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A new interesting article has been published in Microb Drug Resist. 2019 Jul/Aug;25(6):799-804. doi: 10.1089/mdr.2018.0268. Epub 2019 Mar 5. and titled:

Robustness of the Line Probe Assay for the Rapid Diagnosis and Characterization of Mutations in Extensively Drug-Resistant Tuberculosis.

Authors of this article are:

Ninan MM, Rupali P, James P, Michael JS.

A summary of the article is shown below:

Introduction: Extensively drug-resistant tuberculosis (XDRTB) is a public health concern. We evaluated the diagnostic accuracy of Genotype® MTBDRsl for detection of resistance to fluoroquinolones (FQs) and second-line injectable drugs (SLIDs) and characterized mutations seen. Materials and Methods: MTBDRsl was carried out either directly on sputum samples or indirectly on culture isolates (n = 100) from known multidrug-resistant tuberculosis (MDRTB) patients from July 2015 to September 2017. Diagnostic accuracy for the detection of resistance to FQs and SLIDs was calculated in comparison with conventional culture-based drug susceptibility testing. Mutations at the gyrA and rrs loci, as well as discrepant phenotypic and genotypic results, were studied. A subset of isolates underwent pyrosequencing. Results: Out of 100 MDRTB samples/isolates tested, 59% were pre-XDRTB and 7% were XDRTB. The sensitivity and specificity for the detection of resistance to FQs were 96.6% [95% confidence interval (CI): 88.3-99.6] and 80% [95% CI: 64.4-90.9] and those for SLIDs were 70% [95% CI: 34.8-93.3] and 100% [95% CI: 95.9-100]. The most frequent mutations were the absence of wild type 3 with corresponding mutation 3c (20/66) at the gyrA locus, and absence of wild type 1 and corresponding mutation 1 (6/7) at the rrs locus. The absence of a wt2 band with a corresponding mutation at the gyrA locus was seen in four of eight patients with discrepant genotypic and phenotypic results for FQ resistance. All isolates tested by pyrosequencing (n = 5) were concordant with the line probe assay for FQ resistance with identical mutations (D94G) and four of five isolates were concordant with SLIDs with identical mutations (A1401G). Conclusion: The MTBDRsl is a useful test for accurate diagnosis of XDRTB and may help to tailor therapy.

Check out the article’s website on Pubmed for more information:

[link-preview url=https://www.ncbi.nlm.nih.gov/pubmed/30785833 forceshot=true]

This article is a good source of information and a good way to become familiar with topics such as: ;MTBDRsl;XDRTB;drug-resistant TB;line probe assay.

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