To the Editor: The prevalence of drug-resistant tuberculosis (TB) is a serious problem in the People's Republic of China. China is 1 of 22 countries with the highest incidence of TB (1). It is also 1 of 27 countries with the highest incidence of multidrug-resistant TB (MDR TB) and extensively drug-resistant TB (XDR TB). According to the national baseline survey on TB in 2007 and 2008, the frequency of MDR TB among pulmonary TB patients in China was 8.3%. We estimate that there are 120,000 new cases of MDR TB in China per year, which accounts for 24.0% of new cases worldwide (510,000) per year.
XDR TB has recently emerged as a global public health problem (2). It is defined as TB with resistance to at least isoniazid, rifampin, a fluoroquinolone, and 1 of 3 injectable second-line drugs (amikacin, kanamycin, or capreomycin). XDR TB is a type of MDR TB that shows resistance to isoniazid and rifampin. Recent reports on current prevalence of XDR TB (3,4) indicate that China now has the second highest incidence of MDR TB worldwide. However, there is no information available on XDR TB in China.
To obtain information on XDR TB in China, we conducted a study at Shanghai Pulmonary Hospital. It is the only specialized hospital for TB in Shanghai and plays a major role in treating TB patients and providing state-of- the-art treatment. Most patients referred to this hospital have been previously treated or have recurrent TB. Therefore, higher rates of MDR TB and XDR TB are expected in this setting, which is not comparable to community or multicenter-based studies.
Patients with culture-proven MDR TB during January 2008-June 2009 were retrospectively evaluated. All patients were HIV negative. Drug susceptibility testing was conducted for culture-positive isolates by using the BACTEC 960 System (Becton Dickinson, Franklin Lakes, NJ, USA) at concentrations of...