title: Predictors of delayed sputum smear and culture conversion among a Portuguese population with pulmonary tuberculosis.
abstract: BACKGROUND
  Failure of sputum smear and/or culture conversion after 2 months of tuberculosis (TB) treatment has been considered a predictor of patient infectivity and treatment failure. We aimed to identify the factors associated with delayed sputum smear and culture conversion in patients with pulmonary TB who were given anti-TB treatment.
  
  
  METHODS
  Retrospective cohort of 136 adult patients with sputum culture-proven pulmonary TB referred to an urban Chest Disease Centre. Socio-demographic, clinical, radiological, microbiological, and therapeutic data were evaluated.
  
  
  RESULTS
  The median age was 41.0 (interquartile range [IQR] 18.0) years and 75.0% of patients were male. Delayed sputum smear and culture conversion occurred in 25.4% (30/118) and 27.2% (37/136) of patients, respectively. Multivariate analysis indicated that age ≥ 50 years (odds ratio [OR] 4.4, 95% confidence interval [CI] 1.5-13.3), male gender (OR 10.8, 95% CI 1.3-91.1), and smear grade > 1-9 acid fast bacilli (AFB)/field (3+) (OR 11.7, 95% CI 1.4-100.6) were significantly associated with persistent smear positivity after 2 months of treatment. Bilateral radiological involvement (OR 3.7, 95% CI 1.5-9.0) and colony count > 100 (3+) (OR 5.8, 95% CI 1.2-27.4) were significantly associated with persistent culture positivity.
  
  
  CONCLUSIONS
  Delayed sputum smear and culture conversion occurred in about one third of patients. Older age, male gender, and higher bacillary load were independently associated with delayed smear conversion. Bilateral radiological involvement and higher colony count were independently associated with delayed culture conversion.
authors.affiliation: Serviço de Pneumologia, Centro Hospitalar de São João, Porto, Portugal. patmota@net.sapo.pt
authors.forename: P
authors.initials: P
authors.lastname: Caetano Mota
authors.forename: A
authors.initials: A
authors.lastname: Carvalho
authors.forename: I
authors.initials: I
authors.lastname: Valente
authors.forename: R
authors.initials: R
authors.lastname: Braga
authors.forename: R
authors.initials: R
authors.lastname: Duarte
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D011174:Portugal; D012189:Retrospective Studies; D013183:Sputum / Q000382:microbiology*; D013997:Time Factors; D016896:Treatment Outcome; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy* / Q000382:microbiology*