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Evaluation of combined LED-fluorescence microscopy and bleach sedimentation for diagnosis of tuberculosis at peripheral health service level.

Bonnet M, Gagnidze L, Guerin PJ, Bonte L, Ramsay A, Githui W, Varaine F - PLoS ONE (2011)

Bottom Line: Its sensitivity is reduced in high HIV-prevalence settings.Three sputum specimens were collected over 2 days from consecutive TB suspects.Inter-reading agreement (kappa = 0.7) and technicians' acceptability were good.

View Article: PubMed Central - PubMed

Affiliation: Epicentre, Paris, France. maryline.bonnet@geneva.msf.org

ABSTRACT

Background: Sputum microscopy is the only diagnostic for tuberculosis (TB) available at peripheral levels of health service in resource-poor countries. Its sensitivity is reduced in high HIV-prevalence settings. Sodium hypochlorite (NaOCl) specimen sedimentation prior microscopy and light-emitting diode (LED)-fluorescence microscopy (FM) can individually improve performance of microscopy. This study aimed to evaluate the performance of combined LED-FM and NaOCl sputum sedimentation for TB detection at peripheral level of health services.

Methods: A prospective study was conducted in an urban health clinic in Nairobi, Kenya. Three sputum specimens were collected over 2 days from consecutive TB suspects. Smears were prepared and stained with auramine O and Ziehl-Neelsen (ZN) methods. Bleach (3.5%) was added to the remaining specimen before overnight sedimentation at room temperature. Auramine O staining was performed on smears of sediment. A 4(th) specimen was collected for TB culture. Auramine smears were read under the same microscope as used for ZN smears, but equipped with the LED FluoLED™ fluorescence illuminator.

Results: 497 patients were included, and 1394 specimens collected. The yield of positive specimen was significantly increased after NaOCl sedimentation (24.9%) compared to direct LED-FM (20.6%) and direct ZN (20.3%). In detecting smear-positive patients, sensitivity was 78.5% for LED-FM after NaOCl sedimentation compared to 73.2% and 72.0% for direct LED-FM (P = 0.06) and direct ZN (P = 0.06), respectively. Specificity was 87.8% for LED-FM after NaOCl sedimentation compared to 96.7% and 95.9% for direct LED-FM (P<0.01) and direct ZN (P<0.01), respectively. Inter-reading agreement (kappa = 0.7) and technicians' acceptability were good.

Conclusion: NaOCl sedimentation did not improve the performance of LED-FM in the diagnosis of pulmonary TB at peripheral health service level.

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Related in: MedlinePlus

Performance of the LED-FM after NaOCl sedimentation using a case definition of one positive smear out of two collected specimens and different AFB cut-offs to define a positive smear.
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pone-0020175-g002: Performance of the LED-FM after NaOCl sedimentation using a case definition of one positive smear out of two collected specimens and different AFB cut-offs to define a positive smear.

Mentions: When using the latest WHO smear-positive case definition (one positive smear out of 2 specimens), sensitivity of LED-FM after NaOCl sedimentation was 77.4% (95% CI: 67.6–95.4) compared to 72.0% (95% CI: 61.8–80.6) with direct LED-FM (P = 0.06) and 69.9% (95% CI: 59.5–78.0) with ZN (P = 0.03). Specificity of LED-FM after NaOCl sedimentation was 89.9% (95% CI: 85.8–93.0) compared to 97.3% (95% CI: 94.7–98.3) for direct LED-FM (P<0.01) and 96.6% (95% CI: 93.9–98.4) for ZN (P<0.01). Figure 2 presents the results of the ROC analysis of LED-FM performances after NaOCl sedimentation using case definition of at least one positive smear out of 2 collected specimens and different AFB cut-off to define a positive smear.


Evaluation of combined LED-fluorescence microscopy and bleach sedimentation for diagnosis of tuberculosis at peripheral health service level.

Bonnet M, Gagnidze L, Guerin PJ, Bonte L, Ramsay A, Githui W, Varaine F - PLoS ONE (2011)

Performance of the LED-FM after NaOCl sedimentation using a case definition of one positive smear out of two collected specimens and different AFB cut-offs to define a positive smear.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105008&req=5

pone-0020175-g002: Performance of the LED-FM after NaOCl sedimentation using a case definition of one positive smear out of two collected specimens and different AFB cut-offs to define a positive smear.
Mentions: When using the latest WHO smear-positive case definition (one positive smear out of 2 specimens), sensitivity of LED-FM after NaOCl sedimentation was 77.4% (95% CI: 67.6–95.4) compared to 72.0% (95% CI: 61.8–80.6) with direct LED-FM (P = 0.06) and 69.9% (95% CI: 59.5–78.0) with ZN (P = 0.03). Specificity of LED-FM after NaOCl sedimentation was 89.9% (95% CI: 85.8–93.0) compared to 97.3% (95% CI: 94.7–98.3) for direct LED-FM (P<0.01) and 96.6% (95% CI: 93.9–98.4) for ZN (P<0.01). Figure 2 presents the results of the ROC analysis of LED-FM performances after NaOCl sedimentation using case definition of at least one positive smear out of 2 collected specimens and different AFB cut-off to define a positive smear.

Bottom Line: Its sensitivity is reduced in high HIV-prevalence settings.Three sputum specimens were collected over 2 days from consecutive TB suspects.Inter-reading agreement (kappa = 0.7) and technicians' acceptability were good.

View Article: PubMed Central - PubMed

Affiliation: Epicentre, Paris, France. maryline.bonnet@geneva.msf.org

ABSTRACT

Background: Sputum microscopy is the only diagnostic for tuberculosis (TB) available at peripheral levels of health service in resource-poor countries. Its sensitivity is reduced in high HIV-prevalence settings. Sodium hypochlorite (NaOCl) specimen sedimentation prior microscopy and light-emitting diode (LED)-fluorescence microscopy (FM) can individually improve performance of microscopy. This study aimed to evaluate the performance of combined LED-FM and NaOCl sputum sedimentation for TB detection at peripheral level of health services.

Methods: A prospective study was conducted in an urban health clinic in Nairobi, Kenya. Three sputum specimens were collected over 2 days from consecutive TB suspects. Smears were prepared and stained with auramine O and Ziehl-Neelsen (ZN) methods. Bleach (3.5%) was added to the remaining specimen before overnight sedimentation at room temperature. Auramine O staining was performed on smears of sediment. A 4(th) specimen was collected for TB culture. Auramine smears were read under the same microscope as used for ZN smears, but equipped with the LED FluoLED™ fluorescence illuminator.

Results: 497 patients were included, and 1394 specimens collected. The yield of positive specimen was significantly increased after NaOCl sedimentation (24.9%) compared to direct LED-FM (20.6%) and direct ZN (20.3%). In detecting smear-positive patients, sensitivity was 78.5% for LED-FM after NaOCl sedimentation compared to 73.2% and 72.0% for direct LED-FM (P = 0.06) and direct ZN (P = 0.06), respectively. Specificity was 87.8% for LED-FM after NaOCl sedimentation compared to 96.7% and 95.9% for direct LED-FM (P<0.01) and direct ZN (P<0.01), respectively. Inter-reading agreement (kappa = 0.7) and technicians' acceptability were good.

Conclusion: NaOCl sedimentation did not improve the performance of LED-FM in the diagnosis of pulmonary TB at peripheral health service level.

Show MeSH
Related in: MedlinePlus