There’s a strong traditionof tuberculosis research at the University of Leicester, so we’re very interested in reports of a “virtually untreatable” form of TB which has now emerged, according to the World Health Organization (WHO). Extreme drug resistant TB, XDR-TB, has been seen worldwide, including the US, Eastern Europe and Africa. WHO tuberculosis experts have convened in Johannesburg, South Africa, to discuss how to address the problem. Multi-drug resistant TB or MDR TB, is due to strains of Mycobacterium tuberculosis which are resistant to at least two of the main first-line TB drugs, is already a growing concern. XDR-TB is defined as strains which are resistant to all the current the front-line drugs, but also three or more of the six classes of second-line drugs. In a few rare cases, a strain resistant to all currently available drugs have been seen. A recent survey of 18,000 TB samples by CDC and the WHO between November 2004 and November 2005 found 20% of them were multi-drug resistant and a further 2% were extreme drug resistant. In the US, 4% of all MDR TB cases met the criteria for XDR-TB; in South Korea, the figure was 15%. In eastern Europe, 19% of all multi-drug resistant cases were extreme drug resistant too.
Current concerns centre on South Africa, where in Kwazulu-Natal, 53 patients have been found with XDR-TB. Of these, 52 died within 25 days, and 44 were also found to be HIV positive. XDR-TB could have a bigger impact on developing nations, especially in Africa, because of the prevalence of HIV.
MicrobiologyBytes will be following this news closely as the story develops.