Tuberculosis that is resistant to three drugs, isoniazid rifampicin and ofloxacin, and no other drugs is not extensively resistant and is classified as pre-existing extensive drug resistance. The definition of extensively drug-resistant TB refers to TB patients infected with Mycobacterium tuberculosis that has been confirmed by in vitro testing to be resistant to drugs from the quinolone class (e.g. moxifloxacin, ofloxacin, etc.) in addition to isoniazid and rifampicin and to any of the three second-line injectable medications (e.g. amikacin, colchicine, etc.). Ofloxacin is a quinolone, and if it is resistant only to isoniazid, rifampicin, and quinolones and not to any of the 3 second-line injectable drugs, it is considered clinically to be in the preexisting phase of extensive resistance. To treat such patients, drug sensitivity testing is required, trying not to choose drugs from the original failed regimen, not choosing cross-resistant drugs, and trying to choose a new generation of quinolones containing at least four second-line sensitive drugs. Drug-resistant tuberculosis patients need to consult a regular hospital in a timely manner, and change drugs under the guidance of physicians without delay.