The yield of Auramine O staining using led microscopy with bleach treated sputum samples for detection of pulmonary tuberculosis at St. Peter tuberculosis specialized hospital, Addis Ababa, Ethiopia

Nebiyu Gizaw; Adugna Abera; Solomon Sisay; Kassu Desta; Saskia Kreibich; Lisa Gerwing-Adima; Solomon Gebre-Selassie

doi:10.1016/j.jctube.2019.100140

The yield of Auramine O staining using led microscopy with bleach treated sputum samples for detection of pulmonary tuberculosis at St. Peter tuberculosis specialized hospital, Addis Ababa, Ethiopia

J Clin Tuberc Other Mycobact Dis. 2019 Dec 12:18:100140. doi: 10.1016/j.jctube.2019.100140. eCollection 2020 Feb.

Authors

Nebiyu Gizaw¹, Adugna Abera², Solomon Sisay³, Kassu Desta⁴, Saskia Kreibich⁵, Lisa Gerwing-Adima⁶, Solomon Gebre-Selassie¹

Affiliations

¹ Department of Medical Microbiology, Immunology and Parasitology, College of Health Science, Addis Ababa University, Ethiopia.
² Ethiopian Public Health Institute, P.O. BoX 1242, Addis Ababa, Ethiopia.
³ Division of Medical, GLRA-Ethiopia, P.O. Box 5036, Addis Ababa, Ethiopia.
⁴ Department of Medical Laboratory Sciences, College of Health Science, Addis Ababa University, Ethiopia.
⁵ Medical and Social Projects Department, DAHW, Wurzburg, Germany.
⁶ Division of Medical, GLRA -Uganda, Kampala, Uganda.

Abstract

Background: Smear microscopy is the mainstay for diagnosis of Tuberculosis (TB) in Ethiopia. This technique; however, is insensitive to detect Mycobacteria from most clinical specimens. Currently, light emitting diode (LED) fluorescence microscope is advocated to be used in high Tuberculosis (TB) burden settings by World Health Organization (WHO). However, the utility of this method is not evaluated for bleach treated sputum samples in Ethiopia.

Objective: The objective of the study is to evaluate the diagnostic importance of Auramine O (AO) staining in direct and concentrated sputum against conventional Zehil-Neelsen (ZN) and culture from the sputum samples of suspected pulmonary tuberculosis patients.

Methods: A cross-sectional study was conducted on 346 adult new pulmonary TB suspected patients at St. Peter's Specialized Hospital, Addis Ababa, Ethiopia. Three sputum samples (spot-morning-spot) were collected in sterile cups for direct Zehil-Neelsen and AO staining. Morning sputum samples were used for Mycobacterial culture on Mycobacterial Growth Indicator Tube (MGIT) 960. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were evaluated against the gold standard culture method. Data were analyzed using STATA version 13.0. All statistical tests were considered as statistically significant if the two sided P-value was < 0.05.

Results: Bleach treated sputum samples with AO staining yielded more cases as compared to direct ZN and direct AO by 6.3% and 11.5%, respectively. The sensitivity of concentrated AO and direct AO were remarkably high as compared to conventional ZN (71.8% vs. 44.5% and 62.7% vs. 44.5%). The concentrated sputum with staining of AO had a high rate (18.6%) of detecting scanty graded smears as compared to conventional ZN method.

Conclusions: Our findings indicated that the concentrated sputum with AO staining yielded high rate of sensitivity (71.8%) as compared to the conventional ZN method (44.5%). Moreover, the concentrated sputum with AO staining had superior ability in detecting scanty graded smears compared to the conventional ZN method. Therefore, it is recommended to utilize AO staining with LED microscopy for better diagnosis of Acid Fast Bacilli (AFB) from TB suspected cases and patients with pauci-bacillary TB in Ethiopia.

Keywords: Auramine O; Bleach concentration; Light emitting diode; St. Peter Hospital, TB.