Drug resistance in pulmonary tuberculosis in Istanbul.

Antituberculosis drug resistance, especially multidrug resistance, is a major factor threatening the success of tuberculosis control programs [1]. To date, no antituberculosis drug resistance surveys have been conducted in Turkey, although high resistance rates have been reported from various hospital-based studies [2, 3]. The aim of the present study was to determine the rate of drug resistance in patients with pulmonary tuberculosis in Istanbul during 1999. In Turkey, a vertical tuberculosis control program structure exists, which is based on self-treatment in public dispensaries. There are 24 dispensaries in Istanbul, and sputum samples from patients registered in these dispensaries are sent to the Central Microbiology Laboratory of the Istanbul Union Against Tuberculosis. In this laboratory, each sputum sample is processed using a 4% NaOH digestion-decontamination method, inoculated onto Lowenstein-Jensen slants as the stand-alone medium, and then incubated at 37°C for 8 weeks. All culturepositive specimens are tested routinely for susceptibility to isoniazid, rifampicin, streptomycin, and ethambutol. Susceptibility testing is performed using the indirect proportion method on Lowenstein-Jensen medium, as described by Canetti et al. [4]. The following drug concentrations are used to distinguish resistant isolates from susceptible isolates: isoniazid, 0.2 ∝g/ml; streptomycin, 5 ∝g/ml; rifampicin, 40 ∝g/ml; ethambutol, 2 ∝g/ml. Drug resistance is defined as growth on a drug-containing medium that is greater than 1% of that on the control medium.