Quality control of sputum microscopic examinations for acid fast bacilli in southern Ethiopia

Abstract

Abstract
Background: There has been an ongoing effort to strengthen the acid-fast bacilli (AFB) diagnostic laboratory network
in the Southern Region of Ethiopia, and quality control has been initiated as part of this effort.
Objective: To evaluate the level of agreement in the readings of sputum smears for AFB between the peripheral
diagnostic centers and the reference laboratories.
Methods: Blinded rechecking of routine slides collected from the peripheral diagnostic laboratories was undertaken in
nine zones of the southern Ethiopian region between October 2000 and June 2002.
Results: Two thousand two hundred and nine slides, 54% of which were positive and 46% of which were negative
slides, were collected from the peripheral diagnostic centes. Overall, false reading was 3.2% and the overall
agreement was 96.8%. Among the 95 discordant slides that were re-examined at the central reference laboratory, 74%
were found to be in agreement with the regional laboratory readings while 26% were in agreement with the peripheral
readings. Nine zones participated in the quality control activity in 2000, six in 2001 and three in 2002.
Conclusion: Good agreement was recorded in the readings of AFB among the peripheral and reference laboratories.
However, the false positive reading of 3.2% exceeds the recommended cut-off point of 2%. The number of zones
participating decreased from time to time, and there seems to be an urgent need to re-vitalise the quality control
initiative. Regular on the job training of the peripheral laboratory staff together with supportive supervision would help
improve their performance. [Ethiop.J.Health Dev.2005;19(2):104-108]