Association between Xpert MTB/RIF cycle threshold values and sputum smear microscopy in patients with pulmonary tuberculosis

Pagano, Gabriela Carpin; Pereira, Gabriel Ribas; D'Ávila, Karen Gomes; Monaiar, Luciana Rott; Silva, Denise Rossato

doi:10.36416/1806-3756/e20200549

Cited by 2 publications

(2 citation statements)

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“…6 Another study reported a statistically significant difference in the mean Ct value between sputum smear-positive and sputum smear-negative patients (17.8±4.8 and 22.3±6.7, respectively; p=0.002). 15 This could possibly be due to variable sample size in the various studies described above. Moreover, the co-morbid conditions and various other factors associated with the study population also varied in different studies.…”

Section: Discussionmentioning

confidence: 99%

A study on the mycobacterial burden and phenotypic drug resistance pattern with reference to the GeneXpert Cycle Threshold values in pulmonary tuberculosis

Kashyap,

Sarkar,

Singh

et al. 2023

Eur J Clin Exp Med

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Introduction and aim. Tuberculosis (TB) remains a significant global health challenge. Early and accurate diagnosis is crucial to prevent further transmission. The present study aimed to correlate cycle threshold values with smear microscopy and culture positivity, and determine cut-off cycle threshold values for levels of smear grade and culture positivity. Material and methods. Forty presumptive cases of pulmonary TB were included and subjected to Ziehl- Neelsen stain, culture on Lowenstein Jensen media, CBNAAT and drug susceptibility testing for first line anti-tubercular drugs. Results. Our study predicts 3+, 2+, and 1+ sputum smear grade at a cut-off of Ct value ≤ 16.74, ≤19.68, and ≤ 22.32 respectively. A strong positive correlation was found between time to culture positivity and Ct value. A cut-off of Ct value ≤22.32 predicts culture positivity with a sensitivity of 92%, and a specificity of 67%. None of the isolates showed rifampicin resistance by 1% proportion method. Conclusion. Understanding the appropriate utilization of CBNAAT Ct values and their correlation with smear microscopy grade, culture, and drug susceptibility testing can assist clinicians in early identification and prompt initiation of appropriate treatment. This knowledge can contribute to the prevention of drug resistance, reduced transmission, and a decreased disease burden associated with TB.

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Section: Discussionmentioning

confidence: 99%

A study on the mycobacterial burden and phenotypic drug resistance pattern with reference to the GeneXpert Cycle Threshold values in pulmonary tuberculosis

Kashyap,

Sarkar,

Singh

et al. 2023

Eur J Clin Exp Med

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show abstract

“…In this same issue, there are three articles on the diagnosis of tuberculosis: one regarding the quantification of adenosine deaminase to diagnose tuberculous pleural effusion in children 8 ; and two related to the Xpert MTB/RIF test. 9 , 10 Pagano et al 9 described the association between Xpert MTB/RIF cycle threshold (C T ) values and sputum smear microscopy findings in patients with pulmonary tuberculosis; a C T cutoff value of 22.7 showed good predictive value for smear microscopy positivity, that being the first study in Brazil to assess the accuracy of C T values as a measure of bacillary burden. Brito et al 10 demonstrated that, in BAL fluid samples from patients under clinical suspicion of having pulmonary tuberculosis who have tested negative for AFB in sputum samples or those with scarce sputum production, the diagnostic performance of Xpert MTB/RIF is superior to that of smear microscopy.…”

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confidence: 99%