title: M. tuberculosis DNA detection in nasopharyngeal mucosa can precede tuberculosis development in contacts.
abstract: The nasopharynx is a known gateway for some mycobacterial species such as Mycobacterium bovis and M. leprae. M. tuberculosis can cross lymphoepithelial barriers in vitro, but its ability to colonise the nasopharyngeal mucosa in vivo has not been established.
  
  
  
  To determine if M. tuberculosis can be transiently detected in nasopharyngeal mucosa of tuberculosis (TB) contacts as a preliminary step in the development of tuberculous infection.
  
  
  
  Exploratory study conducted among asymptomatic household contacts of pulmonary TB cases. A chest X-ray, QuantiFERON(®) TB-Gold or tuberculin skin test and a bilateral nasopharyngeal swab for Xpert(®) MTB/RIF and mycobacterial culture were performed at baseline and repeated 8-12 weeks later.
  
  
  
  Eighty-nine contacts were enrolled a median of 9 days after the diagnosis of the index case. At baseline, 29.9% were positive for latent tuberculous infection and one subject (1.1%) had a positive Xpert in the nasopharyngeal swab with a normal chest X-ray, negative QuantiFERON and negative induced sputum. After 12 weeks' follow-up, this subject developed a new cough and upper lobe infiltrates and M. tuberculosis grew in sputum. No other cases of active TB were detected at follow-up.
  
  
  
  The detection of M. tuberculosis DNA in the nasopharyngeal mucosa of contacts is an infrequent event that in this instance preceded the development of pulmonary TB. Its pathogenic role requires further investigation.
authors.affiliation: Infectious Diseases Department, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: M E
authors.initials: ME
authors.lastname: Balcells
authors.affiliation: Infectious Diseases Department, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Hospital Dr Gustavo Fricke, Viña del Mar, Chile.
authors.forename: M
authors.initials: M
authors.lastname: Huilcamán
authors.affiliation: Respiratory Department, Hospital San Borja Arriarán, Santiago, Chile.
authors.forename: C
authors.initials: C
authors.lastname: Peña
authors.affiliation: Clinical Laboratory Department, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: C
authors.initials: C
authors.lastname: Castillo
authors.affiliation: Infectious Diseases Department, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: C
authors.initials: C
authors.lastname: Carvajal
authors.affiliation: Clinical Laboratory Department, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: N
authors.initials: N
authors.lastname: Scioscia
authors.affiliation: Clinical Laboratory Department, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: P
authors.initials: P
authors.lastname: García
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004269:DNA, Bacterial / Q000302:isolation & purification*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D055985:Latent Tuberculosis / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D009092:Mucous Membrane / Q000382:microbiology*; D009163:Mycobacterium bovis / Q000302:isolation & purification; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D009305:Nasopharynx / Q000382:microbiology*; D013183:Sputum / Q000382:microbiology; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D004269:DNA, Bacterial