Japan - MDR-TB and XDR-TB

This study from Japan examines MDR/XDR TB. 


We are well aware that these resistant strains of TB evolve through the incorrect or incomplete treatment of TB. It would seem then that an obvious approach to reducing the incidence of MDR/XDR TB is to implement better and more complete treatment of "regular" TB. That is clearly true. However, this study postulates and presents data to support the case that more XDR/MDR TB is now being contracted through transmission, rather than by "creation".

In Japan, TB remains a major infectious disease; in 2008, a total of 19.4 cases/100,000 population were reported (6), and Japan is generally classified as a country with intermediate TB incidence. According to the most recent nationwide drug-resistance survey, the prevalence of MDR TB and XDR TB were 1.9% and 0.5%, respectively (7). Approximately one third of MDR and XDR (MDR/XDR) M. tuberculosis strains were isolated from new TB patients, implying ongoing transmission of MDR/XDR TB in Japan.

A high proportion (71%, 12/17) of the XDR strains were involved in clusters ...

... One possible explanation for the high clustering rate of XDR TB is that new cases of XDR TB are more likely to be caused by transmission than by acquisition of multiple drug resistance as a result of treatment failure. Shah et al. reported that patients with XDR TB were more likely than those without XDR TB to be infectious in terms of duration and proportion of sputum smear positivity

The conclusion is inevitable 

Because these findings and our cluster analysis suggest that the current TB control strategy is insufficient to prevent community transmission of MDR/XDR TB, more detailed investigations of MDR/XDR TB transmission based on contact tracing are urgently needed to improve the infection control strategy

Personally, I find this a little alarming. In truth, I accept the possibility of contracting "regular" TB by contact with an infected person and am reasonably relaxed that the treatment is relatively safe and effective. Knowing that I may be infected with MDR/XDR TB just as easily is somewhat worrying. The treatment for these forms of TB is much more severe and (particularly for XDR TB) has a less than perfect success rate, with failure resulting in mortality.