Discordant results of Xpert MTB/Rif assay and BACTEC MGIT 960 liquid culture to detect Mycobacterium tuberculosis in community screening in Vietnam

Nguyen, Huong Van; Haas, Petra de; Nguyen, Hoa B.; Nguyen, Nhung Viet; Cobelens, Frank; Mirtskhulava, Veriko; Finlay, Alyssa; Nguyen, Hung Van; Huyen, Pham T. T.; Tiemersma, Edine

doi:10.1186/s12879-022-07481-5

Cited by 5 publications

(1 citation statement)

References 28 publications

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“…6 The liquid-culture mycobacterium growth indicator tube (MGIT) contains a fast-acting, sensitive culture media with low contamination potential. 7 But in resource-constrained settings (RLS), its high cost is prohibitive. PANTA is used in the liquid culture method to decreased contamination.…”

Section: Introductionmentioning

confidence: 99%

Effective Use of Penicillin to Improve Culture Yield for Mycobacterium Tuberculosis

Anwar¹,

Fida²,

Mumtaz³

et al. 2023

PJMHS

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Background: The aim of this study to evaluate the Mycobacterium tuberculosis (MTC) sputum culture contamination and recovery between Lowenstein-Jensenmedium (LJ) contains Pencillin+LJ and free Pencillin LJ. Study design: This was a cross sectional study conducted at Khawaja Safdar Medical College, Sialkot /Allama Iqbal Memorial Hospital Sialkot for the duration of six months from September 2022 to February 2023. Methods: A total number of the participants was 140. The male and female gender were both included who suffered pulmonary tuberculosis (PTB). The sample n=140 were analyzed for culture and contamination. The sputum samples were taken in the early morning in the falcon tube and digested, decontaminated, and homogenized by Modified Petroff method. The specimen of sputum was processed on addition of Penicillin+ LJ media, and incubation was carried out at 37°C. After eight weeks, cultures were examined. The data were analyzed by SPSS 21 software. Results: The male 64.2% show greater number of cases as compared to female 36%. The suspected cases of PTB was compared with Pencillin+ LJ media and LJ media alone. 21.4% of the samples were positive mycobacterium (MTB), 79% were contaminated on LJ media while 93% were positive (MTB), and 7.1% of the samples were contaminated on LJ media without penicillin. This difference was statistically significant (p<0.005**). The grade 2+/3+ show 50% recovery by the treatment of pencillin+LJ on positive sample and 47% contaminated sample P<0.001** while graded scanty/+1 show recovery was 38%; p=0.001** with pencillin+LJ then 37% contaminated sample; p=0.002**. The difference in recovery between treatment with penicillin and without pencillin LJ was statistically significant; p<0.005. Conclusion: The contamination rate was reduced by 47% by penicillin+LJ media. Penicillin offered great alternatives for decreasing contamination in LJ alone. Penicillin should be further used as a medium supplement to enhance recovery for LJ media. Keywords: Culture media, Mycobacterium, Penicillin

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Section: Introductionmentioning

confidence: 99%

Effective Use of Penicillin to Improve Culture Yield for Mycobacterium Tuberculosis

Anwar¹,

Fida²,

Mumtaz³

et al. 2023

PJMHS

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Diagnostic accuracy of Xpert MTB/RIF Ultra for childhood tuberculosis in West Africa – a multicenter pragmatic study

Diallo,

Edem,

Fiogbe

et al. 2024

International Journal of Infectious Diseases

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Discordant results between Xpert MTB/RIF assay and Bactec MGIT 960 culture system regarding the detection of rifampin-resistant Mycobacterium tuberculosis isolates in Wenzhou, China

He,

Zheng,

et al. 2024

Microbiol Spectr

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This study aimed to assess the possible causes of discordant results between Xpert MTB/RIF (Xpert) and Bactec MGIT 960 Culture System (MGIT960) regarding rifampicin (RIF) susceptibility in Mycobacterium tuberculosis . Patients with previous RIF-resistant tuberculosis who were admitted to Wenzhou Central Hospital from January 2020 to December 2022 were enrolled. The isolates obtained from these patients were subjected to RIF susceptibility tests using Xpert and MGIT960, and the minimum inhibitory concentration (MIC) of RIF was determined by the MYCOTB MIC plate test. Additionally, molecular docking and molecular dynamics (MD) simulations were performed to evaluate the binding efficacy of rpoB and RIF based on rpoB mutations detected in the isolates with discordant RIF susceptibility results. A total of 28 isolates with discordant RIF susceptibility test results were detected, 15 of them were RIF susceptible with MICs ≤ 0.5 µg/mL. Twelve out of 15 isolates contained borderline RIF resistance-associated mutations [L430P ( n = 6), H445N ( n = 6)], 1 isolate had D435Y and Q429H double mutation, and the remaining 2 isolates had a silent (Q432Q) mutation. Compared with the affinity of RIF toward the wild type (WT) (−45.83 kcal/mol) by MD, its affinity toward L452P (−55.52 kcal/mol), D435Y (−47.39 kcal/mol), L430P (approximately −69.72 kcal/mol), H445N (−49.53 kcal/mol), and Q429H (−55.67 kcal/mol) increased. Borderline RIF resistance-associated mutations were the main cause for the discordant RIF susceptibility results between Xpert and MGIT960, and the mechanisms of the resistance need further investigated. IMPORTANCE This study is aimed at assessing discordant results between Xpert MTB/RIF (Xpert) assay and Bactec MGIT 960 Culture System (MGIT960) regarding the detection of rifampicin (RIF)-resistant Mycobacterium tuberculosis isolates in Wenzhou, China. The discordant results of RIF between these two assays were mainly caused by borderline RIF resistance-associated mutations, subsequently by silent mutations of rpoB. Borderline RIF resistance- associated mutations detected in our study were demonstrated to not be affected by the affinity of rpoB and RIF by molecular dynamics, and the mechanism of resistance was needed to be clarified. For the discordant results of RIF by Xpert and MGIT960 that occurred, rpoB DNA sequencing was recommended to investigate its association with resistance to RIF.

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Discordant results of Xpert MTB/Rif assay and BACTEC MGIT 960 liquid culture to detect Mycobacterium tuberculosis in community screening in Vietnam

Cited by 5 publications

References 28 publications

Effective Use of Penicillin to Improve Culture Yield for Mycobacterium Tuberculosis

Effective Use of Penicillin to Improve Culture Yield for Mycobacterium Tuberculosis

Diagnostic accuracy of Xpert MTB/RIF Ultra for childhood tuberculosis in West Africa – a multicenter pragmatic study

Discordant results between Xpert MTB/RIF assay and Bactec MGIT 960 culture system regarding the detection of rifampin-resistant Mycobacterium tuberculosis isolates in Wenzhou, China

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