Drug-resistant tuberculosis: a worldwide epidemic poses a new challenge

Abstract

Background: Although the incidence of tuberculosis (TB) in Germany is now declining, the world as a whole faces the threat of a catastrophe that will also affect the industrialized nations. The main reason, aside from TB/HIV co-infection, is the increase of resistant TB strains. The situation is already serious because of the spread of multidrug-resistant TB, i.e., TB that is resistant to the two most important antituberculous drugs, and is being further aggravated by resistance to second-line drugs as well.

Method: Selective review of the literature.

Results: There are an estimated half a million cases of multidrug-resistant TB worldwide, and so-called extensively resistant TB (XDR-TB), with additional resistance to defined second-line drugs, is now prevalent in more than 45 countries. An accurate assessment of the situation is hampered by a widespread lack of laboratory capacity and/or proper surveillance. The problem is mainly due to inappropriate treatment, which may have many causes, but is theoretically avoidable. Aside from programmatic weaknesses, a lack of diagnostic and therapeutic tools causes difficulties in many countries.

Discussion: Only rapid and internationally concerted action, combined with intensified research efforts and the support of the affected nations, will be able to prevent the development of a situation that will no longer be manageable even with 21(st)-century technology.

Figure 1

WHO estimates of the incidence of tuberculosis (all types) per 100 000 population per year in the world population for the year 2007, reprinted with the kind permission of the WHO (modified from [4]).

Figure 2

The development of resistance to the five first-line anti-tuberculosis drugs used in Germany from 2002 to 2007; resistance rates in percent (according to [3]). From 2001 onward, the resistance test results were entered into a registry as required by the German Infection Protection Act. The numbers of bacterial strains tested were: 4691in 2002, 4464 in 2003, 4067 in 2004, 3886 in 2005, 3618 in 2006, and 3242 in 2007; ^*1 Resistance to any one of the first-line drugs isoniazid, rifampicin, pyrazinamide, ethambutol, and streptomycin

Figure 3

The estimated percentage of multidrug-resistant (MDR) tuberculosis in newly diagnosed and not previously treated tuberculosis patients worldwide, by region, from 1994 to 2007 (overall percentage, 2.9%); reprinted with the kind permission of the WHO (modified from [1])

eFigure

45 countries with confirmed cases of XDR tuberculosis (by February 2008; the number rose to 55 countries by the end of 2008). Each red point stands for a country in which XDR tuberculosis has been detected. Reprinted with kind permission of the WHO