title: Polyclonal and compartmentalized infection by Mycobacterium tuberculosis in patients with both respiratory and extrarespiratory involvement.
abstract: Infection by Mycobacterium tuberculosis (MTB) is assumed to be caused by a single strain, and several MTB strains within the same patient are rarely considered. The present study analyzes the phenomenon of mixed infections by MTB in a group of 50 patients with both respiratory and extrarespiratory tuberculosis. First, the proportion of patients with infection by >1 strain was defined, and second, the clonal composition of the MTB populations at different infected sites was studied. In 3 (6%) of 50 patients, >1 strain was cultured, which indicates that mixed infections are not anecdotal. The coinfecting strains were not equally distributed at the respiratory and extrarespiratory site, which reflects a compartmentalization of the infection. In 1 patient, although 2 strains were found at the respiratory site, only 1 of these strains was involved in the extrarespiratory infection, which suggests that clonal selection can occur in the dissemination of the infection.
authors.affiliation: Servicio de Microbiología y Enfermedades Infecciosas, Hospital General Universitario Gregorio Marañón, Madrid, Spain. dgviedma@microb.net
authors.forename: Darío
authors.initials: D
authors.lastname: García de Viedma
authors.forename: Mercedes
authors.initials: M
authors.lastname: Marín
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Ruiz Serrano
authors.forename: Luis
authors.initials: L
authors.lastname: Alcalá
authors.forename: Emilio
authors.initials: E
authors.lastname: Bouza
mesh_terms: D015373:Bacterial Typing Techniques; D015342:DNA Probes; D004269:DNA, Bacterial / Q000032:analysis; D021901:DNA, Intergenic; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D014376:Tuberculosis / Q000382:microbiology*
chemical_list: D015342:DNA Probes; D004269:DNA, Bacterial; D021901:DNA, Intergenic