A Retrospective Analysis of Isoniazid-Monoresistant Tuberculosis: Among Iranian Pulmonary Tuberculosis Patients

BACKGROUND AND OBJECTIVES Isoniazid (INH) is one of the most potent anti-tuberculosis (TB) drugs. The spread and transmission of INH- resistant bacilli are likely to pose a significant problem for National TB control Program (NTP). In this study, we aimed to determine the trend of INH-monoresistant TB in Iran. METHODS The susceptibility patterns of Mycobacterium tuberculosis (MTB) strains that were isolated from clinical samples were retrospectively analyzed (January 2003-December 2011). Identification and drug susceptibility testing (DST) were performed using both conventional and molecular methods. The associated risk factors were assessed using the Chi-square test. RESULTS Out of 4825 culture-positive isolates, 6.1% were resistant to INH, with an increasing trend over the study period. The INH-monoresistance from 4.4 in 2003 reached to 9.4% in 2011. Among the studied risk factors, age was significantly associated with INH-monoresistance (p < 0.05). CONCLUSIONS The increased trend in INH-monoresistance underlines the need for greater enforcement of national TB control programs. In this regard, better management of TB cases, establishing advanced diagnostic facilities and use of standard treatment regimens are recommended to avoid further emergence of INH resistant cases.