR).