Comparison of two spot concentrated Sputum AFB Smear versus two direct Sputum AFB Smears done regularly in Revised National Tuberculosis Control Programme

  • Ajoy Samuel Mammen, MBBS, DTCD Madras Medical College, Chennai
  • M Kasi, MBBS, DTCD Madras Medical College
  • A Sundararajaperumal, MD Madras Medical College
  • D Ranganathan, MD, Pulmonary Medicine, DNB, DTCD Madras Medical College
Keywords: Concentrated Sputum AFB smear, Spot Sputum AFB smears, Burden


Background: Direct smear microscopy is one of the most reliable diagnostic methods for Pulmonary tuberculosis. The standard protocol involves 3 patient visits till he collects the result. Drop-out rates during this process are as high as 37%, due to multiple patient visits. Operational research is now focused on reducing the burden of smear microscopy without compromising its effectiveness as a case finding strategy. The diagnostic process could be made much more efficient and convenient for patients if it could be completed in a single day by examining 2 sputum specimens on the same day. Public health point of view also it would create a major impact, as it would help in curtailing transmission of the disease by earlier diagnosis.
Materials and Methods: All 1050 patients were clinically examined and then subjected to chest skiagram, complete blood count, renal and liver function tests, Mantoux and ictc on the first day. The patients were advised to give good quality spot sputum of about 5ml, which will be divided into 2 equal parts. One was subjected to concentration and stained by Ziehl Nielson technique. The other part was smeared as per the regular RNTCP technique. Then after 1 hour another sample of 2-3 ml was again concentrated and smeared. The next day 2nd early morning sample was smeared under the RNTCP technique.
Results: There were 5 initial defaulters in the study. Out of them one was sputum positive. 2 HIV cases were present in the study. In them the detection rate was high in concentration method. There were 1050 smears done by RNTCP method and 1050 smears done by concentration technique that is a total of 2100 smears were analysed. Sample A - RNTCP 1st sample vs 1st spot concentrated sample. Sample B - RNTCP home sample vs 2nd spot concentrated sample. With regard to sample A, the proportion of positives detected by concentration method (27.4%) was significantly higher (mc nemar’s test: p value= 0.0003) than that detected by the conventional method (24.1%). With regard to sample B, the proportion of positives detected by both methods were not significantly different (mc nemar’s test: p value=0.06).

Author Biographies

Ajoy Samuel Mammen, MBBS, DTCD, Madras Medical College, Chennai

Postgraduate, Department of Thoracic Medicine

M Kasi, MBBS, DTCD, Madras Medical College

Postgraduate, Department of Thoracic Medicine

A Sundararajaperumal, MD, Madras Medical College

Pulmonary Medicine, DCH, Assistant Professor, Department of Thoracic Medicine

D Ranganathan, MD, Pulmonary Medicine, DNB, DTCD, Madras Medical College

Professor, Department of Thoracic Medicine

Original Research