Bacteriological analysis of induced sputum for the diagnosis of pulmonary tuberculosis in the clinical practice of a general tertiary hospital.
OBJECTIVE
To determine the diagnostic sensitivity of bacteriological analyses in induced sputum (IS) for the diagnosis of pulmonary tuberculosis (TB) and to identify the clinical characteristics associated with the confirmed diagnosis, as well as to determine the diagnostic yield of bronchoscopy carried out when IS tests negative for AFB in smear microscopy.


METHODS
A retrospective, cross-sectional study of patients suspected of having active pulmonary TB and referred to our clinic for sputum induction. We consecutively reviewed the laboratory data of all patients submitted to sputum induction between June of 2003 and January of 2006, as well as their electronic medical records. In addition, the results of the bacteriological analysis of bronchoscopic specimens collected from the patients whose AFB tests were negative in IS were reviewed.


RESULTS
Of the 417 patients included in the study, 83 (19.9%) presented IS samples that tested positive for TB (smear microscopy or culture). In the logistic regression analysis, radiological findings of cavitation (OR = 3.8; 95% CI: 1.9-7.6) and of miliary infiltrate (OR = 3.7; 95% CI: 1.6-8.6) showed the strongest association with the diagnosis of pulmonary TB. In 134 patients, bronchoscopy was carried out after negative AFB results in IS and added 25 (64.1%) confirmed diagnoses of pulmonary TB.


CONCLUSIONS
In our clinical practice, the frequency of confirmed diagnosis of pulmonary TB using IS (19.9%) was lower than that previously reported in controlled trials. Cavitation and miliary infiltrate increase the diagnostic probability of pulmonary TB using IS. The use of bronchoscopy when IS tests negative for AFB significantly increases sensitivity in the diagnosis of pulmonary TB.
Garcia
Sabrina Bollmann
SB
Department of Pulmonology, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.
Perin
Christiano
C
Silveira
Marcel Muller da
MM
Vergani
Gustavo
G
Menna-Barreto
Sérgio Saldanha
SS
Dalcin
Paulo de Tarso Roth
Pde T
D001999:Bronchoscopy; D004812:Epidemiologic Methods; D005260:Female; D006769:Hospitals, General; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D013048:Specimen Handling / Q000379:methods; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000382:microbiology