Performance of two SARS-CoV-2 rapid antigen detection tests in resource limited settings, the case of Mali.

Introduction: While real-time reverse transcription PCR (RT-PCR) is the recommended laboratory method to diagnose severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) infection, its use in resource limited settings can be difficult to maintain due to high testing demand and shortage of reagents. The aim of this study was to evaluate the performances of Realy Tech™ and Standard Q™ in comparison to RT-PCR in a relatively low COVID-19 prevalence setting, Mali. Methods: We conducted a cross-sectional study between January and April 2021 in Bamako and Kati regions to evaluate both rapid tests during a large SARS-CoV-2 prevalence study in Mali. Results: Of the 390 samples tested, the sensitivity and specificity of Realy Tech™ and Standard Q™ were 57.1% (95%CI: 44.1-69.2), 95.8% (95%CI: 93.1-97.5); 61.9% (95%CI: 46.8-75.0), and 94.1% (95%CI: 89.5-96.8) respectively. Using RT-PCR, the global prevalence of SARS-CoV-2 was 14.4% (56/390). In both rapid antigen tests, the performance was better when used in suspected patients compared to positive patients under treatment. Moreover, higher viral loads equivalent to Ct < 25 were associated with better detection rates. Conclusion: While waiting for more complete data, these preliminary studies suggest that Realy Tech™ and Standard Q™ should not be used alone for COVID-19 diagnosis in Mali.

Performance of Xpert MTB/RIF in comparison with light-emitting diode-fluorescence microscopy and culture for detecting tuberculosis in pulmonary and extrapulmonary specimens in Bamako, Mali.

Background: The diagnosis of tuberculosis (TB) has mostly been relied on a long-used method called sputum smear microscopy. In 2010, Xpert MTB/RIF assay was approved by the World Health Organization for simultaneous TB diagnosis and detection of resistance. Our current study was undertaken to compare the diagnostic performance of Xpert MTB/RIF assay to auramine staining-based light-emitting diode-Fluorescence Microscopy (LED-FM) considering culture as the gold standard method for pulmonary and extrapulmonary TB. Method: Pulmonary and extrapulmonary specimens of suspected TB patients were examined in this study. From January 2016 to June 2019, sputum, urine, superficial swabs, gastric aspirates, and pleural infusion specimens were collected from new and previously treated TB individuals. Specimens were examined using Xpert MTB/RIF, LED-FM, and Mycobacterium culture techniques to evaluate their performance. Results: A total of 697 suspected TB samples were included in this analysis, and of these, 469 (67.29%) were positive for all three used methods. The overall sensitivities, specificities, and positive and negative predictive values were 99.6%, 62.0%, 88.4%, and 98.2% for Xpert MTB/RIF and 88.0%, 95.6%, 99.0%, and 60.7% for LED-FM, respectively, compared to culture method. Conclusion: The sensitivity of Xpert MTB/RIF assay was observed to be higher than the LED-FM method, thus suggesting this molecular technique as a promising tool for the diagnosis of pulmonary and extrapulmonary TB, which will help in the management of TB infections in developing countries such as Mali.

Performance of two SARS-CoV-2 rapid antigen detection tests in resource limited settings, the case of Mali

Introduction: While real-time reverse transcription PCR (RT-PCR) is the recommended laboratory method to diagnose severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) infection, its use in resource limited settings can be difficult to maintain due to high testing demand and shortage of reagents. The aim of this study was to evaluate the performances of Realy Tech™ and Standard Q™ in comparison to RT-PCR in a relatively low COVID-19 prevalence setting, Mali. Methods: We conducted a cross-sectional study between January and April 2021 in Bamako and Kati regions to evaluate both rapid tests during a large SARS-CoV-2 prevalence study in Mali. Results: Of the 390 samples tested, the sensitivity and specificity of Realy Tech™ and Standard Q™ were 57.1% (95%CI: 44.1-69.2), 95.8% (95%CI: 93.1-97.5); 61.9% (95%CI: 46.8-75.0), and 94.1% (95%CI: 89.5-96.8) respectively. Using RT-PCR, the global prevalence of SARS-CoV-2 was 14.4% (56/390). In both rapid antigen tests, the performance was better when used in suspected patients compared to positive patients under treatment. Moreover, higher viral loads equivalent to Ct < 25 were associated with better detection rates. Conclusion: While waiting for more complete data, these preliminary studies suggest that Realy Tech™ and Standard Q™ should not be used alone for COVID-19 diagnosis in Mali.