Tuberculosis caused by RD^Rio Mycobacterium tuberculosis is not associated with differential clinical features

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.