title: Outcome correlation of smear-positivity for acid-fast bacilli at the fifth month of treatment in non-multidrug-resistant TB.
abstract: BACKGROUND
  Sputum samples from patients with non-multidrug-resistant (non-MDR) pulmonary TB may remain smear-positive for acid-fast bacilli (AFB) at the fifth month of anti-TB treatment. However, its significance remains unknown.
  
  
  METHODS
  From January 2004 to April 2009, there were 5,403 patients with culture-confirmed pulmonary TB from four hospitals in Taiwan. Among them, 116 patients (2.2%) with non-MDR TB whose sputum samples were smear-positive by concentration smear method at the fifth month of treatment were evaluated.
  
  
  RESULTS
  Sputum culture yielded Mycobacterium tuberculosis in 10 patients (8.6%, MTB group), nontuberculous mycobacteria in 23 (19.8%, NTM group), and no growth in the remaining 83 (71.6%, no-growth group). The relapse rate (22%) was higher in the MTB group (P = .01). Four predictors, smear grading ≥ 3+ at the fifth month ("S") (OR, 10.73; 95% CI, 2.67-43.17), no sputum culture conversion on the second month ("C") (OR, 7.16; 95% CI, 1.45-35.44), lack of directly observed therapy ("O") (OR, 6.40; 95% CI, 1.54-26.56), and no radiographic improvement at the fifth month ("R") (OR, 4.18; 95% CI, 1.02-17.10), were associated with viable M tuberculosis (MTB group). An integrated "SCOR" index of 1 point for each positive factor had the best discriminatory power for predicting culture results at the fifth month. If the SCOR index was 0, all smear-positive sputum was culture-negative for M tuberculosis.
  
  
  CONCLUSIONS
  Positive sputum smears by a concentrated smear method at the fifth month of treatment in patients with non-MDR TB, especially those with a low SCOR index, may be due to nonviable bacilli and NTM. Careful review of the quality of patient supervision, bacteriologic data, and chest radiography is crucial.
authors.affiliation: Chest Hospital, Department of Health, Executive Yuan, Tainan; Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Jung-Yien
authors.initials: JY
authors.lastname: Chien
authors.affiliation: Department of Internal Medicine, Buddhist Tzu Chi General Hospital, Hualien, Taiwan.
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Chen
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Chin-Chung
authors.initials: CC
authors.lastname: Shu
authors.affiliation: Department of Internal Medicine, Buddhist Tzu Chi General Hospital, Hualien, Taiwan; Department of Internal Medicine, School of Medicine, Tzu Chi University, Hualien, Taiwan.
authors.forename: Jen-Jyh
authors.initials: JJ
authors.lastname: Lee
authors.affiliation: Chest Hospital, Department of Health, Executive Yuan, Tainan. Electronic address: jywang@ntu.edu.tw.
authors.forename: Jann-Yuan
authors.initials: JY
authors.lastname: Wang
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Chong-Jen
authors.initials: CJ
authors.lastname: Yu
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Pan-Chyr
authors.initials: PC
authors.lastname: Yang
mesh_terms: D000368:Aged; D000995:Antitubercular Agents / Q000627:therapeutic use*; D003627:Data Interpretation, Statistical; D023801:Directly Observed Therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D009170:Nontuberculous Mycobacteria / Q000302:isolation & purification; D012008:Recurrence; D013183:Sputum / Q000382:microbiology*; D013624:Taiwan / Q000453:epidemiology; D013997:Time Factors; D016896:Treatment Outcome; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology*
chemical_list: D000995:Antitubercular Agents