Distinct clinical and epidemiological features of tuberculosis in New York City caused by the RDRio Mycobacterium tuberculosis sublineage

Background: Genetic tracking of Mycobacterium tuberculosis is a cornerstone of tuberculosis (TB) control programs. The RDRio M. tuberculosis sublineage was previously associated with TB in Brazil. We investigated 3847 M. tuberculosis isolates and registry data from New York City (NYC) (2001-2005) to: (1) affirm the position of RDRio strains within the M. tuberculosis phylogenetic structure, (2) determine its prevalence, and (3) define transmission, demographic, and clinical characteristics associated with RDRio TB. Methods: Isolates classified as RDRio or non-RDRio M. tuberculosis by multiplex PCR were further classified as clustered (>= 2 isolates) or unique based primarily upon IS6110-RFLP patterns and lineage-specific cluster proportions were calculated. The secondary case rate of RDRio was compared with other prevalent M. tuberculosis lineages. Genotype data were merged with the data from the NYC TB Registry to assess demographic and clinical characteristics. Results: RDRio strains were found to: (1) be restricted to the Latin American-Mediterranean family, (2) cause approximately 8% of TB cases in NYC, and (3) be associated with heightened transmission as shown by: (i) a higher cluster proportion compared. to other prevalent lineages, (ii) a higher secondary case rate, and (iii) cases in children. Furthermore, RDRio strains were significantly associated with US-born Black or Hispanic race, birth in Latin American and Caribbean countries, and isoniazid resistance. Conclusions: The RDRio genotype is a single M. tuberculosis strain population that is emerging in NYC. The findings suggest that expanded RDRio case and exposure identification could be of benefit due to its association with heightened transmission. (C) 2011 Elsevier B.V. All rights reserved.