Introduction The dual challenge of low diagnostic sensitivity of microscopy test and technical ch... more Introduction The dual challenge of low diagnostic sensitivity of microscopy test and technical challenge of performing a TB culture test poses a problem for case detection and initiation of Tuberculosis (TB) second-line treatment. There is thus need for a rapid, reliable and easily accessible assay. This comparative analysis was performed to assess diagnostic performance characteristics of GeneXpert MTB/RIF and Line Probe Assay (LPA) Methods 329 sputum samples of patients across the 47 counties in Kenya suspected to have drug resistant TB were picked and subjected to GeneXpert, LPA and Culture MGIT at the National TB Reference Laboratory. Sensitivity, specificity and predictive values were then determined to assess the performance characteristics of various assays. Results GeneXpert had a sensitivity, specificity, positive predictive value, and negative predictive value of 78.5%, 64.9%, 59.4% and 82.2% respectively while LPA had 98.4%, 66.0%, 65.4% and 98.4%. For diagnosis of rifamp...
The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease, 2007
Although treatment of sputum using bleach has shown increased sensitivity in smear microscopy, th... more Although treatment of sputum using bleach has shown increased sensitivity in smear microscopy, the safety aspect of sodium hypochlorite (NaOCl) has not been addressed. To determine the biocidal effect of NaOCl on Mycobacterium tuberculosis when used as a safety measure in direct sputum smear microscopy for the diagnosis of tuberculosis (TB). A total of 156 smear- and culture-positive pooled sputum specimens were assessed for the viability of M. tuberculosis after treatment with NaOCl. Each specimen was divided into 11 equal portions. One portion was directly cultured. Each of five portions was treated with 3.5% NaOCl and the other five with 5% NaOCl. Specimens were then cultured at intervals of 15 min and 1, 3, 15 and 24 h. A total of 18 (11.5%) specimens showed growth after treatment with NaOCl. Of these, 5 (3.2%) showed growth upon treatment with 3.5% NaOCl at 15 min and 15 and 24 h. Ten (6.4%) showed growth after treatment with 5% NaOCl between 15 min and 3 h, but none showed gro...
National Tuberculosis Reference Laboratory in Dakar, Senegal. Comparison of results with fluoresc... more National Tuberculosis Reference Laboratory in Dakar, Senegal. Comparison of results with fluorescence and bright-field microscopy for acid-fast bacilli. Two smears from 2,630 consecutive sputum specimens between January 1996 and June 1998 were prepared for blinded examination of one smear each by the Ziehl-Neelsen technique and fluorescence microscopy at 1,000x magnification. The time required to declare a slide as negative was determined for both techniques in a sample of 68 slides. Concordancewas 96.9% and 92.3% for diagnostic and follow-up examinations, respectively. The yield was similar with both techniques for specimens with at least 10 bacilli per 100 fields, but higher with fluorescence microscopy in those with fewer than 10 bacilli per 100 fields. The mean time required by fluorescence microscopy before declaring a slide as negative with the same magnification was 3 minutes 34 seconds, compared to 7 minutes 44 seconds with the Ziehl-Neelsen technique. The results obtained with one technique are highly reproducible by the other. Fluorescence microscopy appears to be more likely to detect bacilli in paucibacillary cases than bright-field microscopy, and it more than halves the required examination time.
Introduction The dual challenge of low diagnostic sensitivity of microscopy test and technical ch... more Introduction The dual challenge of low diagnostic sensitivity of microscopy test and technical challenge of performing a TB culture test poses a problem for case detection and initiation of Tuberculosis (TB) second-line treatment. There is thus need for a rapid, reliable and easily accessible assay. This comparative analysis was performed to assess diagnostic performance characteristics of GeneXpert MTB/RIF and Line Probe Assay (LPA) Methods 329 sputum samples of patients across the 47 counties in Kenya suspected to have drug resistant TB were picked and subjected to GeneXpert, LPA and Culture MGIT at the National TB Reference Laboratory. Sensitivity, specificity and predictive values were then determined to assess the performance characteristics of various assays. Results GeneXpert had a sensitivity, specificity, positive predictive value, and negative predictive value of 78.5%, 64.9%, 59.4% and 82.2% respectively while LPA had 98.4%, 66.0%, 65.4% and 98.4%. For diagnosis of rifamp...
The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease, 2007
Although treatment of sputum using bleach has shown increased sensitivity in smear microscopy, th... more Although treatment of sputum using bleach has shown increased sensitivity in smear microscopy, the safety aspect of sodium hypochlorite (NaOCl) has not been addressed. To determine the biocidal effect of NaOCl on Mycobacterium tuberculosis when used as a safety measure in direct sputum smear microscopy for the diagnosis of tuberculosis (TB). A total of 156 smear- and culture-positive pooled sputum specimens were assessed for the viability of M. tuberculosis after treatment with NaOCl. Each specimen was divided into 11 equal portions. One portion was directly cultured. Each of five portions was treated with 3.5% NaOCl and the other five with 5% NaOCl. Specimens were then cultured at intervals of 15 min and 1, 3, 15 and 24 h. A total of 18 (11.5%) specimens showed growth after treatment with NaOCl. Of these, 5 (3.2%) showed growth upon treatment with 3.5% NaOCl at 15 min and 15 and 24 h. Ten (6.4%) showed growth after treatment with 5% NaOCl between 15 min and 3 h, but none showed gro...
National Tuberculosis Reference Laboratory in Dakar, Senegal. Comparison of results with fluoresc... more National Tuberculosis Reference Laboratory in Dakar, Senegal. Comparison of results with fluorescence and bright-field microscopy for acid-fast bacilli. Two smears from 2,630 consecutive sputum specimens between January 1996 and June 1998 were prepared for blinded examination of one smear each by the Ziehl-Neelsen technique and fluorescence microscopy at 1,000x magnification. The time required to declare a slide as negative was determined for both techniques in a sample of 68 slides. Concordancewas 96.9% and 92.3% for diagnostic and follow-up examinations, respectively. The yield was similar with both techniques for specimens with at least 10 bacilli per 100 fields, but higher with fluorescence microscopy in those with fewer than 10 bacilli per 100 fields. The mean time required by fluorescence microscopy before declaring a slide as negative with the same magnification was 3 minutes 34 seconds, compared to 7 minutes 44 seconds with the Ziehl-Neelsen technique. The results obtained with one technique are highly reproducible by the other. Fluorescence microscopy appears to be more likely to detect bacilli in paucibacillary cases than bright-field microscopy, and it more than halves the required examination time.
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