Detection of Isoniazid and Rifampin Resistant Mycobacterium Tuberculosis Isolated from Tuberculosis Patients Using Conventional Method and Pcr

Objective: To investigate the drug susceptibility patterns among TB isolates from patients in Ahvaz, Iran. Study: Descriptive study. Place and duration of study: TB reference laboratory, PHLS, Ahvaz, Iran from May 2001 to December 2001. Patients and methods: A total of 100 sputum samples from patients suspected of having tuberculosis were collected for detection of M. tuberculosis (MTB). For identification of the isolates acid fast stain, cultural and biochemical techniques were used. The isolates were examined for INH and RIF resistance using conventional MIC method and PCR technique in the next step. MIC were done based on proportion method and PCR was performed according to manufacturer’s instruction and by using specific INH (Kat G) and RIF (rpo B) resistant primers. Results: Eighty samples were identified as MTB. Using susceptibility testing, 7 isolates were resistant to both INH and RIF by MIC method. In PCR technique, 5 and 6 out of 7 above mentioned strains showed resistant to INH and RIF respectively. Conclusion: The prevalence of resistance to INH and RIF is high in the region of study. The conventional MIC method despite being time consuming is more sensitive for evaluation of drug resistance among TB isolates. However, PCR as a rapid and sensitive technique is recommended additionally to conventional method for having quicker results to start treatment and disease control management.