Fluorescence microscopy for the diagnosis of smear-negative pulmonary tuberculosis in Ethiopia
Background: Despite its low sensitivity, microscopy remains the main method for the diagnosis of pulmonary tuberculosis in most laboratories in Ethiopia. Few studies have evaluated the performance of light-emitting diode fluorescent microscopy (LED-FM) in bleach-concentrated smear-negative sputum sp...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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AOSIS
2020-09-01
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| Series: | African Journal of Laboratory Medicine |
| Subjects: | |
| Online Access: | https://ajlmonline.org/index.php/ajlm/article/view/810 |
| _version_ | 1818139235770695680 |
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| author | Gemeda Abebe Dossegnaw Aragaw Mulualem Tadesse |
| author_facet | Gemeda Abebe Dossegnaw Aragaw Mulualem Tadesse |
| author_sort | Gemeda Abebe |
| collection | DOAJ |
| description | Background: Despite its low sensitivity, microscopy remains the main method for the diagnosis of pulmonary tuberculosis in most laboratories in Ethiopia. Few studies have evaluated the performance of light-emitting diode fluorescent microscopy (LED-FM) in bleach-concentrated smear-negative sputum specimens.
Objective: This study aimed to evaluate the diagnostic performance of LED-FM for smear-negative pulmonary tuberculosis in Ethiopia.
Methods: A total of 194 adult patients with a cough lasting for more than two weeks, and who had three direct smear-negative sputum tests for Mycobacterium tuberculosis by Ziehl-Neelsen light microscopy, were included. All direct Ziehl-Neelsen-stained smear-negative sputum samples were cultured and were also visualised by LED-FM. Smears for LED-FM were performed from bleach-concentrated sputum sediment. The diagnostic performance of the LED-FM was compared to the culture method (the reference standard).
Results: Of the 194 smear-negative sputum specimens analysed, 28 (14.4%) were culture-positive and 21 (10.8%) were LED-FM-positive for M. tuberculosis. However, only 11 of the 21 (52.4%) LED-FM-positive patients had a confirmed tuberculosis diagnosis by culture. Light-emitting diode fluorescence microscopy (FM) had a sensitivity of 39.3% (95% confidence interval: 21.2–57.4) and specificity of 93.9% (95% confidence interval: 90.4–97.6). Ten LED-FM-positive specimens were culture-negative, and all of these specimens had scanty grading (1–19 bacilli per 40 fields on LED-FM).
Conclusion: This study showed that implementation of LED-FM on bleach pre-treated and concentrated sputum can significantly improve the diagnosis of smear-negative pulmonary tuberculosis. However, all scanty grade, positive smears by LED-FM need to be confirmed by reference culture method. |
| first_indexed | 2024-12-11T10:24:52Z |
| format | Article |
| id | doaj.art-8f08d99d5d0b447f984e77959ce854db |
| institution | Directory Open Access Journal |
| issn | 2225-2002 2225-2010 |
| language | English |
| last_indexed | 2024-12-11T10:24:52Z |
| publishDate | 2020-09-01 |
| publisher | AOSIS |
| record_format | Article |
| series | African Journal of Laboratory Medicine |
| spelling | doaj.art-8f08d99d5d0b447f984e77959ce854db2022-12-22T01:11:13ZengAOSISAfrican Journal of Laboratory Medicine2225-20022225-20102020-09-0191e1e610.4102/ajlm.v9i1.810277Fluorescence microscopy for the diagnosis of smear-negative pulmonary tuberculosis in EthiopiaGemeda Abebe0Dossegnaw Aragaw1Mulualem Tadesse2School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia; and, Mycobacteriology Research Center, Jimma University, JimmaSchool of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, JimmaSchool of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia; and, Mycobacteriology Research Center, Jimma University, JimmaBackground: Despite its low sensitivity, microscopy remains the main method for the diagnosis of pulmonary tuberculosis in most laboratories in Ethiopia. Few studies have evaluated the performance of light-emitting diode fluorescent microscopy (LED-FM) in bleach-concentrated smear-negative sputum specimens. Objective: This study aimed to evaluate the diagnostic performance of LED-FM for smear-negative pulmonary tuberculosis in Ethiopia. Methods: A total of 194 adult patients with a cough lasting for more than two weeks, and who had three direct smear-negative sputum tests for Mycobacterium tuberculosis by Ziehl-Neelsen light microscopy, were included. All direct Ziehl-Neelsen-stained smear-negative sputum samples were cultured and were also visualised by LED-FM. Smears for LED-FM were performed from bleach-concentrated sputum sediment. The diagnostic performance of the LED-FM was compared to the culture method (the reference standard). Results: Of the 194 smear-negative sputum specimens analysed, 28 (14.4%) were culture-positive and 21 (10.8%) were LED-FM-positive for M. tuberculosis. However, only 11 of the 21 (52.4%) LED-FM-positive patients had a confirmed tuberculosis diagnosis by culture. Light-emitting diode fluorescence microscopy (FM) had a sensitivity of 39.3% (95% confidence interval: 21.2–57.4) and specificity of 93.9% (95% confidence interval: 90.4–97.6). Ten LED-FM-positive specimens were culture-negative, and all of these specimens had scanty grading (1–19 bacilli per 40 fields on LED-FM). Conclusion: This study showed that implementation of LED-FM on bleach pre-treated and concentrated sputum can significantly improve the diagnosis of smear-negative pulmonary tuberculosis. However, all scanty grade, positive smears by LED-FM need to be confirmed by reference culture method.https://ajlmonline.org/index.php/ajlm/article/view/810sputum smear-negativelight-emitting diode fluorescent microscopybleach pretreatmentethiopiahealth |
| spellingShingle | Gemeda Abebe Dossegnaw Aragaw Mulualem Tadesse Fluorescence microscopy for the diagnosis of smear-negative pulmonary tuberculosis in Ethiopia African Journal of Laboratory Medicine sputum smear-negative light-emitting diode fluorescent microscopy bleach pretreatment ethiopia health |
| title | Fluorescence microscopy for the diagnosis of smear-negative pulmonary tuberculosis in Ethiopia |
| title_full | Fluorescence microscopy for the diagnosis of smear-negative pulmonary tuberculosis in Ethiopia |
| title_fullStr | Fluorescence microscopy for the diagnosis of smear-negative pulmonary tuberculosis in Ethiopia |
| title_full_unstemmed | Fluorescence microscopy for the diagnosis of smear-negative pulmonary tuberculosis in Ethiopia |
| title_short | Fluorescence microscopy for the diagnosis of smear-negative pulmonary tuberculosis in Ethiopia |
| title_sort | fluorescence microscopy for the diagnosis of smear negative pulmonary tuberculosis in ethiopia |
| topic | sputum smear-negative light-emitting diode fluorescent microscopy bleach pretreatment ethiopia health |
| url | https://ajlmonline.org/index.php/ajlm/article/view/810 |
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