SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH 104 Vol 38 No. 1 January 2007 Correspondence: Dr Wah Wah Aung, Bacteriology Research Division, Department of Medical Research (Lower Myanmar), No 5 Ziwaka Road, Dagon PO, Yangon 11191, Myanmar. Tel: 95-1-251508 ext 149 E-mail: hhlaing@mptmail.net.mm INTRODUCTION The prevalence of tuberculosis (TB) is very high in many parts of the world and has reached epidemic proportions. Approximately one third of the global population is estimated to be infected with Mycobacterium tubercu- losis, the causal bacterium of tuberculosis. The global TB problem has been further compli- cated by a substantial increase in multi-drug resistant tuberculosis (MDR-TB), which is de- fined as TB that is resistant to at least iso- niazid and rifampicin (Drobineski and Wilson, 1998). In Myanmar, TB is described as a sec- ond priority disease in the National Health Plan. The estimated incidence of all TB cases and new smear positive TB cases for Myanmar are 154/100,000 population and 68/100,000, respectively. The TB mortality is 26/100,000 and MDR-TB among new cases is 1.5% (WHO, 2004). Due to the chronicity of the disease and long-term treatment, tuberculosis problems can be compared to an iceberg, with only the part floating above the sea can be seen, it is difficult to know its real magnitude. Long-term treatment of this disease can result in multi- drug resistant cases, which further decrease the cure rate of tuberculosis. Development of resistance to the two most potent drugs, isoniazid and rifampicin, is a serious threat not only to individual pa- STUDY OF DRUG RESISTANT CASES AMONG NEW PULMONARY TUBERCULOSIS PATIENTS ATTENDING A TUBERCULOSIS CENTER, YANGON, MYANMAR Wah Wah Aung 1 , Ti Ti 2 , Kyu Kyu Than 3 , Myat Thida 1 , Mar Mar Nyein 1 ,Yin Yin Htun 4 , Win Maung 2 and Aye Htun 2 1 Bacteriology Research Division, Department of Medical Research (Lower Myanmar); 2 National Tuberculosis Program, Myanmar; 3 Epidemiology Research Division, Department of Medical Research (Lower Myanmar); 4 Department of Medical Research (Central Myanmar) Abstract. A cross-sectional descriptive study was carried out at a tuberculosis center, Yangon, Myanmar from October 2003 to July 2004 to analyze the drug susceptibility of new sputum smear positive pulmonary tuberculosis patients. A total of 202 Mycobacterium tuberculosis isolates were tested for resistance to isoniazid, streptomycin, rifampicin and ethambutol. Re- sistance to at least one anti-tuberculosis drug was documented in 32 (15.8%) isolates. Mono- resistance (resistance to one drug) was noted in 15 (7.4%) isolates and poly-resistance (resis- tance to two or more drugs) was noted in 17 (9.4%) isolates, including 8 (4.0%) multi-drug resistant isolates (resistance to at least isoniazid and rifampicin). Total resistance to individual anti-tuberculosis drugs were: isoniazid (29, 14.3%), streptomycin (11, 5.4%), rifampicin (10, 4.9%) and ethambutol (1, 0.5%). The demographic data and possible contributing factors of drug resistance were evaluated among the drug resistant patients. Poly-resistant cases had significantly longer intervals between symptom appearance and achieving effective anti-tuber- culosis treatment than mono-resistant cases (p = 0.015).