Factors Which Contributed for Low Quality Sputum Smears for the Detection of Acid Fast Bacilli (AFB) at Selected Health Centers in Ethiopia: A Quality Control Perspective

Journal Article
  • Ayehu Mekonen
  • Yeshi Ayele
  • Yifru Berhan
  • Desalegn Woldeyohannes
  • Woldaregay Erku
  • Solomon Sisay
PLoS One
June 2018; vol. 13 (6): e0198947. DOI: https://doi.org/10.1371/journal.pone.0198947.



Quality of tuberculosis (TB) microscopy diagnosis is not a guarantee despite implementation of External Quality Assurance (EQA) service in all laboratories of health facilities. Hence, we aimed at evaluating the technical quality and the findings of sputum smear microscopy for acid fast bacilli (AFB) at health centers in Hararge Zone, Oromia Region, Ethiopia.


A cross-sectional study was carried out between July 8, 2014 and July 7, 2015.A pre-tested structured questionnaire was used to collect data. Lot Quality Assurance Sampling (LQAS) method was put into practice for collecting all necessary sample slides. Data were analyzed by using SPSS (Statistical Package for Social Sciences) version 20 software. P-value < 0.05 was considered as statistically significant.


Of the total 55 health center laboratories which had been assessed during the study period, 20 (36.4%) had major technical errors; 13 (23.6%) had 15 false negative results and 17 (30.9%) had 22 false positive results. Moreover, poor specimen quality, smear size, smear thickness, staining and evenness were indicated in 40 (72.7%), 39 (70.9%), 37 (67.3%), 27(49.1%) and 37 (67.3%) of the collected samples, respectively. False negative AFB findings were significantly associated with lack of Internal Quality Control (IQC) measures (AOR (Adjusted Odds Ratio): 2.90 (95% CI (Confidence Interval): 1.25,6.75) and poor staining procedures (AOR: 2.16(95% CI: 1.01, 5.11).


The qualities of AFB smear microscopy reading and smearing were low in most of the laboratories of the health centers. Therefore, it is essential to strength EQA program through building the capacity of laboratory professionals.