RESUMO
OBJECTIVES/BACKGROUND: The region of differences (RDs) polymorphisms is a potential molecular epidemiology method to distinguish origins of Mycobacterium tuberculosis. To date, 68 RDs have been identified in M. tuberculosis. This study was designed to determine the frequency of RD deletions in M. tuberculosis strains that were isolated from patients with pulmonary tuberculosis who were referred to the National Research Institute of Tuberculosis and Lung Disease for diagnosis and treatment. Therefore, highly polymorphic regions (RD1, RD150, and RD181) among M. tuberculosis strains isolates were investigated. METHODS: A total of 250 M. tuberculosis isolates were identified by conventional and molecular methods. Subsequently, spoligotyping and RD typing (RD1, RD150 and RD181) were performed to genotype these strains. RESULTS: The most frequent spoligotype belonged to Haarlem (n=85, 34.0%) followed by CAS (n=54, 21.6%), T1 (n=27, 10.8%), and Beijing (n=28, 11.2%) lineages. Deletion in RD181 was identified only among the Beijing lineage (Fig. 1). CONCLUSION: As we found a deletion in RD181 in the Beijing strains only, we propose to use this marker as an identification tool for genotyping of the Beijing strain.
RESUMO
BACKGROUND: Iran has extended borders with high-TB burden countries (Afghanistan and Pakistan) and immigrations of these populations influences TB distribution in the region and threatens the control strategies. The aim of this study was to evaluate the extent of recent TB transmission among Iranian and Afghan cases. MATERIALS AND METHODS: Spoligotyping and 15-locus variable number tandem repeat (VNTR) typing were applied to genotype 102 MTB isolates (2009 to 2010). Phylogenetic relationships were analysed by two methods: a cluster-graph method and a minimum spanning tree (MST) method. Furthermore, evaluation of recent TB transmission was assessed with three indices including, RTIn, RTIn-1 and TMI. RESULTS: Using molecular typing, 35 different spoligotypes were detected among the studied isolates. Seventy seven cases (75.4%) were distributed into 10 clusters and the remaining 25 (24.5%) isolates had a unique pattern. The cluster sizes also ranged from 2 to 21 isolates. The most frequent spoligotype in our populations belong to Haarlem (n=30, 29.4%) followed by CAS (n= 29, 28.4%) and Beijing (n=16, 15.6%) lineages. The used indices give the following values: RTIn = 0.75, RTIn-1 = 0.65 and TMI = 0.24. CONCLUSION: The low rate of TB transmission in our findings (24%) showed that the mode of TB transmission in Iran is mostly associated with reactivation of a previous TB infection and that recently a transmitted disease has a minor role. However, the increasing incidence of the intra-community transmission in recent years highlights the need for establishing new strategies for control of TB.
