Assessment of Sputum Quality and Its Importance in the Rapid Diagnosis of Pulmonary Tuberculosis

Background: Sputum smear microscopy is the gold standard method for the diagnosis of pulmonary tuberculosis. Poor quality of sputum might result in missing the diagnosis. In the present study, we aimed at assessing the microscopic quality of sputum with reference to the number of pus cells and squamous epithelial cells observed on Gram’s stained smears as an indirect marker.

Methods: A total number of 200 sputum specimens were collected from 91 suspected TB patients and were subjected to ZN staining, LJ culture to out the acid fast bacilli; gram's staining and Blood agar culture for lower respiratory tract infectious organisms.

Results: Of 200 specimens, 59 from 28 patients were positive for acid fast bacilli. Based on the number of pus cells and squamous epithelial cells, specimens were categorized into four groups. Group 1 (sputum) was significantly associated with ZN smear positivity and Group 4 (saliva) with smear negativity (p<0.001). The specimens with >25 pus cells per field (including group 1&2) were significantly associated with ZN and LJ culture positivity (p<0.001), whereas the presence of >10 SE cells was not associated with smear negativity (p>0.1).

Conclusion: Group 1 (sputum) was associated with ZN smear positivity and Group 4 (saliva) was associated with smear negativity. Pus cells were proved as an indirect marker for sputum quality assessment. Sputum samples with more number of pus cells (regardless of the group) were significantly associated with ZN and LJ culture positivity. So, proper patient education before obtaining the sputum sample and timely monitoring during collection time can be helpful to obtain good quality sputum to enhance the TB disease diagnostic yield.

Author(s):

Mercy Aparna L, Aparna S, Sarada I, Ram D

Abstract | Full-Text | PDF

Share this