Phenotypic and genotypic variant of MDR-Mycobacterium tuberculosis multiple isolates in the same tuberculosis episode, Rio de Janeiro, Brazil

Abstract

Assuming that the IS6110-restriction fragment length polymorphism (RFLP) changes at a constant rate of 3.2 years, this methodology was applied to demonstrate, for the first time, variant patterns of Mycobacterium tuberculosis (MTB) in multiple isolates obtained at short time intervals from sputum and blood of an HIV + patient with multiple admissions to the Emergency Room and to the multidrug-resistant tuberculosis (MDR-TB) Reference Center of a secondary-care hospital in Rio de Janeiro, Brazil. In sputum, the IS6110-RFLP appeared in isolates with two variant patterns with 10 and 13 IS6110 copies. However, blood presented only the pattern corresponding to 10 copies, suggesting compartmentalization. With regard to the exact match of 10 of 13 bands, this may be a subpopulation with the same clonal origin and this may be related to the IS6110 transposition. A susceptibility test demonstrated an MDR profile (INH R , RIF R , SM R , and EMB R ), with the sputum isolate also exhibiting EMB S (R = resistant; S = sensitive). A gene mutation confirmed resistance only to streptomycin. There was agreement between the results of the phenotypic test and the clinical response to MDR-TB treatment, suggesting serious implications with regard to treatment administration based exclusively on molecular methods, and calling attention to the fact that more effective control strategies against the emergence of MDR strains must be implemented by the TB control program to prevent transmission of MDR-MTB strains at health facilities in areas highly endemic for TB.

Systematic Survey of Clonal Complexity in Tuberculosis at a Populational Level and Detailed Characterization of the Isolates Involved

“…From an epidemiological point of view and to ensure precise tracking of recent transmission in molecular epidemiology programs, it is essential to identify those cases coinfected with more than one strain or clonal variant. Another important consideration is the possibility that strains with phenotypic differences (in virulence, infectivity, and susceptibility) can participate in clonally complex infections (28), and this could have an impact on diagnosis, clinical practice, and therapy (6,17,28,29,34).…”

“…Several clonally complex phenomena have been observed, including mixed infections with more than one strain (29,30,35), simultaneous presence of clonal variants (microevolution phenomena) (1, 2), or even different distributions of strains/clonal variants infecting independent anatomical sites in the same patient (6,15).…”

High Genotypic Discordance of Concurrent Mycobacterium tuberculosis Isolates from Sputum and Blood of HIV-Infected Individuals

“…Animal studies show that different strains differ in the severity of disease they cause [ 13 – 15 ], and in humans a subset of the Euro-American MTB lineage was found to be less common in TB meningitis than in pulmonary TB, suggesting an interaction between bacterial genotype and clinical phenotype[ 16 , 17 ]. Moreover, multidrug resistant and extensively drug resistant (MDR/XDR) strains have been isolated from blood of HIV-infected individuals with low CD4 cell counts [ 8 ], and mixed infections of susceptible and MDR strains of different genotype isolated from either sputum or blood have been reported[ 18 ]. Strains involved in mixed infections may consequently have different susceptibility patterns, requiring treatment to be adjusted to the most resistant strain that can however be missed if only one body compartment is sampled [ 19 , 20 ].…”

Characterization of Microevolution Events in Mycobacterium tuberculosis Strains Involved in Recent Transmission Clusters

“…The M. tuberculosis isolates of cases involved in a recent transmission chain generally have identical fingerprints and thus constitute a cluster. However, it is also possible to find one or several cases sharing genotyping patterns that are highly similar, but not identical, to the pattern defining the cluster (7,17,45).The existence of clonal variants in tuberculosis has been described in recurrent episodes (19), in M. tuberculosis isolates from a single episode (4,9,11,37,38), and in the respiratory and extrarespiratory isolates of a single case (12). The presence of these variants indicates a certain degree of genetic plasticity in M. tuberculosis.…”

“…The existence of clonal variants in tuberculosis has been described in recurrent episodes (19), in M. tuberculosis isolates from a single episode (4,9,11,37,38), and in the respiratory and extrarespiratory isolates of a single case (12). The presence of these variants indicates a certain degree of genetic plasticity in M. tuberculosis.…”