Iranian Red Crescent Medical Journal Iran Red Crescent Med J 2012; 14(1):53-55 ©Iranian Red Crescent Medical Journal LETTER TO THE EDITOR Prevalence of Multidrug-Resistant and Extensively Drug-Resistant Tuberculosis in Patients with Pulmo-

Tuberculosis (TB) is responsible for a large portion of morbidity and mortality worldwide. According to WHO report, tuberculosis is responsible for at least 2 million deaths per year, so 90 % of these occurring in developing countries.1,2 Recently, it has been shown that multidrug-resistance (MDR) and extensively drug-resistant tuberculosis (XDR-TB) are the most impor-tant factors cause death in patients with tuberculosis.3,4 Drug resistance of M tuberculosis has been implicated in many etiologies such as inadequate and incomplete treatment, host genetic factors and, HIV infection.5-8 The long duration of treatment, large amount of anti-TB drugs and their gastrointestinal side effects, are the most important causes of noncompliance in patients with TB.4 MDR-TB (when resistance to isoniazid and rifampicin appears in combination), increases the numbers of individuals who need treatment with sec-ond-line drugs worldwide.9,10 After developments of MDR-TB, the development of resistance to second line drugs was another problem.5 XDR-TB is a form of TB caused by bacteria that are resistant to the most effective anti-TB drugs. XDR explained by resistance to both rifampin and isoniazid, as well as to fluoroqui-nolones plus an injectable agent and Pre–XDR TB iso-lates are multidrug resistant bacilli which are resistant to either a fluoroquinolone or an injectable agent, but not both.11 Some believe that XDR-TB strains have emerged from the mismanagement of multidrug-resistant TB and once created, can spread from one person to another.7,12 TB and drug resistant tuberculo-sis is also a serious public health problem in Iran as other developing countries. According to the World Health Organization, the estimated incidence rate of TB in Iran is 28 cases per 100,000 population.2,6 In a report from Southest of Iran,among patients with PTB in Zahedan, where the incidence rate of TB is higher than other regions of Iran,16 % of patients with PTB had MDR TB.9 XDR-TB is higher in patients with MDR-TB and mortality in XDR-TB is higher tha