ASSESSMENT OF DIAGNOSIS OF PULMONARY TUBERCULOSIS BY SPUTUM MICROSCOPY IN A DISTRICT TUBERCULOSIS

Ind. J. Tub., 1971, 28/1, 10-21

Ind. J. Tub., Vol. XVIII, No.

Reprinted from The Indian Journal of Tuberculosis,Vol.XVIII,No1

ASSESSMENT OF DIAGNOSIS OF PULMONARY TUBERCULOSIS BY

SPUTUM MICROSCOPY IN A DISTRICT TUBERCULOSIS PROGRAMME

K.P.RAO, S. S NAIR, N. NAGANATHAN AND R.RAJALAKSHMI

(From National Tuberculosis Institute, Bangalore)

Introduction

An infectious case of pulmonary tuberculosis

is diagnosed by demonstrating tubercle bacilli in

sputum. The laboratory methods available for this

purpose are sputum microscopy, isolation of

tubercle bacilli in culture followed by

identification of the bacilli and animal

pathogenicity tests. Evidence based on all the

three methods establishes bacteriological

diagnosis beyond any doubt, but even

economically advanced countries may not

consider such an elaborate procedure essential for

routine diagnosis. Very often sputum microscopy

alone is considered sufficient for diagnosis, when

combined with clinical findings. Therefore a

realistic and economical approach for developing

countries would be to provide only facilities for

sputum microscopy.

One of the basic principles of the Indian

District Tuberculosis Programme (DTP)1 is to

offer diagnosis by sputum microscopy to persons

presenting at any general health institution with

complaints of symptoms such as cough for 2

weeks or more, pain in chest, fever and

haemoptysis here-in-after called ‘symptomatics’.

In the programme, non specialised staff of general

health institutions perform diagnostic and

treatment activities for tuberculosis, which are co￾ordinated and supervised by a few specialised staff

from District Tuberculosis Centre (DTC). These

non-specialised staff of general health institutions

have, therefore, to be trained in microscopy by the

staff of the DTC. In actual practice the efficiency

of diagnosis by microscopy will depend upon the

skill, aptitude, experience and conscientiousness

of the staff trained. Besides, their multiple

responsibilities, training environment and the

competence of the trainers, the distribution of

work among trained technical persons and such

other operational factors would indirectly

influence the quality of their microscopy.

To achieve and maintain a satisfactory

standard in sputum examination, routine

supervision of the general health institutions at

regular intervals constitutes no less an important

activity of the staff of DTC. At the same time,

periodical technical assessment is essential to

quantify the quality and reliability of microscopy,

organised under such conditions, and to take

timely corrective actions for improving technical

performance. Eventually, such an assessment

might help development of mathematical models

in the field of tuberculosis.

Objectives

The primary objective of the present study was

therefore to assess some aspects of the technical

quality and reliability of sputum microscopy, as

carried out in general health institutions under

conditions of DTP. It was also envisaged to utilise

the data, to formulate simpler assessment

methodologies to measure the efficiency of the

sputum diagnostic technique applied in DTP.

Material and Methods

The Bangalore district tuberculosis programme

(the programme assessed).

The Bangalore District has an area of 7798

square kilometers and had a population of about

1.3 million according to the census of 1961

(excluding the metropolitan area). The District

has 13 towns and 2477 villages. The DTP was

implemented in 1963, not by the staff of the DTC

(as happens in other districts) but by trainees of

two courses held in 1963 at the National

Tuberculosis Institute (NTI) Bangalore. In all, 15

microscopy centres were organised in general

health institutions of the District. Since, at that

time, a mobile X-ray unit was also made to visit 6

centres, these centres were excluded from the

study. Of the remaining 9 centres, 6 centres

belonged to the period of initial implementation

and 3 to the later period with programme running

for 6 months only prior to initiation of the study.

The microscopy centres were placed in different

types of health institutions, with differing staffing

pattern and functions.

Method of data collection :

Under the programme, at each microscopy

centre, a single specimen of sputum is collected

from ‘symptomatics’ and examined by Ziehl￾Neelsen (ZN) method. For the study, these smears,

along with the corresponding sputum specimens,

were collected and brought to NTI laboratory,