Background: We recently described the Mycobacterium tuberculosis RD(Rio) genotype, a clonally derived sublineage within the Latin American-Mediterranean (LAM) family. Genetic diversity of M. tuberculosis likely affects the clinical aspects of tuberculosis (TB). Prospective studies that address this issue are scarce and remain controversial.
Objective: To determine the association of differential clinical features of pulmonary TB with the RD(Rio) M. tuberculosis etiology.
Methods: Culture-proven pulmonary TB patients (n = 272) were clinically evaluated, including history, physical examination, chest X-ray and anti-human immunodeficiency virus serology. Isolates were classified as RD(Rio) or non-RD(Rio) M. tuberculosis by multiplex polymerase chain reaction and further spoligotyped. Clinical and M. tuberculosis genotype data were analyzed.
Results: RD(Rio) M. tuberculosis caused disease in 26.5% (72/270) of all TB cases. The LAM genotype, of which RD(Rio) strains are members, was responsible for 46.0% of the TB cases. Demographic data, major signs and symptoms, radiographic presentation, microbiological features and clinical outcomes were not significantly different among patients with TB caused by RD(Rio) and non-RD(Rio) strains.
Conclusions: Disease caused by M. tuberculosis RD(Rio) strains was not clinically distinctive or more severe than disease caused by non-RD(Rio) strains in this series of TB patients. Larger prospective studies specifically designed to disclose differential clinical characteristics of TB caused by specific M. tuberculosis lineages are needed.