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Objectives: Globally, Multidrug-Resistant Tuberculosis (MDR-TB) remains a public health concern. Rapid identification of MDR-TB using conventional or novel technologies is crucial for effective treatment. Here we assessed the quantity and quality of DNA extracted from MDR-TB isolates, allowing whole-genome sequencing (WGS). Methods: This was a retrospective study carried out on MDR-TB isolates from five studies conducted in Zimbabwe between 2011 and 2019. The isolates were stored under ambient 37 oC and -80 oC temperatures, respectively. These isolates were resuscitated and confirmed to be Mycobacterium tuberculosis (MTB). DNA was extracted using the N-Cetyl-N-trimethylammonium-bromide standard protocol. The concentration (A260nm) and purity (A260/280) of the extracted DNA before WGS (concentration =20ng/ul) were compared among the different storage conditions on Stata v15. Results: A total of 85 samples were successfully recovered from 106 retrieved. The overall recovery rate was 80.2%. We found a significant difference (p=0.005) in the concentration of the DNA samples by storage temperatures, with samples stored at -80 oC having the lowest concentration. Similarly, a significant difference (p=0.018) was found in the purity of the DNA (samples within the optimal range of 1.8 ± 0.2) by storage conditions, with 34/39 (87.2%) stored under ambient temperature, 18/20 (90.0%) stored in a 37 oC incubator and 1/4 (25.0%) stored at -80 oC. Conclusions: The better concentration and purity obtained from samples stored at 37 oC and ambient temperatures provide an impetus that such storage conditions could be used in many resource-limited settings where power supplies are a limitation to long storage conditions. [ABSTRACT FROM AUTHOR]

Background: In Zimbabwe, sputum smear microscopy (SSM) is the routinely used TB diagnostic tool in hospitalised HIV-infected patients. However, SSM has poor sensitivity in HIV-infected patients. We compared performance of urine lipoarabinomannan strip test (LAM) and SSM among hospitalized HIV-infected patients with suspected TB.Methods: Hospitalized HIV-infected patients with suspected TB were randomized to LAM plus SSM or SSM alone groups as part of a larger multi-country parent study. Here we present a comparison of LAM versus SSM performance from the Zimbabwe study site. LAM analyses (grade 2 cut-off) were conducted using (i) a microbiological reference standard (MRS; culture positivity for M.tb and designated definite TB) and (ii) a composite reference standard (CRS; definite TB plus probable TB i.e. patients with clinical TB excluded from the culture negative group). CRS constituted the primary analysis.Results: 82/457 (18%) of the patients randomized to the LAM group were M.tuberculosis culture positive. Using CRS, sensitivity (%, 95% CI) of LAM was significantly higher than SSM [49.2 (42.1-56.4) versus 29.4(23.2-36.3); p < 0.001]. Specificity and PPV were 98.1%, and 95.8%, respectively. By contrast, using MRS, LAM sensitivity was similar to SSM and specificity was significantly lower, however, the combined sensitivity of LAM and SSM was significantly higher than that of SSM alone, p = 0.009. Using CRS, LAM sensitivity (%, CI) was CD4 count dependent [60.6(50.7-69.8) at ≤50 cells/μL; 40.0(22.7-59.4) at 51-100 cells/μL, and 32.8(21.0-46.3) at >100 cells/μL. The combined sensitivity of LAM and SSM was higher than SSM alone being highest at CD4 counts <50 cells/μL [67.6(57.9-76.3); p = <0.001]. Specificity of LAM or SSM alone, or of combined LAM and SSM was >97% in all the 3 CD4 strata.Conclusion: Among hospitalized HIV-infected patients with suspected TB, the sensitivity of LAM is significantly higher than that of SSM, especially at low CD4 counts. LAM and SSM are complimentary tests for diagnosis of TB in HIV-infected patients. We recommend a combination of LAM and SSM for TB diagnosis in HIV-infected patients with low CD4 counts in HIV/TB co-endemic countries, where alternative methods are unavailable. [ABSTRACT FROM AUTHOR]