ABSTRACT
OBJECTIVE: Resistance to anti-tuberculosis (anti-TB) drugs is becoming a major and alarming threat in most regions worldwide. METHODS: This was a descriptive cross-sectional study at a tertiary hospital in Iran, using patient medical records for 2000-2003. The findings were analyzed following the same framework as that used for previous reports from this center. RESULTS: Among 1556 TB patients, drug susceptibility testing (DST) was performed for 548 culture-positive cases. Anti-TB drug resistance to both isoniazid and rifampin was identified in 10 (2.8%) of the new TB cases (multidrug-resistant TB; MDR-TB). Any resistance was detected in 228 (41.6%), showing an increasing trend in both new and retreatment cases. The data analysis revealed that drug-resistant TB had a statistically significant association with Afghan ethnicity, age>65 years, and the type of disease (retreatment vs. new TB case) (p<0.05). Also, assessment of the drug resistance trends showed a significant increase in resistance to any anti-TB agent, to isoniazid, and to streptomycin in new cases, and to all of the first-line anti-TB drugs in retreatment patients. CONCLUSIONS: There has been an increasing trend in drug resistance in recent years, particularly in retreatment cases. Hence, revision of the national TB control program, reevaluation of the role of the World Health Organization category II (CAT II) regimen, as well as the conducting of a nationwide drug resistance survey, are recommended.
Subject(s)
Antitubercular Agents/pharmacology , Mycobacterium tuberculosis/drug effects , Population Surveillance/methods , Tuberculosis, Multidrug-Resistant/epidemiology , Tuberculosis, Pulmonary/epidemiology , Tuberculosis/epidemiology , Adolescent , Aged , Antitubercular Agents/therapeutic use , Drug Resistance, Multiple, Bacterial , Female , Humans , Iran/epidemiology , Iran/ethnology , Isoniazid/pharmacology , Male , Microbial Sensitivity Tests , Middle Aged , Mycobacterium tuberculosis/isolation & purification , National Health Programs , Referral and Consultation , Rifampin/pharmacology , Tuberculosis/drug therapy , Tuberculosis/microbiology , Tuberculosis, Multidrug-Resistant/drug therapy , Tuberculosis, Multidrug-Resistant/microbiology , Tuberculosis, Pulmonary/drug therapy , Tuberculosis, Pulmonary/microbiology , Young AdultABSTRACT
An enzyme-linked immunosorbent assay of nucleic acid sequence-based amplification (NASBA-ELISA) was developed for molecular detection of Mycobacterium tuberculosis. The primers targeting 16S rRNA were used for the amplification of bacterial RNA by the isothermal digoxigenin (DIG)-labeling NASBA process, resulting in the accumulation of DIG-labeled RNA amplicons. The amplicons were hybridized with a specific biotinylated DNA probe which was non-covalently immobilized on streptavidin-coated microtiter plate. The RNA-DNA hybrids were colorimetrically detected by the addition of an anti-DIG antibody HRP conjugate and 2,2-azino-di-(3-ethylbenzthiazolinsulfonate) substrate. Using this method, as little as 1 x 10(2) CFU ml(-1) of M. tuberculosis was detected within less than 5h. Results obtained from the clinical specimens showed 85.7% and 96% sensitivity and specificity, respectively. No interference was encountered in the amplification and detection of M. tuberculosis in the presence of non-target bacteria, confirming the specificity of the method.
