title: Mycobacterium tuberculosis and polymorphonuclear pleural effusion: incidence and clinical pointers.
abstract: BACKGROUND
  Delayed diagnosis and treatment of a polymorphonuclear cell (PMN)-predominant pleural effusion due to Mycobacterium tuberculosis (MTB) are associated with poor outcome and the risk of tuberculosis transmission. We investigated the clinical differences of PMN-predominant pleural effusion due to MTB or other microorganisms.
  
  
  METHODS
  From January 2000 to April 2007, a total of 354 patients with tuberculous pleurisy were identified. Among them, 39 (11.0%) adults had PMN-predominant pleural effusion (MTB group). Their clinical characteristics were compared with the 117 age-/gender-matched controls (1:3) selected from 715 patients with PMN-predominant pleural effusion due to other microorganisms.
  
  
  RESULTS
  Among patients with PMN-predominant septic pleural effusion, 5.2% were due to MTB. The in-hospital mortality rate in the MTB group was 36%, similar to that of the control group. Sputum samples were culture-positive for MTB in 41%. Weight loss (p=0.006), initial leukocyte count <or=11,000/microL (p=0.007), and poor clinical response to empirical antibiotics in the first 3 days (p=0.002) were independent factors suggestive of tuberculous pleurisy. A shift toward mononuclear cell predominance of pleural effusions within 1 week was significantly associated with tuberculous pleurisy. In the MTB group, if anti-tuberculous treatment was started more than 14 days after the initial visit, there was a worse prognosis (p=0.034). Among those with delayed treatment, 96.2% had finding(s) suggestive of tuberculous pleurisy.
  
  
  CONCLUSIONS
  A high index of clinical suspicion can identify MTB in about 5.2% of patients presenting with PMN-predominant septic pleural effusions. Awareness of the clinical pointers can lead to early diagnosis and improved clinical outcome.
authors.affiliation: Department of Internal Medicine, Division of Chest Medicine, National Taiwan University Hospital, 7 Chung-Shan South Road, Taipei 100, Taiwan.
authors.forename: Ming-Tzer
authors.initials: MT
authors.lastname: Lin
authors.forename: Jann-Yuan
authors.initials: JY
authors.lastname: Wang
authors.forename: Chong-Jen
authors.initials: CJ
authors.lastname: Yu
authors.forename: Li-Na
authors.initials: LN
authors.lastname: Lee
authors.forename: Pan-Chyr
authors.initials: PC
authors.lastname: Yang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D057210:Delayed Diagnosis / Q000009:adverse effects; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis; D009504:Neutrophils; D010996:Pleural Effusion / Q000175:diagnosis / Q000382:microbiology* / Q000401:mortality; D012189:Retrospective Studies; D013183:Sputum / Q000166:cytology* / Q000382:microbiology; D016019:Survival Analysis; D013624:Taiwan; D014396:Tuberculosis, Pleural / Q000097:blood / Q000175:diagnosis* / Q000401:mortality; D015431:Weight Loss; D055815:Young Adult