Extreme drug resistant tuberculosis (XDR-TB) or also known as extensive drug-resistant tuberculosis is multi drug-resistant tuberculosis (MDR-TB) that is resistant to three or more of the six classes of second-line drugs use for the treatment of tuberculosis. XDR-TB received widespread media attention in 2008 when a number of cases were reported in KwaZulu Natal (KZN), South Africa. This was due to a study in The Lancet that brought to light the outbreak of the highly virulent XDR-TB in KZN, South Africa.
