Antituberculosis drug resistance in Keelung area-1993 to 1994

Patterns of drug resistance of 176 isolates of Mycobacterium tuberculosis collected from 1993 to 1994 were reviewed retrospectively. The rates of resistance to isoniazid, rifampicin, ethambutol and streptomycin were 84.1%, 17.6%, 23.3% and 11.9% respectively and the incidence of multidrug-resistant M. tuberculosis was 17.0%. Comparisons between 1993 and 1994 showed decrease in rates of resistance to rifampicin (25% vs. 7.5%) and ethambutol (36.5% vs. 7.5%) and the incidence of multidrug-resistant tuberculosis (25% vs. 7.5%). In contrast, the rate of resistance to isoniazid increased from 79.2% to 84.1%. Due to the high frequency of resistance to multiple drugs in tuberculosis isolates at Chang Gung Memorial Hospital, Keelung, three-combined (isoniazid+rifampicin+ethambutol) regimen of antituberculosis drugs may be ineffective as initial therapy for one-fourth of patients in our hospital. Of epidemiological factors, previous treatment was found to influence the rates of drug resistance. Of roentgenographic features, stage of chest roentgenography was found to be a positive predictor of infection with multidrug-resistant tuberculosis. The information provided in this study may help us understanding the epidemiology of M. tuberculosis in Keelung and refining antituberculosis treatment for our patients.