Analysis on drug resistance of 169 cases of pulmonary tuberculosis failing to respond to re-treat-ment in Tibet of China

Objective The present study was designed to gain insight into the status of drug-resis- tance of Mycobacterium tuberculosis(MTB)in patients with tuberculosis(TB)in re-treatment in Tibet for providing a scientific basis for effective prevention and control of the disease.Methods Sputum samples of patients with TB who were treated in Tibet Institute of Tuberculosis Control and failed to respond to re-treatment were collected from Jan.2000 to Dec.2005 and MTB were cultured with Lwenstein-Jensen culture medium and isolated.The absolute concentration method was used to test drug resistance of the isolated strains to the four anti-tuberculosis drugs,streptomycin(SM),isoniazid (1NH),ethambutol(EMB)and Rifampin(RFP).Results A total of 169 strains of Mycobacterium tuberculosis were isolated and tested and 165 of them were found to be resistant to the drugs,with the total rate of drug resistance as high as 97.63%.It was identified that 78.70% of the drug resistant strains(133/165)were multi-drug resistant.The drug resistance rate including the rate of multi-drug resistance among those who failed to respond in re-treatment was higher than the mean value of the whole country(46.50%).The rates of resistance to RFP,INH,SM and EMB were 91.12%(154/169), 84.02%(142/169),75.15% (127/169)and 21.30%(36/169),respectively.Conclusion The surveillance and control of drug resistance of Mycobacterium tuberculosis should be strengthened in Tibet,which is identified to be an area of high drug resistance.