<prompt> A patient presents with fever, cough with sputum and weight loss. He has a history of not completing treatment for tuberculosis thrice in the past. XDR-TB is suspected. How is XDR-Tb defined?Resistant to INH Rifampicin AmikacinResistant to INH Amikacin Ofloxacin EthambutolResistant to INH Rifampicin Amikacin OfloxacinResistant to Rifampicin Amikacin Ofloxacin  <response>: XDR-TB Extensively drug-resistant TB is defined as MDR TB Resistant to rifampicin and isoniazid Resistant to one fluoroquinolone eg. ofloxacin resistance to one injectable second line drug Amikacin or kanamycin or capreomycin. Reference: Ananthanarayan and Paniker;s Textbook of Microbiology Tenth edition 