Drug-resistant tuberculosis is increasing day by day and is a significant t
hreat to tuberculosis control because there are few drugs effective against
Mycobacterium tuberculosis. This study evaluates the resistance of the mic
roorganism to primary anti-tuberculosis drugs over the 21-y period 1976-97.
Records from the bacteriology laboratory of the Department of Chest Diseas
es and Tuberculosis, Ankara University Medical Faculty were evaluated retro
spectively. Among 3,418 mycobacteria strains, 3,319 (97.1%) M, tuberculosis
were isolated and their susceptibility was examined by the proportion meth
od in Loewenstein-Jensen medium. It was found that 60.8% of isolated strain
s were susceptible, whereas 39.2% were resistant to at least one drug. Mult
i-drug resistant tuberculosis (MDR-TB) was found in 194 (5.8%) materials. O
ver the 21-y period studied, total resistance to isoniazid (INH), rifampici
n (RF) and streptomycin (SNI) were determined as 10.5, 6.9 and 7.0%, respec
tively. It was also observed that the resistance rates to INH or SM increas
ed, whereas resistance to RF was not changed within this period. While resi
stance to the 2-drug combination RF+SM increased, resistance to INH+SM decr
eased significantly. There was no change in resistance to the 2-drug INH+RF
or 3-drug INH+RF+SM combinations in the same period. In conclusion, combin
ed therapy is still useful and available for the treatment of resistant tub
erculosis, and INH should be included in the chemotherapeutic regimen even
if high resistance rates are shown to exist.